jpegfileformat.java

源码为Eclipse开源开发平台桌面开发工具SWT的源代码,

		// Progressive jpeg: need to keep all of the data units.
		dataUnits = new int[nComponents][][];
	} else {
		// Sequential jpeg: only need one data unit.
		dataUnit = new int[8 * 8];
	}
	for (int i = 0; i < nComponents; i++) {
		int[] frameComponent = frameComponents[componentIds[i]];
		int bufferSize = frameComponent[CW] * frameComponent[CH];
		imageComponents[i] = new byte[bufferSize];
		if (progressive) {
			dataUnits[i] = new int[bufferSize][];
		}
	}

	/* Process the tables preceding the scan header. */
	processTables();
	
	/* Start of Scan. */
	scanHeader = new JPEGScanHeader(inputStream);
	if (!scanHeader.verify()) SWT.error(SWT.ERROR_INVALID_IMAGE);
	
	/* Process scan(s) and further tables until EOI. */
	int progressiveScanCount = 0;
	boolean done = false;
	while(!done) {
		resetInputBuffer();
		precedingDCs = new int[4];
		decodeScan();
		if (progressive && loader.hasListeners()) {
			ImageData imageData = createImageData();
			loader.notifyListeners(new ImageLoaderEvent(loader, imageData, progressiveScanCount, false));
			progressiveScanCount++;
		}

		/* Unread any buffered data before looking for tables again. */
		int delta = 512 - bufferCurrentPosition - 1;
		if (delta > 0) {
			byte[] unreadBuffer = new byte[delta];
			System.arraycopy(dataBuffer, bufferCurrentPosition + 1, unreadBuffer, 0, delta);
			try {
				inputStream.unread(unreadBuffer);
			} catch (IOException e) {
				SWT.error(SWT.ERROR_IO, e);
			}
		}
		
		/* Process the tables preceding the next scan header. */
		JPEGSegment jpegSegment = processTables();
		if (jpegSegment == null || jpegSegment.getSegmentMarker() == EOI) {
			done = true;
		} else {
			scanHeader = new JPEGScanHeader(inputStream);
			if (!scanHeader.verify()) SWT.error(SWT.ERROR_INVALID_IMAGE);
		}
	}
	
	if (progressive) {
		for (int ymcu = 0; ymcu < interleavedMcuRows; ymcu++) {
			for (int xmcu = 0; xmcu < interleavedMcuCols; xmcu++) {
				for (int iComp = 0; iComp < nComponents; iComp++) {
					int[] frameComponent = frameComponents[componentIds[iComp]];
					int hi = frameComponent[HI];
					int vi = frameComponent[VI];
					int compWidth = frameComponent[CW];
					for (int ivi = 0; ivi < vi; ivi++) {
						for (int ihi = 0; ihi < hi; ihi++) {
							int index = (ymcu * vi + ivi) * compWidth + xmcu * hi + ihi;
							dataUnit = dataUnits[iComp][index];
							dequantize(dataUnit, iComp);
							inverseDCT(dataUnit);
							storeData(dataUnit, iComp, xmcu, ymcu, hi, ihi, vi, ivi);
						}
					}
				}
			}
		}
	}
	ImageData imageData = createImageData();
	if (progressive && loader.hasListeners()) {
		loader.notifyListeners(new ImageLoaderEvent(loader, imageData, progressiveScanCount, true));
	}
	return new ImageData[] {imageData};
}
ImageData createImageData() {
	return ImageData.internal_new(
		imageWidth,
		imageHeight, 
		nComponents * samplePrecision,
		setUpPalette(),
		nComponents == 1 ? 4 : 1,
		decodeImageComponents(),
		0,
		null,
		null,
		-1,
		-1,
		SWT.IMAGE_JPEG,
		0,
		0,
		0,
		0);
}
int nextBit() {
	if (currentBitCount != 0) {
		currentBitCount--;
		currentByte *= 2;
		if (currentByte > 255) {
			currentByte -= 256;
			return 1;
		} else {
			return 0;
		}
	}
	bufferCurrentPosition++;
	if (bufferCurrentPosition >= 512) {
		resetInputBuffer();
		bufferCurrentPosition = 0;
	}
	currentByte = dataBuffer[bufferCurrentPosition] & 0xFF;
	currentBitCount = 8;
	byte nextByte;
	if (bufferCurrentPosition == 511) {
		resetInputBuffer();
		currentBitCount = 8;
		nextByte = dataBuffer[0];
	} else {
		nextByte = dataBuffer[bufferCurrentPosition + 1];
	}
	if (currentByte == 0xFF) {
		if (nextByte == 0) {
			bufferCurrentPosition ++;
			currentBitCount--;
			currentByte *= 2;
			if (currentByte > 255) {
				currentByte -= 256;
				return 1;
			} else {
				return 0;
			}
		} else {
			if ((nextByte & 0xFF) + 0xFF00 == DNL) {
				getDNL();
				return 0;
			} else {
				SWT.error(SWT.ERROR_INVALID_IMAGE);
				return 0;
			}
		}
	} else {
		currentBitCount--;
		currentByte *= 2;
		if (currentByte > 255) {
			currentByte -= 256;
			return 1;
		} else {
			return 0;
		}
	}
}
void processRestartInterval() {
	do {
		bufferCurrentPosition++;
		if (bufferCurrentPosition > 511) {
			resetInputBuffer();
			bufferCurrentPosition = 0;
		}
		currentByte = dataBuffer[bufferCurrentPosition] & 0xFF;
	} while (currentByte != 0xFF);
	while (currentByte == 0xFF) {
		bufferCurrentPosition++;
		if (bufferCurrentPosition > 511) {
			resetInputBuffer();
			bufferCurrentPosition = 0;
		}
		currentByte = dataBuffer[bufferCurrentPosition] & 0xFF;
	}
	if (currentByte != ((RST0 + nextRestartNumber) % 256)) {
		SWT.error(SWT.ERROR_INVALID_IMAGE);
	}
	bufferCurrentPosition++;
	if (bufferCurrentPosition > 511) {
		resetInputBuffer();
		bufferCurrentPosition = 0;
	}
	currentByte = dataBuffer[bufferCurrentPosition] & 0xFF;
	currentBitCount = 8;
	restartsToGo = restartInterval;
	nextRestartNumber = (nextRestartNumber + 1) % 8;
	precedingDCs = new int[4];
	eobrun = 0;
}
/* Process all markers until a frame header, scan header, or EOI is found. */
JPEGSegment processTables() {
	while (true) {
		JPEGSegment jpegSegment = seekUnspecifiedMarker(inputStream);
		if (jpegSegment == null) return null;
		JPEGFrameHeader sof = new JPEGFrameHeader(jpegSegment.reference);
		if (sof.verify()) {
			return jpegSegment;
		}
		int marker = jpegSegment.getSegmentMarker();
		switch (marker) {
			case SOI: // there should only be one SOI per file
				SWT.error(SWT.ERROR_INVALID_IMAGE);
			case EOI:
			case SOS:
				return jpegSegment;
			case DQT:
				getDQT();
				break;
			case DHT:
				getDHT();
				break;
			case DAC:
				getDAC();
				break;
			case DRI:
				getDRI();
				break;
			case APP0:
				getAPP0();
				break;
			case COM:
				getCOM();
				break;
			default:
				skipSegmentFrom(inputStream);
			
		}
	}
}
void quantizeData(int[] dataUnit, int iComp) {
	int[] qTable = quantizationTables[frameComponents[componentIds[iComp]][TQI]];
	for (int i = 0; i < dataUnit.length; i++) {
		int zzIndex = ZigZag8x8[i];
		int data = dataUnit[zzIndex];
		int absData = data < 0 ? 0 - data : data;
		int qValue = qTable[i];
		int q2 = qValue / 2;
		absData += q2;
		if (absData < qValue) {
			dataUnit[zzIndex] = 0;
		} else {
			absData /= qValue;
			if (data >= 0) {
				dataUnit[zzIndex] = absData;
			} else {
				dataUnit[zzIndex] = 0 - absData;
			}
		}
	}
}
int receive(int nBits) {
	int v = 0;
	for (int i = 0; i < nBits; i++) {
		v = v * 2 + nextBit();
	}
	return v;
}
void resetInputBuffer() {
	if (dataBuffer == null) {
		dataBuffer = new byte[512];
	}
	try {
		inputStream.read(dataBuffer);
	} catch (IOException e) {
		SWT.error(SWT.ERROR_IO, e);
	}
	currentBitCount = 0;
	bufferCurrentPosition = -1;
}
void resetOutputBuffer() {
	if (dataBuffer == null) {
		dataBuffer = new byte[512];
	} else {
		try {
			outputStream.write(dataBuffer, 0, bufferCurrentPosition);
		} catch (IOException e) {
			SWT.error(SWT.ERROR_IO, e);
		}
	}
	bufferCurrentPosition = 0;
}
static JPEGSegment seekUnspecifiedMarker(LEDataInputStream byteStream) {
	byte[] byteArray = new byte[2];
	try {
		while (true) {
			if (byteStream.read(byteArray, 0, 1) != 1) return null;
			if (byteArray[0] == (byte) 0xFF) {
				if (byteStream.read(byteArray, 1, 1) != 1) return null;
				if (byteArray[1] != (byte) 0xFF && byteArray[1] != 0) {
					byteStream.unread(byteArray);
					return new JPEGSegment(byteArray);
				}
			}
		}
	} catch (IOException e) {
		SWT.error(SWT.ERROR_IO, e);
	}
	return null;
}
PaletteData setUpPalette() {
	if (nComponents == 1) {
		RGB[] entries = new RGB[256];
		for (int i = 0; i < 256; i++) {
			entries[i] = new RGB(i, i, i);
		}
		return new PaletteData(entries);
	}
	return new PaletteData(0xFF, 0xFF00, 0xFF0000);
}
static void skipSegmentFrom(LEDataInputStream byteStream) {
	try {
		byte[] byteArray = new byte[4];
		JPEGSegment jpegSegment = new JPEGSegment(byteArray);
	
		if (byteStream.read(byteArray) != byteArray.length) {
			SWT.error(SWT.ERROR_INVALID_IMAGE);
		}
		if (!(byteArray[0] == -1 && byteArray[1] != 0 && byteArray[1] != -1)) {
			SWT.error(SWT.ERROR_INVALID_IMAGE);
		}
		int delta = jpegSegment.getSegmentLength() - 2;
		byteStream.skip(delta);
	} catch (Exception e) {
		SWT.error(SWT.ERROR_IO, e);
	}
}
void storeData(int[] dataUnit, int iComp, int xmcu, int ymcu, int hi, int ihi, int vi, int ivi) {
	byte[] compImage = imageComponents[iComp];
	int[] frameComponent = frameComponents[componentIds[iComp]];
	int compWidth = frameComponent[CW];
	int destIndex = ((ymcu * vi + ivi) * compWidth * DCTSIZE) + ((xmcu * hi + ihi) * DCTSIZE);
	int srcIndex = 0;
	for (int i = 0; i < DCTSIZE; i++) {
		for (int col = 0; col < DCTSIZE; col++) {
			int x = dataUnit[srcIndex] + 128;
			if (x < 0) {
				x = 0;
			} else {
				if (x > 255) x = 255;
			}
			compImage[destIndex + col] = (byte)x;
			srcIndex++;
		}
		destIndex += compWidth;
	}
}
void unloadIntoByteStream(ImageData image) {
	if (!new JPEGStartOfImage().writeToStream(outputStream)) {
		SWT.error(SWT.ERROR_IO);
	}
	JPEGAppn appn = new JPEGAppn(new byte[] {(byte)0xFF, (byte)0xE0, 0, 0x10, 0x4A, 0x46, 0x49, 0x46, 0, 1, 1, 0, 0, 1, 0, 1, 0, 0});
	if (!appn.writeToStream(outputStream)) {
		SWT.error(SWT.ERROR_IO);
	}
	quantizationTables = new int[4][];
	JPEGQuantizationTable chromDQT = JPEGQuantizationTable.defaultChrominanceTable();
	chromDQT.scaleBy(encoderQFactor);
	int[] jpegDQTKeys = chromDQT.getQuantizationTablesKeys();
	int[][] jpegDQTValues = chromDQT.getQuantizationTablesValues();
	for (int i = 0; i < jpegDQTKeys.length; i++) {
		quantizationTables[jpegDQTKeys[i]] = jpegDQTValues[i];
	}
	JPEGQuantizationTable lumDQT = JPEGQuantizationTable.defaultLuminanceTable();
	lumDQT.scaleBy(encoderQFactor);
	jpegDQTKeys = lumDQT.getQuantizationTablesKeys();
	jpegDQTValues = lumDQT.getQuantizationTablesValues();
	for (int i = 0; i < jpegDQTKeys.length; i++) {
		quantizationTables[jpegDQTKeys[i]] = jpegDQTValues[i];
	}
	if (!lumDQT.writeToStream(outputStream)) {
		SWT.error(SWT.ERROR_IO);
	}
	if (!chromDQT.writeToStream(outputStream)) {
		SWT.error(SWT.ERROR_IO);
	}
	int frameLength, scanLength, precision;
	int[][] frameParams, scanParams;
	if (image.depth == 1) {
		frameLength = 11;
		frameParams = new int[1][];
		frameParams[0] = new int[] {1, 1, 1, 0, 0};
		scanParams = new int[1][];
		scanParams[0] = new int[] {0, 0};
		scanLength = 8;
		nComponents = 1;
		precision = 1;
	} else {
		frameLength = 17;
		frameParams = new int[3][];
		frameParams[0] = new int[] {0, 2, 2, 0, 0};
		frameParams[1] = new int[] {1, 1, 1, 0, 0};
		frameParams[2] = new int[] {1, 1, 1, 0, 0};
		scanParams = new int[3][];
		scanParams[0] = new int[] {0, 0};
		scanParams[1] = new int[] {1, 1};
		scanParams[2] = new int[] {1, 1};
		scanLength = 12;
		nComponents = 3;
		precision = 8;
	}
	imageWidth = image.width;
	imageHeight = image.height;
	frameHeader = new JPEGFrameHeader(new byte[19]);
	frameHeader.setSegmentMarker(SOF0);
	frameHeader.setSegmentLength(frameLength);
	frameHeader.setSamplePrecision(precision);
	frameHeader.setSamplesPerLine(imageWidth);
	frameHeader.setNumberOfLines(imageHeight);
	frameHeader.setNumberOfImageComponents(nComponents);
	frameHeader.componentParameters = frameParams;
	frameHeader.componentIdentifiers = new int[] {0, 1, 2};
	frameHeader.initializeContents();
	if (!frameHeader.writeToStream(outputStream)) {
		SWT.error(SWT.ERROR_IO);
	}
	frameComponents = frameParams;
	componentIds = frameHeader.componentIdentifiers;
	maxH = frameHeader.getMaxHFactor();
	maxV = frameHeader.getMaxVFactor();
	int mcuWidth = maxH * DCTSIZE;
	int mcuHeight = maxV * DCTSIZE;
	interleavedMcuCols = (imageWidth + mcuWidth - 1) / mcuWidth;
	interleavedMcuRows = (imageHeight + mcuHeight - 1) / mcuHeight;
	acHuffmanTables = new JPEGHuffmanTable[4];
	dcHuffmanTables = new JPEGHuffmanTable[4];
	JPEGHuffmanTable[] dhtTables = new JPEGHuffmanTable[] {
		JPEGHuffmanTable.getDefaultDCLuminanceTable(),
		JPEGHuffmanTable.getDefaultDCChrominanceTable(),
		JPEGHuffmanTable.getDefaultACLuminanceTable(),
		JPEGHuffmanTable.getDefaultACChrominanceTable()
	};
	for (int i = 0; i < dhtTables.length; i++) {
		JPEGHuffmanTable dhtTable = dhtTables[i];
		if (!dhtTable.writeToStream(outputStream)) {
			SWT.error(SWT.ERROR_IO);
		}
		JPEGHuffmanTable[] allTables = dhtTable.getAllTables();
		for (int j = 0; j < allTables.length; j++) {
			JPEGHuffmanTable huffmanTable = allTables[j];
			if (huffmanTable.getTableClass() == 0) {
				dcHuffmanTables[huffmanTable.getTableIdentifier()] = huffmanTable;
			} else {
				acHuffmanTables[huffmanTable.getTableIdentifier()] = huffmanTable;
			}
		}
	}
	precedingDCs = new int[4];
	scanHeader = new JPEGScanHeader(new byte[14]);
	scanHeader.setSegmentMarker(SOS);
	scanHeader.setSegmentLength(scanLength);
	scanHeader.setNumberOfImageComponents(nComponents);
	scanHeader.setStartOfSpectralSelection(0);
	scanHeader.setEndOfSpectralSelection(63);
	scanHeader.componentParameters = scanParams;
	scanHeader.initializeContents();
	if (!scanHeader.writeToStream(outputStream)) {
		SWT.error(SWT.ERROR_IO);
	}
	convertImageToYCbCr(image);
	resetOutputBuffer();
	currentByte = 0;
	currentBitCount = 0;
	encodeScan();
	if (!new JPEGEndOfImage().writeToStream(outputStream)) {
		SWT.error(SWT.ERROR_IO);
	}
}
}