Source for java.awt.GradientPaint

   1: /* GradientPaint.java -- 
   2:    Copyright (C) 2002, 2005, Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package java.awt;
  40: 
  41: import java.awt.geom.AffineTransform;
  42: import java.awt.geom.Point2D;
  43: import java.awt.geom.Rectangle2D;
  44: import java.awt.image.ColorModel;
  45: import gnu.java.awt.GradientPaintContext;
  46: 
  47: /**
  48:  * A paint object that can be used to color a region by blending two colors. 
  49:  * Instances of this class are immutable.
  50:  */
  51: public class GradientPaint implements Paint
  52: {
  53:   private final float x1;
  54:   private final float y1;
  55:   private final Color c1;
  56:   private final float x2;
  57:   private final float y2;
  58:   private final Color c2;
  59:   private final boolean cyclic;
  60: 
  61:   /**
  62:    * Creates a new acyclic <code>GradientPaint</code>.
  63:    * 
  64:    * @param x1  the x-coordinate of the anchor point for color 1.
  65:    * @param y1  the y-coordinate of the anchor point for color 1.
  66:    * @param c1  color 1 (<code>null</code> not permitted).
  67:    * @param x2  the x-coordinate of the anchor point for color 2.
  68:    * @param y2  the y-coordinate of the anchor point for color 2.
  69:    * @param c2  the second color (<code>null</code> not permitted).
  70:    */
  71:   public GradientPaint(float x1, float y1, Color c1,
  72:                        float x2, float y2, Color c2)
  73:   {
  74:     this(x1, y1, c1, x2, y2, c2, false);
  75:   }
  76: 
  77:   /**
  78:    * Creates a new acyclic <code>GradientPaint</code>.
  79:    * 
  80:    * @param p1  anchor point 1 (<code>null</code> not permitted).
  81:    * @param c1  color 1 (<code>null</code> not permitted).
  82:    * @param p2  anchor point 2 (<code>null</code> not permitted).
  83:    * @param c2  color 2 (<code>null</code> not permitted).
  84:    */
  85:   public GradientPaint(Point2D p1, Color c1, Point2D p2, Color c2)
  86:   {
  87:     this((float) p1.getX(), (float) p1.getY(), c1,
  88:          (float) p2.getX(), (float) p2.getY(), c2, false);
  89:   }
  90: 
  91:   /**
  92:    * Creates a new cyclic or acyclic <code>GradientPaint</code>.
  93:    * 
  94:    * @param x1  the x-coordinate of the anchor point for color 1.
  95:    * @param y1  the y-coordinate of the anchor point for color 1.
  96:    * @param c1  color 1 (<code>null</code> not permitted).
  97:    * @param x2  the x-coordinate of the anchor point for color 2.
  98:    * @param y2  the y-coordinate of the anchor point for color 2.
  99:    * @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