src/java.desktop/share/classes/java/awt/image/IndexColorModel.java

*** 26,35 ****
--- 26,37 ----
  package java.awt.image;
  
  import java.awt.Transparency;
  import java.awt.color.ColorSpace;
  import java.math.BigInteger;
+ import java.util.Arrays;
+ import java.util.Objects;
  
  /**
   * The {@code IndexColorModel} class is a {@code ColorModel}
   * class that works with pixel values consisting of a
   * single sample that is an index into a fixed colormap in the default
*** 127,136 ****
--- 129,139 ----
      private int map_size;
      private int pixel_mask;
      private int transparent_index = -1;
      private boolean allgrayopaque;
      private BigInteger validBits;
+     private volatile int hashCode;
  
      private sun.awt.image.BufImgSurfaceData.ICMColorData colorData = null;
  
      private static int[] opaqueBits = {8, 8, 8};
      private static int[] alphaBits = {8, 8, 8, 8};
*** 1530,1535 ****
--- 1533,1624 ----
                           + " transIndex   = "+transparent_index
                           + " has alpha = "+supportsAlpha
                           + " isAlphaPre = "+isAlphaPremultiplied
                           );
      }
+ 
+     /**
+      * Tests if the specified {@code Object} equals this
+      * {@code IndexColorModel}.
+      * In order to protect the symmetry property of
+      * {@code (a.equals(b) == b.equals(a))},
+      * the target object must be the same class(and not a subclass)
+      * as this object to evaluate as {equals}.
+      * <p>
+      * To verify equality we also check following properties:
+      *
+      * <ul>
+      * <li>ColorMap size.
+      * <li>Index of a transparent pixel in {@code IndexColorModel}
+      * <li>ColorMap values.
+      * <li>Valid bits of ColorMap.
+      * </ul>
+      * <p>
+      * @param obj the {@code Object} to test for equality
+      * @return {@code true} if the specified {@code Object}
+      * equals this {@code IndexColorModel}; {@code false} otherwise.
+      */
+     @Override
+     public boolean equals(Object obj) {
+         /*
+          * We verify the type of argument obj in super.equals() where we check
+          * for equality of class name.
+          */
+         if (!super.equals(obj)) {
+             return false;
+         }
+ 
+         IndexColorModel cm = (IndexColorModel) obj;
+         if (map_size != cm.map_size ||
+             transparent_index != cm.transparent_index)
+         {
+             return false;
+         }
+ 
+         // verify whether we have to check equality of all bits in validBits
+         boolean testValidBits;
+         if (validBits == cm.validBits) {
+             testValidBits = false;
+         } else if (validBits == null || cm.validBits == null) {
+             return false;
+         } else if (validBits.equals(cm.validBits)) {
+             testValidBits = false;
+         } else {
+             testValidBits = true;
+         }
+ 
+         if (testValidBits) {
+             for (int i = 0; i < map_size; i++) {
+                 if (rgb[i] != cm.rgb[i] ||
+                     validBits.testBit(i) != cm.validBits.testBit(i))
+                 {
+                     return false;
+                 }
+             }
+         } else {
+             for (int i = 0; i < map_size; i++) {
+                 if (rgb[i] != cm.rgb[i]) {
+                     return false;
+                 }
+             }
+         }
+         return true;
+     }
+ 
+     /**
+      * Returns the hash code for IndexColorModel.
+      *
+      * @return    a hash code for IndexColorModel
+      */
+     @Override
+     public int hashCode() {
+         int result = hashCode;
+         if (result == 0) {
+             result = super.hashCode();
+             result = 43 * result + Arrays.hashCode(this.rgb);
+             result = 43 * result + this.map_size;
+             result = 43 * result + this.transparent_index;
+             hashCode = result;
+         }
+         return result;
+     }
  }