modifies DXT code to allow for concurrent calls

All static variables/arrays have been converted to member variables of
corresponding compressor objects.

.gitignore

@@ -0,0 +1 @@
+target/

build.sbt

@@ -0,0 +1,19 @@
+name := "jsquish"
+
+organization := "com.github.memo33"
+
+version := "2.0.0-SNAPSHOT"
+
+scalaVersion := "2.11.8"
+
+javacOptions in (Compile, compile) ++= Seq(
+  "-source", "1.6",
+  "-target", "1.6",
+  "-encoding", "UTF-8")
+
+crossPaths := false
+
+autoScalaLibrary := false
+
+
+libraryDependencies += "org.scalatest" %% "scalatest" % "2.1.5" % "test"

src/main/java/com/github/memo33/jsquish/ColourBlock.java

@@ -1,6 +1,7 @@
 /* -----------------------------------------------------------------------------
 
     Copyright (c) 2006 Simon Brown                          [email protected]
+    Copyright (c) 2016 memo
 
     Permission is hereby granted, free of charge, to any person obtaining
     a copy of this software and associated documentation files (the
@@ -32,13 +33,11 @@ a copy of this software and associated documentation files (the
 
 final class ColourBlock {
 
-    private static final int[] remapped = new int[16];
+    private final int[] remapped = new int[16];
+    private final int[] indices = new int[16];
+    private final int[] codes = new int[16];
 
-    private static final int[] indices = new int[16];
-
-    private static final int[] codes = new int[16];
-
-    private ColourBlock() {}
+    ColourBlock() {}
 
     static int gammaColour(final float colour, final float scale) {
         //return round(scale * (float)Math.pow(colour, 1.0 / 2.2));
@@ -69,7 +68,7 @@ private static void writeColourBlock(final int a, final int b, final int[] indic
         }
     }
 
-    static void writeColourBlock3(final Vec start, final Vec end, final int[] indices, final byte[] block, final int offset) {
+    void writeColourBlock3(final Vec start, final Vec end, final int[] indices, final byte[] block, final int offset) {
         // get the packed values
         int a = floatTo565(start);
         int b = floatTo565(end);
@@ -97,7 +96,7 @@ else if ( indices[i] == 1 )
         writeColourBlock(a, b, remapped, block, offset);
     }
 
-    static void writeColourBlock4(final Vec start, final Vec end, final int[] indices, final byte[] block, final int offset) {
+    void writeColourBlock4(final Vec start, final Vec end, final int[] indices, final byte[] block, final int offset) {
         // get the packed values
         int a = floatTo565(start);
         int b = floatTo565(end);
@@ -123,10 +122,8 @@ static void writeColourBlock4(final Vec start, final Vec end, final int[] indice
         writeColourBlock(a, b, remapped, block, offset);
     }
 
-    static void decompressColour(final byte[] rgba, final byte[] block, final int offset, final boolean isDXT1) {
+    void decompressColour(final byte[] rgba, final byte[] block, final int offset, final boolean isDXT1) {
         // unpack the endpoints
-        final int[] codes = ColourBlock.codes;
-
         final int a = unpack565(block, offset, codes, 0);
         final int b = unpack565(block, offset + 2, codes, 4);
 
@@ -149,8 +146,6 @@ static void decompressColour(final byte[] rgba, final byte[] block, final int of
         codes[12 + 3] = (isDXT1 && a <= b) ? 0 : 255;
 
         // unpack the indices
-        final int[] indices = ColourBlock.indices;
-
         for ( int i = 0; i < 4; ++i ) {
             final int index = 4 * i;
             final int packed = (block[offset + 4 + i] & 0xFF);

src/main/java/com/github/memo33/jsquish/ColourSet.java

@@ -1,6 +1,7 @@
 /* -----------------------------------------------------------------------------
 
     Copyright (c) 2006 Simon Brown                          [email protected]
+    Copyright (c) 2016 memo
 
     Permission is hereby granted, free of charge, to any person obtaining
     a copy of this software and associated documentation files (the

src/main/java/com/github/memo33/jsquish/CompressorAlpha.java

@@ -1,6 +1,7 @@
 /* -----------------------------------------------------------------------------
 
     Copyright (c) 2006 Simon Brown                          [email protected]
+    Copyright (c) 2016 memo
 
     Permission is hereby granted, free of charge, to any person obtaining
     a copy of this software and associated documentation files (the
@@ -29,20 +30,20 @@ a copy of this software and associated documentation files (the
 
 final class CompressorAlpha {
 
-    private static final int[] swapped = new int[16];
+    private final int[] swapped = new int[16];
 
-    private static final int[] codes5 = new int[8];
-    private static final int[] codes7 = new int[8];
+    private final int[] codes5 = new int[8];
+    private final int[] codes7 = new int[8];
 
-    private static final int[] indices5 = new int[16];
-    private static final int[] indices7 = new int[16];
+    private final int[] indices5 = new int[16];
+    private final int[] indices7 = new int[16];
 
-    private static final int[] codes = new int[8];
-    private static final int[] indices = new int[16];
+    private final int[] codes = new int[8];
+    private final int[] indices = new int[16];
 
-    private CompressorAlpha() {}
+    CompressorAlpha() {}
 
-    static void compressAlphaDxt3(final byte[] rgba, final int mask, final byte[] block, final int offset) {
+    void compressAlphaDxt3(final byte[] rgba, final int mask, final byte[] block, final int offset) {
         // quantise and pack the alpha values pairwise
         for ( int i = 0; i < 8; ++i ) {
             // quantise down to 4 bits
@@ -64,7 +65,7 @@ static void compressAlphaDxt3(final byte[] rgba, final int mask, final byte[] bl
         }
     }
 
-    static void decompressAlphaDxt3(final byte[] rgba, final byte[] block, final int offset) {
+    void decompressAlphaDxt3(final byte[] rgba, final byte[] block, final int offset) {
         // unpack the alpha values pairwise
         for ( int i = 0; i < 8; ++i ) {
             // quantise down to 4 bits
@@ -80,7 +81,7 @@ static void decompressAlphaDxt3(final byte[] rgba, final byte[] block, final int
         }
     }
 
-    private static int fitCodes(final byte[] rgba, final int mask, final int[] codes, final int[] indices) {
+    private int fitCodes(final byte[] rgba, final int mask, final int[] codes, final int[] indices) {
         // fit each alpha value to the codebook
         int err = 0;
         for ( int i = 0; i < 16; ++i ) {
@@ -117,7 +118,7 @@ private static int fitCodes(final byte[] rgba, final int mask, final int[] codes
         return err;
     }
 
-    private static void writeAlphaBlock(final int alpha0, final int alpha1, final int[] indices, final byte[] block, final int offset) {
+    private void writeAlphaBlock(final int alpha0, final int alpha1, final int[] indices, final byte[] block, final int offset) {
         // write the first two bytes
         block[offset + 0] = (byte)alpha0;
         block[offset + 1] = (byte)alpha1;
@@ -139,10 +140,8 @@ private static void writeAlphaBlock(final int alpha0, final int alpha1, final in
         }
     }
 
-    private static void writeAlphaBlock5(final int alpha0, final int alpha1, final int[] indices, final byte[] block, final int offset) {
+    private void writeAlphaBlock5(final int alpha0, final int alpha1, final int[] indices, final byte[] block, final int offset) {
         // check the relative values of the endpoints
-        final int[] swapped = CompressorAlpha.swapped;
-
         if ( alpha0 > alpha1 ) {
             // swap the indices
             for ( int i = 0; i < 16; ++i ) {
@@ -165,10 +164,8 @@ else if ( index <= 5 )
         }
     }
 
-    private static void writeAlphaBlock7(final int alpha0, final int alpha1, final int[] indices, final byte[] block, final int offset) {
+    private void writeAlphaBlock7(final int alpha0, final int alpha1, final int[] indices, final byte[] block, final int offset) {
         // check the relative values of the endpoints
-        final int[] swapped = CompressorAlpha.swapped;
-
         if ( alpha0 < alpha1 ) {
             // swap the indices
             for ( int i = 0; i < 16; ++i ) {
@@ -189,7 +186,7 @@ else if ( index == 1 )
         }
     }
 
-    static void compressAlphaDxt5(final byte[] rgba, final int mask, final byte[] block, final int offset) {
+    void compressAlphaDxt5(final byte[] rgba, final int mask, final byte[] block, final int offset) {
         // get the range for 5-alpha and 7-alpha interpolation
         int min5 = 255;
         int max5 = 0;
@@ -231,8 +228,6 @@ static void compressAlphaDxt5(final byte[] rgba, final int mask, final byte[] bl
             min7 = max(0, max7 - 7);
 
         // set up the 5-alpha code book
-        final int[] codes5 = CompressorAlpha.codes5;
-
         codes5[0] = min5;
         codes5[1] = max5;
         for ( int i = 1; i < 5; ++i )
@@ -241,8 +236,6 @@ static void compressAlphaDxt5(final byte[] rgba, final int mask, final byte[] bl
         codes5[7] = 255;
 
         // set up the 7-alpha code book
-        final int[] codes7 = CompressorAlpha.codes7;
-
         codes7[0] = min7;
         codes7[1] = max7;
         for ( int i = 1; i < 7; ++i )
@@ -259,14 +252,12 @@ static void compressAlphaDxt5(final byte[] rgba, final int mask, final byte[] bl
             writeAlphaBlock7(min7, max7, indices7, block, offset);
     }
 
-    static void decompressAlphaDxt5(final byte[] rgba, final byte[] block, final int offset) {
+    void decompressAlphaDxt5(final byte[] rgba, final byte[] block, final int offset) {
         // get the two alpha values
         final int alpha0 = (block[offset + 0] & 0xFF);
         final int alpha1 = (block[offset + 1] & 0xFF);
 
         // compare the values to build the codebook
-        final int[] codes = CompressorAlpha.codes;
-
         codes[0] = alpha0;
         codes[1] = alpha1;
         if ( alpha0 <= alpha1 ) {
@@ -282,8 +273,6 @@ static void decompressAlphaDxt5(final byte[] rgba, final byte[] block, final int
         }
 
         // decode the indices
-        final int[] indices = CompressorAlpha.indices;
-
         int src = 2;
         int dest = 0;
         for ( int i = 0; i < 2; ++i ) {