winbmpfileformat.java

源码为Eclipse开源开发平台桌面开发工具SWT的源代码,

/*******************************************************************************
 * Copyright (c) 2000, 2004 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Common Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/cpl-v10.html
 * 
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.internal.image;


import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import java.io.*;

final class WinBMPFileFormat extends FileFormat {
	int importantColors;
	Point pelsPerMeter = new Point(0, 0);
	public static final int BMPHeaderFixedSize = 40;

/**
 * Compress numBytes bytes of image data from src, storing in dest
 * (starting at 0), using the technique specified by comp.
 * If last is true, this indicates the last line of the image.
 * Answer the size of the compressed data.
 */
int compress(int comp, byte[] src, int srcOffset, int numBytes, byte[] dest, boolean last) {
	if (comp == 1) { // BMP_RLE8_COMPRESSION
		return compressRLE8Data(src, srcOffset, numBytes, dest, last);
	}
	if (comp == 2) { // BMP_RLE4_COMPRESSION
		return compressRLE4Data(src, srcOffset, numBytes, dest, last);
	}
	SWT.error(SWT.ERROR_INVALID_IMAGE);
	return 0;
}
int compressRLE4Data(byte[] src, int srcOffset, int numBytes, byte[] dest, boolean last) {
	int sp = srcOffset, end = srcOffset + numBytes, dp = 0;
	int size = 0, left, i, n;
	byte theByte;
	while (sp < end) {
		/* find two consecutive bytes that are the same in the next 128 */
		left = end - sp - 1;
		if (left > 127)
			left = 127;
		for (n = 0; n < left; n++) {
			if (src[sp + n] == src[sp + n + 1])
				break;
		}
		/* if there is only one more byte in the scan line, include it */
		if (n < 127 && n == left)
			n++;
		/* store the intervening data */
		switch (n) {
			case 0:
				break;
			case 1: /* handled separately because 0,2 is a command */
				dest[dp] = 2; dp++; /* 1 byte == 2 pixels */
				dest[dp] = src[sp];
				dp++; sp++;
				size += 2;
				break;
			default:
				dest[dp] = 0; dp++;
				dest[dp] = (byte)(n + n); dp++; /* n bytes = n*2 pixels */
				for (i = n; i > 0; i--) {
					dest[dp] = src[sp];
					dp++; sp++;
				}
				size += 2 + n;
				if ((n & 1) != 0) { /* pad to word */
					dest[dp] = 0;
					dp++;
					size++;
				}
				break;
		}
		/* find the length of the next run (up to 127) and store it */
		left = end - sp;
		if (left > 0) {
			if (left > 127)
				left = 127;
			theByte = src[sp];
			for (n = 1; n < left; n++) {
				if (src[sp + n] != theByte)
					break;
			}
			dest[dp] = (byte)(n + n); dp++; /* n bytes = n*2 pixels */
			dest[dp] = theByte; dp++;
			sp += n;
			size += 2;
		}
	}

	/* store the end of line or end of bitmap codes */
	dest[dp] = 0; dp++;
	if (last) {
		dest[dp] = 1; dp++;
	} else {
		dest[dp] = 0; dp++;
	}
	size += 2;
	
	return size;
}
int compressRLE8Data(byte[] src, int srcOffset, int numBytes, byte[] dest, boolean last) {
	int sp = srcOffset, end = srcOffset + numBytes, dp = 0;
	int size = 0, left, i, n;
	byte theByte;
	while (sp < end) {
		/* find two consecutive bytes that are the same in the next 256 */
		left = end - sp - 1;
		if (left > 254)
			left = 254;
		for (n = 0; n < left; n++) {
			if (src[sp + n] == src[sp + n + 1])
				break;
		}
		/* if there is only one more byte in the scan line, include it */
		if (n == left)
			n++;
		/* store the intervening data */
		switch (n) {
			case 0:
				break;
			case 2: /* handled separately because 0,2 is a command */
				dest[dp] = 1; dp++;
				dest[dp] = src[sp];
				dp++; sp++;
				size += 2;
				/* don't break, fall through */
			case 1: /* handled separately because 0,1 is a command */
				dest[dp] = 1; dp++;
				dest[dp] = src[sp];
				dp++; sp++;
				size += 2;
				break;
			default:
				dest[dp] = 0; dp++;
				dest[dp] = (byte)n; dp++;
				for (i = n; i > 0; i--) {
					dest[dp] = src[sp];
					dp++; sp++;
				}
				size += 2 + n;
				if ((n & 1) != 0) { /* pad to word */
					dest[dp] = 0;
					dp++;
					size++;
				}
				break;
		}
		/* find the length of the next run (up to 255) and store it */
		left = end - sp;
		if (left > 0) {
			if (left > 255)
				left = 255;
			theByte = src[sp];
			for (n = 1; n < left; n++) {
				if (src[sp + n] != theByte)
					break;
			}
			dest[dp] = (byte)n; dp++;
			dest[dp] = theByte; dp++;
			sp += n;
			size += 2;
		}
	}

	/* store the end of line or end of bitmap codes */
	dest[dp] = 0; dp++;
	if (last) {
		dest[dp] = 1; dp++;
	} else {
		dest[dp] = 0; dp++;
	}
	size += 2;
	
	return size;
}
void decompressData(byte[] src, byte[] dest, int stride, int cmp) {
	if (cmp == 1) { // BMP_RLE8_COMPRESSION
		if (decompressRLE8Data(src, src.length, stride, dest, dest.length) <= 0)
			SWT.error(SWT.ERROR_INVALID_IMAGE);
		return;
	}
	if (cmp == 2) { // BMP_RLE4_COMPRESSION
		if (decompressRLE4Data(src, src.length, stride, dest, dest.length) <= 0)
			SWT.error(SWT.ERROR_INVALID_IMAGE);
		return;
	}
	SWT.error(SWT.ERROR_INVALID_IMAGE);
}
int decompressRLE4Data(byte[] src, int numBytes, int stride, byte[] dest, int destSize) {
	int sp = 0;
	int se = numBytes;
	int dp = 0;
	int de = destSize;
	int x = 0, y = 0;
	while (sp < se) {
		int len = src[sp] & 0xFF;
		sp++;
		if (len == 0) {
			len = src[sp] & 0xFF;
			sp++;
			switch (len) {
				case 0: /* end of line */
					y++;
					x = 0;
					dp = y * stride;
					if (dp >= de)
						return -1;
					break;
				case 1: /* end of bitmap */
					return 1;
				case 2: /* delta */
					x += src[sp] & 0xFF;
					sp++;
					y += src[sp] & 0xFF;
					sp++;
					dp = y * stride + x / 2;
					if (dp >= de)
						return -1;
					break;
				default: /* absolute mode run */
					if ((len & 1) != 0) /* odd run lengths not currently supported */
						return -1;
					x += len;
					len = len / 2;
					if (len > (se - sp))
						return -1;
					if (len > (de - dp))
						return -1;
					for (int i = 0; i < len; i++) {
						dest[dp] = src[sp];
						dp++;
						sp++;
					}
					if ((sp & 1) != 0)
						sp++; /* word align sp? */
					break;
			}
		} else {
			if ((len & 1) != 0)
				return -1;
			x += len;
			len = len / 2;
			byte theByte = src[sp];
			sp++;
			if (len > (de - dp))
				return -1;
			for (int i = 0; i < len; i++) {
				dest[dp] = theByte;
				dp++;
			}
		}
	}
	return 1;
}
int decompressRLE8Data(byte[] src, int numBytes, int stride, byte[] dest, int destSize) {
	int sp = 0;
	int se = numBytes;
	int dp = 0;
	int de = destSize;
	int x = 0, y = 0;
	while (sp < se) {
		int len = src[sp] & 0xFF;
		sp++;
		if (len == 0) {
			len = src[sp] & 0xFF;
			sp++;
			switch (len) {
				case 0: /* end of line */
					y++;
					x = 0;
					dp = y * stride;
					if (dp >= de)
						return -1;
					break;
				case 1: /* end of bitmap */
					return 1;
				case 2: /* delta */
					x += src[sp] & 0xFF;
					sp++;
					y += src[sp] & 0xFF;
					sp++;
					dp = y * stride + x;
					if (dp >= de)
						return -1;
					break;
				default: /* absolute mode run */
					if (len > (se - sp))
						return -1;
					if (len > (de - dp))
						return -1;
					for (int i = 0; i < len; i++) {
						dest[dp] = src[sp];
						dp++;
						sp++;
					}
					if ((sp & 1) != 0)
						sp++; /* word align sp? */
					x += len;
					break;
			}
		} else {
			byte theByte = src[sp];
			sp++;
			if (len > (de - dp))
				return -1;
			for (int i = 0; i < len; i++) {
				dest[dp] = theByte;
				dp++;
			}
			x += len;
		}
	}
	return 1;
}
boolean isFileFormat(LEDataInputStream stream) {
	try {
		byte[] header = new byte[2];
		stream.read(header);
		stream.unread(header);
		return header[0] == 0x42 && header[1] == 0x4D;
	} catch (Exception e) {
		return false;
	}
}
byte[] loadData(byte[] infoHeader) {
	int width = (infoHeader[4] & 0xFF) | ((infoHeader[5] & 0xFF) << 8) | ((infoHeader[6] & 0xFF) << 16) | ((infoHeader[7] & 0xFF) << 24);
	int height = (infoHeader[8] & 0xFF) | ((infoHeader[9] & 0xFF) << 8) | ((infoHeader[10] & 0xFF) << 16) | ((infoHeader[11] & 0xFF) << 24);
	int bitCount = (infoHeader[14] & 0xFF) | ((infoHeader[15] & 0xFF) << 8);