1 /*
2 * Copyright (c) 2010, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package javafx.scene.control.skin;
27
28 import com.sun.javafx.scene.ParentHelper;
29 import com.sun.javafx.scene.control.Logging;
30 import com.sun.javafx.scene.control.Properties;
31 import com.sun.javafx.scene.control.VirtualScrollBar;
32 import com.sun.javafx.scene.control.skin.Utils;
33 import com.sun.javafx.scene.traversal.Algorithm;
34 import com.sun.javafx.scene.traversal.Direction;
35 import com.sun.javafx.scene.traversal.ParentTraversalEngine;
36 import com.sun.javafx.scene.traversal.TraversalContext;
37 import javafx.animation.KeyFrame;
38 import javafx.animation.Timeline;
39 import javafx.beans.InvalidationListener;
40 import javafx.beans.Observable;
41 import javafx.beans.property.BooleanProperty;
42 import javafx.beans.property.BooleanPropertyBase;
43 import javafx.beans.property.DoubleProperty;
44 import javafx.beans.property.IntegerProperty;
45 import javafx.beans.property.ObjectProperty;
46 import javafx.beans.property.SimpleBooleanProperty;
47 import javafx.beans.property.SimpleDoubleProperty;
48 import javafx.beans.property.SimpleIntegerProperty;
49 import javafx.beans.property.SimpleObjectProperty;
50 import javafx.beans.value.ChangeListener;
51 import javafx.collections.ObservableList;
52 import javafx.event.EventDispatcher;
53 import javafx.event.EventHandler;
54 import javafx.geometry.Orientation;
55 import javafx.scene.AccessibleRole;
56 import javafx.scene.Group;
57 import javafx.scene.Node;
58 import javafx.scene.Parent;
59 import javafx.scene.Scene;
60 import javafx.scene.control.Cell;
61 import javafx.scene.control.IndexedCell;
62 import javafx.scene.control.ScrollBar;
63 import javafx.scene.input.MouseEvent;
64 import javafx.scene.input.ScrollEvent;
65 import javafx.scene.layout.Region;
66 import javafx.scene.layout.StackPane;
67 import javafx.scene.shape.Rectangle;
68 import javafx.util.Callback;
69 import javafx.util.Duration;
70 import sun.util.logging.PlatformLogger;
71
72 import java.util.AbstractList;
73 import java.util.ArrayList;
74 import java.util.BitSet;
75 import java.util.List;
76
77 /**
78 * Implementation of a virtualized container using a cell based mechanism. This
79 * is used by the skin implementations for UI controls such as
80 * {@link javafx.scene.control.ListView}, {@link javafx.scene.control.TreeView},
81 * {@link javafx.scene.control.TableView}, and {@link javafx.scene.control.TreeTableView}.
82 *
83 * @since 9
84 */
85 public class VirtualFlow<T extends IndexedCell> extends Region {
86
87 /***************************************************************************
88 * *
89 * Static fields *
90 * *
91 **************************************************************************/
92
93 /**
94 * Scroll events may request to scroll about a number of "lines". We first
95 * decide how big one "line" is - for fixed cell size it's clear,
96 * for variable cell size we settle on a single number so that the scrolling
97 * speed is consistent. Now if the line is so big that
98 * MIN_SCROLLING_LINES_PER_PAGE of them don't fit into one page, we make
99 * them smaller to prevent the scrolling step to be too big (perhaps
100 * even more than one page).
101 */
102 private static final int MIN_SCROLLING_LINES_PER_PAGE = 8;
103
104 /**
105 * Indicates that this is a newly created cell and we need call processCSS for it.
106 *
107 * See RT-23616 for more details.
108 */
109 private static final String NEW_CELL = "newcell";
110
111 private static final double GOLDEN_RATIO_MULTIPLIER = 0.618033987;
112
113
114
115 /***************************************************************************
116 * *
117 * Private fields *
118 * *
119 **************************************************************************/
120
121 private boolean touchDetected = false;
122 private boolean mouseDown = false;
123
124 /**
125 * The width of the VirtualFlow the last time it was laid out. We
126 * use this information for several fast paths during the layout pass.
127 */
128 double lastWidth = -1;
129
130 /**
131 * The height of the VirtualFlow the last time it was laid out. We
132 * use this information for several fast paths during the layout pass.
133 */
134 double lastHeight = -1;
135
136 /**
137 * The number of "virtual" cells in the flow the last time it was laid out.
138 * For example, there may have been 1000 virtual cells, but only 20 actual
139 * cells created and in use. In that case, lastCellCount would be 1000.
140 */
141 int lastCellCount = 0;
142
143 /**
144 * We remember the last value for vertical the last time we laid out the
145 * flow. If vertical has changed, we will want to change the max & value
146 * for the different scroll bars. Since we do all the scroll bar update
147 * work in the layoutChildren function, we need to know what the old value for
148 * vertical was.
149 */
150 boolean lastVertical;
151
152 /**
153 * The position last time we laid out. If none of the lastXXX vars have
154 * changed respective to their values in layoutChildren, then we can just punt
155 * out of the method (I hope...)
156 */
157 double lastPosition;
158
159 /**
160 * The breadth of the first visible cell last time we laid out.
161 */
162 double lastCellBreadth = -1;
163
164 /**
165 * The length of the first visible cell last time we laid out.
166 */
167 double lastCellLength = -1;
168
169 /**
170 * The list of cells representing those cells which actually make up the
171 * current view. The cells are ordered such that the first cell in this
172 * list is the first in the view, and the last cell is the last in the
173 * view. When pixel scrolling, the list is simply shifted and items drop
174 * off the beginning or the end, depending on the order of scrolling.
175 * <p>
176 * This is package private ONLY FOR TESTING
177 */
178 final ArrayLinkedList<T> cells = new ArrayLinkedList<T>();
179
180 /**
181 * A structure containing cells that can be reused later. These are cells
182 * that at one time were needed to populate the view, but now are no longer
183 * needed. We keep them here until they are needed again.
184 * <p>
185 * This is package private ONLY FOR TESTING
186 */
187 final ArrayLinkedList<T> pile = new ArrayLinkedList<T>();
188
189 /**
190 * A special cell used to accumulate bounds, such that we reduce object
191 * churn. This cell must be recreated whenever the cell factory function
192 * changes. This has package access ONLY for testing.
193 */
194 T accumCell;
195
196 /**
197 * This group is used for holding the 'accumCell'. 'accumCell' must
198 * be added to the skin for it to be styled. Otherwise, it doesn't
199 * report the correct width/height leading to issues when scrolling
200 * the flow
201 */
202 Group accumCellParent;
203
204 /**
205 * The group which holds the cells.
206 */
207 final Group sheet;
208
209 final ObservableList<Node> sheetChildren;
210
211 /**
212 * The scroll bar used for scrolling horizontally. This has package access
213 * ONLY for testing.
214 */
215 private VirtualScrollBar hbar = new VirtualScrollBar(this);
216
217 /**
218 * The scroll bar used to scrolling vertically. This has package access
219 * ONLY for testing.
220 */
221 private VirtualScrollBar vbar = new VirtualScrollBar(this);
222
223 /**
224 * Control in which the cell's sheet is placed and forms the viewport. The
225 * viewportBreadth and viewportLength are simply the dimensions of the
226 * clipView. This has package access ONLY for testing.
227 */
228 ClippedContainer clipView;
229
230 /**
231 * When both the horizontal and vertical scroll bars are visible,
232 * we have to 'fill in' the bottom right corner where the two scroll bars
233 * meet. This is handled by this corner region. This has package access
234 * ONLY for testing.
235 */
236 StackPane corner;
237
238 // used for panning the virtual flow
239 private double lastX;
240 private double lastY;
241 private boolean isPanning = false;
242
243 private boolean fixedCellSizeEnabled = false;
244
245 private boolean needsReconfigureCells = false; // when cell contents are the same
246 private boolean needsRecreateCells = false; // when cell factory changed
247 private boolean needsRebuildCells = false; // when cell contents have changed
248 private boolean needsCellsLayout = false;
249 private boolean sizeChanged = false;
250 private final BitSet dirtyCells = new BitSet();
251
252 Timeline sbTouchTimeline;
253 KeyFrame sbTouchKF1;
254 KeyFrame sbTouchKF2;
255
256 private boolean needBreadthBar;
257 private boolean needLengthBar;
258 private boolean tempVisibility = false;
259
260
261
262 /***************************************************************************
263 * *
264 * Constructors *
265 * *
266 **************************************************************************/
267
268 /**
269 * Creates a new VirtualFlow instance.
270 */
271 public VirtualFlow() {
272 getStyleClass().add("virtual-flow");
273 setId("virtual-flow");
274
275 // initContent
276 // --- sheet
277 sheet = new Group();
278 sheet.getStyleClass().add("sheet");
279 sheet.setAutoSizeChildren(false);
280
281 sheetChildren = sheet.getChildren();
282
283 // --- clipView
284 clipView = new ClippedContainer(this);
285 clipView.setNode(sheet);
286 getChildren().add(clipView);
287
288 // --- accumCellParent
289 accumCellParent = new Group();
290 accumCellParent.setVisible(false);
291 getChildren().add(accumCellParent);
292
293
294 /*
295 ** don't allow the ScrollBar to handle the ScrollEvent,
296 ** In a VirtualFlow a vertical scroll should scroll on the vertical only,
297 ** whereas in a horizontal ScrollBar it can scroll horizontally.
298 */
299 // block the event from being passed down to children
300 final EventDispatcher blockEventDispatcher = (event, tail) -> event;
301 // block ScrollEvent from being passed down to scrollbar's skin
302 final EventDispatcher oldHsbEventDispatcher = hbar.getEventDispatcher();
303 hbar.setEventDispatcher((event, tail) -> {
304 if (event.getEventType() == ScrollEvent.SCROLL &&
305 !((ScrollEvent)event).isDirect()) {
306 tail = tail.prepend(blockEventDispatcher);
307 tail = tail.prepend(oldHsbEventDispatcher);
308 return tail.dispatchEvent(event);
309 }
310 return oldHsbEventDispatcher.dispatchEvent(event, tail);
311 });
312 // block ScrollEvent from being passed down to scrollbar's skin
313 final EventDispatcher oldVsbEventDispatcher = vbar.getEventDispatcher();
314 vbar.setEventDispatcher((event, tail) -> {
315 if (event.getEventType() == ScrollEvent.SCROLL &&
316 !((ScrollEvent)event).isDirect()) {
317 tail = tail.prepend(blockEventDispatcher);
318 tail = tail.prepend(oldVsbEventDispatcher);
319 return tail.dispatchEvent(event);
320 }
321 return oldVsbEventDispatcher.dispatchEvent(event, tail);
322 });
323 /*
324 ** listen for ScrollEvents over the whole of the VirtualFlow
325 ** area, the above dispatcher having removed the ScrollBars
326 ** scroll event handling.
327 */
328 setOnScroll(new EventHandler<ScrollEvent>() {
329 @Override public void handle(ScrollEvent event) {
330 if (Properties.IS_TOUCH_SUPPORTED) {
331 if (touchDetected == false && mouseDown == false ) {
332 startSBReleasedAnimation();
333 }
334 }
335 /*
336 ** calculate the delta in the direction of the flow.
337 */
338 double virtualDelta = 0.0;
339 if (isVertical()) {
340 switch(event.getTextDeltaYUnits()) {
341 case PAGES:
342 virtualDelta = event.getTextDeltaY() * lastHeight;
343 break;
344 case LINES:
345 double lineSize;
346 if (fixedCellSizeEnabled) {
347 lineSize = getFixedCellSize();
348 } else {
349 // For the scrolling to be reasonably consistent
350 // we set the lineSize to the average size
351 // of all currently loaded lines.
352 T lastCell = cells.getLast();
353 lineSize =
354 (getCellPosition(lastCell)
355 + getCellLength(lastCell)
356 - getCellPosition(cells.getFirst()))
357 / cells.size();
358 }
359
360 if (lastHeight / lineSize < MIN_SCROLLING_LINES_PER_PAGE) {
361 lineSize = lastHeight / MIN_SCROLLING_LINES_PER_PAGE;
362 }
363
364 virtualDelta = event.getTextDeltaY() * lineSize;
365 break;
366 case NONE:
367 virtualDelta = event.getDeltaY();
368 }
369 } else { // horizontal
370 switch(event.getTextDeltaXUnits()) {
371 case CHARACTERS:
372 // can we get character size here?
373 // for now, fall through to pixel values
374 case NONE:
375 double dx = event.getDeltaX();
376 double dy = event.getDeltaY();
377
378 virtualDelta = (Math.abs(dx) > Math.abs(dy) ? dx : dy);
379 }
380 }
381
382 if (virtualDelta != 0.0) {
383 /*
384 ** only consume it if we use it
385 */
386 double result = scrollPixels(-virtualDelta);
387 if (result != 0.0) {
388 event.consume();
389 }
390 }
391
392 ScrollBar nonVirtualBar = isVertical() ? hbar : vbar;
393 if (needBreadthBar) {
394 double nonVirtualDelta = isVertical() ? event.getDeltaX() : event.getDeltaY();
395 if (nonVirtualDelta != 0.0) {
396 double newValue = nonVirtualBar.getValue() - nonVirtualDelta;
397 if (newValue < nonVirtualBar.getMin()) {
398 nonVirtualBar.setValue(nonVirtualBar.getMin());
399 } else if (newValue > nonVirtualBar.getMax()) {
400 nonVirtualBar.setValue(nonVirtualBar.getMax());
401 } else {
402 nonVirtualBar.setValue(newValue);
403 }
404 event.consume();
405 }
406 }
407 }
408 });
409
410
411 addEventFilter(MouseEvent.MOUSE_PRESSED, new EventHandler<MouseEvent>() {
412 @Override
413 public void handle(MouseEvent e) {
414 mouseDown = true;
415 if (Properties.IS_TOUCH_SUPPORTED) {
416 scrollBarOn();
417 }
418 if (isFocusTraversable()) {
419 // We check here to see if the current focus owner is within
420 // this VirtualFlow, and if so we back-off from requesting
421 // focus back to the VirtualFlow itself. This is particularly
422 // relevant given the bug identified in RT-32869. In this
423 // particular case TextInputControl was clearing selection
424 // when the focus on the TextField changed, meaning that the
425 // right-click context menu was not showing the correct
426 // options as there was no selection in the TextField.
427 boolean doFocusRequest = true;
428 Node focusOwner = getScene().getFocusOwner();
429 if (focusOwner != null) {
430 Parent parent = focusOwner.getParent();
431 while (parent != null) {
432 if (parent.equals(VirtualFlow.this)) {
433 doFocusRequest = false;
434 break;
435 }
436 parent = parent.getParent();
437 }
438 }
439
440 if (doFocusRequest) {
441 requestFocus();
442 }
443 }
444
445 lastX = e.getX();
446 lastY = e.getY();
447
448 // determine whether the user has push down on the virtual flow,
449 // or whether it is the scrollbar. This is done to prevent
450 // mouse events being 'doubled up' when dragging the scrollbar
451 // thumb - it has the side-effect of also starting the panning
452 // code, leading to flicker
453 isPanning = ! (vbar.getBoundsInParent().contains(e.getX(), e.getY())
454 || hbar.getBoundsInParent().contains(e.getX(), e.getY()));
455 }
456 });
457 addEventFilter(MouseEvent.MOUSE_RELEASED, e -> {
458 mouseDown = false;
459 if (Properties.IS_TOUCH_SUPPORTED) {
460 startSBReleasedAnimation();
461 }
462 });
463 addEventFilter(MouseEvent.MOUSE_DRAGGED, e -> {
464 if (Properties.IS_TOUCH_SUPPORTED) {
465 scrollBarOn();
466 }
467 if (! isPanning || ! isPannable()) return;
468
469 // With panning enabled, we support panning in both vertical
470 // and horizontal directions, regardless of the fact that
471 // VirtualFlow is virtual in only one direction.
472 double xDelta = lastX - e.getX();
473 double yDelta = lastY - e.getY();
474
475 // figure out the distance that the mouse moved in the virtual
476 // direction, and then perform the movement along that axis
477 // virtualDelta will contain the amount we actually did move
478 double virtualDelta = isVertical() ? yDelta : xDelta;
479 double actual = scrollPixels(virtualDelta);
480 if (actual != 0) {
481 // update last* here, as we know we've just adjusted the
482 // scrollbar. This means we don't get the situation where a
483 // user presses-and-drags a long way past the min or max
484 // values, only to change directions and see the scrollbar
485 // start moving immediately.
486 if (isVertical()) lastY = e.getY();
487 else lastX = e.getX();
488 }
489
490 // similarly, we do the same in the non-virtual direction
491 double nonVirtualDelta = isVertical() ? xDelta : yDelta;
492 ScrollBar nonVirtualBar = isVertical() ? hbar : vbar;
493 if (nonVirtualBar.isVisible()) {
494 double newValue = nonVirtualBar.getValue() + nonVirtualDelta;
495 if (newValue < nonVirtualBar.getMin()) {
496 nonVirtualBar.setValue(nonVirtualBar.getMin());
497 } else if (newValue > nonVirtualBar.getMax()) {
498 nonVirtualBar.setValue(nonVirtualBar.getMax());
499 } else {
500 nonVirtualBar.setValue(newValue);
501
502 // same as the last* comment above
503 if (isVertical()) lastX = e.getX();
504 else lastY = e.getY();
505 }
506 }
507 });
508
509 /*
510 * We place the scrollbars _above_ the rectangle, such that the drag
511 * operations often used in conjunction with scrollbars aren't
512 * misinterpreted as drag operations on the rectangle as well (which
513 * would be the case if the scrollbars were underneath it as the
514 * rectangle itself doesn't block the mouse.
515 */
516 // --- vbar
517 vbar.setOrientation(Orientation.VERTICAL);
518 vbar.addEventHandler(MouseEvent.ANY, event -> {
519 event.consume();
520 });
521 getChildren().add(vbar);
522
523 // --- hbar
524 hbar.setOrientation(Orientation.HORIZONTAL);
525 hbar.addEventHandler(MouseEvent.ANY, event -> {
526 event.consume();
527 });
528 getChildren().add(hbar);
529
530 // --- corner
531 corner = new StackPane();
532 corner.getStyleClass().setAll("corner");
533 getChildren().add(corner);
534
535
536
537 // initBinds
538 // clipView binds
539 InvalidationListener listenerX = valueModel -> {
540 updateHbar();
541 };
542 verticalProperty().addListener(listenerX);
543 hbar.valueProperty().addListener(listenerX);
544 hbar.visibleProperty().addListener(listenerX);
545
546 // ChangeListener listenerY = new ChangeListener() {
547 // @Override public void handle(Bean bean, PropertyReference property) {
548 // clipView.setClipY(isVertical() ? 0 : vbar.getValue());
549 // }
550 // };
551 // addChangedListener(VERTICAL, listenerY);
552 // vbar.addChangedListener(ScrollBar.VALUE, listenerY);
553
554 ChangeListener<Number> listenerY = (ov, t, t1) -> {
555 clipView.setClipY(isVertical() ? 0 : vbar.getValue());
556 };
557 vbar.valueProperty().addListener(listenerY);
558
559 super.heightProperty().addListener((observable, oldHeight, newHeight) -> {
560 // Fix for RT-8480, where the VirtualFlow does not show its content
561 // after changing size to 0 and back.
562 if (oldHeight.doubleValue() == 0 && newHeight.doubleValue() > 0) {
563 recreateCells();
564 }
565 });
566
567
568 /*
569 ** there are certain animations that need to know if the touch is
570 ** happening.....
571 */
572 setOnTouchPressed(e -> {
573 touchDetected = true;
574 scrollBarOn();
575 });
576
577 setOnTouchReleased(e -> {
578 touchDetected = false;
579 startSBReleasedAnimation();
580 });
581
582 ParentHelper.setTraversalEngine(this, new ParentTraversalEngine(this, new Algorithm() {
583
584 Node selectNextAfterIndex(int index, TraversalContext context) {
585 T nextCell;
586 while ((nextCell = getVisibleCell(++index)) != null) {
587 if (nextCell.isFocusTraversable()) {
588 return nextCell;
589 }
590 Node n = context.selectFirstInParent(nextCell);
591 if (n != null) {
592 return n;
593 }
594 }
595 return null;
596 }
597
598 Node selectPreviousBeforeIndex(int index, TraversalContext context) {
599 T prevCell;
600 while ((prevCell = getVisibleCell(--index)) != null) {
601 Node prev = context.selectLastInParent(prevCell);
602 if (prev != null) {
603 return prev;
604 }
605 if (prevCell.isFocusTraversable()) {
606 return prevCell;
607 }
608 }
609 return null;
610 }
611
612 @Override
613 public Node select(Node owner, Direction dir, TraversalContext context) {
614 T cell;
615 if (cells.isEmpty()) return null;
616 if (cells.contains(owner)) {
617 cell = (T) owner;
618 } else {
619 cell = findOwnerCell(owner);
620 Node next = context.selectInSubtree(cell, owner, dir);
621 if (next != null) {
622 return next;
623 }
624 if (dir == Direction.NEXT) dir = Direction.NEXT_IN_LINE;
625 }
626 int cellIndex = cell.getIndex();
627 switch(dir) {
628 case PREVIOUS:
629 return selectPreviousBeforeIndex(cellIndex, context);
630 case NEXT:
631 Node n = context.selectFirstInParent(cell);
632 if (n != null) {
633 return n;
634 }
635 // Intentional fall-through
636 case NEXT_IN_LINE:
637 return selectNextAfterIndex(cellIndex, context);
638 }
639 return null;
640 }
641
642 private T findOwnerCell(Node owner) {
643 Parent p = owner.getParent();
644 while (!cells.contains(p)) {
645 p = p.getParent();
646 }
647 return (T)p;
648 }
649
650 @Override
651 public Node selectFirst(TraversalContext context) {
652 T firstCell = cells.getFirst();
653 if (firstCell == null) return null;
654 if (firstCell.isFocusTraversable()) return firstCell;
655 Node n = context.selectFirstInParent(firstCell);
656 if (n != null) {
657 return n;
658 }
659 return selectNextAfterIndex(firstCell.getIndex(), context);
660 }
661
662 @Override
663 public Node selectLast(TraversalContext context) {
664 T lastCell = cells.getLast();
665 if (lastCell == null) return null;
666 Node p = context.selectLastInParent(lastCell);
667 if (p != null) {
668 return p;
669 }
670 if (lastCell.isFocusTraversable()) return lastCell;
671 return selectPreviousBeforeIndex(lastCell.getIndex(), context);
672 }
673 }));
674 }
675
676
677
678 /***************************************************************************
679 * *
680 * Properties *
681 * *
682 **************************************************************************/
683
684 /**
685 * There are two main complicating factors in the implementation of the
686 * VirtualFlow, which are made even more complicated due to the performance
687 * sensitive nature of this code. The first factor is the actual
688 * virtualization mechanism, wired together with the PositionMapper.
689 * The second complicating factor is the desire to do minimal layout
690 * and minimal updates to CSS.
691 *
692 * Since the layout mechanism runs at most once per pulse, we want to hook
693 * into this mechanism for minimal recomputation. Whenever a layout pass
694 * is run we record the width/height that the virtual flow was last laid
695 * out to. In subsequent passes, if the width/height has not changed then
696 * we know we only have to rebuild the cells. If the width or height has
697 * changed, then we can make appropriate decisions based on whether the
698 * width / height has been reduced or expanded.
699 *
700 * In various places, if requestLayout is called it is generally just
701 * used to indicate that some form of layout needs to happen (either the
702 * entire thing has to be reconstructed, or just the cells need to be
703 * reconstructed, generally).
704 *
705 * The accumCell is a special cell which is used in some computations
706 * when an actual cell for that item isn't currently available. However,
707 * the accumCell must be cleared whenever the cellFactory function is
708 * changed because we need to use the cells that come from the new factory.
709 *
710 * In addition to storing the lastWidth and lastHeight, we also store the
711 * number of cells that existed last time we performed a layout. In this
712 * way if the number of cells change, we can request a layout and when it
713 * occurs we can tell that the number of cells has changed and react
714 * accordingly.
715 *
716 * Because the VirtualFlow can be laid out horizontally or vertically a
717 * naming problem is present when trying to conceptualize and implement
718 * the flow. In particular, the words "width" and "height" are not
719 * precise when describing the unit of measure along the "virtualized"
720 * axis and the "orthogonal" axis. For example, the height of a cell when
721 * the flow is vertical is the magnitude along the "virtualized axis",
722 * and the width is along the axis orthogonal to it.
723 *
724 * Since "height" and "width" are not reliable terms, we use the words
725 * "length" and "breadth" to describe the magnitude of a cell along
726 * the virtualized axis and orthogonal axis. For example, in a vertical
727 * flow, the height=length and the width=breadth. In a horizontal axis,
728 * the height=breadth and the width=length.
729 *
730 * These terms are somewhat arbitrary, but chosen so that when reading
731 * most of the below code you can think in just one dimension, with
732 * helper functions converting width/height in to length/breadth, while
733 * also being different from width/height so as not to get confused with
734 * the actual width/height of a cell.
735 */
736
737 // --- vertical
738 /**
739 * Indicates the primary direction of virtualization. If true, then the
740 * primary direction of virtualization is vertical, meaning that cells will
741 * stack vertically on top of each other. If false, then they will stack
742 * horizontally next to each other.
743 */
744 private BooleanProperty vertical;
745 public final void setVertical(boolean value) {
746 verticalProperty().set(value);
747 }
748
749 public final boolean isVertical() {
750 return vertical == null ? true : vertical.get();
751 }
752
753 public final BooleanProperty verticalProperty() {
754 if (vertical == null) {
755 vertical = new BooleanPropertyBase(true) {
756 @Override protected void invalidated() {
757 pile.clear();
758 sheetChildren.clear();
759 cells.clear();
760 lastWidth = lastHeight = -1;
761 setMaxPrefBreadth(-1);
762 setViewportBreadth(0);
763 setViewportLength(0);
764 lastPosition = 0;
765 hbar.setValue(0);
766 vbar.setValue(0);
767 setPosition(0.0f);
768 setNeedsLayout(true);
769 requestLayout();
770 }
771
772 @Override
773 public Object getBean() {
774 return VirtualFlow.this;
775 }
776
777 @Override
778 public String getName() {
779 return "vertical";
780 }
781 };
782 }
783 return vertical;
784 }
785
786 // --- pannable
787 /**
788 * Indicates whether the VirtualFlow viewport is capable of being panned
789 * by the user (either via the mouse or touch events).
790 */
791 private BooleanProperty pannable = new SimpleBooleanProperty(this, "pannable", true);
792 public final boolean isPannable() { return pannable.get(); }
793 public final void setPannable(boolean value) { pannable.set(value); }
794 public final BooleanProperty pannableProperty() { return pannable; }
795
796 // --- cell count
797 /**
798 * Indicates the number of cells that should be in the flow. The user of
799 * the VirtualFlow must set this appropriately. When the cell count changes
800 * the VirtualFlow responds by updating the visuals. If the items backing
801 * the cells change, but the count has not changed, you must call the
802 * reconfigureCells() function to update the visuals.
803 */
804 private IntegerProperty cellCount = new SimpleIntegerProperty(this, "cellCount", 0) {
805 private int oldCount = 0;
806
807 @Override protected void invalidated() {
808 int cellCount = get();
809
810 boolean countChanged = oldCount != cellCount;
811 oldCount = cellCount;
812
813 // ensure that the virtual scrollbar adjusts in size based on the current
814 // cell count.
815 if (countChanged) {
816 VirtualScrollBar lengthBar = isVertical() ? vbar : hbar;
817 lengthBar.setMax(cellCount);
818 }
819
820 // I decided *not* to reset maxPrefBreadth here for the following
821 // situation. Suppose I have 30 cells and then I add 10 more. Just
822 // because I added 10 more doesn't mean the max pref should be
823 // reset. Suppose the first 3 cells were extra long, and I was
824 // scrolled down such that they weren't visible. If I were to reset
825 // maxPrefBreadth when subsequent cells were added or removed, then the
826 // scroll bars would erroneously reset as well. So I do not reset
827 // the maxPrefBreadth here.
828
829 // Fix for RT-12512, RT-14301 and RT-14864.
830 // Without this, the VirtualFlow length-wise scrollbar would not change
831 // as expected. This would leave items unable to be shown, as they
832 // would exist outside of the visible area, even when the scrollbar
833 // was at its maximum position.
834 // FIXME this should be only executed on the pulse, so this will likely
835 // lead to performance degradation until it is handled properly.
836 if (countChanged) {
837 layoutChildren();
838
839 // Fix for RT-13965: Without this line of code, the number of items in
840 // the sheet would constantly grow, leaking memory for the life of the
841 // application. This was especially apparent when the total number of
842 // cells changes - regardless of whether it became bigger or smaller.
843 sheetChildren.clear();
844
845 Parent parent = getParent();
846 if (parent != null) parent.requestLayout();
847 }
848 // TODO suppose I had 100 cells and I added 100 more. Further
849 // suppose I was scrolled to the bottom when that happened. I
850 // actually want to update the position of the mapper such that
851 // the view remains "stable".
852 }
853 };
854 public final int getCellCount() { return cellCount.get(); }
855 public final void setCellCount(int value) { cellCount.set(value); }
856 public final IntegerProperty cellCountProperty() { return cellCount; }
857
858
859 // --- position
860 /**
861 * The position of the VirtualFlow within its list of cells. This is a value
862 * between 0 and 1.
863 */
864 private DoubleProperty position = new SimpleDoubleProperty(this, "position") {
865 @Override public void setValue(Number v) {
866 super.setValue(com.sun.javafx.util.Utils.clamp(0, get(), 1));
867 }
868
869 @Override protected void invalidated() {
870 super.invalidated();
871 requestLayout();
872 }
873 };
874 public final double getPosition() { return position.get(); }
875 public final void setPosition(double value) { position.set(value); }
876 public final DoubleProperty positionProperty() { return position; }
877
878 // --- fixed cell size
879 /**
880 * For optimisation purposes, some use cases can trade dynamic cell length
881 * for speed - if fixedCellSize is greater than zero we'll use that rather
882 * than determine it by querying the cell itself.
883 */
884 private DoubleProperty fixedCellSize = new SimpleDoubleProperty(this, "fixedCellSize") {
885 @Override protected void invalidated() {
886 fixedCellSizeEnabled = get() > 0;
887 needsCellsLayout = true;
888 layoutChildren();
889 }
890 };
891 public final void setFixedCellSize(final double value) { fixedCellSize.set(value); }
892 public final double getFixedCellSize() { return fixedCellSize.get(); }
893 public final DoubleProperty fixedCellSizeProperty() { return fixedCellSize; }
894
895
896 // --- Cell Factory
897 private ObjectProperty<Callback<VirtualFlow<T>, T>> cellFactory;
898
899 /**
900 * Sets a new cell factory to use in the VirtualFlow. This forces all old
901 * cells to be thrown away, and new cells to be created with
902 * the new cell factory.
903 * @param value the new cell factory
904 */
905 public final void setCellFactory(Callback<VirtualFlow<T>, T> value) {
906 cellFactoryProperty().set(value);
907 }
908
909 /**
910 * Returns the current cell factory.
911 * @return the current cell factory
912 */
913 public final Callback<VirtualFlow<T>, T> getCellFactory() {
914 return cellFactory == null ? null : cellFactory.get();
915 }
916
917 /**
918 * <p>Setting a custom cell factory has the effect of deferring all cell
919 * creation, allowing for total customization of the cell. Internally, the
920 * VirtualFlow is responsible for reusing cells - all that is necessary
921 * is for the custom cell factory to return from this function a cell
922 * which might be usable for representing any item in the VirtualFlow.
923 *
924 * <p>Refer to the {@link Cell} class documentation for more detail.
925 * @return the cell factory property
926 */
927 public final ObjectProperty<Callback<VirtualFlow<T>, T>> cellFactoryProperty() {
928 if (cellFactory == null) {
929 cellFactory = new SimpleObjectProperty<Callback<VirtualFlow<T>, T>>(this, "cellFactory") {
930 @Override protected void invalidated() {
931 if (get() != null) {
932 accumCell = null;
933 setNeedsLayout(true);
934 recreateCells();
935 if (getParent() != null) getParent().requestLayout();
936 }
937 }
938 };
939 }
940 return cellFactory;
941 }
942
943
944
945 /***************************************************************************
946 * *
947 * Public API *
948 * *
949 **************************************************************************/
950
951 /**
952 * Overridden to implement somewhat more efficient support for layout. The
953 * VirtualFlow can generally be considered as being unmanaged, in that
954 * whenever the position changes, or other such things change, we need
955 * to perform a layout but there is no reason to notify the parent. However
956 * when things change which may impact the preferred size (such as
957 * vertical, createCell, and configCell) then we need to notify the
958 * parent.
959 */
960 @Override public void requestLayout() {
961 // Note: This block is commented as it was relaying on a bad assumption on how
962 // layout request was handled in parent class that is now fixed.
963 //
964 // // isNeedsLayout() is commented out due to RT-21417. This does not
965 // // appear to impact performance (indeed, it may help), and resolves the
966 // // issue identified in RT-21417.
967 // setNeedsLayout(true);
968
969 // The fix is to prograte this layout request to its parent class.
970 // A better fix will be required if performance is negatively affected
971 // by this fix.
972 super.requestLayout();
973 }
974
975 /** {@inheritDoc} */
976 @Override protected void layoutChildren() {
977 if (needsRecreateCells) {
978 lastWidth = -1;
979 lastHeight = -1;
980 releaseCell(accumCell);
981 // accumCell = null;
982 // accumCellParent.getChildren().clear();
983 sheet.getChildren().clear();
984 for (int i = 0, max = cells.size(); i < max; i++) {
985 cells.get(i).updateIndex(-1);
986 }
987 cells.clear();
988 pile.clear();
989 releaseAllPrivateCells();
990 } else if (needsRebuildCells) {
991 lastWidth = -1;
992 lastHeight = -1;
993 releaseCell(accumCell);
994 for (int i = 0, max = cells.size(); i < max; i++) {
995 cells.get(i).updateIndex(-1);
996 }
997 addAllToPile();
998 releaseAllPrivateCells();
999 } else if (needsReconfigureCells) {
1000 setMaxPrefBreadth(-1);
1001 lastWidth = -1;
1002 lastHeight = -1;
1003 }
1004
1005 if (! dirtyCells.isEmpty()) {
1006 int index;
1007 final int cellsSize = cells.size();
1008 while ((index = dirtyCells.nextSetBit(0)) != -1 && index < cellsSize) {
1009 T cell = cells.get(index);
1010 // updateIndex(-1) works for TableView, but breaks ListView.
1011 // For now, the TableView just does not use the dirtyCells API
1012 // cell.updateIndex(-1);
1013 if (cell != null) {
1014 cell.requestLayout();
1015 }
1016 dirtyCells.clear(index);
1017 }
1018
1019 setMaxPrefBreadth(-1);
1020 lastWidth = -1;
1021 lastHeight = -1;
1022 }
1023
1024 final boolean hasSizeChange = sizeChanged;
1025 boolean recreatedOrRebuilt = needsRebuildCells || needsRecreateCells || sizeChanged;
1026
1027 needsRecreateCells = false;
1028 needsReconfigureCells = false;
1029 needsRebuildCells = false;
1030 sizeChanged = false;
1031
1032 if (needsCellsLayout) {
1033 for (int i = 0, max = cells.size(); i < max; i++) {
1034 Cell<?> cell = cells.get(i);
1035 if (cell != null) {
1036 cell.requestLayout();
1037 }
1038 }
1039 needsCellsLayout = false;
1040
1041 // yes, we return here - if needsCellsLayout was set to true, we
1042 // only did it to do the above - not rerun the entire layout.
1043 return;
1044 }
1045
1046 final double width = getWidth();
1047 final double height = getHeight();
1048 final boolean isVertical = isVertical();
1049 final double position = getPosition();
1050
1051 // if the width and/or height is 0, then there is no point doing
1052 // any of this work. In particular, this can happen during startup
1053 if (width <= 0 || height <= 0) {
1054 addAllToPile();
1055 lastWidth = width;
1056 lastHeight = height;
1057 hbar.setVisible(false);
1058 vbar.setVisible(false);
1059 corner.setVisible(false);
1060 return;
1061 }
1062
1063 // we check if any of the cells in the cells list need layout. This is a
1064 // sign that they are perhaps animating their sizes. Without this check,
1065 // we may not perform a layout here, meaning that the cell will likely
1066 // 'jump' (in height normally) when the user drags the virtual thumb as
1067 // that is the first time the layout would occur otherwise.
1068 boolean cellNeedsLayout = false;
1069 boolean thumbNeedsLayout = false;
1070
1071 if (Properties.IS_TOUCH_SUPPORTED) {
1072 if ((tempVisibility == true && (hbar.isVisible() == false || vbar.isVisible() == false)) ||
1073 (tempVisibility == false && (hbar.isVisible() == true || vbar.isVisible() == true))) {
1074 thumbNeedsLayout = true;
1075 }
1076 }
1077
1078 if (!cellNeedsLayout) {
1079 for (int i = 0; i < cells.size(); i++) {
1080 Cell<?> cell = cells.get(i);
1081 cellNeedsLayout = cell.isNeedsLayout();
1082 if (cellNeedsLayout) break;
1083 }
1084 }
1085
1086 final int cellCount = getCellCount();
1087 final T firstCell = getFirstVisibleCell();
1088
1089 // If no cells need layout, we check other criteria to see if this
1090 // layout call is even necessary. If it is found that no layout is
1091 // needed, we just punt.
1092 if (! cellNeedsLayout && !thumbNeedsLayout) {
1093 boolean cellSizeChanged = false;
1094 if (firstCell != null) {
1095 double breadth = getCellBreadth(firstCell);
1096 double length = getCellLength(firstCell);
1097 cellSizeChanged = (breadth != lastCellBreadth) || (length != lastCellLength);
1098 lastCellBreadth = breadth;
1099 lastCellLength = length;
1100 }
1101
1102 if (width == lastWidth &&
1103 height == lastHeight &&
1104 cellCount == lastCellCount &&
1105 isVertical == lastVertical &&
1106 position == lastPosition &&
1107 ! cellSizeChanged)
1108 {
1109 // TODO this happens to work around the problem tested by
1110 // testCellLayout_LayoutWithoutChangingThingsUsesCellsInSameOrderAsBefore
1111 // but isn't a proper solution. Really what we need to do is, when
1112 // laying out cells, we need to make sure that if a cell is pressed
1113 // AND we are doing a full rebuild then we need to make sure we
1114 // use that cell in the same physical location as before so that
1115 // it gets the mouse release event.
1116 return;
1117 }
1118 }
1119
1120 /*
1121 * This function may get called under a variety of circumstances.
1122 * It will determine what has changed from the last time it was laid
1123 * out, and will then take one of several execution paths based on
1124 * what has changed so as to perform minimal layout work and also to
1125 * give the expected behavior. One or more of the following may have
1126 * happened:
1127 *
1128 * 1) width/height has changed
1129 * - If the width and/or height has been reduced (but neither of
1130 * them has been expanded), then we simply have to reposition and
1131 * resize the scroll bars
1132 * - If the width (in the vertical case) has expanded, then we
1133 * need to resize the existing cells and reposition and resize
1134 * the scroll bars
1135 * - If the height (in the vertical case) has expanded, then we
1136 * need to resize and reposition the scroll bars and add
1137 * any trailing cells
1138 *
1139 * 2) cell count has changed
1140 * - If the number of cells is bigger, or it is smaller but not
1141 * so small as to move the position then we can just update the
1142 * cells in place without performing layout and update the
1143 * scroll bars.
1144 * - If the number of cells has been reduced and it affects the
1145 * position, then move the position and rebuild all the cells
1146 * and update the scroll bars
1147 *
1148 * 3) size of the cell has changed
1149 * - If the size changed in the virtual direction (ie: height
1150 * in the case of vertical) then layout the cells, adding
1151 * trailing cells as necessary and updating the scroll bars
1152 * - If the size changed in the non virtual direction (ie: width
1153 * in the case of vertical) then simply adjust the widths of
1154 * the cells as appropriate and adjust the scroll bars
1155 *
1156 * 4) vertical changed, cells is empty, maxPrefBreadth == -1, etc
1157 * - Full rebuild.
1158 *
1159 * Each of the conditions really resolves to several of a handful of
1160 * possible outcomes:
1161 * a) reposition & rebuild scroll bars
1162 * b) resize cells in non-virtual direction
1163 * c) add trailing cells
1164 * d) update cells
1165 * e) resize cells in the virtual direction
1166 * f) all of the above
1167 *
1168 * So this function first determines what outcomes need to occur, and
1169 * then will execute all the ones that really need to happen. Every code
1170 * path ends up touching the "reposition & rebuild scroll bars" outcome,
1171 * so that one will be executed every time.
1172 */
1173 boolean needTrailingCells = false;
1174 boolean rebuild = cellNeedsLayout ||
1175 isVertical != lastVertical ||
1176 cells.isEmpty() ||
1177 getMaxPrefBreadth() == -1 ||
1178 position != lastPosition ||
1179 cellCount != lastCellCount ||
1180 hasSizeChange ||
1181 (isVertical && height < lastHeight) || (! isVertical && width < lastWidth);
1182
1183 if (!rebuild) {
1184 // Check if maxPrefBreadth didn't change
1185 double maxPrefBreadth = getMaxPrefBreadth();
1186 boolean foundMax = false;
1187 for (int i = 0; i < cells.size(); ++i) {
1188 double breadth = getCellBreadth(cells.get(i));
1189 if (maxPrefBreadth == breadth) {
1190 foundMax = true;
1191 } else if (breadth > maxPrefBreadth) {
1192 rebuild = true;
1193 break;
1194 }
1195 }
1196 if (!foundMax) { // All values were lower
1197 rebuild = true;
1198 }
1199 }
1200
1201 if (! rebuild) {
1202 if ((isVertical && height > lastHeight) || (! isVertical && width > lastWidth)) {
1203 // resized in the virtual direction
1204 needTrailingCells = true;
1205 }
1206 }
1207
1208 initViewport();
1209
1210 // Get the index of the "current" cell
1211 int currentIndex = computeCurrentIndex();
1212 if (lastCellCount != cellCount) {
1213 // The cell count has changed. We want to keep the viewport
1214 // stable if possible. If position was 0 or 1, we want to keep
1215 // the position in the same place. If the new cell count is >=
1216 // the currentIndex, then we will adjust the position to be 1.
1217 // Otherwise, our goal is to leave the index of the cell at the
1218 // top consistent, with the same translation etc.
1219 if (position == 0 || position == 1) {
1220 // Update the item count
1221 // setItemCount(cellCount);
1222 } else if (currentIndex >= cellCount) {
1223 setPosition(1.0f);
1224 // setItemCount(cellCount);
1225 } else if (firstCell != null) {
1226 double firstCellOffset = getCellPosition(firstCell);
1227 int firstCellIndex = getCellIndex(firstCell);
1228 // setItemCount(cellCount);
1229 adjustPositionToIndex(firstCellIndex);
1230 double viewportTopToCellTop = -computeOffsetForCell(firstCellIndex);
1231 adjustByPixelAmount(viewportTopToCellTop - firstCellOffset);
1232 }
1233
1234 // Update the current index
1235 currentIndex = computeCurrentIndex();
1236 }
1237
1238 if (rebuild) {
1239 setMaxPrefBreadth(-1);
1240 // Start by dumping all the cells into the pile
1241 addAllToPile();
1242
1243 // The distance from the top of the viewport to the top of the
1244 // cell for the current index.
1245 double offset = -computeViewportOffset(getPosition());
1246
1247 // Add all the leading and trailing cells (the call to add leading
1248 // cells will add the current cell as well -- that is, the one that
1249 // represents the current position on the mapper).
1250 addLeadingCells(currentIndex, offset);
1251
1252 // Force filling of space with empty cells if necessary
1253 addTrailingCells(true);
1254 } else if (needTrailingCells) {
1255 addTrailingCells(true);
1256 }
1257
1258 computeBarVisiblity();
1259
1260 recreatedOrRebuilt = recreatedOrRebuilt || rebuild;
1261 updateScrollBarsAndCells(recreatedOrRebuilt);
1262
1263 lastWidth = getWidth();
1264 lastHeight = getHeight();
1265 lastCellCount = getCellCount();
1266 lastVertical = isVertical();
1267 lastPosition = getPosition();
1268
1269 cleanPile();
1270 }
1271
1272 /** {@inheritDoc} */
1273 @Override protected void setWidth(double value) {
1274 if (value != lastWidth) {
1275 super.setWidth(value);
1276 sizeChanged = true;
1277 setNeedsLayout(true);
1278 requestLayout();
1279 }
1280 }
1281
1282 /** {@inheritDoc} */
1283 @Override protected void setHeight(double value) {
1284 if (value != lastHeight) {
1285 super.setHeight(value);
1286 sizeChanged = true;
1287 setNeedsLayout(true);
1288 requestLayout();
1289 }
1290 }
1291
1292 /**
1293 * Get a cell which can be used in the layout. This function will reuse
1294 * cells from the pile where possible, and will create new cells when
1295 * necessary.
1296 * @param prefIndex the preferred index
1297 * @return the available cell
1298 */
1299 protected T getAvailableCell(int prefIndex) {
1300 T cell = null;
1301
1302 // Fix for RT-12822. We try to retrieve the cell from the pile rather
1303 // than just grab a random cell from the pile (or create another cell).
1304 for (int i = 0, max = pile.size(); i < max; i++) {
1305 T _cell = pile.get(i);
1306 assert _cell != null;
1307
1308 if (getCellIndex(_cell) == prefIndex) {
1309 cell = _cell;
1310 pile.remove(i);
1311 break;
1312 }
1313 }
1314
1315 if (cell == null && !pile.isEmpty()) {
1316 cell = pile.removeLast();
1317 }
1318
1319 if (cell == null) {
1320 cell = getCellFactory().call(this);
1321 cell.getProperties().put(NEW_CELL, null);
1322 }
1323
1324 if (cell.getParent() == null) {
1325 sheetChildren.add(cell);
1326 }
1327
1328 return cell;
1329 }
1330
1331 /**
1332 * This method will remove all cells from the VirtualFlow and remove them,
1333 * adding them to the 'pile' (that is, a place from where cells can be used
1334 * at a later date). This method is protected to allow subclasses to clean up
1335 * appropriately.
1336 */
1337 protected void addAllToPile() {
1338 for (int i = 0, max = cells.size(); i < max; i++) {
1339 addToPile(cells.removeFirst());
1340 }
1341 }
1342
1343 /**
1344 * Gets a cell for the given index if the cell has been created and laid out.
1345 * "Visible" is a bit of a misnomer, the cell might not be visible in the
1346 * viewport (it may be clipped), but does distinguish between cells that
1347 * have been created and are in use vs. those that are in the pile or
1348 * not created.
1349 * @param index the index
1350 * @return the visible cell
1351 */
1352 public T getVisibleCell(int index) {
1353 if (cells.isEmpty()) return null;
1354
1355 // check the last index
1356 T lastCell = cells.getLast();
1357 int lastIndex = getCellIndex(lastCell);
1358 if (index == lastIndex) return lastCell;
1359
1360 // check the first index
1361 T firstCell = cells.getFirst();
1362 int firstIndex = getCellIndex(firstCell);
1363 if (index == firstIndex) return firstCell;
1364
1365 // if index is > firstIndex and < lastIndex then we can get the index
1366 if (index > firstIndex && index < lastIndex) {
1367 T cell = cells.get(index - firstIndex);
1368 if (getCellIndex(cell) == index) return cell;
1369 }
1370
1371 // there is no visible cell for the specified index
1372 return null;
1373 }
1374
1375 /**
1376 * Locates and returns the last non-empty IndexedCell that is currently
1377 * partially or completely visible. This function may return null if there
1378 * are no cells, or if the viewport length is 0.
1379 * @return the last visible cell
1380 */
1381 public T getLastVisibleCell() {
1382 if (cells.isEmpty() || getViewportLength() <= 0) return null;
1383
1384 T cell;
1385 for (int i = cells.size() - 1; i >= 0; i--) {
1386 cell = cells.get(i);
1387 if (! cell.isEmpty()) {
1388 return cell;
1389 }
1390 }
1391
1392 return null;
1393 }
1394
1395 /**
1396 * Locates and returns the first non-empty IndexedCell that is partially or
1397 * completely visible. This really only ever returns null if there are no
1398 * cells or the viewport length is 0.
1399 * @return the first visible cell
1400 */
1401 public T getFirstVisibleCell() {
1402 if (cells.isEmpty() || getViewportLength() <= 0) return null;
1403 T cell = cells.getFirst();
1404 return cell.isEmpty() ? null : cell;
1405 }
1406
1407 /**
1408 * Adjust the position of cells so that the specified cell
1409 * will be positioned at the start of the viewport. The given cell must
1410 * already be "live".
1411 * @param firstCell the first cell
1412 */
1413 public void scrollToTop(T firstCell) {
1414 if (firstCell != null) {
1415 scrollPixels(getCellPosition(firstCell));
1416 }
1417 }
1418
1419 /**
1420 * Adjust the position of cells so that the specified cell
1421 * will be positioned at the end of the viewport. The given cell must
1422 * already be "live".
1423 * @param lastCell the last cell
1424 */
1425 public void scrollToBottom(T lastCell) {
1426 if (lastCell != null) {
1427 scrollPixels(getCellPosition(lastCell) + getCellLength(lastCell) - getViewportLength());
1428 }
1429 }
1430
1431 /**
1432 * Adjusts the cells such that the selected cell will be fully visible in
1433 * the viewport (but only just).
1434 * @param cell the cell
1435 */
1436 public void scrollTo(T cell) {
1437 if (cell != null) {
1438 final double start = getCellPosition(cell);
1439 final double length = getCellLength(cell);
1440 final double end = start + length;
1441 final double viewportLength = getViewportLength();
1442
1443 if (start < 0) {
1444 scrollPixels(start);
1445 } else if (end > viewportLength) {
1446 scrollPixels(end - viewportLength);
1447 }
1448 }
1449 }
1450
1451 /**
1452 * Adjusts the cells such that the cell in the given index will be fully visible in
1453 * the viewport.
1454 * @param index the index
1455 */
1456 public void scrollTo(int index) {
1457 T cell = getVisibleCell(index);
1458 if (cell != null) {
1459 scrollTo(cell);
1460 } else {
1461 adjustPositionToIndex(index);
1462 addAllToPile();
1463 requestLayout();
1464 }
1465 }
1466
1467 /**
1468 * Adjusts the cells such that the cell in the given index will be fully visible in
1469 * the viewport, and positioned at the very top of the viewport.
1470 * @param index the index
1471 */
1472 public void scrollToTop(int index) {
1473 boolean posSet = false;
1474
1475 if (index >= getCellCount() - 1) {
1476 setPosition(1);
1477 posSet = true;
1478 } else if (index < 0) {
1479 setPosition(0);
1480 posSet = true;
1481 }
1482
1483 if (! posSet) {
1484 adjustPositionToIndex(index);
1485 double offset = - computeOffsetForCell(index);
1486 adjustByPixelAmount(offset);
1487 }
1488
1489 requestLayout();
1490 }
1491
1492 // //TODO We assume all the cell have the same length. We will need to support
1493 // // cells of different lengths.
1494 // public void scrollToOffset(int offset) {
1495 // scrollPixels(offset * getCellLength(0));
1496 // }
1497
1498 /**
1499 * Given a delta value representing a number of pixels, this method attempts
1500 * to move the VirtualFlow in the given direction (positive is down/right,
1501 * negative is up/left) the given number of pixels. It returns the number of
1502 * pixels actually moved.
1503 * @param delta the delta value
1504 * @return the number of pixels actually moved
1505 */
1506 public double scrollPixels(final double delta) {
1507 // Short cut this method for cases where nothing should be done
1508 if (delta == 0) return 0;
1509
1510 final boolean isVertical = isVertical();
1511 if (((isVertical && (tempVisibility ? !needLengthBar : !vbar.isVisible())) ||
1512 (! isVertical && (tempVisibility ? !needLengthBar : !hbar.isVisible())))) return 0;
1513
1514 double pos = getPosition();
1515 if (pos == 0.0f && delta < 0) return 0;
1516 if (pos == 1.0f && delta > 0) return 0;
1517
1518 adjustByPixelAmount(delta);
1519 if (pos == getPosition()) {
1520 // The pos hasn't changed, there's nothing to do. This is likely
1521 // to occur when we hit either extremity
1522 return 0;
1523 }
1524
1525 // Now move stuff around. Translating by pixels fundamentally means
1526 // moving the cells by the delta. However, after having
1527 // done that, we need to go through the cells and see which cells,
1528 // after adding in the translation factor, now fall off the viewport.
1529 // Also, we need to add cells as appropriate to the end (or beginning,
1530 // depending on the direction of travel).
1531 //
1532 // One simplifying assumption (that had better be true!) is that we
1533 // will only make it this far in the function if the virtual scroll
1534 // bar is visible. Otherwise, we never will pixel scroll. So as we go,
1535 // if we find that the maxPrefBreadth exceeds the viewportBreadth,
1536 // then we will be sure to show the breadthBar and update it
1537 // accordingly.
1538 if (cells.size() > 0) {
1539 for (int i = 0; i < cells.size(); i++) {
1540 T cell = cells.get(i);
1541 assert cell != null;
1542 positionCell(cell, getCellPosition(cell) - delta);
1543 }
1544
1545 // Fix for RT-32908
1546 T firstCell = cells.getFirst();
1547 double layoutY = firstCell == null ? 0 : getCellPosition(firstCell);
1548 for (int i = 0; i < cells.size(); i++) {
1549 T cell = cells.get(i);
1550 assert cell != null;
1551 double actualLayoutY = getCellPosition(cell);
1552 if (Math.abs(actualLayoutY - layoutY) > 0.001) {
1553 // we need to shift the cell to layoutY
1554 positionCell(cell, layoutY);
1555 }
1556
1557 layoutY += getCellLength(cell);
1558 }
1559 // end of fix for RT-32908
1560 cull();
1561 firstCell = cells.getFirst();
1562
1563 // Add any necessary leading cells
1564 if (firstCell != null) {
1565 int firstIndex = getCellIndex(firstCell);
1566 double prevIndexSize = getCellLength(firstIndex - 1);
1567 addLeadingCells(firstIndex - 1, getCellPosition(firstCell) - prevIndexSize);
1568 } else {
1569 int currentIndex = computeCurrentIndex();
1570
1571 // The distance from the top of the viewport to the top of the
1572 // cell for the current index.
1573 double offset = -computeViewportOffset(getPosition());
1574
1575 // Add all the leading and trailing cells (the call to add leading
1576 // cells will add the current cell as well -- that is, the one that
1577 // represents the current position on the mapper).
1578 addLeadingCells(currentIndex, offset);
1579 }
1580
1581 // Starting at the tail of the list, loop adding cells until
1582 // all the space on the table is filled up. We want to make
1583 // sure that we DO NOT add empty trailing cells (since we are
1584 // in the full virtual case and so there are no trailing empty
1585 // cells).
1586 if (! addTrailingCells(false)) {
1587 // Reached the end, but not enough cells to fill up to
1588 // the end. So, remove the trailing empty space, and translate
1589 // the cells down
1590 final T lastCell = getLastVisibleCell();
1591 final double lastCellSize = getCellLength(lastCell);
1592 final double cellEnd = getCellPosition(lastCell) + lastCellSize;
1593 final double viewportLength = getViewportLength();
1594
1595 if (cellEnd < viewportLength) {
1596 // Reposition the nodes
1597 double emptySize = viewportLength - cellEnd;
1598 for (int i = 0; i < cells.size(); i++) {
1599 T cell = cells.get(i);
1600 positionCell(cell, getCellPosition(cell) + emptySize);
1601 }
1602 setPosition(1.0f);
1603 // fill the leading empty space
1604 firstCell = cells.getFirst();
1605 int firstIndex = getCellIndex(firstCell);
1606 double prevIndexSize = getCellLength(firstIndex - 1);
1607 addLeadingCells(firstIndex - 1, getCellPosition(firstCell) - prevIndexSize);
1608 }
1609 }
1610 }
1611
1612 // Now throw away any cells that don't fit
1613 cull();
1614
1615 // Finally, update the scroll bars
1616 updateScrollBarsAndCells(false);
1617 lastPosition = getPosition();
1618
1619 // notify
1620 return delta; // TODO fake
1621 }
1622
1623 /** {@inheritDoc} */
1624 @Override protected double computePrefWidth(double height) {
1625 double w = isVertical() ? getPrefBreadth(height) : getPrefLength();
1626 return w + vbar.prefWidth(-1);
1627 }
1628
1629 /** {@inheritDoc} */
1630 @Override protected double computePrefHeight(double width) {
1631 double h = isVertical() ? getPrefLength() : getPrefBreadth(width);
1632 return h + hbar.prefHeight(-1);
1633 }
1634
1635 /**
1636 * Return a cell for the given index. This may be called for any cell,
1637 * including beyond the range defined by cellCount, in which case an
1638 * empty cell will be returned. The returned value should not be stored for
1639 * any reason.
1640 * @param index the index
1641 * @return the cell
1642 */
1643 public T getCell(int index) {
1644 // If there are cells, then we will attempt to get an existing cell
1645 if (! cells.isEmpty()) {
1646 // First check the cells that have already been created and are
1647 // in use. If this call returns a value, then we can use it
1648 T cell = getVisibleCell(index);
1649 if (cell != null) return cell;
1650 }
1651
1652 // check the pile
1653 for (int i = 0; i < pile.size(); i++) {
1654 T cell = pile.get(i);
1655 if (getCellIndex(cell) == index) {
1656 // Note that we don't remove from the pile: if we do it leads
1657 // to a severe performance decrease. This seems to be OK, as
1658 // getCell() is only used for cell measurement purposes.
1659 // pile.remove(i);
1660 return cell;
1661 }
1662 }
1663
1664 if (pile.size() > 0) {
1665 return pile.get(0);
1666 }
1667
1668 // We need to use the accumCell and return that
1669 if (accumCell == null) {
1670 Callback<VirtualFlow<T>,T> cellFactory = getCellFactory();
1671 if (cellFactory != null) {
1672 accumCell = cellFactory.call(this);
1673 accumCell.getProperties().put(NEW_CELL, null);
1674 accumCellParent.getChildren().setAll(accumCell);
1675
1676 // Note the screen reader will attempt to find all
1677 // the items inside the view to calculate the item count.
1678 // Having items under different parents (sheet and accumCellParent)
1679 // leads the screen reader to compute wrong values.
1680 // The regular scheme to provide items to the screen reader
1681 // uses getPrivateCell(), which places the item in the sheet.
1682 // The accumCell, and its children, should be ignored by the
1683 // screen reader.
1684 accumCell.setAccessibleRole(AccessibleRole.NODE);
1685 accumCell.getChildrenUnmodifiable().addListener((Observable c) -> {
1686 for (Node n : accumCell.getChildrenUnmodifiable()) {
1687 n.setAccessibleRole(AccessibleRole.NODE);
1688 }
1689 });
1690 }
1691 }
1692 setCellIndex(accumCell, index);
1693 resizeCellSize(accumCell);
1694 return accumCell;
1695 }
1696
1697 /**
1698 * The VirtualFlow uses this method to set a cells index (rather than calling
1699 * {@link IndexedCell#updateIndex(int)} directly), so it is a perfect place
1700 * for subclasses to override if this if of interest.
1701 *
1702 * @param cell The cell whose index will be updated.
1703 * @param index The new index for the cell.
1704 */
1705 protected void setCellIndex(T cell, int index) {
1706 assert cell != null;
1707
1708 cell.updateIndex(index);
1709
1710 // make sure the cell is sized correctly. This is important for both
1711 // general layout of cells in a VirtualFlow, but also in cases such as
1712 // RT-34333, where the sizes were being reported incorrectly to the
1713 // ComboBox popup.
1714 if ((cell.isNeedsLayout() && cell.getScene() != null) || cell.getProperties().containsKey(NEW_CELL)) {
1715 cell.applyCss();
1716 cell.getProperties().remove(NEW_CELL);
1717 }
1718 }
1719
1720 /**
1721 * Return the index for a given cell. This allows subclasses to customise
1722 * how cell indices are retrieved.
1723 * @param cell the cell
1724 * @return the index
1725 */
1726 protected int getCellIndex(T cell){
1727 return cell.getIndex();
1728 }
1729
1730
1731
1732 /***************************************************************************
1733 * *
1734 * Private implementation *
1735 * *
1736 **************************************************************************/
1737
1738 final VirtualScrollBar getHbar() {
1739 return hbar;
1740 }
1741 final VirtualScrollBar getVbar() {
1742 return vbar;
1743 }
1744
1745 /**
1746 * The maximum preferred size in the non-virtual direction. For example,
1747 * if vertical, then this is the max pref width of all cells encountered.
1748 * <p>
1749 * In general, this is the largest preferred size in the non-virtual
1750 * direction that we have ever encountered. We don't reduce this size
1751 * unless instructed to do so, so as to reduce the amount of scroll bar
1752 * jitter. The access on this variable is package ONLY FOR TESTING.
1753 */
1754 private double maxPrefBreadth;
1755 private final void setMaxPrefBreadth(double value) {
1756 this.maxPrefBreadth = value;
1757 }
1758 final double getMaxPrefBreadth() {
1759 return maxPrefBreadth;
1760 }
1761
1762 /**
1763 * The breadth of the viewport portion of the VirtualFlow as computed during
1764 * the layout pass. In a vertical flow this would be the same as the clip
1765 * view width. In a horizontal flow this is the clip view height.
1766 * The access on this variable is package ONLY FOR TESTING.
1767 */
1768 private double viewportBreadth;
1769 private final void setViewportBreadth(double value) {
1770 this.viewportBreadth = value;
1771 }
1772 private final double getViewportBreadth() {
1773 return viewportBreadth;
1774 }
1775
1776 /**
1777 * The length of the viewport portion of the VirtualFlow as computed
1778 * during the layout pass. In a vertical flow this would be the same as the
1779 * clip view height. In a horizontal flow this is the clip view width.
1780 * The access on this variable is package ONLY FOR TESTING.
1781 */
1782 private double viewportLength;
1783 void setViewportLength(double value) {
1784 this.viewportLength = value;
1785 }
1786 double getViewportLength() {
1787 return viewportLength;
1788 }
1789
1790 /**
1791 * Compute and return the length of the cell for the given index. This is
1792 * called both internally when adjusting by pixels, and also at times
1793 * by PositionMapper (see the getItemSize callback). When called by
1794 * PositionMapper, it is possible that it will be called for some index
1795 * which is not associated with any cell, so we have to do a bit of work
1796 * to use a cell as a helper for computing cell size in some cases.
1797 */
1798 double getCellLength(int index) {
1799 if (fixedCellSizeEnabled) return getFixedCellSize();
1800
1801 T cell = getCell(index);
1802 double length = getCellLength(cell);
1803 releaseCell(cell);
1804 return length;
1805 }
1806
1807 /**
1808 */
1809 double getCellBreadth(int index) {
1810 T cell = getCell(index);
1811 double b = getCellBreadth(cell);
1812 releaseCell(cell);
1813 return b;
1814 }
1815
1816 /**
1817 * Gets the length of a specific cell
1818 */
1819 double getCellLength(T cell) {
1820 if (cell == null) return 0;
1821 if (fixedCellSizeEnabled) return getFixedCellSize();
1822
1823 return isVertical() ?
1824 cell.getLayoutBounds().getHeight()
1825 : cell.getLayoutBounds().getWidth();
1826 }
1827
1828 /**
1829 * Gets the breadth of a specific cell
1830 */
1831 double getCellBreadth(Cell cell) {
1832 return isVertical() ?
1833 cell.prefWidth(-1)
1834 : cell.prefHeight(-1);
1835 }
1836
1837 /**
1838 * Gets the layout position of the cell along the length axis
1839 */
1840 double getCellPosition(T cell) {
1841 if (cell == null) return 0;
1842
1843 return isVertical() ?
1844 cell.getLayoutY()
1845 : cell.getLayoutX();
1846 }
1847
1848 private void positionCell(T cell, double position) {
1849 if (isVertical()) {
1850 cell.setLayoutX(0);
1851 cell.setLayoutY(snapSizeY(position));
1852 } else {
1853 cell.setLayoutX(snapSizeX(position));
1854 cell.setLayoutY(0);
1855 }
1856 }
1857
1858 private void resizeCellSize(T cell) {
1859 if (cell == null) return;
1860
1861 if (isVertical()) {
1862 double width = Math.max(getMaxPrefBreadth(), getViewportBreadth());
1863 cell.resize(width, fixedCellSizeEnabled ? getFixedCellSize() : Utils.boundedSize(cell.prefHeight(width), cell.minHeight(width), cell.maxHeight(width)));
1864 } else {
1865 double height = Math.max(getMaxPrefBreadth(), getViewportBreadth());
1866 cell.resize(fixedCellSizeEnabled ? getFixedCellSize() : Utils.boundedSize(cell.prefWidth(height), cell.minWidth(height), cell.maxWidth(height)), height);
1867 }
1868 }
1869
1870 private List<T> getCells() {
1871 return cells;
1872 }
1873
1874 // Returns last visible cell whose bounds are entirely within the viewport
1875 T getLastVisibleCellWithinViewPort() {
1876 if (cells.isEmpty() || getViewportLength() <= 0) return null;
1877
1878 T cell;
1879 final double max = getViewportLength();
1880 for (int i = cells.size() - 1; i >= 0; i--) {
1881 cell = cells.get(i);
1882 if (cell.isEmpty()) continue;
1883
1884 final double cellStart = getCellPosition(cell);
1885 final double cellEnd = cellStart + getCellLength(cell);
1886
1887 // we use the magic +2 to allow for a little bit of fuzziness,
1888 // this is to help in situations such as RT-34407
1889 if (cellEnd <= (max + 2)) {
1890 return cell;
1891 }
1892 }
1893
1894 return null;
1895 }
1896
1897 // Returns first visible cell whose bounds are entirely within the viewport
1898 T getFirstVisibleCellWithinViewPort() {
1899 if (cells.isEmpty() || getViewportLength() <= 0) return null;
1900
1901 T cell;
1902 for (int i = 0; i < cells.size(); i++) {
1903 cell = cells.get(i);
1904 if (cell.isEmpty()) continue;
1905
1906 final double cellStart = getCellPosition(cell);
1907 if (cellStart >= 0) {
1908 return cell;
1909 }
1910 }
1911
1912 return null;
1913 }
1914
1915 /**
1916 * Adds all the cells prior to and including the given currentIndex, until
1917 * no more can be added without falling off the flow. The startOffset
1918 * indicates the distance from the leading edge (top) of the viewport to
1919 * the leading edge (top) of the currentIndex.
1920 */
1921 void addLeadingCells(int currentIndex, double startOffset) {
1922 // The offset will keep track of the distance from the top of the
1923 // viewport to the top of the current index. We will increment it
1924 // as we lay out leading cells.
1925 double offset = startOffset;
1926 // The index is the absolute index of the cell being laid out
1927 int index = currentIndex;
1928
1929 // Offset should really be the bottom of the current index
1930 boolean first = true; // first time in, we just fudge the offset and let
1931 // it be the top of the current index then redefine
1932 // it as the bottom of the current index thereafter
1933 // while we have not yet laid out so many cells that they would fall
1934 // off the flow, we will continue to create and add cells. The
1935 // offset is our indication of whether we can lay out additional
1936 // cells. If the offset is ever < 0, except in the case of the very
1937 // first cell, then we must quit.
1938 T cell = null;
1939
1940 // special case for the position == 1.0, skip adding last invisible cell
1941 if (index == getCellCount() && offset == getViewportLength()) {
1942 index--;
1943 first = false;
1944 }
1945 while (index >= 0 && (offset > 0 || first)) {
1946 cell = getAvailableCell(index);
1947 setCellIndex(cell, index);
1948 resizeCellSize(cell); // resize must be after config
1949 cells.addFirst(cell);
1950
1951 // A little gross but better than alternatives because it reduces
1952 // the number of times we have to update a cell or compute its
1953 // size. The first time into this loop "offset" is actually the
1954 // top of the current index. On all subsequent visits, it is the
1955 // bottom of the current index.
1956 if (first) {
1957 first = false;
1958 } else {
1959 offset -= getCellLength(cell);
1960 }
1961
1962 // Position the cell, and update the maxPrefBreadth variable as we go.
1963 positionCell(cell, offset);
1964 setMaxPrefBreadth(Math.max(getMaxPrefBreadth(), getCellBreadth(cell)));
1965 cell.setVisible(true);
1966 --index;
1967 }
1968
1969 // There are times when after laying out the cells we discover that
1970 // the top of the first cell which represents index 0 is below the top
1971 // of the viewport. In these cases, we have to adjust the cells up
1972 // and reset the mapper position. This might happen when items got
1973 // removed at the top or when the viewport size increased.
1974 if (cells.size() > 0) {
1975 cell = cells.getFirst();
1976 int firstIndex = getCellIndex(cell);
1977 double firstCellPos = getCellPosition(cell);
1978 if (firstIndex == 0 && firstCellPos > 0) {
1979 setPosition(0.0f);
1980 offset = 0;
1981 for (int i = 0; i < cells.size(); i++) {
1982 cell = cells.get(i);
1983 positionCell(cell, offset);
1984 offset += getCellLength(cell);
1985 }
1986 }
1987 } else {
1988 // reset scrollbar to top, so if the flow sees cells again it starts at the top
1989 vbar.setValue(0);
1990 hbar.setValue(0);
1991 }
1992 }
1993
1994 /**
1995 * Adds all the trailing cells that come <em>after</em> the last index in
1996 * the cells ObservableList.
1997 */
1998 boolean addTrailingCells(boolean fillEmptyCells) {
1999 // If cells is empty then addLeadingCells bailed for some reason and
2000 // we're hosed, so just punt
2001 if (cells.isEmpty()) return false;
2002
2003 // While we have not yet laid out so many cells that they would fall
2004 // off the flow, so we will continue to create and add cells. When the
2005 // offset becomes greater than the width/height of the flow, then we
2006 // know we cannot add any more cells.
2007 T startCell = cells.getLast();
2008 double offset = getCellPosition(startCell) + getCellLength(startCell);
2009 int index = getCellIndex(startCell) + 1;
2010 final int cellCount = getCellCount();
2011 boolean filledWithNonEmpty = index <= cellCount;
2012
2013 final double viewportLength = getViewportLength();
2014
2015 // Fix for RT-37421, which was a regression caused by RT-36556
2016 if (offset < 0 && !fillEmptyCells) {
2017 return false;
2018 }
2019
2020 //
2021 // RT-36507: viewportLength gives the maximum number of
2022 // additional cells that should ever be able to fit in the viewport if
2023 // every cell had a height of 1. If index ever exceeds this count,
2024 // then offset is not incrementing fast enough, or at all, which means
2025 // there is something wrong with the cell size calculation.
2026 //
2027 final double maxCellCount = viewportLength;
2028 while (offset < viewportLength) {
2029 if (index >= cellCount) {
2030 if (offset < viewportLength) filledWithNonEmpty = false;
2031 if (! fillEmptyCells) return filledWithNonEmpty;
2032 // RT-36507 - return if we've exceeded the maximum
2033 if (index > maxCellCount) {
2034 final PlatformLogger logger = Logging.getControlsLogger();
2035 if (logger.isLoggable(PlatformLogger.Level.INFO)) {
2036 logger.info("index exceeds maxCellCount. Check size calculations for " + startCell.getClass());
2037 }
2038 return filledWithNonEmpty;
2039 }
2040 }
2041 T cell = getAvailableCell(index);
2042 setCellIndex(cell, index);
2043 resizeCellSize(cell); // resize happens after config!
2044 cells.addLast(cell);
2045
2046 // Position the cell and update the max pref
2047 positionCell(cell, offset);
2048 setMaxPrefBreadth(Math.max(getMaxPrefBreadth(), getCellBreadth(cell)));
2049
2050 offset += getCellLength(cell);
2051 cell.setVisible(true);
2052 ++index;
2053 }
2054
2055 // Discover whether the first cell coincides with index #0. If after
2056 // adding all the trailing cells we find that a) the first cell was
2057 // not index #0 and b) there are trailing cells, then we have a
2058 // problem. We need to shift all the cells down and add leading cells,
2059 // one at a time, until either the very last non-empty cells is aligned
2060 // with the bottom OR we have laid out cell index #0 at the first
2061 // position.
2062 T firstCell = cells.getFirst();
2063 index = getCellIndex(firstCell);
2064 T lastNonEmptyCell = getLastVisibleCell();
2065 double start = getCellPosition(firstCell);
2066 double end = getCellPosition(lastNonEmptyCell) + getCellLength(lastNonEmptyCell);
2067 if ((index != 0 || (index == 0 && start < 0)) && fillEmptyCells &&
2068 lastNonEmptyCell != null && getCellIndex(lastNonEmptyCell) == cellCount - 1 && end < viewportLength) {
2069
2070 double prospectiveEnd = end;
2071 double distance = viewportLength - end;
2072 while (prospectiveEnd < viewportLength && index != 0 && (-start) < distance) {
2073 index--;
2074 T cell = getAvailableCell(index);
2075 setCellIndex(cell, index);
2076 resizeCellSize(cell); // resize must be after config
2077 cells.addFirst(cell);
2078 double cellLength = getCellLength(cell);
2079 start -= cellLength;
2080 prospectiveEnd += cellLength;
2081 positionCell(cell, start);
2082 setMaxPrefBreadth(Math.max(getMaxPrefBreadth(), getCellBreadth(cell)));
2083 cell.setVisible(true);
2084 }
2085
2086 // The amount by which to translate the cells down
2087 firstCell = cells.getFirst();
2088 start = getCellPosition(firstCell);
2089 double delta = viewportLength - end;
2090 if (getCellIndex(firstCell) == 0 && delta > (-start)) {
2091 delta = (-start);
2092 }
2093 // Move things
2094 for (int i = 0; i < cells.size(); i++) {
2095 T cell = cells.get(i);
2096 positionCell(cell, getCellPosition(cell) + delta);
2097 }
2098
2099 // Check whether the first cell, subsequent to our adjustments, is
2100 // now index #0 and aligned with the top. If so, change the position
2101 // to be at 0 instead of 1.
2102 start = getCellPosition(firstCell);
2103 if (getCellIndex(firstCell) == 0 && start == 0) {
2104 setPosition(0);
2105 } else if (getPosition() != 1) {
2106 setPosition(1);
2107 }
2108 }
2109
2110 return filledWithNonEmpty;
2111 }
2112
2113 void reconfigureCells() {
2114 needsReconfigureCells = true;
2115 requestLayout();
2116 }
2117
2118 void recreateCells() {
2119 needsRecreateCells = true;
2120 requestLayout();
2121 }
2122
2123 void rebuildCells() {
2124 needsRebuildCells = true;
2125 requestLayout();
2126 }
2127
2128 void requestCellLayout() {
2129 needsCellsLayout = true;
2130 requestLayout();
2131 }
2132
2133 void setCellDirty(int index) {
2134 dirtyCells.set(index);
2135 requestLayout();
2136 }
2137
2138 private void startSBReleasedAnimation() {
2139 if (sbTouchTimeline == null) {
2140 /*
2141 ** timeline to leave the scrollbars visible for a short
2142 ** while after a scroll/drag
2143 */
2144 sbTouchTimeline = new Timeline();
2145 sbTouchKF1 = new KeyFrame(Duration.millis(0), event -> {
2146 tempVisibility = true;
2147 requestLayout();
2148 });
2149
2150 sbTouchKF2 = new KeyFrame(Duration.millis(1000), event -> {
2151 if (touchDetected == false && mouseDown == false) {
2152 tempVisibility = false;
2153 requestLayout();
2154 }
2155 });
2156 sbTouchTimeline.getKeyFrames().addAll(sbTouchKF1, sbTouchKF2);
2157 }
2158 sbTouchTimeline.playFromStart();
2159 }
2160
2161 private void scrollBarOn() {
2162 tempVisibility = true;
2163 requestLayout();
2164 }
2165
2166 void updateHbar() {
2167 if (! isVisible() || getScene() == null) return;
2168 // Bring the clipView.clipX back to 0 if control is vertical or
2169 // the hbar isn't visible (fix for RT-11666)
2170 if (isVertical()) {
2171 if (hbar.isVisible()) {
2172 clipView.setClipX(hbar.getValue());
2173 } else {
2174 // all cells are now less than the width of the flow,
2175 // so we should shift the hbar/clip such that
2176 // everything is visible in the viewport.
2177 clipView.setClipX(0);
2178 hbar.setValue(0);
2179 }
2180 }
2181 }
2182
2183 /**
2184 * @return true if bar visibility changed
2185 */
2186 private boolean computeBarVisiblity() {
2187 if (cells.isEmpty()) {
2188 // In case no cells are set yet, we assume no bars are needed
2189 needLengthBar = false;
2190 needBreadthBar = false;
2191 return true;
2192 }
2193
2194 final boolean isVertical = isVertical();
2195 boolean barVisibilityChanged = false;
2196
2197 VirtualScrollBar breadthBar = isVertical ? hbar : vbar;
2198 VirtualScrollBar lengthBar = isVertical ? vbar : hbar;
2199
2200 final double viewportBreadth = getViewportBreadth();
2201
2202 final int cellsSize = cells.size();
2203 final int cellCount = getCellCount();
2204 for (int i = 0; i < 2; i++) {
2205 final boolean lengthBarVisible = getPosition() > 0
2206 || cellCount > cellsSize
2207 || (cellCount == cellsSize && (getCellPosition(cells.getLast()) + getCellLength(cells.getLast())) > getViewportLength())
2208 || (cellCount == cellsSize - 1 && barVisibilityChanged && needBreadthBar);
2209
2210 if (lengthBarVisible ^ needLengthBar) {
2211 needLengthBar = lengthBarVisible;
2212 barVisibilityChanged = true;
2213 }
2214
2215 // second conditional removed for RT-36669.
2216 final boolean breadthBarVisible = (maxPrefBreadth > viewportBreadth);// || (needLengthBar && maxPrefBreadth > (viewportBreadth - lengthBarBreadth));
2217 if (breadthBarVisible ^ needBreadthBar) {
2218 needBreadthBar = breadthBarVisible;
2219 barVisibilityChanged = true;
2220 }
2221 }
2222
2223 // Start by optimistically deciding whether the length bar and
2224 // breadth bar are needed and adjust the viewport dimensions
2225 // accordingly. If during layout we find that one or the other of the
2226 // bars actually is needed, then we will perform a cleanup pass
2227
2228 if (!Properties.IS_TOUCH_SUPPORTED) {
2229 updateViewportDimensions();
2230 breadthBar.setVisible(needBreadthBar);
2231 lengthBar.setVisible(needLengthBar);
2232 } else {
2233 breadthBar.setVisible(needBreadthBar && tempVisibility);
2234 lengthBar.setVisible(needLengthBar && tempVisibility);
2235 }
2236
2237 return barVisibilityChanged;
2238 }
2239
2240 private void updateViewportDimensions() {
2241 final boolean isVertical = isVertical();
2242 final double breadthBarLength = isVertical ? snapSizeY(hbar.prefHeight(-1)) : snapSizeX(vbar.prefWidth(-1));
2243 final double lengthBarBreadth = isVertical ? snapSizeX(vbar.prefWidth(-1)) : snapSizeY(hbar.prefHeight(-1));
2244
2245 setViewportBreadth((isVertical ? getWidth() : getHeight()) - (needLengthBar ? lengthBarBreadth : 0));
2246 setViewportLength((isVertical ? getHeight() : getWidth()) - (needBreadthBar ? breadthBarLength : 0));
2247 }
2248
2249 private void initViewport() {
2250 // Initialize the viewportLength and viewportBreadth to match the
2251 // width/height of the flow
2252 final boolean isVertical = isVertical();
2253
2254 updateViewportDimensions();
2255
2256 VirtualScrollBar breadthBar = isVertical ? hbar : vbar;
2257 VirtualScrollBar lengthBar = isVertical ? vbar : hbar;
2258
2259 // If there has been a switch between the virtualized bar, then we
2260 // will want to do some stuff TODO.
2261 breadthBar.setVirtual(false);
2262 lengthBar.setVirtual(true);
2263 }
2264
2265 private void updateScrollBarsAndCells(boolean recreate) {
2266 // Assign the hbar and vbar to the breadthBar and lengthBar so as
2267 // to make some subsequent calculations easier.
2268 final boolean isVertical = isVertical();
2269 VirtualScrollBar breadthBar = isVertical ? hbar : vbar;
2270 VirtualScrollBar lengthBar = isVertical ? vbar : hbar;
2271
2272 // We may have adjusted the viewport length and breadth after the
2273 // layout due to scroll bars becoming visible. So we need to perform
2274 // a follow up pass and resize and shift all the cells to fit the
2275 // viewport. Note that the prospective viewport size is always >= the
2276 // final viewport size, so we don't have to worry about adding
2277 // cells during this cleanup phase.
2278 fitCells();
2279
2280 // Update cell positions.
2281 // When rebuilding the cells, we add the cells and along the way compute
2282 // the maxPrefBreadth. Based on the computed value, we may add
2283 // the breadth scrollbar which changes viewport length, so we need
2284 // to re-position the cells.
2285 if (!cells.isEmpty()) {
2286 final double currOffset = -computeViewportOffset(getPosition());
2287 final int currIndex = computeCurrentIndex() - cells.getFirst().getIndex();
2288 final int size = cells.size();
2289
2290 // position leading cells
2291 double offset = currOffset;
2292
2293 for (int i = currIndex - 1; i >= 0 && i < size; i--) {
2294 final T cell = cells.get(i);
2295
2296 offset -= getCellLength(cell);
2297
2298 positionCell(cell, offset);
2299 }
2300
2301 // position trailing cells
2302 offset = currOffset;
2303 for (int i = currIndex; i >= 0 && i < size; i++) {
2304 final T cell = cells.get(i);
2305 positionCell(cell, offset);
2306
2307 offset += getCellLength(cell);
2308 }
2309 }
2310
2311 // Toggle visibility on the corner
2312 corner.setVisible(breadthBar.isVisible() && lengthBar.isVisible());
2313
2314 double sumCellLength = 0;
2315 double flowLength = (isVertical ? getHeight() : getWidth()) -
2316 (breadthBar.isVisible() ? breadthBar.prefHeight(-1) : 0);
2317
2318 final double viewportBreadth = getViewportBreadth();
2319 final double viewportLength = getViewportLength();
2320
2321 // Now position and update the scroll bars
2322 if (breadthBar.isVisible()) {
2323 /*
2324 ** Positioning the ScrollBar
2325 */
2326 if (!Properties.IS_TOUCH_SUPPORTED) {
2327 if (isVertical) {
2328 hbar.resizeRelocate(0, viewportLength,
2329 viewportBreadth, hbar.prefHeight(viewportBreadth));
2330 } else {
2331 vbar.resizeRelocate(viewportLength, 0,
2332 vbar.prefWidth(viewportBreadth), viewportBreadth);
2333 }
2334 }
2335 else {
2336 if (isVertical) {
2337 hbar.resizeRelocate(0, (viewportLength-hbar.getHeight()),
2338 viewportBreadth, hbar.prefHeight(viewportBreadth));
2339 } else {
2340 vbar.resizeRelocate((viewportLength-vbar.getWidth()), 0,
2341 vbar.prefWidth(viewportBreadth), viewportBreadth);
2342 }
2343 }
2344
2345 if (getMaxPrefBreadth() != -1) {
2346 double newMax = Math.max(1, getMaxPrefBreadth() - viewportBreadth);
2347 if (newMax != breadthBar.getMax()) {
2348 breadthBar.setMax(newMax);
2349
2350 double breadthBarValue = breadthBar.getValue();
2351 boolean maxed = breadthBarValue != 0 && newMax == breadthBarValue;
2352 if (maxed || breadthBarValue > newMax) {
2353 breadthBar.setValue(newMax);
2354 }
2355
2356 breadthBar.setVisibleAmount((viewportBreadth / getMaxPrefBreadth()) * newMax);
2357 }
2358 }
2359 }
2360
2361 // determine how many cells there are on screen so that the scrollbar
2362 // thumb can be appropriately sized
2363 if (recreate && (lengthBar.isVisible() || Properties.IS_TOUCH_SUPPORTED)) {
2364 final int cellCount = getCellCount();
2365 int numCellsVisibleOnScreen = 0;
2366 for (int i = 0, max = cells.size(); i < max; i++) {
2367 T cell = cells.get(i);
2368 if (cell != null && !cell.isEmpty()) {
2369 sumCellLength += (isVertical ? cell.getHeight() : cell.getWidth());
2370 if (sumCellLength > flowLength) {
2371 break;
2372 }
2373
2374 numCellsVisibleOnScreen++;
2375 }
2376 }
2377
2378 lengthBar.setMax(1);
2379 if (numCellsVisibleOnScreen == 0 && cellCount == 1) {
2380 // special case to help resolve RT-17701 and the case where we have
2381 // only a single row and it is bigger than the viewport
2382 lengthBar.setVisibleAmount(flowLength / sumCellLength);
2383 } else {
2384 lengthBar.setVisibleAmount(numCellsVisibleOnScreen / (float) cellCount);
2385 }
2386 }
2387
2388 if (lengthBar.isVisible()) {
2389 // Fix for RT-11873. If this isn't here, we can have a situation where
2390 // the scrollbar scrolls endlessly. This is possible when the cell
2391 // count grows as the user hits the maximal position on the scrollbar
2392 // (i.e. the list size dynamically grows as the user needs more).
2393 //
2394 // This code was commented out to resolve RT-14477 after testing
2395 // whether RT-11873 can be recreated. It could not, and therefore
2396 // for now this code will remained uncommented until it is deleted
2397 // following further testing.
2398 // if (lengthBar.getValue() == 1.0 && lastCellCount != cellCount) {
2399 // lengthBar.setValue(0.99);
2400 // }
2401
2402 /*
2403 ** Positioning the ScrollBar
2404 */
2405 if (!Properties.IS_TOUCH_SUPPORTED) {
2406 if (isVertical) {
2407 vbar.resizeRelocate(viewportBreadth, 0, vbar.prefWidth(viewportLength), viewportLength);
2408 } else {
2409 hbar.resizeRelocate(0, viewportBreadth, viewportLength, hbar.prefHeight(-1));
2410 }
2411 }
2412 else {
2413 if (isVertical) {
2414 vbar.resizeRelocate((viewportBreadth-vbar.getWidth()), 0, vbar.prefWidth(viewportLength), viewportLength);
2415 } else {
2416 hbar.resizeRelocate(0, (viewportBreadth-hbar.getHeight()), viewportLength, hbar.prefHeight(-1));
2417 }
2418 }
2419 }
2420
2421 if (corner.isVisible()) {
2422 if (!Properties.IS_TOUCH_SUPPORTED) {
2423 corner.resize(vbar.getWidth(), hbar.getHeight());
2424 corner.relocate(hbar.getLayoutX() + hbar.getWidth(), vbar.getLayoutY() + vbar.getHeight());
2425 }
2426 else {
2427 corner.resize(vbar.getWidth(), hbar.getHeight());
2428 corner.relocate(hbar.getLayoutX() + (hbar.getWidth()-vbar.getWidth()), vbar.getLayoutY() + (vbar.getHeight()-hbar.getHeight()));
2429 hbar.resize(hbar.getWidth()-vbar.getWidth(), hbar.getHeight());
2430 vbar.resize(vbar.getWidth(), vbar.getHeight()-hbar.getHeight());
2431 }
2432 }
2433
2434 clipView.resize(snapSizeX(isVertical ? viewportBreadth : viewportLength),
2435 snapSizeY(isVertical ? viewportLength : viewportBreadth));
2436
2437 // If the viewportLength becomes large enough that all cells fit
2438 // within the viewport, then we want to update the value to match.
2439 if (getPosition() != lengthBar.getValue()) {
2440 lengthBar.setValue(getPosition());
2441 }
2442 }
2443
2444 /**
2445 * Adjusts the cells location and size if necessary. The breadths of all
2446 * cells will be adjusted to fit the viewportWidth or maxPrefBreadth, and
2447 * the layout position will be updated if necessary based on index and
2448 * offset.
2449 */
2450 private void fitCells() {
2451 double size = Math.max(getMaxPrefBreadth(), getViewportBreadth());
2452 boolean isVertical = isVertical();
2453
2454 // Note: Do not optimise this loop by pre-calculating the cells size and
2455 // storing that into a int value - this can lead to RT-32828
2456 for (int i = 0; i < cells.size(); i++) {
2457 Cell<?> cell = cells.get(i);
2458 if (isVertical) {
2459 cell.resize(size, cell.prefHeight(size));
2460 } else {
2461 cell.resize(cell.prefWidth(size), size);
2462 }
2463 }
2464 }
2465
2466 private void cull() {
2467 final double viewportLength = getViewportLength();
2468 for (int i = cells.size() - 1; i >= 0; i--) {
2469 T cell = cells.get(i);
2470 double cellSize = getCellLength(cell);
2471 double cellStart = getCellPosition(cell);
2472 double cellEnd = cellStart + cellSize;
2473 if (cellStart >= viewportLength || cellEnd < 0) {
2474 addToPile(cells.remove(i));
2475 }
2476 }
2477 }
2478
2479 /**
2480 * After using the accum cell, it needs to be released!
2481 */
2482 private void releaseCell(T cell) {
2483 if (accumCell != null && cell == accumCell) {
2484 accumCell.updateIndex(-1);
2485 }
2486 }
2487
2488 /**
2489 * This method is an experts-only method - if the requested index is not
2490 * already an existing visible cell, it will create a cell for the
2491 * given index and insert it into the sheet. From that point on it will be
2492 * unmanaged, and is up to the caller of this method to manage it.
2493 */
2494 T getPrivateCell(int index) {
2495 T cell = null;
2496
2497 // If there are cells, then we will attempt to get an existing cell
2498 if (! cells.isEmpty()) {
2499 // First check the cells that have already been created and are
2500 // in use. If this call returns a value, then we can use it
2501 cell = getVisibleCell(index);
2502 if (cell != null) {
2503 // Force the underlying text inside the cell to be updated
2504 // so that when the screen reader runs, it will match the
2505 // text in the cell (force updateDisplayedText())
2506 cell.layout();
2507 return cell;
2508 }
2509 }
2510
2511 // check the existing sheet children
2512 if (cell == null) {
2513 for (int i = 0; i < sheetChildren.size(); i++) {
2514 T _cell = (T) sheetChildren.get(i);
2515 if (getCellIndex(_cell) == index) {
2516 return _cell;
2517 }
2518 }
2519 }
2520
2521 Callback<VirtualFlow<T>, T> cellFactory = getCellFactory();
2522 if (cellFactory != null) {
2523 cell = cellFactory.call(this);
2524 }
2525
2526 if (cell != null) {
2527 setCellIndex(cell, index);
2528 resizeCellSize(cell);
2529 cell.setVisible(false);
2530 sheetChildren.add(cell);
2531 privateCells.add(cell);
2532 }
2533
2534 return cell;
2535 }
2536
2537 private final List<T> privateCells = new ArrayList<>();
2538
2539 private void releaseAllPrivateCells() {
2540 sheetChildren.removeAll(privateCells);
2541 }
2542
2543 /**
2544 * Puts the given cell onto the pile. This is called whenever a cell has
2545 * fallen off the flow's start.
2546 */
2547 private void addToPile(T cell) {
2548 assert cell != null;
2549 pile.addLast(cell);
2550 }
2551
2552 private void cleanPile() {
2553 boolean wasFocusOwner = false;
2554
2555 for (int i = 0, max = pile.size(); i < max; i++) {
2556 T cell = pile.get(i);
2557 wasFocusOwner = wasFocusOwner || doesCellContainFocus(cell);
2558 cell.setVisible(false);
2559 }
2560
2561 // Fix for RT-35876: Rather than have the cells do weird things with
2562 // focus (in particular, have focus jump between cells), we return focus
2563 // to the VirtualFlow itself.
2564 if (wasFocusOwner) {
2565 requestFocus();
2566 }
2567 }
2568
2569 private boolean doesCellContainFocus(Cell<?> c) {
2570 Scene scene = c.getScene();
2571 final Node focusOwner = scene == null ? null : scene.getFocusOwner();
2572
2573 if (focusOwner != null) {
2574 if (c.equals(focusOwner)) {
2575 return true;
2576 }
2577
2578 Parent p = focusOwner.getParent();
2579 while (p != null && ! (p instanceof VirtualFlow)) {
2580 if (c.equals(p)) {
2581 return true;
2582 }
2583 p = p.getParent();
2584 }
2585 }
2586
2587 return false;
2588 }
2589
2590 private double getPrefBreadth(double oppDimension) {
2591 double max = getMaxCellWidth(10);
2592
2593 // This primarily exists for the case where we do not want the breadth
2594 // to grow to ensure a golden ratio between width and height (for example,
2595 // when a ListView is used in a ComboBox - the width should not grow
2596 // just because items are being added to the ListView)
2597 if (oppDimension > -1) {
2598 double prefLength = getPrefLength();
2599 max = Math.max(max, prefLength * GOLDEN_RATIO_MULTIPLIER);
2600 }
2601
2602 return max;
2603 }
2604
2605 private double getPrefLength() {
2606 double sum = 0.0;
2607 int rows = Math.min(10, getCellCount());
2608 for (int i = 0; i < rows; i++) {
2609 sum += getCellLength(i);
2610 }
2611 return sum;
2612 }
2613
2614 double getMaxCellWidth(int rowsToCount) {
2615 double max = 0.0;
2616
2617 // we always measure at least one row
2618 int rows = Math.max(1, rowsToCount == -1 ? getCellCount() : rowsToCount);
2619 for (int i = 0; i < rows; i++) {
2620 max = Math.max(max, getCellBreadth(i));
2621 }
2622 return max;
2623 }
2624
2625 // Old PositionMapper
2626 /**
2627 * Given a position value between 0 and 1, compute and return the viewport
2628 * offset from the "current" cell associated with that position value.
2629 * That is, if the return value of this function where used as a translation
2630 * factor for a sheet that contained all the items, then the current
2631 * item would end up positioned correctly.
2632 */
2633 private double computeViewportOffset(double position) {
2634 double p = com.sun.javafx.util.Utils.clamp(0, position, 1);
2635 double fractionalPosition = p * getCellCount();
2636 int cellIndex = (int) fractionalPosition;
2637 double fraction = fractionalPosition - cellIndex;
2638 double cellSize = getCellLength(cellIndex);
2639 double pixelOffset = cellSize * fraction;
2640 double viewportOffset = getViewportLength() * p;
2641 return pixelOffset - viewportOffset;
2642 }
2643
2644 private void adjustPositionToIndex(int index) {
2645 int cellCount = getCellCount();
2646 if (cellCount <= 0) {
2647 setPosition(0.0f);
2648 } else {
2649 setPosition(((double)index) / cellCount);
2650 }
2651 }
2652
2653 /**
2654 * Adjust the position based on a delta of pixels. If negative, then the
2655 * position will be adjusted negatively. If positive, then the position will
2656 * be adjusted positively. If the pixel amount is too great for the range of
2657 * the position, then it will be clamped such that position is always
2658 * strictly between 0 and 1
2659 */
2660 private void adjustByPixelAmount(double numPixels) {
2661 if (numPixels == 0) return;
2662 // Starting from the current cell, we move in the direction indicated
2663 // by numPixels one cell at a team. For each cell, we discover how many
2664 // pixels the "position" line would move within that cell, and adjust
2665 // our count of numPixels accordingly. When we come to the "final" cell,
2666 // then we can take the remaining number of pixels and multiply it by
2667 // the "travel rate" of "p" within that cell to get the delta. Add
2668 // the delta to "p" to get position.
2669
2670 // get some basic info about the list and the current cell
2671 boolean forward = numPixels > 0;
2672 int cellCount = getCellCount();
2673 double fractionalPosition = getPosition() * cellCount;
2674 int cellIndex = (int) fractionalPosition;
2675 if (forward && cellIndex == cellCount) return;
2676 double cellSize = getCellLength(cellIndex);
2677 double fraction = fractionalPosition - cellIndex;
2678 double pixelOffset = cellSize * fraction;
2679
2680 // compute the percentage of "position" that represents each cell
2681 double cellPercent = 1.0 / cellCount;
2682
2683 // To help simplify the algorithm, we pretend as though the current
2684 // position is at the beginning of the current cell. This reduces some
2685 // of the corner cases and provides a simpler algorithm without adding
2686 // any overhead to performance.
2687 double start = computeOffsetForCell(cellIndex);
2688 double end = cellSize + computeOffsetForCell(cellIndex + 1);
2689
2690 // We need to discover the distance that the fictional "position line"
2691 // would travel within this cell, from its current position to the end.
2692 double remaining = end - start;
2693
2694 // Keep track of the number of pixels left to travel
2695 double n = forward ?
2696 numPixels + pixelOffset - (getViewportLength() * getPosition()) - start
2697 : -numPixels + end - (pixelOffset - (getViewportLength() * getPosition()));
2698
2699 // "p" represents the most recent value for position. This is always
2700 // based on the edge between two cells, except at the very end of the
2701 // algorithm where it is added to the computed "p" offset for the final
2702 // value of Position.
2703 double p = cellPercent * cellIndex;
2704
2705 // Loop over the cells one at a time until either we reach the end of
2706 // the cells, or we find that the "n" will fall within the cell we're on
2707 while (n > remaining && ((forward && cellIndex < cellCount - 1) || (! forward && cellIndex > 0))) {
2708 if (forward) cellIndex++; else cellIndex--;
2709 n -= remaining;
2710 cellSize = getCellLength(cellIndex);
2711 start = computeOffsetForCell(cellIndex);
2712 end = cellSize + computeOffsetForCell(cellIndex + 1);
2713 remaining = end - start;
2714 p = cellPercent * cellIndex;
2715 }
2716
2717 // if remaining is < n, then we must have hit an end, so as a
2718 // fast path, we can just set position to 1.0 or 0.0 and return
2719 // because we know we hit the end
2720 if (n > remaining) {
2721 setPosition(forward ? 1.0f : 0.0f);
2722 } else if (forward) {
2723 double rate = cellPercent / Math.abs(end - start);
2724 setPosition(p + (rate * n));
2725 } else {
2726 double rate = cellPercent / Math.abs(end - start);
2727 setPosition((p + cellPercent) - (rate * n));
2728 }
2729 }
2730
2731 private int computeCurrentIndex() {
2732 return (int) (getPosition() * getCellCount());
2733 }
2734
2735 /**
2736 * Given an item index, this function will compute and return the viewport
2737 * offset from the beginning of the specified item. Notice that because each
2738 * item has the same percentage of the position dedicated to it, and since
2739 * we are measuring from the start of each item, this is a very simple
2740 * calculation.
2741 */
2742 private double computeOffsetForCell(int itemIndex) {
2743 double cellCount = getCellCount();
2744 double p = com.sun.javafx.util.Utils.clamp(0, itemIndex, cellCount) / cellCount;
2745 return -(getViewportLength() * p);
2746 }
2747
2748 // /**
2749 // * Adjust the position based on a chunk of pixels. The position is based
2750 // * on the start of the scrollbar position.
2751 // */
2752 // private void adjustByPixelChunk(double numPixels) {
2753 // setPosition(0);
2754 // adjustByPixelAmount(numPixels);
2755 // }
2756 // end of old PositionMapper code
2757
2758
2759
2760
2761 /***************************************************************************
2762 * *
2763 * Support classes *
2764 * *
2765 **************************************************************************/
2766
2767 /**
2768 * A simple extension to Region that ensures that anything wanting to flow
2769 * outside of the bounds of the Region is clipped.
2770 */
2771 static class ClippedContainer extends Region {
2772
2773 /**
2774 * The Node which is embedded within this {@code ClipView}.
2775 */
2776 private Node node;
2777 public Node getNode() { return this.node; }
2778 public void setNode(Node n) {
2779 this.node = n;
2780
2781 getChildren().clear();
2782 getChildren().add(node);
2783 }
2784
2785 public void setClipX(double clipX) {
2786 setLayoutX(-clipX);
2787 clipRect.setLayoutX(clipX);
2788 }
2789
2790 public void setClipY(double clipY) {
2791 setLayoutY(-clipY);
2792 clipRect.setLayoutY(clipY);
2793 }
2794
2795 private final Rectangle clipRect;
2796
2797 public ClippedContainer(final VirtualFlow<?> flow) {
2798 if (flow == null) {
2799 throw new IllegalArgumentException("VirtualFlow can not be null");
2800 }
2801
2802 getStyleClass().add("clipped-container");
2803
2804 // clipping
2805 clipRect = new Rectangle();
2806 clipRect.setSmooth(false);
2807 setClip(clipRect);
2808 // --- clipping
2809
2810 super.widthProperty().addListener(valueModel -> {
2811 clipRect.setWidth(getWidth());
2812 });
2813 super.heightProperty().addListener(valueModel -> {
2814 clipRect.setHeight(getHeight());
2815 });
2816 }
2817 }
2818
2819 /**
2820 * A List-like implementation that is exceedingly efficient for the purposes
2821 * of the VirtualFlow. Typically there is not much variance in the number of
2822 * cells -- it is always some reasonably consistent number. Yet for efficiency
2823 * in code, we like to use a linked list implementation so as to append to
2824 * start or append to end. However, at times when we need to iterate, LinkedList
2825 * is expensive computationally as well as requiring the construction of
2826 * temporary iterators.
2827 * <p>
2828 * This linked list like implementation is done using an array. It begins by
2829 * putting the first item in the center of the allocated array, and then grows
2830 * outward (either towards the first or last of the array depending on whether
2831 * we are inserting at the head or tail). It maintains an index to the start
2832 * and end of the array, so that it can efficiently expose iteration.
2833 * <p>
2834 * This class is package private solely for the sake of testing.
2835 */
2836 static class ArrayLinkedList<T> extends AbstractList<T> {
2837 /**
2838 * The array list backing this class. We default the size of the array
2839 * list to be fairly large so as not to require resizing during normal
2840 * use, and since that many ArrayLinkedLists won't be created it isn't
2841 * very painful to do so.
2842 */
2843 private final ArrayList<T> array;
2844
2845 private int firstIndex = -1;
2846 private int lastIndex = -1;
2847
2848 public ArrayLinkedList() {
2849 array = new ArrayList<T>(50);
2850
2851 for (int i = 0; i < 50; i++) {
2852 array.add(null);
2853 }
2854 }
2855
2856 public T getFirst() {
2857 return firstIndex == -1 ? null : array.get(firstIndex);
2858 }
2859
2860 public T getLast() {
2861 return lastIndex == -1 ? null : array.get(lastIndex);
2862 }
2863
2864 public void addFirst(T cell) {
2865 // if firstIndex == -1 then that means this is the first item in the
2866 // list and we need to initialize firstIndex and lastIndex
2867 if (firstIndex == -1) {
2868 firstIndex = lastIndex = array.size() / 2;
2869 array.set(firstIndex, cell);
2870 } else if (firstIndex == 0) {
2871 // we're already at the head of the array, so insert at position
2872 // 0 and then increment the lastIndex to compensate
2873 array.add(0, cell);
2874 lastIndex++;
2875 } else {
2876 // we're not yet at the head of the array, so insert at the
2877 // firstIndex - 1 position and decrement first position
2878 array.set(--firstIndex, cell);
2879 }
2880 }
2881
2882 public void addLast(T cell) {
2883 // if lastIndex == -1 then that means this is the first item in the
2884 // list and we need to initialize the firstIndex and lastIndex
2885 if (firstIndex == -1) {
2886 firstIndex = lastIndex = array.size() / 2;
2887 array.set(lastIndex, cell);
2888 } else if (lastIndex == array.size() - 1) {
2889 // we're at the end of the array so need to "add" so as to force
2890 // the array to be expanded in size
2891 array.add(++lastIndex, cell);
2892 } else {
2893 array.set(++lastIndex, cell);
2894 }
2895 }
2896
2897 public int size() {
2898 return firstIndex == -1 ? 0 : lastIndex - firstIndex + 1;
2899 }
2900
2901 public boolean isEmpty() {
2902 return firstIndex == -1;
2903 }
2904
2905 public T get(int index) {
2906 if (index > (lastIndex - firstIndex) || index < 0) {
2907 // Commented out exception due to RT-29111
2908 // throw new java.lang.ArrayIndexOutOfBoundsException();
2909 return null;
2910 }
2911
2912 return array.get(firstIndex + index);
2913 }
2914
2915 public void clear() {
2916 for (int i = 0; i < array.size(); i++) {
2917 array.set(i, null);
2918 }
2919
2920 firstIndex = lastIndex = -1;
2921 }
2922
2923 public T removeFirst() {
2924 if (isEmpty()) return null;
2925 return remove(0);
2926 }
2927
2928 public T removeLast() {
2929 if (isEmpty()) return null;
2930 return remove(lastIndex - firstIndex);
2931 }
2932
2933 public T remove(int index) {
2934 if (index > lastIndex - firstIndex || index < 0) {
2935 throw new ArrayIndexOutOfBoundsException();
2936 }
2937
2938 // if the index == 0, then we're removing the first
2939 // item and can simply set it to null in the array and increment
2940 // the firstIndex unless there is only one item, in which case
2941 // we have to also set first & last index to -1.
2942 if (index == 0) {
2943 T cell = array.get(firstIndex);
2944 array.set(firstIndex, null);
2945 if (firstIndex == lastIndex) {
2946 firstIndex = lastIndex = -1;
2947 } else {
2948 firstIndex++;
2949 }
2950 return cell;
2951 } else if (index == lastIndex - firstIndex) {
2952 // if the index == lastIndex - firstIndex, then we're removing the
2953 // last item and can simply set it to null in the array and
2954 // decrement the lastIndex
2955 T cell = array.get(lastIndex);
2956 array.set(lastIndex--, null);
2957 return cell;
2958 } else {
2959 // if the index is somewhere in between, then we have to remove the
2960 // item and decrement the lastIndex
2961 T cell = array.get(firstIndex + index);
2962 array.set(firstIndex + index, null);
2963 for (int i = (firstIndex + index + 1); i <= lastIndex; i++) {
2964 array.set(i - 1, array.get(i));
2965 }
2966 array.set(lastIndex--, null);
2967 return cell;
2968 }
2969 }
2970 }
2971 }