jpegfileformat.java

源码为Eclipse开源开发平台桌面开发工具SWT的源代码,

	for (int row = 0; row < 8; row++) {
		int rIndex = row * DCTSIZE;
		int tmp0 = dataUnit[rIndex] + dataUnit[rIndex + 7];
		int tmp7 = dataUnit[rIndex] - dataUnit[rIndex + 7];
		int tmp1 = dataUnit[rIndex + 1] + dataUnit[rIndex + 6];
		int tmp6 = dataUnit[rIndex + 1] - dataUnit[rIndex + 6];
		int tmp2 = dataUnit[rIndex + 2] + dataUnit[rIndex + 5];
		int tmp5 = dataUnit[rIndex + 2] - dataUnit[rIndex + 5];
		int tmp3 = dataUnit[rIndex + 3] + dataUnit[rIndex + 4];
		int tmp4 = dataUnit[rIndex + 3] - dataUnit[rIndex + 4];

		/**
		 * Even part per LL&M figure 1 --- note that published figure 
		 * is faulty; rotator 'sqrt(2)*c1' should be 'sqrt(2)*c6'.
		 */
		int tmp10 = tmp0 + tmp3;
		int tmp13 = tmp0 - tmp3;
		int tmp11 = tmp1 + tmp2;
		int tmp12 = tmp1 - tmp2;

		dataUnit[rIndex] = (tmp10 + tmp11) * 4;
		dataUnit[rIndex + 4]  = (tmp10 - tmp11) * 4;

		int z1 = (tmp12 + tmp13) * FIX_0_541196100;
		int scaleFactor1 = ExtendTest[11];
		int scaleFactor2 = ExtendTest[12];
		int n = z1 + (tmp13 * FIX_0_765366865) + scaleFactor1;
		dataUnit[rIndex + 2] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[rIndex + 2]--;
		n = z1 + (tmp12 * (0 - FIX_1_847759065)) + scaleFactor1;
 		dataUnit[rIndex + 6] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[rIndex + 6]--;

		/**
		 * Odd part per figure 8 --- note paper omits factor of sqrt(2).
		 * cK represents cos(K*pi/16).
		 * i0..i3 in the paper are tmp4..tmp7 here.
		 */
		z1 = tmp4 + tmp7;
		int z2 = tmp5 + tmp6;
		int z3 = tmp4 + tmp6;
		int z4 = tmp5 + tmp7;
		int z5 = (z3 + z4) * FIX_1_175875602;	// sqrt(2) * c3

		tmp4 = tmp4 * FIX_0_298631336;	// sqrt(2) * (-c1+c3+c5-c7)
		tmp5 = tmp5 * FIX_2_053119869;	// sqrt(2) * ( c1+c3-c5+c7)
		tmp6 = tmp6 * FIX_3_072711026;	// sqrt(2) * ( c1+c3+c5-c7)
		tmp7 = tmp7 * FIX_1_501321110;	// sqrt(2) * ( c1+c3-c5-c7)
		z1 = z1 * (0 - FIX_0_899976223);	// sqrt(2) * (c7-c3)
		z2 = z2 * (0 - FIX_2_562915447);	// sqrt(2) * (-c1-c3)
		z3 = z3 * (0 - FIX_1_961570560);	// sqrt(2) * (-c3-c5)
		z4 = z4 * (0 - FIX_0_390180644);	// sqrt(2) * (c5-c3)

		z3 = z3 + z5;
		z4 = z4 + z5;

		n = tmp4 + z1 + z3 + scaleFactor1;
		dataUnit[rIndex + 7] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[rIndex + 7]--;
		n = tmp5 + z2 + z4 + scaleFactor1;
		dataUnit[rIndex + 5] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[rIndex + 5]--;
		n = tmp6 + z2 + z3 + scaleFactor1;
		dataUnit[rIndex + 3] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[rIndex + 3]--;
		n = tmp7 + z1 + z4 + scaleFactor1;
		dataUnit[rIndex + 1] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[rIndex + 1]--;
	}

	/**
	 * Pass 2: process columns.
	 * Note that we must descale the results by a factor of 8 == 2**3,
	 * and also undo the PASS1_BITS scaling.
	 */
	for (int col = 0; col < 8; col++) {
		int c0 = col;
		int c1 = col + 8;
		int c2 = col + 16;
		int c3 = col + 24;
		int c4 = col + 32;
		int c5 = col + 40;
		int c6 = col + 48;
		int c7 = col + 56;
		int tmp0 = dataUnit[c0] + dataUnit[c7];
		int tmp7 = dataUnit[c0] - dataUnit[c7];
		int tmp1 = dataUnit[c1] + dataUnit[c6];
		int tmp6 = dataUnit[c1] - dataUnit[c6];
		int tmp2 = dataUnit[c2] + dataUnit[c5];
		int tmp5 = dataUnit[c2] - dataUnit[c5];
		int tmp3 = dataUnit[c3] + dataUnit[c4];
		int tmp4 = dataUnit[c3] - dataUnit[c4];

		/**
		 * Even part per LL&M figure 1 --- note that published figure 
		 * is faulty; rotator 'sqrt(2)*c1' should be 'sqrt(2)*c6'.
		 */
		int tmp10 = tmp0 + tmp3;
		int tmp13 = tmp0 - tmp3;
		int tmp11 = tmp1 + tmp2;
		int tmp12 = tmp1 - tmp2;

		int scaleFactor1 = ExtendTest[5];
		int scaleFactor2 = ExtendTest[6];
		int n = tmp10 + tmp11 + scaleFactor1;
		dataUnit[c0] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[c0]--;
		n = tmp10 - tmp11 + scaleFactor1;
		dataUnit[c4] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[c4]--;

		int z1 = (tmp12 + tmp13) * FIX_0_541196100;
		scaleFactor1 = ExtendTest[18];
		scaleFactor2 = ExtendTest[19];
		n = z1 + (tmp13 * FIX_0_765366865) + scaleFactor1;
		dataUnit[c2] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[c2]--;
		n = z1 + (tmp12 * (0 - FIX_1_847759065)) + scaleFactor1;
		dataUnit[c6] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[c6]--;

		/**
		 * Odd part per figure 8 --- note paper omits factor of sqrt(2).
		 * cK represents cos(K*pi/16).
		 * i0..i3 in the paper are tmp4..tmp7 here.
		 */
		z1 = tmp4 + tmp7;
		int z2 = tmp5 + tmp6;
		int z3 = tmp4 + tmp6;
		int z4 = tmp5 + tmp7;
		int z5 = (z3 + z4) * FIX_1_175875602;	// sqrt(2) * c3

		tmp4 = tmp4 * FIX_0_298631336;	// sqrt(2) * (-c1+c3+c5-c7)
		tmp5 = tmp5 * FIX_2_053119869;	// sqrt(2) * ( c1+c3-c5+c7)
		tmp6 = tmp6 * FIX_3_072711026;	// sqrt(2) * ( c1+c3+c5-c7)
		tmp7 = tmp7 * FIX_1_501321110;	// sqrt(2) * ( c1+c3-c5-c7)
		z1 = z1 * (0 - FIX_0_899976223);	// sqrt(2) * (c7-c3)
		z2 = z2 * (0 - FIX_2_562915447);	// sqrt(2) * (-c1-c3)
		z3 = z3 * (0 - FIX_1_961570560);	// sqrt(2) * (-c3-c5)
		z4 = z4 * (0 - FIX_0_390180644);	// sqrt(2) * (c5-c3)

		z3 = z3 + z5;
		z4 = z4 + z5;

		n = tmp4 + z1 + z3 + scaleFactor1;
		dataUnit[c7] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[c7]--;
		n = tmp5 + z2 + z4 + scaleFactor1;
		dataUnit[c5] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[c5]--;
		n = tmp6 + z2 + z3 + scaleFactor1;
		dataUnit[c3] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[c3]--;
		n = tmp7 + z1 + z4 + scaleFactor1;
		dataUnit[c1] = n / scaleFactor2;
		if ((n < 0) && (n % scaleFactor2 != 0)) dataUnit[c1]--;
	}
}
void getAPP0() {
	JPEGAppn appn = new JPEGAppn(inputStream);
	if (!appn.verify()) {
		SWT.error(SWT.ERROR_INVALID_IMAGE);
	}
}
void getCOM() {
	new JPEGComment(inputStream);
}
void getDAC() {
	JPEGArithmeticConditioningTable dac = new JPEGArithmeticConditioningTable(inputStream);
	arithmeticTables = dac;
}
void getDHT() {
	JPEGHuffmanTable dht = new JPEGHuffmanTable(inputStream);
	if (!dht.verify()) {
		SWT.error(SWT.ERROR_INVALID_IMAGE);
	}
	if (acHuffmanTables == null) {
		acHuffmanTables = new JPEGHuffmanTable[4];
	}
	if (dcHuffmanTables == null) {
		dcHuffmanTables = new JPEGHuffmanTable[4];
	}
	JPEGHuffmanTable[] dhtTables = dht.getAllTables();
	for (int i = 0; i < dhtTables.length; i++) {
		JPEGHuffmanTable dhtTable = dhtTables[i];
		if (dhtTable.getTableClass() == 0) {
			dcHuffmanTables[dhtTable.getTableIdentifier()] = dhtTable;
		} else {
			acHuffmanTables[dhtTable.getTableIdentifier()] = dhtTable;
		}
	}
}
void getDNL() {
	new JPEGRestartInterval(inputStream);
}
void getDQT() {
	JPEGQuantizationTable dqt = new JPEGQuantizationTable(inputStream);
	int[][] currentTables = quantizationTables;
	if (currentTables == null) {
		currentTables = new int[4][];
	}
	int[] dqtTablesKeys = dqt.getQuantizationTablesKeys();
	int[][] dqtTablesValues = dqt.getQuantizationTablesValues();
	for (int i = 0; i < dqtTablesKeys.length; i++) {
		int index = dqtTablesKeys[i];
		currentTables[index] = dqtTablesValues[i];
	}
	quantizationTables = currentTables;
}
void getDRI() {
	JPEGRestartInterval dri = new JPEGRestartInterval(inputStream);
	if (!dri.verify()) {
		SWT.error(SWT.ERROR_INVALID_IMAGE);
	}
	restartInterval = dri.getRestartInterval();
}
static void initialize() {
	initializeRGBYCbCrTables();
	initializeYCbCrRGBTables();
	initializeBitCountTable();
}
static void initializeBitCountTable() {
	int nBits = 1;
	int power2 = 2;
	NBitsTable = new int[2048];
	NBitsTable[0] = 0;
	for (int i = 1; i < NBitsTable.length; i++) {
		if (!(i < power2)) {
			nBits++;
			power2 *= 2;
		}
		NBitsTable[i] = nBits;
	}
}
static void initializeRGBYCbCrTables() {
	RYTable = new int[256];
	GYTable = new int[256];
	BYTable = new int[256];
	RCbTable = new int[256];
	GCbTable = new int[256];
	BCbTable = new int[256];
	RCrTable = BCbTable;
	GCrTable = new int[256];
	BCrTable = new int[256];
	for (int i = 0; i < 256; i++) {
		RYTable[i] = i * 19595;
		GYTable[i] = i * 38470;
		BYTable[i] = i * 7471 + 32768;
		RCbTable[i] = i * -11059;
		GCbTable[i] = i * -21709;
		BCbTable[i] = i * 32768 + 8388608;
		GCrTable[i] = i * -27439;
		BCrTable[i] = i * -5329;
	}
}
static void initializeYCbCrRGBTables() {
	CrRTable = new int[256];
	CbBTable = new int[256];
	CrGTable = new int[256];
	CbGTable = new int[256];
	for (int i = 0; i < 256; i++) {
		int x2 = 2 * i - 255;
		CrRTable[i] = (45941 * x2 + 32768) / 65536;
		CbBTable[i] = (58065 * x2 + 32768) / 65536;
		CrGTable[i] = -23401 * x2;
		CbGTable[i] = -11277 * x2 + 32768;
	}
}
void inverseDCT(int[] dataUnit) {
	for (int row = 0; row < 8; row++) {
		int rIndex = row * DCTSIZE;
		/**
		 * Due to quantization, we will usually find that many of the input
		 * coefficients are zero, especially the AC terms.  We can exploit this
		 * by short-circuiting the IDCT calculation for any row in which all
		 * the AC terms are zero.  In that case each output is equal to the
		 * DC coefficient (with scale factor as needed).
		 * With typical images and quantization tables, half or more of the
		 * row DCT calculations can be simplified this way.
		 */
		if (isZeroInRow(dataUnit, rIndex)) {
			int dcVal = dataUnit[rIndex] * 4;
			for (int i = rIndex; i < rIndex + 8; i++) {
				dataUnit[i] = dcVal;
			}
		} else {
			/**
			 * Even part: reverse the even part of the forward DCT.
			 * The rotator is sqrt(2)*c(-6).
			 */
			int z2 = dataUnit[rIndex + 2];
			int z3 = dataUnit[rIndex + 6];
			int z1 = (z2 + z3) * FIX_0_541196100;
			int tmp2 = z1 + (z3 * (0 - FIX_1_847759065));
			int tmp3 = z1 + (z2 * FIX_0_765366865);
			int tmp0 = (dataUnit[rIndex] + dataUnit[rIndex + 4]) * 8192;
			int tmp1 = (dataUnit[rIndex] - dataUnit[rIndex + 4]) * 8192;
			int tmp10 = tmp0 + tmp3;
			int tmp13 = tmp0 - tmp3;
			int tmp11 = tmp1 + tmp2;
			int tmp12 = tmp1 - tmp2;
			/**
			 * Odd part per figure 8; the matrix is unitary and hence its
			 * transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively.
			 */
			tmp0 = dataUnit[rIndex + 7];
			tmp1 = dataUnit[rIndex + 5];
			tmp2 = dataUnit[rIndex + 3];
			tmp3 = dataUnit[rIndex + 1];
			z1 = tmp0 + tmp3;
			z2 = tmp1 + tmp2;
			z3 = tmp0 + tmp2;
			int z4 = tmp1 + tmp3;
			int z5 = (z3 + z4)* FIX_1_175875602; /* sqrt(2) * c3 */
			  
			tmp0 = tmp0 * FIX_0_298631336;		/* sqrt(2) * (-c1+c3+c5-c7) */
			tmp1 = tmp1 * FIX_2_053119869;		/* sqrt(2) * ( c1+c3-c5+c7) */
			tmp2 = tmp2 * FIX_3_072711026;		/* sqrt(2) * ( c1+c3+c5-c7) */
			tmp3 = tmp3 * FIX_1_501321110;		/* sqrt(2) * ( c1+c3-c5-c7) */
			z1 = z1 * (0 - FIX_0_899976223);	/* sqrt(2) * (c7-c3) */
			z2 = z2 * (0 - FIX_2_562915447);	/* sqrt(2) * (-c1-c3) */
			z3 = z3 * (0 - FIX_1_961570560);	/* sqrt(2) * (-c3-c5) */
			z4 = z4 * (0 - FIX_0_390180644);	/* sqrt(2) * (c5-c3) */

			z3 = z3 + z5;
			z4 = z4 + z5;
			tmp0 = tmp0 + z1 + z3;
			tmp1 = tmp1 + z2 + z4;
			tmp2 = tmp2 + z2 + z3;
			tmp3 = tmp3 + z1 + z4;

			int descaleFactor1 = ExtendTest[11];
			int descaleFactor2 = ExtendTest[12];
			dataUnit[rIndex] = (tmp10 + tmp3 + descaleFactor1) / descaleFactor2;
			dataUnit[rIndex + 7] = (tmp10 - tmp3 + descaleFactor1) / descaleFactor2;
			dataUnit[rIndex + 1] = (tmp11 + tmp2 + descaleFactor1) / descaleFactor2;
			dataUnit[rIndex + 6] = (tmp11 - tmp2 + descaleFactor1) / descaleFactor2;
			dataUnit[rIndex + 2] = (tmp12 + tmp1 + descaleFactor1) / descaleFactor2;
			dataUnit[rIndex + 5] = (tmp12 - tmp1 + descaleFactor1) / descaleFactor2;
			dataUnit[rIndex + 3] = (tmp13 + tmp0 + descaleFactor1) / descaleFactor2;
			dataUnit[rIndex + 4] = (tmp13 - tmp0 + descaleFactor1) / descaleFactor2;
		 }
	}
	/**
	 * Pass 2: process columns.
	 * Note that we must descale the results by a factor of 8 == 2**3,
	 * and also undo the PASS1_BITS scaling.
	 */
	for (int col = 0; col < 8; col++) {
		int c0 = col;
		int c1 = col + 8;
		int c2 = col + 16;
		int c3 = col + 24;
		int c4 = col + 32;
		int c5 = col + 40;
		int c6 = col + 48;
		int c7 = col + 56;
		if (isZeroInColumn(dataUnit, col)) {
			int dcVal = (dataUnit[c0] + 16) / 32;
			dataUnit[c0] = dcVal;
			dataUnit[c1] = dcVal;
			dataUnit[c2] = dcVal;
			dataUnit[c3] = dcVal;
			dataUnit[c4] = dcVal;
			dataUnit[c5] = dcVal;
			dataUnit[c6] = dcVal;
			dataUnit[c7] = dcVal;
		} else {
			/**
			 * Even part: reverse the even part of the forward DCT.
			 * The rotator is sqrt(2)*c(-6).
			 */
			int z2 = dataUnit[c2];
			int z3 = dataUnit[c6];
			int z1 = (z2 + z3) * FIX_0_541196100;
			int tmp2 = z1 + (z3 * (0 - FIX_1_847759065));
			int tmp3 = z1 + (z2 * FIX_0_765366865);
			int tmp0 = (dataUnit[c0] + dataUnit[c4]) * 8192;
			int tmp1 = (dataUnit[c0] - dataUnit[c4]) * 8192;
			int tmp10 = tmp0 + tmp3;
			int tmp13 = tmp0 - tmp3;
			int tmp11 = tmp1 + tmp2;
			int tmp12 = tmp1 - tmp2;
			/**
			 * Odd part per figure 8; the matrix is unitary and hence its
			 * transpose is its inverse. i0..i3 are y7,y5,y3,y1 respectively.
			 */
			tmp0 = dataUnit[c7];
			tmp1 = dataUnit[c5];
			tmp2 = dataUnit[c3];
			tmp3 = dataUnit[c1];
			z1 = tmp0 + tmp3;
			z2 = tmp1 + tmp2;
			z3 = tmp0 + tmp2;
			int z4 = tmp1 + tmp3;
			int z5 = (z3 + z4) * FIX_1_175875602;	/* sqrt(2) * c3 */
			
			tmp0 = tmp0 * FIX_0_298631336;		/* sqrt(2) * (-c1+c3+c5-c7) */
			tmp1 = tmp1 * FIX_2_053119869;		/* sqrt(2) * ( c1+c3-c5+c7) */
			tmp2 = tmp2 * FIX_3_072711026;		/* sqrt(2) * ( c1+c3+c5-c7) */
			tmp3 = tmp3 * FIX_1_501321110;		/* sqrt(2) * ( c1+c3-c5-c7) */
			z1 = z1 * (0 - FIX_0_899976223);	/* sqrt(2) * (c7-c3) */
			z2 = z2 * (0 - FIX_2_562915447);	/* sqrt(2) * (-c1-c3) */
			z3 = z3 * (0 - FIX_1_961570560);	/* sqrt(2) * (-c3-c5) */
			z4 = z4 * (0 - FIX_0_390180644);	/* sqrt(2) * (c5-c3) */
			
			z3 = z3 + z5;
			z4 = z4 + z5;
			
			tmp0 = tmp0 + z1 + z3;
			tmp1 = tmp1 + z2 + z4;
			tmp2 = tmp2 + z2 + z3;
			tmp3 = tmp3 + z1 + z4;

			/* Final output stage: inputs are tmp10..tmp13, tmp0..tmp3 */
			int descaleFactor1 = ExtendTest[18];
			int descaleFactor2 = ExtendTest[19];
			dataUnit[c0] = (tmp10 + tmp3 + descaleFactor1) / descaleFactor2;
			dataUnit[c7] = (tmp10 - tmp3 + descaleFactor1) / descaleFactor2;
			dataUnit[c1] = (tmp11 + tmp2 + descaleFactor1) / descaleFactor2;
			dataUnit[c6] = (tmp11 - tmp2 + descaleFactor1) / descaleFactor2;
			dataUnit[c2] = (tmp12 + tmp1 + descaleFactor1) / descaleFactor2;
			dataUnit[c5] = (tmp12 - tmp1 + descaleFactor1) / descaleFactor2;
			dataUnit[c3] = (tmp13 + tmp0 + descaleFactor1) / descaleFactor2;
			dataUnit[c4] = (tmp13 - tmp0 + descaleFactor1) / descaleFactor2;
		}
	}
}
boolean isFileFormat(LEDataInputStream stream) {
	try {
		JPEGStartOfImage soi = new JPEGStartOfImage(stream);
		stream.unread(soi.reference);
		return soi.verify();  // we no longer check for appN
	} catch (Exception e) {
		return false;
	}
}
boolean isZeroInColumn(int[] dataUnit, int col) {
	return (dataUnit[col + 8] + dataUnit[col + 16] +
		dataUnit[col + 24] + dataUnit[col + 32] +
		dataUnit[col + 40] + dataUnit[col + 48] +
		dataUnit[col + 56]) == 0;
}
boolean isZeroInRow(int[] dataUnit, int rIndex) {
	return (dataUnit[rIndex + 1] + dataUnit[rIndex + 2] +
		dataUnit[rIndex + 3] + dataUnit[rIndex + 4] +
		dataUnit[rIndex + 5] + dataUnit[rIndex + 6] +
		dataUnit[rIndex + 7]) == 0;
}
ImageData[] loadFromByteStream() {
	JPEGStartOfImage soi = new JPEGStartOfImage(inputStream);
	if (!soi.verify()) SWT.error(SWT.ERROR_INVALID_IMAGE);
	restartInterval = 0;

	/* Process the tables preceding the frame header. */
	processTables();
	
	/* Start of Frame. */
	frameHeader = new JPEGFrameHeader(inputStream);
	if (!frameHeader.verify()) SWT.error(SWT.ERROR_INVALID_IMAGE);
	imageWidth = frameHeader.getSamplesPerLine();
	imageHeight = frameHeader.getNumberOfLines();
	maxH = frameHeader.getMaxHFactor();
	maxV = frameHeader.getMaxVFactor();
	int mcuWidth = maxH * DCTSIZE;
	int mcuHeight = maxV * DCTSIZE;
	interleavedMcuCols = (imageWidth + mcuWidth - 1) / mcuWidth;
	interleavedMcuRows = (imageHeight + mcuHeight - 1) / mcuHeight;
	progressive = frameHeader.isProgressive();
	samplePrecision = frameHeader.getSamplePrecision();
	nComponents = frameHeader.getNumberOfImageComponents();
	frameComponents = frameHeader.componentParameters;
	componentIds = frameHeader.componentIdentifiers;
	imageComponents = new byte[nComponents][];
	if (progressive) {