001: /*
002: * Copyright 1997-2002 Sun Microsystems, Inc. All Rights Reserved.
003: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004: *
005: * This code is free software; you can redistribute it and/or modify it
006: * under the terms of the GNU General Public License version 2 only, as
007: * published by the Free Software Foundation. Sun designates this
008: * particular file as subject to the "Classpath" exception as provided
009: * by Sun in the LICENSE file that accompanied this code.
010: *
011: * This code is distributed in the hope that it will be useful, but WITHOUT
012: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014: * version 2 for more details (a copy is included in the LICENSE file that
015: * accompanied this code).
016: *
017: * You should have received a copy of the GNU General Public License version
018: * 2 along with this work; if not, write to the Free Software Foundation,
019: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020: *
021: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022: * CA 95054 USA or visit www.sun.com if you need additional information or
023: * have any questions.
024: */
025:
026: package java.awt;
027:
028: import java.awt.geom.Point2D;
029: import java.awt.geom.Rectangle2D;
030: import java.awt.geom.AffineTransform;
031: import java.awt.image.ColorModel;
032:
033: /**
034: * The <code>GradientPaint</code> class provides a way to fill
035: * a {@link Shape} with a linear color gradient pattern.
036: * If {@link Point} P1 with {@link Color} C1 and <code>Point</code> P2 with
037: * <code>Color</code> C2 are specified in user space, the
038: * <code>Color</code> on the P1, P2 connecting line is proportionally
039: * changed from C1 to C2. Any point P not on the extended P1, P2
040: * connecting line has the color of the point P' that is the perpendicular
041: * projection of P on the extended P1, P2 connecting line.
042: * Points on the extended line outside of the P1, P2 segment can be colored
043: * in one of two ways.
044: * <ul>
045: * <li>
046: * If the gradient is cyclic then the points on the extended P1, P2
047: * connecting line cycle back and forth between the colors C1 and C2.
048: * <li>
049: * If the gradient is acyclic then points on the P1 side of the segment
050: * have the constant <code>Color</code> C1 while points on the P2 side
051: * have the constant <code>Color</code> C2.
052: * </ul>
053: *
054: * @see Paint
055: * @see Graphics2D#setPaint
056: * @version 10 Feb 1997
057: */
058:
059: public class GradientPaint implements Paint {
060: Point2D.Float p1;
061: Point2D.Float p2;
062: Color color1;
063: Color color2;
064: boolean cyclic;
065:
066: /**
067: * Constructs a simple acyclic <code>GradientPaint</code> object.
068: * @param x1 x coordinate of the first specified
069: * <code>Point</code> in user space
070: * @param y1 y coordinate of the first specified
071: * <code>Point</code> in user space
072: * @param color1 <code>Color</code> at the first specified
073: * <code>Point</code>
074: * @param x2 x coordinate of the second specified
075: * <code>Point</code> in user space
076: * @param y2 y coordinate of the second specified
077: * <code>Point</code> in user space
078: * @param color2 <code>Color</code> at the second specified
079: * <code>Point</code>
080: * @throws NullPointerException if either one of colors is null
081: */
082: public GradientPaint(float x1, float y1, Color color1, float x2,
083: float y2, Color color2) {
084: if ((color1 == null) || (color2 == null)) {
085: throw new NullPointerException("Colors cannot be null");
086: }
087:
088: p1 = new Point2D.Float(x1, y1);
089: p2 = new Point2D.Float(x2, y2);
090: this .color1 = color1;
091: this .color2 = color2;
092: }
093:
094: /**
095: * Constructs a simple acyclic <code>GradientPaint</code> object.
096: * @param pt1 the first specified <code>Point</code> in user space
097: * @param color1 <code>Color</code> at the first specified
098: * <code>Point</code>
099: * @param pt2 the second specified <code>Point</code> in user space
100: * @param color2 <code>Color</code> at the second specified
101: * <code>Point</code>
102: * @throws NullPointerException if either one of colors or points
103: * is null
104: */
105: public GradientPaint(Point2D pt1, Color color1, Point2D pt2,
106: Color color2) {
107: if ((color1 == null) || (color2 == null) || (pt1 == null)
108: || (pt2 == null)) {
109: throw new NullPointerException(
110: "Colors and points should be non-null");
111: }
112:
113: p1 = new Point2D.Float((float) pt1.getX(), (float) pt1.getY());
114: p2 = new Point2D.Float((float) pt2.getX(), (float) pt2.getY());
115: this .color1 = color1;
116: this .color2 = color2;
117: }
118:
119: /**
120: * Constructs either a cyclic or acyclic <code>GradientPaint</code>
121: * object depending on the <code>boolean</code> parameter.
122: * @param x1 x coordinate of the first specified
123: * <code>Point</code> in user space
124: * @param y1 y coordinate of the first specified
125: * <code>Point</code> in user space
126: * @param color1 <code>Color</code> at the first specified
127: * <code>Point</code>
128: * @param x2 x coordinate of the second specified
129: * <code>Point</code> in user space
130: * @param y2 y coordinate of the second specified
131: * <code>Point</code> in user space
132: * @param color2 <code>Color</code> at the second specified
133: * <code>Point</code>
134: * @param cyclic <code>true</code> if the gradient pattern should cycle
135: * repeatedly between the two colors; <code>false</code> otherwise
136: */
137: public GradientPaint(float x1, float y1, Color color1, float x2,
138: float y2, Color color2, boolean cyclic) {
139: this (x1, y1, color1, x2, y2, color2);
140: this .cyclic = cyclic;
141: }
142:
143: /**
144: * Constructs either a cyclic or acyclic <code>GradientPaint</code>
145: * object depending on the <code>boolean</code> parameter.
146: * @param pt1 the first specified <code>Point</code>
147: * in user space
148: * @param color1 <code>Color</code> at the first specified
149: * <code>Point</code>
150: * @param pt2 the second specified <code>Point</code>
151: * in user space
152: * @param color2 <code>Color</code> at the second specified
153: * <code>Point</code>
154: * @param cyclic <code>true</code> if the gradient pattern should cycle
155: * repeatedly between the two colors; <code>false</code> otherwise
156: * @throws NullPointerException if either one of colors or points
157: * is null
158: */
159: public GradientPaint(Point2D pt1, Color color1, Point2D pt2,
160: Color color2, boolean cyclic) {
161: this (pt1, color1, pt2, color2);
162: this .cyclic = cyclic;
163: }
164:
165: /**
166: * Returns a copy of the point P1 that anchors the first color.
167: * @return a {@link Point2D} object that is a copy of the point
168: * that anchors the first color of this
169: * <code>GradientPaint</code>.
170: */
171: public Point2D getPoint1() {
172: return new Point2D.Float(p1.x, p1.y);
173: }
174:
175: /**
176: * Returns the color C1 anchored by the point P1.
177: * @return a <code>Color</code> object that is the color
178: * anchored by P1.
179: */
180: public Color getColor1() {
181: return color1;
182: }
183:
184: /**
185: * Returns a copy of the point P2 which anchors the second color.
186: * @return a {@link Point2D} object that is a copy of the point
187: * that anchors the second color of this
188: * <code>GradientPaint</code>.
189: */
190: public Point2D getPoint2() {
191: return new Point2D.Float(p2.x, p2.y);
192: }
193:
194: /**
195: * Returns the color C2 anchored by the point P2.
196: * @return a <code>Color</code> object that is the color
197: * anchored by P2.
198: */
199: public Color getColor2() {
200: return color2;
201: }
202:
203: /**
204: * Returns <code>true</code> if the gradient cycles repeatedly
205: * between the two colors C1 and C2.
206: * @return <code>true</code> if the gradient cycles repeatedly
207: * between the two colors; <code>false</code> otherwise.
208: */
209: public boolean isCyclic() {
210: return cyclic;
211: }
212:
213: /**
214: * Creates and returns a context used to generate the color pattern.
215: * @param cm {@link ColorModel} that receives
216: * the <code>Paint</code> data. This is used only as a hint.
217: * @param deviceBounds the device space bounding box of the
218: * graphics primitive being rendered
219: * @param userBounds the user space bounding box of the
220: * graphics primitive being rendered
221: * @param xform the {@link AffineTransform} from user
222: * space into device space
223: * @param hints the hints that the context object uses to choose
224: * between rendering alternatives
225: * @return the {@link PaintContext} that generates color patterns.
226: * @see PaintContext
227: */
228: public PaintContext createContext(ColorModel cm,
229: Rectangle deviceBounds, Rectangle2D userBounds,
230: AffineTransform xform, RenderingHints hints) {
231:
232: return new GradientPaintContext(cm, p1, p2, xform, color1,
233: color2, cyclic);
234: }
235:
236: /**
237: * Returns the transparency mode for this <code>GradientPaint</code>.
238: * @return an integer value representing this <code>GradientPaint</code>
239: * object's transparency mode.
240: * @see Transparency
241: */
242: public int getTransparency() {
243: int a1 = color1.getAlpha();
244: int a2 = color2.getAlpha();
245: return (((a1 & a2) == 0xff) ? OPAQUE : TRANSLUCENT);
246: }
247:
248: }
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