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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24 */
25 package javax.swing.text;
26
27 import java.util.Vector;
28 import java.awt.*;
29 import javax.swing.event.*;
30
31 /**
32 * ZoneView is a View implementation that creates zones for which
33 * the child views are not created or stored until they are needed
34 * for display or model/view translations. This enables a substantial
35 * reduction in memory consumption for situations where the model
36 * being represented is very large, by building view objects only for
37 * the region being actively viewed/edited. The size of the children
38 * can be estimated in some way, or calculated asynchronously with
39 * only the result being saved.
40 * <p>
41 * ZoneView extends BoxView to provide a box that implements
42 * zones for its children. The zones are special View implementations
43 * (the children of an instance of this class) that represent only a
44 * portion of the model that an instance of ZoneView is responsible
45 * for. The zones don't create child views until an attempt is made
46 * to display them. A box shaped view is well suited to this because:
47 * <ul>
48 * <li>
49 * Boxes are a heavily used view, and having a box that
50 * provides this behavior gives substantial opportunity
51 * to plug the behavior into a view hierarchy from the
52 * view factory.
53 * <li>
54 * Boxes are tiled in one direction, so it is easy to
55 * divide them into zones in a reliable way.
56 * <li>
57 * Boxes typically have a simple relationship to the model (i.e. they
58 * create child views that directly represent the child elements).
59 * <li>
60 * Boxes are easier to estimate the size of than some other shapes.
61 * </ul>
62 * <p>
63 * The default behavior is controlled by two properties, maxZoneSize
64 * and maxZonesLoaded. Setting maxZoneSize to Integer.MAX_VALUE would
65 * have the effect of causing only one zone to be created. This would
66 * effectively turn the view into an implementation of the decorator
67 * pattern. Setting maxZonesLoaded to a value of Integer.MAX_VALUE would
68 * cause zones to never be unloaded. For simplicity, zones are created on
69 * boundaries represented by the child elements of the element the view is
70 * responsible for. The zones can be any View implementation, but the
71 * default implementation is based upon AsyncBoxView which supports fairly
72 * large zones efficiently.
73 *
74 * @author Timothy Prinzing
75 * @see View
76 * @since 1.3
77 */
78 public class ZoneView extends BoxView {
79
80 int maxZoneSize = 8 * 1024;
81 int maxZonesLoaded = 3;
82 Vector<View> loadedZones;
83
84 /**
85 * Constructs a ZoneView.
86 *
87 * @param elem the element this view is responsible for
88 * @param axis either View.X_AXIS or View.Y_AXIS
89 */
90 public ZoneView(Element elem, int axis) {
91 super(elem, axis);
92 loadedZones = new Vector<View>();
93 }
94
95 /**
96 * Get the current maximum zone size.
97 * @return the current maximum zone size
98 */
99 public int getMaximumZoneSize() {
100 return maxZoneSize;
101 }
102
103 /**
104 * Set the desired maximum zone size. A
105 * zone may get larger than this size if
106 * a single child view is larger than this
107 * size since zones are formed on child view
108 * boundaries.
109 *
110 * @param size the number of characters the zone
111 * may represent before attempting to break
112 * the zone into a smaller size.
113 */
114 public void setMaximumZoneSize(int size) {
115 maxZoneSize = size;
116 }
117
118 /**
119 * Get the current setting of the number of zones
120 * allowed to be loaded at the same time.
121 * @return current setting of the number of zones
122 * allowed to be loaded at the same time
123 */
124 public int getMaxZonesLoaded() {
125 return maxZonesLoaded;
126 }
127
128 /**
129 * Sets the current setting of the number of zones
130 * allowed to be loaded at the same time. This will throw an
131 * <code>IllegalArgumentException</code> if <code>mzl</code> is less
132 * than 1.
133 *
134 * @param mzl the desired maximum number of zones
135 * to be actively loaded, must be greater than 0
136 * @exception IllegalArgumentException if <code>mzl</code> is < 1
137 */
138 public void setMaxZonesLoaded(int mzl) {
139 if (mzl < 1) {
140 throw new IllegalArgumentException("ZoneView.setMaxZonesLoaded must be greater than 0.");
141 }
142 maxZonesLoaded = mzl;
143 unloadOldZones();
144 }
145
146 /**
147 * Called by a zone when it gets loaded. This happens when
148 * an attempt is made to display or perform a model/view
149 * translation on a zone that was in an unloaded state.
150 * This is implemented to check if the maximum number of
151 * zones was reached and to unload the oldest zone if so.
152 *
153 * @param zone the child view that was just loaded.
154 */
155 protected void zoneWasLoaded(View zone) {
156 //System.out.println("loading: " + zone.getStartOffset() + "," + zone.getEndOffset());
157 loadedZones.addElement(zone);
158 unloadOldZones();
159 }
160
161 void unloadOldZones() {
162 while (loadedZones.size() > getMaxZonesLoaded()) {
163 View zone = loadedZones.elementAt(0);
164 loadedZones.removeElementAt(0);
165 unloadZone(zone);
166 }
167 }
168
169 /**
170 * Unload a zone (Convert the zone to its memory saving state).
171 * The zones are expected to represent a subset of the
172 * child elements of the element this view is responsible for.
173 * Therefore, the default implementation is to simple remove
174 * all the children.
175 *
176 * @param zone the child view desired to be set to an
177 * unloaded state.
178 */
179 protected void unloadZone(View zone) {
180 //System.out.println("unloading: " + zone.getStartOffset() + "," + zone.getEndOffset());
181 zone.removeAll();
182 }
183
184 /**
185 * Determine if a zone is in the loaded state.
186 * The zones are expected to represent a subset of the
187 * child elements of the element this view is responsible for.
188 * Therefore, the default implementation is to return
189 * true if the view has children.
190 * param zone the child view
191 * @param zone the zone
192 * @return whether or not the zone is in the loaded state.
193 */
194 protected boolean isZoneLoaded(View zone) {
195 return (zone.getViewCount() > 0);
196 }
197
198 /**
199 * Create a view to represent a zone for the given
200 * range within the model (which should be within
201 * the range of this objects responsibility). This
202 * is called by the zone management logic to create
203 * new zones. Subclasses can provide a different
204 * implementation for a zone by changing this method.
205 *
206 * @param p0 the start of the desired zone. This should
207 * be >= getStartOffset() and < getEndOffset(). This
208 * value should also be < p1.
209 * @param p1 the end of the desired zone. This should
210 * be > getStartOffset() and <= getEndOffset(). This
211 * value should also be > p0.
212 * @return a view to represent a zone for the given range within
213 * the model
214 */
215 protected View createZone(int p0, int p1) {
216 Document doc = getDocument();
217 View zone;
218 try {
219 zone = new Zone(getElement(),
220 doc.createPosition(p0),
221 doc.createPosition(p1));
222 } catch (BadLocationException ble) {
223 // this should puke in some way.
224 throw new StateInvariantError(ble.getMessage());
225 }
226 return zone;
227 }
228
229 /**
230 * Loads all of the children to initialize the view.
231 * This is called by the <code>setParent</code> method.
232 * This is reimplemented to not load any children directly
233 * (as they are created by the zones). This method creates
234 * the initial set of zones. Zones don't actually get
235 * populated however until an attempt is made to display
236 * them or to do model/view coordinate translation.
237 *
238 * @param f the view factory
239 */
240 protected void loadChildren(ViewFactory f) {
241 // build the first zone.
242 Document doc = getDocument();
243 int offs0 = getStartOffset();
244 int offs1 = getEndOffset();
245 append(createZone(offs0, offs1));
246 handleInsert(offs0, offs1 - offs0);
247 }
248
249 /**
250 * Returns the child view index representing the given position in
251 * the model.
252 *
253 * @param pos the position >= 0
254 * @return index of the view representing the given position, or
255 * -1 if no view represents that position
256 */
257 protected int getViewIndexAtPosition(int pos) {
258 // PENDING(prinz) this could be done as a binary
259 // search, and probably should be.
260 int n = getViewCount();
261 if (pos == getEndOffset()) {
262 return n - 1;
263 }
264 for(int i = 0; i < n; i++) {
265 View v = getView(i);
266 if(pos >= v.getStartOffset() &&
267 pos < v.getEndOffset()) {
268 return i;
269 }
270 }
271 return -1;
272 }
273
274 void handleInsert(int pos, int length) {
275 int index = getViewIndex(pos, Position.Bias.Forward);
276 View v = getView(index);
277 int offs0 = v.getStartOffset();
278 int offs1 = v.getEndOffset();
279 if ((offs1 - offs0) > maxZoneSize) {
280 splitZone(index, offs0, offs1);
281 }
282 }
283
284 void handleRemove(int pos, int length) {
285 // IMPLEMENT
286 }
287
288 /**
289 * Break up the zone at the given index into pieces
290 * of an acceptable size.
291 */
292 void splitZone(int index, int offs0, int offs1) {
293 // divide the old zone into a new set of bins
294 Element elem = getElement();
295 Document doc = elem.getDocument();
296 Vector<View> zones = new Vector<View>();
297 int offs = offs0;
298 do {
299 offs0 = offs;
300 offs = Math.min(getDesiredZoneEnd(offs0), offs1);
301 zones.addElement(createZone(offs0, offs));
302 } while (offs < offs1);
303 View oldZone = getView(index);
304 View[] newZones = new View[zones.size()];
305 zones.copyInto(newZones);
306 replace(index, 1, newZones);
307 }
308
309 /**
310 * Returns the zone position to use for the
311 * end of a zone that starts at the given
312 * position. By default this returns something
313 * close to half the max zone size.
314 */
315 int getDesiredZoneEnd(int pos) {
316 Element elem = getElement();
317 int index = elem.getElementIndex(pos + (maxZoneSize / 2));
318 Element child = elem.getElement(index);
319 int offs0 = child.getStartOffset();
320 int offs1 = child.getEndOffset();
321 if ((offs1 - pos) > maxZoneSize) {
322 if (offs0 > pos) {
323 return offs0;
324 }
325 }
326 return offs1;
327 }
328
329 // ---- View methods ----------------------------------------------------
330
331 /**
332 * The superclass behavior will try to update the child views
333 * which is not desired in this case, since the children are
334 * zones and not directly effected by the changes to the
335 * associated element. This is reimplemented to do nothing
336 * and return false.
337 */
338 protected boolean updateChildren(DocumentEvent.ElementChange ec,
339 DocumentEvent e, ViewFactory f) {
340 return false;
341 }
342
343 /**
344 * Gives notification that something was inserted into the document
345 * in a location that this view is responsible for. This is largely
346 * delegated to the superclass, but is reimplemented to update the
347 * relevant zone (i.e. determine if a zone needs to be split into a
348 * set of 2 or more zones).
349 *
350 * @param changes the change information from the associated document
351 * @param a the current allocation of the view
352 * @param f the factory to use to rebuild if the view has children
353 * @see View#insertUpdate
354 */
355 public void insertUpdate(DocumentEvent changes, Shape a, ViewFactory f) {
356 handleInsert(changes.getOffset(), changes.getLength());
357 super.insertUpdate(changes, a, f);
358 }
359
360 /**
361 * Gives notification that something was removed from the document
362 * in a location that this view is responsible for. This is largely
363 * delegated to the superclass, but is reimplemented to update the
364 * relevant zones (i.e. determine if zones need to be removed or
365 * joined with another zone).
366 *
367 * @param changes the change information from the associated document
368 * @param a the current allocation of the view
369 * @param f the factory to use to rebuild if the view has children
370 * @see View#removeUpdate
371 */
372 public void removeUpdate(DocumentEvent changes, Shape a, ViewFactory f) {
373 handleRemove(changes.getOffset(), changes.getLength());
374 super.removeUpdate(changes, a, f);
375 }
376
377 /**
378 * Internally created view that has the purpose of holding
379 * the views that represent the children of the ZoneView
380 * that have been arranged in a zone.
381 */
382 class Zone extends AsyncBoxView {
383
384 private Position start;
385 private Position end;
386
387 public Zone(Element elem, Position start, Position end) {
388 super(elem, ZoneView.this.getAxis());
389 this.start = start;
390 this.end = end;
391 }
392
393 /**
394 * Creates the child views and populates the
395 * zone with them. This is done by translating
396 * the positions to child element index locations
397 * and building views to those elements. If the
398 * zone is already loaded, this does nothing.
399 */
400 public void load() {
401 if (! isLoaded()) {
402 setEstimatedMajorSpan(true);
403 Element e = getElement();
404 ViewFactory f = getViewFactory();
405 int index0 = e.getElementIndex(getStartOffset());
406 int index1 = e.getElementIndex(getEndOffset());
407 View[] added = new View[index1 - index0 + 1];
408 for (int i = index0; i <= index1; i++) {
409 added[i - index0] = f.create(e.getElement(i));
410 }
411 replace(0, 0, added);
412
413 zoneWasLoaded(this);
414 }
415 }
416
417 /**
418 * Removes the child views and returns to a
419 * state of unloaded.
420 */
421 public void unload() {
422 setEstimatedMajorSpan(true);
423 removeAll();
424 }
425
426 /**
427 * Determines if the zone is in the loaded state
428 * or not.
429 */
430 public boolean isLoaded() {
431 return (getViewCount() != 0);
432 }
433
434 /**
435 * This method is reimplemented to not build the children
436 * since the children are created when the zone is loaded
437 * rather then when it is placed in the view hierarchy.
438 * The major span is estimated at this point by building
439 * the first child (but not storing it), and calling
440 * setEstimatedMajorSpan(true) followed by setSpan for
441 * the major axis with the estimated span.
442 */
443 protected void loadChildren(ViewFactory f) {
444 // mark the major span as estimated
445 setEstimatedMajorSpan(true);
446
447 // estimate the span
448 Element elem = getElement();
449 int index0 = elem.getElementIndex(getStartOffset());
450 int index1 = elem.getElementIndex(getEndOffset());
451 int nChildren = index1 - index0;
452
453 // replace this with something real
454 //setSpan(getMajorAxis(), nChildren * 10);
455
456 View first = f.create(elem.getElement(index0));
457 first.setParent(this);
458 float w = first.getPreferredSpan(X_AXIS);
459 float h = first.getPreferredSpan(Y_AXIS);
460 if (getMajorAxis() == X_AXIS) {
461 w *= nChildren;
462 } else {
463 h += nChildren;
464 }
465
466 setSize(w, h);
467 }
468
469 /**
470 * Publish the changes in preferences upward to the parent
471 * view.
472 * <p>
473 * This is reimplemented to stop the superclass behavior
474 * if the zone has not yet been loaded. If the zone is
475 * unloaded for example, the last seen major span is the
476 * best estimate and a calculated span for no children
477 * is undesirable.
478 */
479 protected void flushRequirementChanges() {
480 if (isLoaded()) {
481 super.flushRequirementChanges();
482 }
483 }
484
485 /**
486 * Returns the child view index representing the given position in
487 * the model. Since the zone contains a cluster of the overall
488 * set of child elements, we can determine the index fairly
489 * quickly from the model by subtracting the index of the
490 * start offset from the index of the position given.
491 *
492 * @param pos the position >= 0
493 * @return index of the view representing the given position, or
494 * -1 if no view represents that position
495 * @since 1.3
496 */
497 public int getViewIndex(int pos, Position.Bias b) {
498 boolean isBackward = (b == Position.Bias.Backward);
499 pos = (isBackward) ? Math.max(0, pos - 1) : pos;
500 Element elem = getElement();
501 int index1 = elem.getElementIndex(pos);
502 int index0 = elem.getElementIndex(getStartOffset());
503 return index1 - index0;
504 }
505
506 protected boolean updateChildren(DocumentEvent.ElementChange ec,
507 DocumentEvent e, ViewFactory f) {
508 // the structure of this element changed.
509 Element[] removedElems = ec.getChildrenRemoved();
510 Element[] addedElems = ec.getChildrenAdded();
511 Element elem = getElement();
512 int index0 = elem.getElementIndex(getStartOffset());
513 int index1 = elem.getElementIndex(getEndOffset()-1);
514 int index = ec.getIndex();
515 if ((index >= index0) && (index <= index1)) {
516 // The change is in this zone
517 int replaceIndex = index - index0;
518 int nadd = Math.min(index1 - index0 + 1, addedElems.length);
519 int nremove = Math.min(index1 - index0 + 1, removedElems.length);
520 View[] added = new View[nadd];
521 for (int i = 0; i < nadd; i++) {
522 added[i] = f.create(addedElems[i]);
523 }
524 replace(replaceIndex, nremove, added);
525 }
526 return true;
527 }
528
529 // --- View methods ----------------------------------
530
531 /**
532 * Fetches the attributes to use when rendering. This view
533 * isn't directly responsible for an element so it returns
534 * the outer classes attributes.
535 */
536 public AttributeSet getAttributes() {
537 return ZoneView.this.getAttributes();
538 }
539
540 /**
541 * Renders using the given rendering surface and area on that
542 * surface. This is implemented to load the zone if its not
543 * already loaded, and then perform the superclass behavior.
544 *
545 * @param g the rendering surface to use
546 * @param a the allocated region to render into
547 * @see View#paint
548 */
549 public void paint(Graphics g, Shape a) {
550 load();
551 super.paint(g, a);
552 }
553
554 /**
555 * Provides a mapping from the view coordinate space to the logical
556 * coordinate space of the model. This is implemented to first
557 * make sure the zone is loaded before providing the superclass
558 * behavior.
559 *
560 * @param x x coordinate of the view location to convert >= 0
561 * @param y y coordinate of the view location to convert >= 0
562 * @param a the allocated region to render into
563 * @return the location within the model that best represents the
564 * given point in the view >= 0
565 * @see View#viewToModel
566 */
567 public int viewToModel(float x, float y, Shape a, Position.Bias[] bias) {
568 load();
569 return super.viewToModel(x, y, a, bias);
570 }
571
572 /**
573 * Provides a mapping from the document model coordinate space
574 * to the coordinate space of the view mapped to it. This is
575 * implemented to provide the superclass behavior after first
576 * making sure the zone is loaded (The zone must be loaded to
577 * make this calculation).
578 *
579 * @param pos the position to convert
580 * @param a the allocated region to render into
581 * @return the bounding box of the given position
582 * @exception BadLocationException if the given position does not represent a
583 * valid location in the associated document
584 * @see View#modelToView
585 */
586 public Shape modelToView(int pos, Shape a, Position.Bias b) throws BadLocationException {
587 load();
588 return super.modelToView(pos, a, b);
589 }
590
591 /**
592 * Start of the zones range.
593 *
594 * @see View#getStartOffset
595 */
596 public int getStartOffset() {
597 return start.getOffset();
598 }
599
600 /**
601 * End of the zones range.
602 */
603 public int getEndOffset() {
604 return end.getOffset();
605 }
606
607 /**
608 * Gives notification that something was inserted into
609 * the document in a location that this view is responsible for.
610 * If the zone has been loaded, the superclass behavior is
611 * invoked, otherwise this does nothing.
612 *
613 * @param e the change information from the associated document
614 * @param a the current allocation of the view
615 * @param f the factory to use to rebuild if the view has children
616 * @see View#insertUpdate
617 */
618 public void insertUpdate(DocumentEvent e, Shape a, ViewFactory f) {
619 if (isLoaded()) {
620 super.insertUpdate(e, a, f);
621 }
622 }
623
624 /**
625 * Gives notification that something was removed from the document
626 * in a location that this view is responsible for.
627 * If the zone has been loaded, the superclass behavior is
628 * invoked, otherwise this does nothing.
629 *
630 * @param e the change information from the associated document
631 * @param a the current allocation of the view
632 * @param f the factory to use to rebuild if the view has children
633 * @see View#removeUpdate
634 */
635 public void removeUpdate(DocumentEvent e, Shape a, ViewFactory f) {
636 if (isLoaded()) {
637 super.removeUpdate(e, a, f);
638 }
639 }
640
641 /**
642 * Gives notification from the document that attributes were changed
643 * in a location that this view is responsible for.
644 * If the zone has been loaded, the superclass behavior is
645 * invoked, otherwise this does nothing.
646 *
647 * @param e the change information from the associated document
648 * @param a the current allocation of the view
649 * @param f the factory to use to rebuild if the view has children
650 * @see View#removeUpdate
651 */
652 public void changedUpdate(DocumentEvent e, Shape a, ViewFactory f) {
653 if (isLoaded()) {
654 super.changedUpdate(e, a, f);
655 }
656 }
657
658 }
659 }