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 javafx.scene.control.Control;
29 import javafx.scene.control.IndexedCell;
30 import javafx.scene.control.ScrollToEvent;
31 import javafx.scene.control.SkinBase;
32
33 /**
34 * Parent class to control skins whose contents are virtualized and scrollable.
35 * This class handles the interaction with the VirtualFlow class, which is the
36 * main class handling the virtualization of the contents of this container.
37 *
38 * @since 9
39 */
40 public abstract class VirtualContainerBase<C extends Control, I extends IndexedCell> extends SkinBase<C> {
41
42 /***************************************************************************
43 * *
44 * Private fields *
45 * *
46 **************************************************************************/
47
48 private boolean itemCountDirty;
49
50 /**
51 * The virtualized container which handles the layout and scrolling of
52 * all the cells.
53 */
54 private final VirtualFlow<I> flow;
55
56
57
58 /***************************************************************************
59 * *
60 * Constructors *
61 * *
62 **************************************************************************/
63
64 /**
65 *
66 * @param control
67 */
68 public VirtualContainerBase(final C control) {
69 super(control);
70 flow = createVirtualFlow();
71
72 control.addEventHandler(ScrollToEvent.scrollToTopIndex(), event -> {
73 // Fix for RT-24630: The row count in VirtualFlow was incorrect
74 // (normally zero), so the scrollTo call was misbehaving.
75 if (itemCountDirty) {
76 // update row count before we do a scroll
77 updateItemCount();
78 itemCountDirty = false;
79 }
80 flow.scrollToTop(event.getScrollTarget());
81 });
82 }
83
84
85
86 /***************************************************************************
87 * *
88 * Abstract API *
89 * *
90 **************************************************************************/
91
92 /**
93 * Returns the total number of items in this container, including those
94 * that are currently hidden because they are out of view.
95 */
96 protected abstract int getItemCount();
97
98 /**
99 * This method is called when it is possible that the item count has changed (i.e. scrolling has occurred,
100 * the control has resized, etc). This method should recalculate the item count and store that for future
101 * use by the {@link #getItemCount} method.
102 */
103 protected abstract void updateItemCount();
104
105
106
107 /***************************************************************************
108 * *
109 * Public API *
110 * *
111 **************************************************************************/
112
113 /**
114 * Call this method to indicate that the item count should be updated on the next pulse.
115 */
116 protected final void markItemCountDirty() {
117 itemCountDirty = true;
118 }
119
120 /** {@inheritDoc} */
121 @Override protected void layoutChildren(double x, double y, double w, double h) {
122 checkState();
123 }
124
125
126
127 /***************************************************************************
128 * *
129 * Private methods *
130 * *
131 **************************************************************************/
132
133 /**
134 * This enables skin subclasses to provide a custom VirtualFlow implementation,
135 * rather than have VirtualContainerBase instantiate the default instance.
136 */
137 VirtualFlow<I> createVirtualFlow() {
138 return new VirtualFlow<>();
139 }
140
141 final VirtualFlow<I> getVirtualFlow() {
142 return flow;
143 }
144
145 double getMaxCellWidth(int rowsToCount) {
146 return snappedLeftInset() + flow.getMaxCellWidth(rowsToCount) + snappedRightInset();
147 }
148
149 double getVirtualFlowPreferredHeight(int rows) {
150 double height = 1.0;
151
152 for (int i = 0; i < rows && i < getItemCount(); i++) {
153 height += flow.getCellLength(i);
154 }
155
156 return height + snappedTopInset() + snappedBottomInset();
157 }
158
159 void checkState() {
160 if (itemCountDirty) {
161 updateItemCount();
162 itemCountDirty = false;
163 }
164 }
165
166 void requestRebuildCells() {
167 flow.rebuildCells();
168 }
169
170 }