fixed PNG loader to support indexed color

src/main/java/com/baislsl/png/chunk/Chunk.java

@@ -26,7 +26,6 @@ public class Chunk {
 		return output;
 	}
 
-
 	protected Chunk(byte[] length, byte[] type, byte[] data, byte[] crc) {
 		this.length = ByteHandler.byteToLong(length);
 		this.data = data;

src/main/java/com/baislsl/png/chunk/ChunkType.java

@@ -14,6 +14,12 @@ public enum ChunkType {
 			png.setIhdr(new IHDR(length, type, data, crc));
 		}
 	},
+	tRNS {
+		@Override
+		public void apply(PNG png, byte[] length, byte[] type, byte[] data, byte[] crc) throws DecodeException {
+			png.setTrns(new tRNS(length, type, data, crc));
+		}
+	},
 	PLTE {
 		@Override
 		public void apply(PNG png, byte[] length, byte[] type, byte[] data, byte[] crc) throws DecodeException {

src/main/java/com/baislsl/png/chunk/IHDR.java

@@ -11,14 +11,11 @@ public class IHDR extends Chunk {
 	private int bitDepth, colorType, compressionMethod, filterMethod, interlaceMethod;
 
 	final private static int[] colorTypeValid = { 0, 2, 3, 4, 6 };
-    final private static int[][] mapColorBitDepth = {
+	final private static int[][] mapColorBitDepth = { { 1, 2, 4, 8, 16 }, // color type = 0
-            {1, 2, 4, 8, 16},   // color type = 0
+			{}, { 8, 16 }, // color type = 2
-            {},
-            {8, 16},            // color type = 2
 			{ 1, 2, 4, 8 }, // color type = 3
 			{ 8, 16 }, // color type = 4
-            {},
+			{}, { 8, 16 } // color type = 6
-            {8, 16}             // color type = 6
 	};
 
 	// the number of bytes per complete pixel, rounding up to one
@@ -44,17 +41,23 @@ public class IHDR extends Chunk {
 	@Override
 	public String toString() {
 		StringBuilder sb = new StringBuilder();
-        sb.append("width=");sb.append(width);
+		sb.append("width=");
-        sb.append("height=");sb.append(height);
+		sb.append(width);
-        sb.append("bitDepth=");sb.append(bitDepth);
+		sb.append("height=");
-        sb.append("colorType=");sb.append(colorType);
+		sb.append(height);
-        sb.append("compressionMethod=");sb.append(compressionMethod);
+		sb.append("bitDepth=");
-        sb.append("filterMethod=");sb.append(filterMethod);
+		sb.append(bitDepth);
-        sb.append("interlaceMethod=");sb.append(interlaceMethod);
+		sb.append("colorType=");
+		sb.append(colorType);
+		sb.append("compressionMethod=");
+		sb.append(compressionMethod);
+		sb.append("filterMethod=");
+		sb.append(filterMethod);
+		sb.append("interlaceMethod=");
+		sb.append(interlaceMethod);
 		return sb.toString();
 	}
 
-
 	private void build() {
 		this.width = ByteHandler.byteToLong(data);
 		this.height = ByteHandler.byteToLong(data, 4);
@@ -65,7 +68,6 @@ public class IHDR extends Chunk {
 		this.interlaceMethod = ((int) data[12]) & 0xFF;
 	}
 
-
 	private void checkLegal() throws DecodeException {
 		boolean legal = false;
 		for (int c : colorTypeValid) {
@@ -82,10 +84,10 @@ public class IHDR extends Chunk {
 				return;
 			}
 		}
-        throw new DecodeException("Initialzie IHDR : bit depth " + bitDepth + " not valid matching color type " + colorType);
+		throw new DecodeException(
+				"Initialzie IHDR : bit depth " + bitDepth + " not valid matching color type " + colorType);
 	}
 
-
 	public long getWidth() {
 		return this.width;
 	}
@@ -114,5 +116,4 @@ public class IHDR extends Chunk {
 		return interlaceMethod;
 	}
 
-
 }

src/main/java/com/baislsl/png/chunk/PLTE.java

@@ -2,7 +2,6 @@ package com.baislsl.png.chunk;
 
 import com.baislsl.png.decode.DecodeException;
 
-
 /**
  * Created by baislsl on 17-7-9.
  */
@@ -14,15 +13,14 @@ public class PLTE extends Chunk {
 		build();
 	}
 
-
 	private void build() throws DecodeException {
 		if (this.length % 3 != 0)
 			throw new DecodeException("PLTE length can not be divide by 3");
-
 		int size = (int) length / 3;
 		color = new int[size];
 		for (int i = 0; i < size; i++) {
-            color[i] = (((int)data[i*3]) & 0xFF) << 16 | (((int)data[i*3 + 1]) & 0xFF) << 8 | (((int)data[i*3 + 2]) & 0xFF);
+			color[i] = (((int) data[i * 3]) & 0xFF) << 16 | (((int) data[i * 3 + 1]) & 0xFF) << 8
+					| (((int) data[i * 3 + 2]) & 0xFF) | 0xFF000000;
 		}
 	}
 
@@ -34,5 +32,4 @@ public class PLTE extends Chunk {
 		return color.length;
 	}
 
-
 }

src/main/java/com/baislsl/png/chunk/tRNS.java

@@ -0,0 +1,18 @@
+package com.baislsl.png.chunk;
+
+import com.baislsl.png.decode.DecodeException;
+
+/**
+ * Created by baislsl on 17-7-9.
+ */
+public class tRNS extends Chunk {
+
+	public tRNS(byte[] length, byte[] type, byte[] data, byte[] crc) throws DecodeException {
+		super(length, type, data, crc);
+	}
+
+	public int getAlpha() {
+		return (int)data[0] & 0xFF;
+	}
+
+}

src/main/java/com/baislsl/png/decode/DecodeException.java

@@ -5,7 +5,8 @@ package com.baislsl.png.decode;
  */
 public class DecodeException extends Exception {
 
-    public DecodeException() {}
+	public DecodeException() {
+	}
 
 	public DecodeException(String message) {
 		super(message);

src/main/java/com/baislsl/png/decode/Decoder.java

@@ -16,9 +16,7 @@ public class Decoder {
 	// private final static Logger LOG = LoggerFactory.getLogger(Decoder.class);
 	private final InputStream in;
 
-    private final static char[] head = {
+	private final static char[] head = { 0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a };
-            0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a
-    };
 
 	public Decoder(InputStream in) {
 		this.in = in;
@@ -33,11 +31,10 @@ public class Decoder {
 		// LOG.info(ByteHandler.byteToString(header));
 	}
 
-    private boolean readChunk(PNG png, String chunkName,
+	private boolean readChunk(PNG png, String chunkName, byte[] length, byte[] type, byte[] data, byte[] crc)
-                              byte[] length, byte[] type,
+			throws IOException, DecodeException {
-                              byte[] data, byte[] crc) throws IOException, DecodeException {
 		for (ChunkType chunkType : ChunkType.values()) {
-            if (chunkType.name().equals(chunkName)) {
+			if (chunkType.name().equalsIgnoreCase(chunkName)) {
 				chunkType.apply(png, length, type, data, crc);
 				return true;
 			}
@@ -88,13 +85,12 @@ public class Decoder {
 		return png;
 	}
 
-
 	private byte[] readBytes(int size) throws IOException {
 		byte[] result = new byte[size];
 		int ret = in.read(result, 0, size);
-        if (ret == -1) return null;
+		if (ret == -1)
+			return null;
 		return result;
 	}
 
-
 }

src/main/java/com/baislsl/png/decode/PNG.java

@@ -15,16 +15,14 @@ public class PNG {
 	public IHDR ihdr;
 	public IDATManager idats = new IDATManager();
 	public PLTE plte;
+	public tRNS trns;
 	public IEND iend;
 
 	public PNG() {
 	}
 	
-    public PNG(IHDR ihdr, IDATManager idats, PLTE plte, IEND iend) {
+	public boolean isAlpha() {
-        this.ihdr = ihdr;
+		return this.trns != null || ihdr.getBpp() == 4;
-        this.idats = idats;
-        this.plte = plte;
-        this.iend = iend;
 	}
 
 	public int[] getColor() throws DecodeException {
@@ -48,14 +46,16 @@ public class PNG {
 				switch (colorType) {
 				case 2:
 					if (bitDepth == 8) { // bpp = 3
-                            colors[idx] = ((int)data[i][bpp * j] & 0xff) << 16 | ((int)data[i][bpp * j + 1] & 0xff) << 8 | ((int)data[i][bpp * j + 2] & 0xff);
+						colors[idx] = ((int) data[i][bpp * j] & 0xff) << 16 | ((int) data[i][bpp * j + 1] & 0xff) << 8
+								| ((int) data[i][bpp * j + 2] & 0xff);
 					} else {
 						throw new DecodeException("not supported");
 					}
 					break;
 				case 6:
 					if (bitDepth == 8) { // bpp = 4
-                            colors[idx] = ((int)data[i][bpp * j] & 0xff) << 16 | ((int)data[i][bpp * j + 1] & 0xff) << 8 | ((int)data[i][bpp * j + 2] & 0xff) | ((int)data[i][bpp * j + 3] & 0xff) << 24;
+						colors[idx] = ((int) data[i][bpp * j] & 0xff) << 16 | ((int) data[i][bpp * j + 1] & 0xff) << 8
+								| ((int) data[i][bpp * j + 2] & 0xff) | ((int) data[i][bpp * j + 3] & 0xff) << 24;
 					} else {
 						throw new DecodeException("not supported");
 					}
@@ -63,7 +63,13 @@ public class PNG {
 				case 3:
 					int gap = 8 / bitDepth;
 					int a = (1 << bitDepth) - 1;
-                    	colors[idx] = plte.getColor(data[i][j / gap] & a);
+					int b = gap - (j % gap) - 1;
+					int pi = (data[i][j / gap] >> (b * bitDepth)) & a;
+					if (trns != null && trns.getAlpha() == pi) {
+						colors[idx] = 0;
+					}else {
+						colors[idx] = plte.getColor(pi);
+					}
 					break;
 				default:
 					throw new DecodeException("Do not support color type " + colorType);
@@ -103,6 +109,10 @@ public class PNG {
 		this.plte = plte;
 	}
 
+	public void setTrns(tRNS trns) {
+		this.trns = trns;
+	}
+
 	public void setIend(IEND iend) {
 		this.iend = iend;
 	}

src/main/java/com/baislsl/png/util/ByteHandler.java

@@ -22,7 +22,6 @@ public class ByteHandler {
 		return byteToLong(data, 0, 4);
 	}
 
-
 	public static String byteToString(byte[] data) {
 		StringBuilder str = new StringBuilder();
 		for (byte b : data) {

src/main/java/com/baislsl/png/util/CRC.java

@@ -20,7 +20,6 @@ public class CRC {
 		}
 	}
 
-
 	private static long updateCrc(long crc, byte[] buf, int size) {
 		long ans = crc;
 		for (int i = 0; i < size; i++) {

src/main/java/com/baislsl/png/util/ReverseFilter.java

@@ -1,15 +1,16 @@
 package com.baislsl.png.util;
 
-
-
 public class ReverseFilter {
-    private ReverseFilter(){}
+	private ReverseFilter() {
+	}
 
 	private static int paethPredictor(int a, int b, int c) {
 		int p = a + b - c;
 		int pa = Math.abs(p - a), pb = Math.abs(p - b), pc = Math.abs(p - c);
-        if (pa <= pb && pa <= pc) return a;
+		if (pa <= pb && pa <= pc)
-        if (pb <= pc) return b;
+			return a;
+		if (pb <= pc)
+			return b;
 		return c;
 	}
 

src/main/java/net/lax1dude/eaglercraft/EaglerImage.java

@@ -39,7 +39,7 @@ public class EaglerImage {
 	public static final EaglerImage loadImage(byte[] file) {
 		try {
 			PNG p = (new Decoder(new ByteArrayInputStream(file))).readInPNG();
-			return new EaglerImage(p.getColor(), (int)p.getWidth(), (int)p.getHeight(), p.ihdr.getBpp() == 4);
+			return new EaglerImage(p.getColor(), (int)p.getWidth(), (int)p.getHeight(), p.isAlpha());
 		} catch (IOException e) {
 			e.printStackTrace();
 			return null;