1 /*
2 * Copyright (c) 1999, 2018, 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 sun.awt;
27
28 import java.awt.Component;
29 import java.awt.Graphics;
30 import java.awt.Rectangle;
31 import java.awt.event.PaintEvent;
32
33 /**
34 * The {@code RepaintArea} is a geometric construct created for the
35 * purpose of holding the geometry of several coalesced paint events.
36 * This geometry is accessed synchronously, although it is written such
37 * that painting may still be executed asynchronously.
38 *
39 * @author Eric Hawkes
40 * @since 1.3
41 */
42 public class RepaintArea {
43
44 /**
45 * Maximum ratio of bounding rectangle to benefit for which
46 * both the vertical and horizontal unions are repainted.
47 * For smaller ratios the whole bounding rectangle is repainted.
48 * @see #paint
49 */
50 private static final int MAX_BENEFIT_RATIO = 4;
51
52 private static final int HORIZONTAL = 0;
53 private static final int VERTICAL = 1;
54 private static final int UPDATE = 2;
55
56 private static final int RECT_COUNT = UPDATE + 1;
57
58 private Rectangle[] paintRects = new Rectangle[RECT_COUNT];
59
60
61 /**
62 * Constructs a new {@code RepaintArea}
63 * @since 1.3
64 */
65 public RepaintArea() {
66 }
67
68 /**
69 * Constructs a new {@code RepaintArea} initialized to match
70 * the values of the specified RepaintArea.
71 *
72 * @param ra the {@code RepaintArea} from which to copy initial
73 * values to a newly constructed RepaintArea
74 * @since 1.3
75 */
76 private RepaintArea(RepaintArea ra) {
77 // This constructor is private because it should only be called
78 // from the cloneAndReset method
79 for (int i = 0; i < RECT_COUNT; i++) {
80 paintRects[i] = ra.paintRects[i];
81 }
82 }
83
84 /**
85 * Adds a {@code Rectangle} to this {@code RepaintArea}.
86 * PAINT Rectangles are divided into mostly vertical and mostly horizontal.
87 * Each group is unioned together.
88 * UPDATE Rectangles are unioned.
89 *
90 * @param r the specified {@code Rectangle}
91 * @param id possible values PaintEvent.UPDATE or PaintEvent.PAINT
92 * @since 1.3
93 */
94 public synchronized void add(Rectangle r, int id) {
95 // Make sure this new rectangle has positive dimensions
96 if (r.isEmpty()) {
97 return;
98 }
99 int addTo = UPDATE;
100 if (id == PaintEvent.PAINT) {
101 addTo = (r.width > r.height) ? HORIZONTAL : VERTICAL;
102 }
103 if (paintRects[addTo] != null) {
104 paintRects[addTo].add(r);
105 } else {
106 paintRects[addTo] = new Rectangle(r);
107 }
108 }
109
110
111 /**
112 * Creates a new {@code RepaintArea} with the same geometry as this
113 * RepaintArea, then removes all of the geometry from this
114 * RepaintArea and restores it to an empty RepaintArea.
115 *
116 * @return ra a new {@code RepaintArea} having the same geometry as
117 * this RepaintArea.
118 * @since 1.3
119 */
120 private synchronized RepaintArea cloneAndReset() {
121 RepaintArea ra = new RepaintArea(this);
122 for (int i = 0; i < RECT_COUNT; i++) {
123 paintRects[i] = null;
124 }
125 return ra;
126 }
127
128 public boolean isEmpty() {
129 for (int i = 0; i < RECT_COUNT; i++) {
130 if (paintRects[i] != null) {
131 return false;
132 }
133 }
134 return true;
135 }
136
137 /**
138 * Constrains the size of the repaint area to the passed in bounds.
139 */
140 public synchronized void constrain(int x, int y, int w, int h) {
141 for (int i = 0; i < RECT_COUNT; i++) {
142 Rectangle rect = paintRects[i];
143 if (rect != null) {
144 if (rect.x < x) {
145 rect.width -= (x - rect.x);
146 rect.x = x;
147 }
148 if (rect.y < y) {
149 rect.height -= (y - rect.y);
150 rect.y = y;
151 }
152 int xDelta = rect.x + rect.width - x - w;
153 if (xDelta > 0) {
154 rect.width -= xDelta;
155 }
156 int yDelta = rect.y + rect.height - y - h;
157 if (yDelta > 0) {
158 rect.height -= yDelta;
159 }
160 if (rect.width <= 0 || rect.height <= 0) {
161 paintRects[i] = null;
162 }
163 }
164 }
165 }
166
167 /**
168 * Marks the passed in region as not needing to be painted. It's possible
169 * this will do nothing.
170 */
171 public synchronized void subtract(int x, int y, int w, int h) {
172 Rectangle subtract = new Rectangle(x, y, w, h);
173 for (int i = 0; i < RECT_COUNT; i++) {
174 if (subtract(paintRects[i], subtract)) {
175 if (paintRects[i] != null && paintRects[i].isEmpty()) {
176 paintRects[i] = null;
177 }
178 }
179 }
180 }
181
182 /**
183 * Invokes paint and update on target Component with optimal
184 * rectangular clip region.
185 * If PAINT bounding rectangle is less than
186 * MAX_BENEFIT_RATIO times the benefit, then the vertical and horizontal unions are
187 * painted separately. Otherwise the entire bounding rectangle is painted.
188 *
189 * @param target Component to {@code paint} or {@code update}
190 * @since 1.4
191 */
192 public void paint(Object target, boolean shouldClearRectBeforePaint) {
193 Component comp = (Component)target;
194
195 if (isEmpty()) {
196 return;
197 }
198
199 if (!comp.isVisible()) {
200 return;
201 }
202
203 RepaintArea ra = this.cloneAndReset();
204
205 if (!subtract(ra.paintRects[VERTICAL], ra.paintRects[HORIZONTAL])) {
206 subtract(ra.paintRects[HORIZONTAL], ra.paintRects[VERTICAL]);
207 }
208
209 if (ra.paintRects[HORIZONTAL] != null && ra.paintRects[VERTICAL] != null) {
210 Rectangle paintRect = ra.paintRects[HORIZONTAL].union(ra.paintRects[VERTICAL]);
211 int square = paintRect.width * paintRect.height;
212 int benefit = square - ra.paintRects[HORIZONTAL].width
213 * ra.paintRects[HORIZONTAL].height - ra.paintRects[VERTICAL].width
214 * ra.paintRects[VERTICAL].height;
215 // if benefit is comparable with bounding box
216 if (MAX_BENEFIT_RATIO * benefit < square) {
217 ra.paintRects[HORIZONTAL] = paintRect;
218 ra.paintRects[VERTICAL] = null;
219 }
220 }
221 for (int i = 0; i < paintRects.length; i++) {
222 if (ra.paintRects[i] != null
223 && !ra.paintRects[i].isEmpty())
224 {
225 // Should use separate Graphics for each paint() call,
226 // since paint() can change Graphics state for next call.
227 Graphics g = comp.getGraphics();
228 if (g != null) {
229 try {
230 g.setClip(ra.paintRects[i]);
231 if (i == UPDATE) {
232 updateComponent(comp, g);
233 } else {
234 if (shouldClearRectBeforePaint) {
235 g.clearRect( ra.paintRects[i].x,
236 ra.paintRects[i].y,
237 ra.paintRects[i].width,
238 ra.paintRects[i].height);
239 }
240 paintComponent(comp, g);
241 }
242 } finally {
243 g.dispose();
244 }
245 }
246 }
247 }
248 }
249
250 /**
251 * Calls {@code Component.update(Graphics)} with given Graphics.
252 */
253 protected void updateComponent(Component comp, Graphics g) {
254 if (comp != null) {
255 comp.update(g);
256 }
257 }
258
259 /**
260 * Calls {@code Component.paint(Graphics)} with given Graphics.
261 */
262 protected void paintComponent(Component comp, Graphics g) {
263 if (comp != null) {
264 comp.paint(g);
265 }
266 }
267
268 /**
269 * Subtracts subtr from rect. If the result is rectangle
270 * changes rect and returns true. Otherwise false.
271 */
272 static boolean subtract(Rectangle rect, Rectangle subtr) {
273 if (rect == null || subtr == null) {
274 return true;
275 }
276 Rectangle common = rect.intersection(subtr);
277 if (common.isEmpty()) {
278 return true;
279 }
280 if (rect.x == common.x && rect.y == common.y) {
281 if (rect.width == common.width) {
282 rect.y += common.height;
283 rect.height -= common.height;
284 return true;
285 } else
286 if (rect.height == common.height) {
287 rect.x += common.width;
288 rect.width -= common.width;
289 return true;
290 }
291 } else
292 if (rect.x + rect.width == common.x + common.width
293 && rect.y + rect.height == common.y + common.height)
294 {
295 if (rect.width == common.width) {
296 rect.height -= common.height;
297 return true;
298 } else
299 if (rect.height == common.height) {
300 rect.width -= common.width;
301 return true;
302 }
303 }
304 return false;
305 }
306
307 public String toString() {
308 return super.toString() + "[ horizontal=" + paintRects[0] +
309 " vertical=" + paintRects[1] +
310 " update=" + paintRects[2] + "]";
311 }
312 }