001 /* GradientPaint.java --
002 Copyright (C) 2002, 2005, Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt;
040
041 import java.awt.geom.AffineTransform;
042 import java.awt.geom.Point2D;
043 import java.awt.geom.Rectangle2D;
044 import java.awt.image.ColorModel;
045 import gnu.java.awt.GradientPaintContext;
046
047 /**
048 * A paint object that can be used to color a region by blending two colors.
049 * Instances of this class are immutable.
050 */
051 public class GradientPaint implements Paint
052 {
053 private final float x1;
054 private final float y1;
055 private final Color c1;
056 private final float x2;
057 private final float y2;
058 private final Color c2;
059 private final boolean cyclic;
060
061 /**
062 * Creates a new acyclic <code>GradientPaint</code>.
063 *
064 * @param x1 the x-coordinate of the anchor point for color 1.
065 * @param y1 the y-coordinate of the anchor point for color 1.
066 * @param c1 color 1 (<code>null</code> not permitted).
067 * @param x2 the x-coordinate of the anchor point for color 2.
068 * @param y2 the y-coordinate of the anchor point for color 2.
069 * @param c2 the second color (<code>null</code> not permitted).
070 */
071 public GradientPaint(float x1, float y1, Color c1,
072 float x2, float y2, Color c2)
073 {
074 this(x1, y1, c1, x2, y2, c2, false);
075 }
076
077 /**
078 * Creates a new acyclic <code>GradientPaint</code>.
079 *
080 * @param p1 anchor point 1 (<code>null</code> not permitted).
081 * @param c1 color 1 (<code>null</code> not permitted).
082 * @param p2 anchor point 2 (<code>null</code> not permitted).
083 * @param c2 color 2 (<code>null</code> not permitted).
084 */
085 public GradientPaint(Point2D p1, Color c1, Point2D p2, Color c2)
086 {
087 this((float) p1.getX(), (float) p1.getY(), c1,
088 (float) p2.getX(), (float) p2.getY(), c2, false);
089 }
090
091 /**
092 * Creates a new cyclic or acyclic <code>GradientPaint</code>.
093 *
094 * @param x1 the x-coordinate of the anchor point for color 1.
095 * @param y1 the y-coordinate of the anchor point for color 1.
096 * @param c1 color 1 (<code>null</code> not permitted).
097 * @param x2 the x-coordinate of the anchor point for color 2.
098 * @param y2 the y-coordinate of the anchor point for color 2.
099 * @param c2 the second color (<code>null</code> not permitted).
100 * @param cyclic a flag that controls whether the gradient is cyclic or
101 * acyclic.
102 */
103 public GradientPaint(float x1, float y1, Color c1,
104 float x2, float y2, Color c2, boolean cyclic)
105 {
106 if (c1 == null || c2 == null)
107 throw new NullPointerException();
108 this.x1 = x1;
109 this.y1 = y1;
110 this.c1 = c1;
111 this.x2 = x2;
112 this.y2 = y2;
113 this.c2 = c2;
114 this.cyclic = cyclic;
115 }
116
117 /**
118 * Creates a new cyclic or acyclic <code>GradientPaint</code>.
119 *
120 * @param p1 anchor point 1 (<code>null</code> not permitted).
121 * @param c1 color 1 (<code>null</code> not permitted).
122 * @param p2 anchor point 2 (<code>null</code> not permitted).
123 * @param c2 color 2 (<code>null</code> not permitted).
124 * @param cyclic a flag that controls whether the gradient is cyclic or
125 * acyclic.
126 */
127 public GradientPaint(Point2D p1, Color c1, Point2D p2, Color c2,
128 boolean cyclic)
129 {
130 this((float) p1.getX(), (float) p1.getY(), c1,
131 (float) p2.getX(), (float) p2.getY(), c2, cyclic);
132 }
133
134 /**
135 * Returns a point with the same coordinates as the anchor point for color 1.
136 * Note that if you modify this point, the <code>GradientPaint</code> remains
137 * unchanged.
138 *
139 * @return A point with the same coordinates as the anchor point for color 1.
140 */
141 public Point2D getPoint1()
142 {
143 return new Point2D.Float(x1, y1);
144 }
145
146 /**
147 * Returns the first color.
148 *
149 * @return The color (never <code>null</code>).
150 */
151 public Color getColor1()
152 {
153 return c1;
154 }
155
156 /**
157 * Returns a point with the same coordinates as the anchor point for color 2.
158 * Note that if you modify this point, the <code>GradientPaint</code> remains
159 * unchanged.
160 *
161 * @return A point with the same coordinates as the anchor point for color 2.
162 */
163 public Point2D getPoint2()
164 {
165 return new Point2D.Float(x2, y2);
166 }
167
168 /**
169 * Returns the second color.
170 *
171 * @return The color (never <code>null</code>).
172 */
173 public Color getColor2()
174 {
175 return c2;
176 }
177
178 /**
179 * Returns <code>true</code> if this <code>GradientPaint</code> instance is
180 * cyclic, and <code>false</code> otherwise.
181 *
182 * @return A boolean.
183 */
184 public boolean isCyclic()
185 {
186 return cyclic;
187 }
188
189 /**
190 * Returns the {@link PaintContext} used to generate the color pattern.
191 *
192 * @param cm the color model, used as a hint (ignored in this
193 * implementation).
194 * @param deviceBounds the device space bounding box of the painted area.
195 * @param userBounds the user space bounding box of the painted area.
196 * @param xform the transformation from user space to device space.
197 * @param hints any hints for choosing between rendering alternatives.
198 *
199 * @return The context for performing the paint
200 */
201 public PaintContext createContext(ColorModel cm, Rectangle deviceBounds,
202 Rectangle2D userBounds,
203 AffineTransform xform,
204 RenderingHints hints)
205 {
206 Point2D xp1 = xform.transform(getPoint1(), null);
207 Point2D xp2 = xform.transform(getPoint2(), null);
208 return new GradientPaintContext((float) xp1.getX(), (float) xp1.getY(), c1,
209 (float) xp2.getX(), (float) xp2.getY(), c2, cyclic);
210 }
211
212 /**
213 * Returns the transparency code for this <code>GradientPaint</code> instance.
214 * This is derived from the two {@link Color} objects used in creating this
215 * object: if both colors are opaque, this method returns
216 * {@link Transparency#OPAQUE}, otherwise it returns
217 * {@link Transparency#TRANSLUCENT}.
218 *
219 * @return {@link Transparency#OPAQUE} or {@link Transparency#TRANSLUCENT}.
220 */
221 public int getTransparency()
222 {
223 if (c1.getAlpha() == 255 && c2.getAlpha() == 255)
224 return Transparency.OPAQUE;
225 else
226 return Transparency.TRANSLUCENT;
227 }
228
229 } // class GradientPaint