1 /*
   2  * Copyright (c) 2016, 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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /*
  25  * @test
  26  * @bug     8139183
  27  * @summary Test verifies whether alpha channel of a translucent
  28  *          image is proper or not after scaling through drawImage.
  29  * @run     main ScaledImageAlphaTest
  30  */
  31 
  32 import java.awt.*;
  33 import java.awt.image.*;
  34 
  35 public class ScaledImageAlphaTest {
  36 
  37     public static void main(String[] args){
  38 
  39         int width = 50, height = 50;
  40         // create BufferedImage of dimension (50,50)
  41         BufferedImage img = new
  42             BufferedImage(width, height, BufferedImage.TYPE_INT_ARGB);
  43         Graphics2D imgGraphics = (Graphics2D)img.getGraphics();
  44 
  45         int scaleX = 5, scaleY = 5, scaleWidth = 40, scaleHeight = 40;
  46         int translucentAlpha = 128;
  47 
  48         /* scale image to smaller dimension and set background color
  49          * to green with translucent alpha.
  50          */
  51         Color translucentGreen = new Color(0, 255, 0, translucentAlpha);
  52         imgGraphics.
  53             drawImage(img, scaleX, scaleY, scaleWidth, scaleHeight,
  54                       translucentGreen, null);
  55         imgGraphics.dispose();
  56 
  57         /* get pixel information for background green color with
  58          * scaled coordinates and extract alpha.
  59          */
  60         Color c = new Color(img.getRGB(scaleX, scaleY), true);
  61         int alpha = c.getAlpha();
  62 
  63         /* if alpha value is translucent, alpha channel is not lost
  64          * while scaling otherwise we have lost alpha channel.
  65          */
  66         if(alpha != translucentAlpha) {
  67             throw new RuntimeException("Alpha channel is lost while scaling");
  68         }
  69     }
  70 }