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comparison dwt/custom/StyledTextDropTargetEffect.d @ 0:380af2bdd8e5

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author Jacob Carlborg <doob@me.com> <jacob.carlborg@gmail.com>
date Sat, 09 Aug 2008 17:00:02 +0200
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1 /*******************************************************************************
2 * Copyright (c) 2000, 2007 IBM Corporation and others.
3 * All rights reserved. This program and the accompanying materials
4 * are made available under the terms of the Eclipse Public License v1.0
5 * which accompanies this distribution, and is available at
6 * http://www.eclipse.org/legal/epl-v10.html
7 *
8 * Contributors:
9 * IBM Corporation - initial API and implementation
10 *******************************************************************************/
11 module dwt.custom;
12
13 import dwt.*;
14 import dwt.dnd.*;
15 import dwt.graphics.*;
16 import dwt.widgets.*;
17
18 /**
19 * This adapter class provides a default drag under effect (eg. select and scroll)
20 * when a drag occurs over a <code>StyledText</code>.
21 *
22 * <p>Classes that wish to provide their own drag under effect for a <code>StyledText</code>
23 * can extend this class, override the <code>StyledTextDropTargetEffect.dragOver</code>
24 * method and override any other applicable methods in <code>StyledTextDropTargetEffect</code> to
25 * display their own drag under effect.</p>
26 *
27 * Subclasses that override any methods of this class should call the corresponding
28 * <code>super</code> method to get the default drag under effect implementation.
29 *
30 * <p>The feedback value is either one of the FEEDBACK constants defined in
31 * class <code>DND</code> which is applicable to instances of this class,
32 * or it must be built by <em>bitwise OR</em>'ing together
33 * (that is, using the <code>int</code> "|" operator) two or more
34 * of those <code>DND</code> effect constants.
35 * </p>
36 * <p>
37 * <dl>
38 * <dt><b>Feedback:</b></dt>
39 * <dd>FEEDBACK_SELECT, FEEDBACK_SCROLL</dd>
40 * </dl>
41 * </p>
42 *
43 * @see DropTargetAdapter
44 * @see DropTargetEvent
45 *
46 * @since 3.3
47 */
48 public class StyledTextDropTargetEffect : DropTargetEffect {
49 static final int CARET_WIDTH = 2;
50 static final int SCROLL_HYSTERESIS = 100; // milli seconds
51 static final int SCROLL_TOLERANCE = 20; // pixels
52
53 int currentOffset = -1;
54 long scrollBeginTime;
55 int scrollX = -1, scrollY = -1;
56 Listener paintListener;
57
58 /**
59 * Creates a new <code>StyledTextDropTargetEffect</code> to handle the drag under effect on the specified
60 * <code>StyledText</code>.
61 *
62 * @param styledText the <code>StyledText</code> over which the user positions the cursor to drop the data
63 */
64 public StyledTextDropTargetEffect(StyledText styledText) {
65 super(styledText);
66 paintListener = new Listener () {
67 public void handleEvent (Event event) {
68 if (currentOffset !is -1) {
69 StyledText text = (StyledText) getControl();
70 Point position = text.getLocationAtOffset(currentOffset);
71 int height = text.getLineHeight(currentOffset);
72 event.gc.setBackground(event.display.getSystemColor (DWT.COLOR_BLACK));
73 event.gc.fillRectangle(position.x, position.y, CARET_WIDTH, height);
74 }
75 }
76 };
77 }
78
79 /**
80 * This implementation of <code>dragEnter</code> provides a default drag under effect
81 * for the feedback specified in <code>event.feedback</code>.
82 *
83 * For additional information see <code>DropTargetAdapter.dragEnter</code>.
84 *
85 * Subclasses that override this method should call <code>super.dragEnter(event)</code>
86 * to get the default drag under effect implementation.
87 *
88 * @param event the information associated with the drag start event
89 *
90 * @see DropTargetAdapter
91 * @see DropTargetEvent
92 */
93 public void dragEnter(DropTargetEvent event) {
94 currentOffset = -1;
95 scrollBeginTime = 0;
96 scrollX = -1;
97 scrollY = -1;
98 getControl().removeListener(DWT.Paint, paintListener);
99 getControl().addListener (DWT.Paint, paintListener);
100 }
101
102 /**
103 * This implementation of <code>dragLeave</code> provides a default drag under effect
104 * for the feedback specified in <code>event.feedback</code>.
105 *
106 * For additional information see <code>DropTargetAdapter.dragLeave</code>.
107 *
108 * Subclasses that override this method should call <code>super.dragLeave(event)</code>
109 * to get the default drag under effect implementation.
110 *
111 * @param event the information associated with the drag leave event
112 *
113 * @see DropTargetAdapter
114 * @see DropTargetEvent
115 */
116 public void dragLeave(DropTargetEvent event) {
117 StyledText text = (StyledText) getControl();
118 if (currentOffset !is -1) {
119 refreshCaret(text, currentOffset, -1);
120 }
121 text.removeListener(DWT.Paint, paintListener);
122 scrollBeginTime = 0;
123 scrollX = -1;
124 scrollY = -1;
125 }
126
127 /**
128 * This implementation of <code>dragOver</code> provides a default drag under effect
129 * for the feedback specified in <code>event.feedback</code>.
130 *
131 * For additional information see <code>DropTargetAdapter.dragOver</code>.
132 *
133 * Subclasses that override this method should call <code>super.dragOver(event)</code>
134 * to get the default drag under effect implementation.
135 *
136 * @param event the information associated with the drag over event
137 *
138 * @see DropTargetAdapter
139 * @see DropTargetEvent
140 * @see DND#FEEDBACK_SELECT
141 * @see DND#FEEDBACK_SCROLL
142 */
143 public void dragOver(DropTargetEvent event) {
144 int effect = event.feedback;
145 StyledText text = (StyledText) getControl();
146
147 Point pt = text.getDisplay().map(null, text, event.x, event.y);
148 if ((effect & DND.FEEDBACK_SCROLL) is 0) {
149 scrollBeginTime = 0;
150 scrollX = scrollY = -1;
151 } else {
152 if (text.getCharCount() is 0) {
153 scrollBeginTime = 0;
154 scrollX = scrollY = -1;
155 } else {
156 if (scrollX !is -1 && scrollY !is -1 && scrollBeginTime !is 0 &&
157 (pt.x >= scrollX && pt.x <= (scrollX + SCROLL_TOLERANCE) ||
158 pt.y >= scrollY && pt.y <= (scrollY + SCROLL_TOLERANCE))) {
159 if (System.currentTimeMillis() >= scrollBeginTime) {
160 Rectangle area = text.getClientArea();
161 GC gc = new GC(text);
162 FontMetrics fm = gc.getFontMetrics();
163 gc.dispose();
164 int charWidth = fm.getAverageCharWidth();
165 int scrollAmount = 10*charWidth;
166 if (pt.x < area.x + 3*charWidth) {
167 int leftPixel = text.getHorizontalPixel();
168 text.setHorizontalPixel(leftPixel - scrollAmount);
169 }
170 if (pt.x > area.width - 3*charWidth) {
171 int leftPixel = text.getHorizontalPixel();
172 text.setHorizontalPixel(leftPixel + scrollAmount);
173 }
174 int lineHeight = text.getLineHeight();
175 if (pt.y < area.y + lineHeight) {
176 int topPixel = text.getTopPixel();
177 text.setTopPixel(topPixel - lineHeight);
178 }
179 if (pt.y > area.height - lineHeight) {
180 int topPixel = text.getTopPixel();
181 text.setTopPixel(topPixel + lineHeight);
182 }
183 scrollBeginTime = 0;
184 scrollX = scrollY = -1;
185 }
186 } else {
187 scrollBeginTime = System.currentTimeMillis() + SCROLL_HYSTERESIS;
188 scrollX = pt.x;
189 scrollY = pt.y;
190 }
191 }
192 }
193
194 if ((effect & DND.FEEDBACK_SELECT) !is 0) {
195 int[] trailing = new int [1];
196 int newOffset = text.getOffsetAtPoint(pt.x, pt.y, trailing, false);
197 newOffset += trailing [0];
198 if (newOffset !is currentOffset) {
199 refreshCaret(text, currentOffset, newOffset);
200 currentOffset = newOffset;
201 }
202 }
203 }
204
205 void refreshCaret(StyledText text, int oldOffset, int newOffset) {
206 if (oldOffset !is newOffset) {
207 if (oldOffset !is -1) {
208 Point oldPos = text.getLocationAtOffset(oldOffset);
209 int oldHeight = text.getLineHeight(oldOffset);
210 text.redraw (oldPos.x, oldPos.y, CARET_WIDTH, oldHeight, false);
211 }
212 if (newOffset !is -1) {
213 Point newPos = text.getLocationAtOffset(newOffset);
214 int newHeight = text.getLineHeight(newOffset);
215 text.redraw (newPos.x, newPos.y, CARET_WIDTH, newHeight, false);
216 }
217 }
218 }
219
220 /**
221 * This implementation of <code>dropAccept</code> provides a default drag under effect
222 * for the feedback specified in <code>event.feedback</code>.
223 *
224 * For additional information see <code>DropTargetAdapter.dropAccept</code>.
225 *
226 * Subclasses that override this method should call <code>super.dropAccept(event)</code>
227 * to get the default drag under effect implementation.
228 *
229 * @param event the information associated with the drop accept event
230 *
231 * @see DropTargetAdapter
232 * @see DropTargetEvent
233 */
234 public void dropAccept(DropTargetEvent event) {
235 if (currentOffset !is -1) {
236 StyledText text = (StyledText) getControl();
237 text.setSelection(currentOffset);
238 currentOffset = -1;
239 }
240 }
241 }