1 /*
   2  * Copyright (c) 1997, 2007, 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 java.awt;
  27 
  28 import java.awt.image.Raster;
  29 import sun.awt.image.IntegerComponentRaster;
  30 import java.awt.image.ColorModel;
  31 import java.awt.image.DirectColorModel;
  32 import java.awt.geom.Point2D;
  33 import java.awt.geom.AffineTransform;
  34 import java.awt.geom.NoninvertibleTransformException;
  35 import java.lang.ref.WeakReference;
  36 
  37 class GradientPaintContext implements PaintContext {
  38     static ColorModel xrgbmodel =
  39         new DirectColorModel(24, 0x00ff0000, 0x0000ff00, 0x000000ff);
  40     static ColorModel xbgrmodel =
  41         new DirectColorModel(24, 0x000000ff, 0x0000ff00, 0x00ff0000);
  42 
  43     static ColorModel cachedModel;
  44     static WeakReference cached;
  45 
  46     static synchronized Raster getCachedRaster(ColorModel cm, int w, int h) {
  47         if (cm == cachedModel) {
  48             if (cached != null) {
  49                 Raster ras = (Raster) cached.get();
  50                 if (ras != null &&
  51                     ras.getWidth() >= w &&
  52                     ras.getHeight() >= h)
  53                 {
  54                     cached = null;
  55                     return ras;
  56                 }
  57             }
  58         }
  59         return cm.createCompatibleWritableRaster(w, h);
  60     }
  61 
  62     static synchronized void putCachedRaster(ColorModel cm, Raster ras) {
  63         if (cached != null) {
  64             Raster cras = (Raster) cached.get();
  65             if (cras != null) {
  66                 int cw = cras.getWidth();
  67                 int ch = cras.getHeight();
  68                 int iw = ras.getWidth();
  69                 int ih = ras.getHeight();
  70                 if (cw >= iw && ch >= ih) {
  71                     return;
  72                 }
  73                 if (cw * ch >= iw * ih) {
  74                     return;
  75                 }
  76             }
  77         }
  78         cachedModel = cm;
  79         cached = new WeakReference(ras);
  80     }
  81 
  82     double x1;
  83     double y1;
  84     double dx;
  85     double dy;
  86     boolean cyclic;
  87     int interp[];
  88     Raster saved;
  89     ColorModel model;
  90 
  91     public GradientPaintContext(ColorModel cm,
  92                                 Point2D p1, Point2D p2, AffineTransform xform,
  93                                 Color c1, Color c2, boolean cyclic) {
  94         // First calculate the distance moved in user space when
  95         // we move a single unit along the X & Y axes in device space.
  96         Point2D xvec = new Point2D.Double(1, 0);
  97         Point2D yvec = new Point2D.Double(0, 1);
  98         try {
  99             AffineTransform inverse = xform.createInverse();
 100             inverse.deltaTransform(xvec, xvec);
 101             inverse.deltaTransform(yvec, yvec);
 102         } catch (NoninvertibleTransformException e) {
 103             xvec.setLocation(0, 0);
 104             yvec.setLocation(0, 0);
 105         }
 106 
 107         // Now calculate the (square of the) user space distance
 108         // between the anchor points. This value equals:
 109         //     (UserVec . UserVec)
 110         double udx = p2.getX() - p1.getX();
 111         double udy = p2.getY() - p1.getY();
 112         double ulenSq = udx * udx + udy * udy;
 113 
 114         if (ulenSq <= Double.MIN_VALUE) {
 115             dx = 0;
 116             dy = 0;
 117         } else {
 118             // Now calculate the proportional distance moved along the
 119             // vector from p1 to p2 when we move a unit along X & Y in
 120             // device space.
 121             //
 122             // The length of the projection of the Device Axis Vector is
 123             // its dot product with the Unit User Vector:
 124             //     (DevAxisVec . (UserVec / Len(UserVec))
 125             //
 126             // The "proportional" length is that length divided again
 127             // by the length of the User Vector:
 128             //     (DevAxisVec . (UserVec / Len(UserVec))) / Len(UserVec)
 129             // which simplifies to:
 130             //     ((DevAxisVec . UserVec) / Len(UserVec)) / Len(UserVec)
 131             // which simplifies to:
 132             //     (DevAxisVec . UserVec) / LenSquared(UserVec)
 133             dx = (xvec.getX() * udx + xvec.getY() * udy) / ulenSq;
 134             dy = (yvec.getX() * udx + yvec.getY() * udy) / ulenSq;
 135 
 136             if (cyclic) {
 137                 dx = dx % 1.0;
 138                 dy = dy % 1.0;
 139             } else {
 140                 // We are acyclic
 141                 if (dx < 0) {
 142                     // If we are using the acyclic form below, we need
 143                     // dx to be non-negative for simplicity of scanning
 144                     // across the scan lines for the transition points.
 145                     // To ensure that constraint, we negate the dx/dy
 146                     // values and swap the points and colors.
 147                     Point2D p = p1; p1 = p2; p2 = p;
 148                     Color c = c1; c1 = c2; c2 = c;
 149                     dx = -dx;
 150                     dy = -dy;
 151                 }
 152             }
 153         }
 154 
 155         Point2D dp1 = xform.transform(p1, null);
 156         this.x1 = dp1.getX();
 157         this.y1 = dp1.getY();
 158 
 159         this.cyclic = cyclic;
 160         int rgb1 = c1.getRGB();
 161         int rgb2 = c2.getRGB();
 162         int a1 = (rgb1 >> 24) & 0xff;
 163         int r1 = (rgb1 >> 16) & 0xff;
 164         int g1 = (rgb1 >>  8) & 0xff;
 165         int b1 = (rgb1      ) & 0xff;
 166         int da = ((rgb2 >> 24) & 0xff) - a1;
 167         int dr = ((rgb2 >> 16) & 0xff) - r1;
 168         int dg = ((rgb2 >>  8) & 0xff) - g1;
 169         int db = ((rgb2      ) & 0xff) - b1;
 170         if (a1 == 0xff && da == 0) {
 171             model = xrgbmodel;
 172             if (cm instanceof DirectColorModel) {
 173                 DirectColorModel dcm = (DirectColorModel) cm;
 174                 int tmp = dcm.getAlphaMask();
 175                 if ((tmp == 0 || tmp == 0xff) &&
 176                     dcm.getRedMask() == 0xff &&
 177                     dcm.getGreenMask() == 0xff00 &&
 178                     dcm.getBlueMask() == 0xff0000)
 179                 {
 180                     model = xbgrmodel;
 181                     tmp = r1; r1 = b1; b1 = tmp;
 182                     tmp = dr; dr = db; db = tmp;
 183                 }
 184             }
 185         } else {
 186             model = ColorModel.getRGBdefault();
 187         }
 188         interp = new int[cyclic ? 513 : 257];
 189         for (int i = 0; i <= 256; i++) {
 190             float rel = i / 256.0f;
 191             int rgb =
 192                 (((int) (a1 + da * rel)) << 24) |
 193                 (((int) (r1 + dr * rel)) << 16) |
 194                 (((int) (g1 + dg * rel)) <<  8) |
 195                 (((int) (b1 + db * rel))      );
 196             interp[i] = rgb;
 197             if (cyclic) {
 198                 interp[512 - i] = rgb;
 199             }
 200         }
 201     }
 202 
 203     /**
 204      * Release the resources allocated for the operation.
 205      */
 206     public void dispose() {
 207         if (saved != null) {
 208             putCachedRaster(model, saved);
 209             saved = null;
 210         }
 211     }
 212 
 213     /**
 214      * Return the ColorModel of the output.
 215      */
 216     public ColorModel getColorModel() {
 217         return model;
 218     }
 219 
 220     /**
 221      * Return a Raster containing the colors generated for the graphics
 222      * operation.
 223      * @param x,y,w,h The area in device space for which colors are
 224      * generated.
 225      */
 226     public Raster getRaster(int x, int y, int w, int h) {
 227         double rowrel = (x - x1) * dx + (y - y1) * dy;
 228 
 229         Raster rast = saved;
 230         if (rast == null || rast.getWidth() < w || rast.getHeight() < h) {
 231             rast = getCachedRaster(model, w, h);
 232             saved = rast;
 233         }
 234         IntegerComponentRaster irast = (IntegerComponentRaster) rast;
 235         int off = irast.getDataOffset(0);
 236         int adjust = irast.getScanlineStride() - w;
 237         int[] pixels = irast.getDataStorage();
 238 
 239         if (cyclic) {
 240             cycleFillRaster(pixels, off, adjust, w, h, rowrel, dx, dy);
 241         } else {
 242             clipFillRaster(pixels, off, adjust, w, h, rowrel, dx, dy);
 243         }
 244 
 245         irast.markDirty();
 246 
 247         return rast;
 248     }
 249 
 250     void cycleFillRaster(int[] pixels, int off, int adjust, int w, int h,
 251                          double rowrel, double dx, double dy) {
 252         rowrel = rowrel % 2.0;
 253         int irowrel = ((int) (rowrel * (1 << 30))) << 1;
 254         int idx = (int) (-dx * (1 << 31));
 255         int idy = (int) (-dy * (1 << 31));
 256         while (--h >= 0) {
 257             int icolrel = irowrel;
 258             for (int j = w; j > 0; j--) {
 259                 pixels[off++] = interp[icolrel >>> 23];
 260                 icolrel += idx;
 261             }
 262 
 263             off += adjust;
 264             irowrel += idy;
 265         }
 266     }
 267 
 268     void clipFillRaster(int[] pixels, int off, int adjust, int w, int h,
 269                         double rowrel, double dx, double dy) {
 270         while (--h >= 0) {
 271             double colrel = rowrel;
 272             int j = w;
 273             if (colrel <= 0.0) {
 274                 int rgb = interp[0];
 275                 do {
 276                     pixels[off++] = rgb;
 277                     colrel += dx;
 278                 } while (--j > 0 && colrel <= 0.0);
 279             }
 280             while (colrel < 1.0 && --j >= 0) {
 281                 pixels[off++] = interp[(int) (colrel * 256)];
 282                 colrel += dx;
 283             }
 284             if (j > 0) {
 285                 int rgb = interp[256];
 286                 do {
 287                     pixels[off++] = rgb;
 288                 } while (--j > 0);
 289             }
 290 
 291             off += adjust;
 292             rowrel += dy;
 293         }
 294     }
 295 }