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From-SVN: r102074

1 files changed, 164 insertions, 0 deletions

diff --git a/libjava/classpath/gnu/java/awt/GradientPaintContext.java b/libjava/classpath/gnu/java/awt/GradientPaintContext.java
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+/* GradientPaintContext.java -- 
+   Copyright (C) 2005, Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package gnu.java.awt;
+
+import java.awt.geom.Point2D;
+import java.awt.image.ColorModel;
+import java.awt.image.Raster;
+import java.awt.image.WritableRaster;
+import java.awt.PaintContext;
+import java.awt.Color;
+
+/**
+ * A {@link PaintContext} used by the {@link GradientPaint} class.
+ */
+public class GradientPaintContext implements PaintContext 
+{
+
+  // This implementation follows the technique described in 
+  // "Java(tm) 2D Graphics" by Jonathan Knudsen (O'Reilly 1999).
+    
+  /** The x-coordinate of the anchor point for color 1. */
+  private final float x1;
+    
+  /** The y-coordinate of the anchor point for color 1. */
+  private final float y1;
+    
+  /** Color 1. */
+  private final Color c1;
+    
+  /** The x-coordinate of the anchor point for color 2. */
+  private final float x2;
+    
+  /** The y-coordinate of the anchor point for color 2. */
+  private final float y2;
+    
+  /** Color 2. */
+  private final Color c2;
+    
+  /** A flag indicating whether the gradient is cyclic or acyclic. */
+  private final boolean cyclic;
+    
+  /** The length of the gradient line - computed from the two anchor points. */
+  private final double length; 
+
+  /**
+   * Creates a new instance.
+   * 
+   * @param x1  the x-coordinate for the anchor point for color 1.
+   * @param y1  the y-coordinate for the anchor point for color 1.
+   * @param c1  color 1.
+   * @param x2  the x-coordinate for the anchor point for color 2.
+   * @param y2  the y-coordinate for the anchor point for color 2.
+   * @param c2  color 2.
+   * @param cyclic  a flag that determines whether the gradient is cyclic
+   *                or acyclic.
+   */
+  public GradientPaintContext(float x1, float y1, Color c1, 
+                              float x2, float y2, Color c2, boolean cyclic) 
+  {     
+    this.x1 = x1;
+    this.y1 = y1;
+    this.c1 = c1;
+    this.x2 = x2;
+    this.y2 = y2;
+    this.c2 = c2;
+    this.cyclic = cyclic;
+    length = Point2D.distance(x1, y1, x2, y2);
+  }
+    
+  /**
+   * Return the color model of this context. It may be different from the
+   * hint specified during createContext, as not all contexts can generate
+   * color patterns in an arbitrary model.
+   *
+   * @return the context color model
+   */
+  public ColorModel getColorModel() 
+  {
+    return ColorModel.getRGBdefault();   
+  }
+
+  /**
+   * Return a raster containing the colors for the graphics operation.
+   *
+   * @param x the x-coordinate, in device space
+   * @param y the y-coordinate, in device space
+   * @param w the width, in device space
+   * @param h the height, in device space
+   * @return a raster for the given area and color
+   */
+  public Raster getRaster(int x, int y, int w, int h) {
+    ColorModel cm = getColorModel();
+    WritableRaster raster = cm.createCompatibleWritableRaster(w, h);
+    int[] data = new int[w * h * 4];
+    double pd2 = (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
+    for (int r = 0; r < h; r++) {
+      for (int c = 0; c < w; c++) {
+        double u = 0.0;
+        if (pd2 != 0) 
+          u = (((x + c) - x1) * (x2 - x1) + ((y + r) - y1) * (y2 - y1)) 
+                  / Math.sqrt(pd2);
+        double ratio = u / length;
+        if (cyclic)
+          ratio = Math.abs(ratio - Math.floor((ratio + 1.0) / 2.0) * 2.0);
+        else 
+          ratio = Math.max(0.0, Math.min(1.0, ratio));
+        int base = (r * w + c) * 4;
+        data[base] = (int) (c1.getRed() + ratio * (c2.getRed() - c1.getRed()));
+        data[base + 1] 
+          = (int) (c1.getGreen() + ratio * (c2.getGreen() - c1.getGreen()));
+        data[base + 2] 
+          = (int) (c1.getBlue() + ratio * (c2.getBlue() - c1.getBlue()));
+        data[base + 3] 
+          = (int) (c1.getAlpha() + ratio * (c2.getAlpha() - c1.getAlpha()));
+      }
+    }
+    raster.setPixels(0, 0, w, h, data);
+    return raster;
+  }
+
+  /**
+   * Release the resources allocated for the paint (none in this 
+   * implementation).
+   */
+  public void dispose() {
+    // nothing to do    
+  }
+    
+}