Support for alpha channel and bug fix

app/src/main/java/com/n4no/webpencoder/webp/muxer/WebpChunk.java

@@ -27,6 +27,8 @@ public class WebpChunk {
 	public boolean useAlphaBlending;
 	public boolean disposeToBackgroundColor;
 
+	public byte[] alphaData;
+
 	public WebpChunk(WebpChunkType t) {
 		type = t;
 	}

app/src/main/java/com/n4no/webpencoder/webp/muxer/WebpChunkType.java

@@ -9,5 +9,7 @@ public enum WebpChunkType {
 	VP8,
 	VP8L,
 	ANIM,
-	ANMF
+	ANMF,
+	ICCP,
+	ALPH
 }

app/src/main/java/com/n4no/webpencoder/webp/muxer/WebpContainerReader.java

@@ -1,5 +1,8 @@
 package com.n4no.webpencoder.webp.muxer;
 
+import android.util.Log;
+
+import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.nio.ByteBuffer;
@@ -52,6 +55,10 @@ public WebpChunk read() throws IOException {
 				return readAnim();
 			if (isFourCc(fcc, 'A', 'N', 'M', 'F'))
 				return readAnmf();
+			if (isFourCc(fcc, 'I', 'C', 'C', 'P'))
+				return readIccp();
+			if (isFourCc(fcc, 'A', 'L', 'P', 'H'))
+				return readAlph();
 
 			throw new IOException(String.format("Not supported FourCC: %c.%c.%c.%c.",
 					fcc[0], fcc[1], fcc[2], fcc[3]));
@@ -63,6 +70,24 @@ public WebpChunk read() throws IOException {
 		return null;
 	}
 
+	private WebpChunk readAlph() throws IOException {
+		int chunkSize = readUInt32();
+		WebpChunk chunk = new WebpChunk(WebpChunkType.ALPH);
+		chunk.alphaData = readPayload(chunkSize);
+		chunk.hasAlpha = true;
+		return chunk;
+	}
+
+	private WebpChunk readIccp() throws IOException {
+		int chunkSize = readUInt32();
+		WebpChunk chunk = new WebpChunk(WebpChunkType.ICCP);
+
+		readPayload(chunkSize);
+		// no need to store the payload to this chunk as Animated Webp does not require ICCP
+
+		return chunk;
+	}
+
 	private WebpChunk readVp8x() throws IOException {
 		int chunkSize = readUInt32();
 		if (chunkSize != 10)
@@ -74,11 +99,12 @@ private WebpChunk readVp8x() throws IOException {
 		read(flags, 4);
 		BitSet bs = BitSet.valueOf(flags);
 
-		chunk.hasIccp = bs.get(0);
-		chunk.hasAnim = bs.get(1);
-		chunk.hasExif = bs.get(2);
-		chunk.hasXmp = bs.get(3);
-		chunk.hasAlpha = bs.get(4);
+		bs.get(0); 					 // R reserved
+		chunk.hasAnim	= bs.get(1); // A Animation
+		chunk.hasXmp	= bs.get(2); // X XMP
+		chunk.hasExif	= bs.get(3); // E Exif
+		chunk.hasAlpha	= bs.get(4); // L Alpha
+		chunk.hasIccp	= bs.get(5); // I ICCP
 
 		chunk.width = readUInt24();
 		chunk.height = readUInt24();
@@ -110,7 +136,10 @@ private WebpChunk readVp8l() throws IOException {
 
 		WebpChunk chunk = new WebpChunk(WebpChunkType.VP8L);
 		chunk.isLossless = true;
-		chunk.payload = readPayload(chunkSize);
+//		chunkSize is not telling the correct size of payload to read.
+//		chunk.payload = readPayload(chunkSize);
+//		So reading all bytes remained (Max 1024 bytes)
+		chunk.payload = readAllBytes();
 
 		debug(String.format("VP8L: bytes = %d", chunkSize));
 		return chunk;
@@ -193,6 +222,17 @@ private boolean isFourCc(byte[] h, char a, char b, char c, char d) {
 		return h[0] == a && h[1] == b && h[2] == c && h[3] == d;
 	}
 
+	private byte[] readAllBytes() throws IOException {
+		try (ByteArrayOutputStream outputStream = new ByteArrayOutputStream()) {
+			byte[] buffer = new byte[1024];
+			int numRead;
+			while ((numRead = _inputStream.read(buffer)) != -1) {
+				outputStream.write(buffer, 0, numRead);
+				_offset += numRead;
+			}
+			return outputStream.toByteArray();
+		}
+	}
 	private void debug(String message) {
 		if (_debug)
 			System.out.println(message);

app/src/main/java/com/n4no/webpencoder/webp/muxer/WebpContainerWriter.java

@@ -1,5 +1,7 @@
 package com.n4no.webpencoder.webp.muxer;
 
+import android.util.Log;
+
 import com.n4no.webpencoder.webp.muxer.stream.SeekableOutputStream;
 
 import java.io.IOException;
@@ -87,7 +89,15 @@ private void writeAnim(WebpChunk chunk) throws IOException {
 
 	private void writeAnmf(WebpChunk chunk) throws IOException {
 		write(new byte[] { 'A', 'N', 'M', 'F' });
-		writeUInt32(chunk.payload.length + 24);
+
+		// if ALPH chunk present, get size
+		int AlphaSize = 0;
+		if(chunk.alphaData != null){
+			AlphaSize = 4 + 4 + chunk.alphaData.length;
+			// 4 bytes (ALPH header) + 4 bytes (chunk size) + length of Alpha BitStream
+		}
+
+		writeUInt32(chunk.payload.length + 24 + AlphaSize);
 
 		writeUInt24(chunk.x); // 3 bytes (3)
 		writeUInt24(chunk.y); // 3 bytes (6)
@@ -100,6 +110,11 @@ private void writeAnmf(WebpChunk chunk) throws IOException {
 		bs.set(0, chunk.disposeToBackgroundColor);
 		write(bitSetToBytes(bs, 1)); // 1 byte (16)
 
+		// Insert ALPH chunk
+		if(chunk.alphaData != null){
+			writeAlph(chunk.alphaData);
+		}
+
 		if (chunk.isLossless)
 			write(new byte[] { 'V', 'P', '8', 'L' }); // 4 bytes (20)
 		else
@@ -108,6 +123,12 @@ private void writeAnmf(WebpChunk chunk) throws IOException {
 		write(chunk.payload);
 	}
 
+	private void writeAlph(byte[] alphaData) throws IOException {
+		write(new byte[] { 'A', 'L', 'P', 'H' }); // 4
+		writeUInt32(alphaData.length); // 4
+		write(alphaData); // x
+	}
+
 	//
 
 	private void write(byte[] bytes) throws IOException {

app/src/main/java/com/n4no/webpencoder/webp/muxer/WebpMuxer.java

@@ -1,5 +1,7 @@
 package com.n4no.webpencoder.webp.muxer;
 
+import android.util.Log;
+
 import java.io.IOException;
 import java.io.InputStream;
 
@@ -16,6 +18,9 @@ public class WebpMuxer {
     private int _width;
     private int _height;
 
+    private byte[] _alphaData;
+    private boolean _hasAlpha;
+
     public WebpMuxer(WebpContainerWriter writer) {
         _writer = writer;
     }
@@ -42,13 +47,13 @@ public void writeFirstFrameFromWebm(InputStream inputStream) throws IOException
         WebpChunk chunk = readFirstChunkWithPayload(reader);
         reader.close();
 
-        writeFrame(chunk.payload, chunk.isLossless);
+        writeFrame(chunk, chunk.payload, chunk.isLossless);
     }
 
-    public void writeFrame(byte[] payload, boolean isLossless) throws IOException {
+    public void writeFrame(WebpChunk chunk,byte[] payload, boolean isLossless) throws IOException {
         if (_isFirstFrame) {
             _isFirstFrame = false;
-            writeHeader();
+            writeHeader(chunk);
         }
 
         if (hasAnim())
@@ -70,18 +75,25 @@ private boolean hasAnim() {
     private WebpChunk readFirstChunkWithPayload(WebpContainerReader reader) throws IOException {
         WebpChunk chunk;
         while ((chunk = reader.read()) != null) {
+
+            if (chunk.type == WebpChunkType.ALPH)
+                _alphaData = chunk.alphaData;
+
+            if (chunk.type == WebpChunkType.VP8X)
+                _hasAlpha = chunk.hasAlpha;
+
             if (chunk.payload != null)
                 return chunk;
         }
         throw new IOException("Can not find chunk with payload.");
     }
 
-    private void writeHeader() throws IOException {
+    private void writeHeader(WebpChunk chunk) throws IOException {
         _writer.writeHeader();
 
         WebpChunk vp8x = new WebpChunk(WebpChunkType.VP8X);
         vp8x.hasAnim = hasAnim();
-        vp8x.hasAlpha = false;
+        vp8x.hasAlpha = _hasAlpha;
         vp8x.hasXmp = false;
         vp8x.hasExif = false;
         vp8x.hasIccp = false;
@@ -111,6 +123,8 @@ private void writeAnmf(byte[] payload, boolean isLossless) throws IOException {
         anmf.useAlphaBlending = false;
         anmf.disposeToBackgroundColor = false;
 
+        anmf.alphaData = _alphaData;
+
         _writer.write(anmf);
     }