2006-03-31 Thomas Fitzsimmons <fitzsim@redhat.com>

	* javax/imageio/plugins/jpeg/JPEGHuffmanTable.java: Eliminate
	unnecessary copying.
	* javax/imageio/plugins/jpeg/JPEGQTable.java: Likewise.

2 files changed, 77 insertions, 34 deletions

diff --git a/javax/imageio/plugins/jpeg/JPEGHuffmanTable.java b/javax/imageio/plugins/jpeg/JPEGHuffmanTable.java
index 39e2ebd32..c0567be78 100644
--- a/javax/imageio/plugins/jpeg/JPEGHuffmanTable.java
+++ b/javax/imageio/plugins/jpeg/JPEGHuffmanTable.java
@@ -55,6 +55,8 @@ public class JPEGHuffmanTable
    */
   private short[] values;
 
+  // The private constructors are used for these final fields to avoid
+  // unnecessary copying.
   /**
    * The standard JPEG AC chrominance Huffman table.
    */
@@ -93,7 +95,7 @@ public class JPEGHuffmanTable
                                           0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
                                           0xe8, 0xe9, 0xea, 0xf2, 0xf3,
                                           0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
-                                          0xf9, 0xfa });
+                                          0xf9, 0xfa }, false);
 
   /**
    * The standard JPEG AC luminance Huffman table.
@@ -133,7 +135,7 @@ public class JPEGHuffmanTable
                                          0xe4, 0xe5, 0xe6, 0xe7, 0xe8,
                                          0xe9, 0xea, 0xf1, 0xf2, 0xf3,
                                          0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
-                                         0xf9, 0xfa });
+                                         0xf9, 0xfa }, false);
 
   /**
    * The standard JPEG DC chrominance Huffman table.
@@ -142,7 +144,7 @@ public class JPEGHuffmanTable
       new JPEGHuffmanTable(new short[] { 0, 3, 1, 1, 1, 1, 1, 1, 1, 1,
                                          1, 0, 0, 0, 0, 0 },
                            new short[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
-                                         10, 11 });
+                                         10, 11 }, false);
 
   /**
    * The standard JPEG DC luminance Huffman table.
@@ -151,7 +153,7 @@ public class JPEGHuffmanTable
       new JPEGHuffmanTable(new short[] { 0, 1, 5, 1, 1, 1, 1, 1, 1, 0,
                                          0, 0, 0, 0, 0, 0 },
                            new short[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
-                                         10, 11 });
+                                         10, 11 }, false);
 
   /**
    * Construct and initialize a Huffman table. Copies are created of
@@ -168,9 +170,28 @@ public class JPEGHuffmanTable
    */
   public JPEGHuffmanTable(short[] lengths, short[] values)
   {
-    if (lengths == null || values == null || lengths.length > 16
-        || values.length > 256)
-      throw new IllegalArgumentException("invalid length or values array");
+    // Create copies of the lengths and values arguments.
+    this(checkLengths(lengths), checkValues(values, lengths), true);
+  }
+
+  /**
+   * Private constructor that avoids unnecessary copying and argument
+   * checking.
+   *
+   * @param lengths an array of Huffman code lengths
+   * @param values a sorted array of Huffman values
+   * @param copy true if copies should be created of the given arrays
+   */
+  private JPEGHuffmanTable(short[] lengths, short[] values, boolean copy)
+  {
+    this.lengths = copy ? (short[]) lengths.clone() : lengths;
+    this.values = copy ? (short[]) values.clone() : values;
+  }
+
+  private static short[] checkLengths(short[] lengths)
+  {
+    if (lengths == null || lengths.length > 16)
+      throw new IllegalArgumentException("invalid length array");
 
     for (int i = 0; i < lengths.length; i++)
       {
@@ -178,12 +199,6 @@ public class JPEGHuffmanTable
           throw new IllegalArgumentException("negative length");
       }
 
-    for (int i = 0; i < values.length; i++)
-      {
-        if (values[i] < 0)
-          throw new IllegalArgumentException("negative value");
-      }
-
     int sum = 0;
     for (int i = 0; i < lengths.length; i++)
       {
@@ -192,15 +207,30 @@ public class JPEGHuffmanTable
                                              + " for code length " + (i + 1));
         sum += lengths[i];
       }
+
+    return lengths;
+  }
+
+  private static short[] checkValues(short[] values, short[] lengths)
+  {
+    if (values == null || values.length > 256)
+      throw new IllegalArgumentException("invalid values array");
+
+    for (int i = 0; i < values.length; i++)
+      {
+        if (values[i] < 0)
+          throw new IllegalArgumentException("negative value");
+      }
+    // lengths is known-valid by this point.
+    int sum = 0;
+    for (int i = 0; i < lengths.length; i++)
+      sum += lengths[i];
+
     if (values.length != sum)
       throw new IllegalArgumentException("invalid number of values"
                                          + " for number of codes");
 
-    this.lengths = new short[lengths.length];
-    System.arraycopy(lengths, 0, this.lengths, 0, lengths.length);
-
-    this.values = new short[values.length];
-    System.arraycopy(values, 0, this.values, 0, values.length);
+    return values;
   }
 
   /**
@@ -212,9 +242,7 @@ public class JPEGHuffmanTable
    */
   public short[] getLengths()
   {
-    short[] lengthsCopy = new short[lengths.length];
-    System.arraycopy(lengths, 0, lengthsCopy, 0, lengths.length);
-    return lengthsCopy;
+    return (short[]) lengths.clone();
   }
 
   /**
@@ -225,9 +253,7 @@ public class JPEGHuffmanTable
    */
   public short[] getValues()
   {
-    short[] valuesCopy = new short[values.length];
-    System.arraycopy(values, 0, valuesCopy, 0, values.length);
-    return valuesCopy;
+    return (short[]) values.clone();
   }
 
   /**
diff --git a/javax/imageio/plugins/jpeg/JPEGQTable.java b/javax/imageio/plugins/jpeg/JPEGQTable.java
index f9cf76495..a94e8b188 100644
--- a/javax/imageio/plugins/jpeg/JPEGQTable.java
+++ b/javax/imageio/plugins/jpeg/JPEGQTable.java
@@ -66,7 +66,7 @@ public class JPEGQTable
         24, 35, 55, 64,  81, 104, 113,  92,
         49, 64, 78, 87, 103, 121, 120, 101,
         72, 92, 95, 98, 112, 100, 103,  99
-      });
+      }, false);
 
   /**
    * The standard JPEG luminance quantization table, scaled by
@@ -89,7 +89,7 @@ public class JPEGQTable
         99, 99, 99, 99, 99, 99, 99, 99,
         99, 99, 99, 99, 99, 99, 99, 99,
         99, 99, 99, 99, 99, 99, 99, 99
-      });
+      }, false);
 
   /**
    * The standard JPEG chrominance quantization table, scaled by
@@ -99,20 +99,37 @@ public class JPEGQTable
     K2Chrominance.getScaledInstance(0.5f, true);
 
   /**
-   * Construct a new JPEG quantization table.
+   * Construct a new JPEG quantization table.  A copy is created of
+   * the table argument.
    *
-   * @param table the 64-element value table, stored in natural order.
+   * @param table the 64-element value table, stored in natural order
    *
    * @throws IllegalArgumentException if the table is null or if
    * table's length is not equal to 64.
    */
   public JPEGQTable(int[] table)
   {
+    this(checkTable(table), true);
+  }
+
+  /**
+   * Private constructor that avoids unnecessary copying and argument
+   * checking.
+   *
+   * @param table the 64-element value table, stored in natural order
+   * @param copy true if a copy should be created of the given table
+   */
+  private JPEGQTable(int[] table, boolean copy)
+  {
+    this.table = copy ? (int[]) table.clone() : table;
+  }
+
+  private static int[] checkTable(int[] table)
+  {
     if (table == null || table.length != 64)
       throw new IllegalArgumentException("invalid JPEG quantization table");
 
-    this.table = new int[table.length];
-    System.arraycopy(table, 0, this.table, 0, table.length);
+    return table;
   }
 
   /**
@@ -122,9 +139,7 @@ public class JPEGQTable
    */
   public int[] getTable()
   {
-    int[] tableCopy = new int[table.length];
-    System.arraycopy(table, 0, tableCopy, 0, table.length);
-    return tableCopy;
+    return (int[]) table.clone();
   }
 
   /**
@@ -153,7 +168,9 @@ public class JPEGQTable
           scaledTable[i] = max;
       }
 
-    return new JPEGQTable(scaledTable);
+    // Do not copy scaledTable.  It is already a copy because we used
+    // getTable to retrieve it.
+    return new JPEGQTable(scaledTable, false);
   }
 
   /**