on my way to bigger PNGs

Author: OleStrohm

main.cpp

@@ -6,15 +6,15 @@
 #include "bitarray.h"
 #include "tree.h"
 
-static const unsigned short order[19] = {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}; /* permutation of code lengths */
+static const unsigned short huffmanTreeOrder[19] = {16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
 static const unsigned short lengths[29] = {3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, 35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258};
 static const unsigned short lengthsExtraBits[29] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0};
 static const unsigned int offsets[30] = {1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, 257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, 8193, 12289, 16385, 24577};
 static const unsigned int offsetsExtraBits[30] = {0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 13, 13};
 
 int main() {
-	Image image("smile.png");
-	
+	Image image("goat.png");
+
 	Format format = image.getFormat();
 	LOG("Size: " << format.width << "x" << format.height);
 	LOG("Bit depth: " << (int) format.bitDepth);
@@ -23,30 +23,35 @@ int main() {
 	LOG("Filter method: " << (int) format.filterMethod);
 	LOG("Interlace method: " << (int) format.interlaceMethod);
 	LOG("");
-	
+
 	int index = 0;
+	int count = 0;
 	while (image.chunks[++index]->type != "IDAT");
+	int index2 = index;
+	while (index < image.chunks.size() && image.chunks[index2++]->type == "IDAT") count++;
+	LOG("IDAT chunk count: " << count);
 	Chunk pixelChunk = *image.chunks[index];
 	LOG("Chunk type: " << pixelChunk.type);
 	LOG("Chunk size (bytes): " << pixelChunk.length);
 	LOG("");
-	
+
 	std::vector<unsigned char> compressedData = image.extractCompressedPixelData(pixelChunk);
 	BitArray CMFbits(compressedData[0], 8);
 	LOG("CMF:");
 	LOG("\tHopefully this is 8: " << CMFbits.read(0, 4));
 	LOG("\tCINFO: " << CMFbits.read(4, 4));
-	
+
 	BitArray flagBits(compressedData[1], 8);
 	LOG("FLG:");
 	LOG("\tFDICT: " << (flagBits.read(4, 1) == 1 ? "yep" : "no"));
 	bool fDict = flagBits.read(4, 1) != 0;
 	LOG("\tChecks out: " << ((((CMFbits.read(0, 8) << 8) + (flagBits.read(0, 8))) % 31 == 0) ? "yeeaaah" : "no... :/"));
 	LOG("");
-	
+
 	BitArray nextBits(compressedData[2], 8);
 	LOG("Last block?: " << (nextBits.read(0, 1) ? "yes" : "no"));
-	switch (nextBits.read(1, 2)) {
+	unsigned short compressionMethod = nextBits.read(1, 2);
+	switch (compressionMethod) {
 		case 0:
 			LOG("Compression method: uncompressed");
 			break;
@@ -64,9 +69,9 @@ int main() {
 	for (unsigned int i = 3; i < compressedData.size(); i++) {
 		actualData.pushBack(compressedData[i]);
 	}
-	
+
 	LOG("\n");
-	
+
 	std::string pngSymbols[288];
 	unsigned int pngLengths[288];
 	for (unsigned int i = 0; i < 288; i++) {
@@ -79,51 +84,82 @@ int main() {
 			pngLengths[i] = 7;
 	}
 	Tree pngTree(pngSymbols, pngLengths, 288);
-	
+
 	std::vector<unsigned int> stream;
 	stream.reserve((1 + format.width) * format.height);
-	
+
 	unsigned int end = 0;
-	while (true) {
-		std::stringstream convert(pngTree.uncompressOneCode(actualData, end, &end));
-		
-		unsigned int code = 0;
-		convert >> code;
-		
-		if (code < 256) {
-			LOG(code);
-			stream.emplace_back(code);
-		} else if (code == 256) {
+	if (compressionMethod == 2) {
+		unsigned int hlit = actualData.read(end, 5, true) + 257;
+		end += 5;
+		unsigned int hdist = actualData.read(end, 5, true) + 1;
+		end += 5;
+		unsigned int hlen = actualData.read(end, 5, true) + 4;
+		end += 4;
+
+		std::vector<unsigned char> huffman1Lengths;
+		huffman1Lengths.reserve(19);
+		std::vector<unsigned char> huffman1Symbols;
+		huffman1Symbols.reserve(19);
+		{
+			unsigned int i = 0;
+			for (; i < hlen; i++) {
+				huffman1Symbols.push_back((unsigned char) i);
+				huffman1Lengths[huffmanTreeOrder[i]] = (unsigned char) actualData.read(end, 3, false);
+				end+=3;
+			}
+			for(; i < 19; i++) {
+				huffman1Symbols.push_back((unsigned char)i);
+				huffman1Lengths[huffmanTreeOrder[i]] = 0;
+			}
+		}
+
+		for(unsigned int i = 0; i < 19; i++) {
+			LOG((unsigned int) huffman1Lengths[i]);
+		}
+	} else if (compressionMethod == 1) {
+		while (true) {
+			std::stringstream convert(pngTree.uncompressOneCode(actualData, end, &end));
+
+			unsigned int code = 0;
+			convert >> code;
+
+			if (code < 256) {
+				LOG(code);
+				stream.emplace_back(code);
+			} else if (code == 256) {
 //			LOG("\n");
 //			for (auto i : stream)
 //				LOG(i);
-			LOG("END");
-			break;
-		} else {
-			code -= 257;
-			unsigned int length = lengths[code];
-			length += actualData.read(end, lengthsExtraBits[code]);
-			end += lengthsExtraBits[code];
-			
-			unsigned int offsetCode = actualData.read(end, 5, true);
-			end += 5;
-			unsigned int offset = offsets[offsetCode];
-			offset += actualData.read(end, offsetsExtraBits[offsetCode]);
-			end += offsetsExtraBits[offsetCode];
-			
-			LOG("<" << offset << ", " << length << ">");
-			for (int i = 0; i < length; i++) {
-				stream.emplace_back(stream[stream.size() - offset]);
+				LOG("END");
+				break;
+			} else {
+				code -= 257;
+				unsigned int length = lengths[code];
+				length += actualData.read(end, lengthsExtraBits[code]);
+				end += lengthsExtraBits[code];
+
+				unsigned int offsetCode = actualData.read(end, 5, true);
+				end += 5;
+				unsigned int offset = offsets[offsetCode];
+				offset += actualData.read(end, offsetsExtraBits[offsetCode]);
+				end += offsetsExtraBits[offsetCode];
+
+				LOG("<" << length << ", " << offset << ">");
+				for (int i = 0; i < length; i++) {
+					stream.emplace_back(stream[stream.size() - offset]);
+				}
 			}
 		}
 	}
-	
-	LOG("");
-	
-	
+
+	LOG("\n");
+
+
+#if 0
 	std::vector<unsigned int> imageArray;
 	imageArray.reserve(format.width * format.height);
-	
+
 	for (int y = 0; y < format.height; y++) {
 		for (int x = 0; x < format.width; x++) {
 			int i = 1 + 4 * x + y * (1 + format.width * 4);
@@ -133,10 +169,9 @@ int main() {
 			imageArray.push_back(stream[i + 3]);
 		}
 	}
-	
+
 	for (int y = 0; y < format.height; y++) {
 		for (int x = 0; x < format.width; x++) {
-//			int i = 1 + y + (y * (format.width) + x) * 4;
 			int i = (y * (format.width) + x) * 4;
 			int r = imageArray[i];
 			int g = imageArray[i + 1];
@@ -149,5 +184,7 @@ int main() {
 		}
 		std::printf("\n");
 	}
-	
+#endif
+
+	return 0;
 }