imagedata.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.graphics;


import java.io.*;
import org.eclipse.swt.*;
import org.eclipse.swt.internal.CloneableCompatibility;

/**
 * Instances of this class are device-independent descriptions
 * of images. They are typically used as an intermediate format
 * between loading from or writing to streams and creating an 
 * <code>Image</code>.
 * <p>
 * Note that the public fields <code>x</code>, <code>y</code>, 
 * <code>disposalMethod</code> and <code>delayTime</code> are
 * typically only used when the image is in a set of images used
 * for animation.
 * </p>
 *
 * @see Image
 * @see ImageLoader
 */

public final class ImageData implements CloneableCompatibility {
	
	/**
	 * The width of the image, in pixels.
	 */
	public int width;

	/**
	 * The height of the image, in pixels.
	 */
	public int height;

	/**
	 * The color depth of the image, in bits per pixel.
	 * <p>
	 * Note that a depth of 8 or less does not necessarily
	 * mean that the image is palette indexed, or
	 * conversely that a depth greater than 8 means that
	 * the image is direct color.  Check the associated
	 * PaletteData's isDirect field for such determinations.
	 */
	public int depth;

	/**
	 * The scanline padding.
	 * <p>
	 * If one scanline of the image is not a multiple of
	 * this number, it will be padded with zeros until it is.
	 * </p>
	 */
	public int scanlinePad;

	/**
	 * The number of bytes per scanline.
	 * <p>
	 * This is a multiple of the scanline padding.
	 * </p>
	 */
	public int bytesPerLine;

	/**
	 * The pixel data of the image.
	 * <p>
	 * Note that for 16 bit depth images the pixel data is stored
	 * in least significant byte order; however, for 24bit and
	 * 32bit depth images the pixel data is stored in most
	 * significant byte order.
	 * </p>
	 */
	public byte[] data;

	/**
	 * The color table for the image.
	 */
	public PaletteData palette;

	/**
	 * The transparent pixel.
	 * <p>
	 * Pixels with this value are transparent.
	 * </p><p>
	 * The default is -1 which means 'no transparent pixel'.
	 * </p>
	 */
	public int transparentPixel;

	/**
	 * An icon-specific field containing the data from the icon mask.
	 * <p>
	 * This is a 1 bit bitmap stored with the most significant
	 * bit first.  The number of bytes per scanline is
	 * '((width + 7) / 8 + (maskPad - 1)) / maskPad * maskPad'.
	 * </p><p>
	 * The default is null which means 'no transparency mask'.
	 * </p>
	 */
	public byte[] maskData;

	/**
	 * An icon-specific field containing the scanline pad of the mask.
	 * <p>
	 * If one scanline of the transparency mask is not a
	 * multiple of this number, it will be padded with zeros until
	 * it is.
	 * </p>
	 */
	public int maskPad;
	
	/**
	 * The alpha data of the image.
	 * <p>
	 * Every pixel can have an <em>alpha blending</em> value that
	 * varies from 0, meaning fully transparent, to 255 meaning
	 * fully opaque.  The number of bytes per scanline is
	 * 'width'.
	 * </p>
	 */
	public byte[] alphaData;
	
	/**
	 * The global alpha value to be used for every pixel.
	 * <p>
	 * If this value is set, the <code>alphaData</code> field
	 * is ignored and when the image is rendered each pixel
	 * will be blended with the background an amount
	 * proportional to this value.
	 * </p><p>
	 * The default is -1 which means 'no global alpha value'
	 * </p>
	 */
	public int alpha;

	/**
	 * The type of file from which the image was read.
	 * 
	 * It is expressed as one of the following values:
	 * <dl>
	 * <dt><code>IMAGE_BMP</code></dt>
	 * <dd>Windows BMP file format, no compression</dd>
	 * <dt><code>IMAGE_BMP_RLE</code></dt>
	 * <dd>Windows BMP file format, RLE compression if appropriate</dd>
	 * <dt><code>IMAGE_GIF</code></dt>
	 * <dd>GIF file format</dd>
	 * <dt><code>IMAGE_ICO</code></dt>
	 * <dd>Windows ICO file format</dd>
	 * <dt><code>IMAGE_JPEG</code></dt>
	 * <dd>JPEG file format</dd>
	 * <dt><code>IMAGE_PNG</code></dt>
	 * <dd>PNG file format</dd>
	 * </dl>
	 */
	public int type;

	/**
	 * The x coordinate of the top left corner of the image
	 * within the logical screen (this field corresponds to
	 * the GIF89a Image Left Position value).
	 */
	public int x;

	/**
	 * The y coordinate of the top left corner of the image
	 * within the logical screen (this field corresponds to
	 * the GIF89a Image Top Position value).
	 */
	public int y;

	/**
	 * A description of how to dispose of the current image
	 * before displaying the next.
	 * 
	 * It is expressed as one of the following values:
	 * <dl>
	 * <dt><code>DM_UNSPECIFIED</code></dt>
	 * <dd>disposal method not specified</dd>
	 * <dt><code>DM_FILL_NONE</code></dt>
	 * <dd>do nothing - leave the image in place</dd>
	 * <dt><code>DM_FILL_BACKGROUND</code></dt>
	 * <dd>fill with the background color</dd>
	 * <dt><code>DM_FILL_PREVIOUS</code></dt>
	 * <dd>restore the previous picture</dd>
	 * </dl>
	 * (this field corresponds to the GIF89a Disposal Method value)
	 */
	public int disposalMethod;

	/**
	 * The time to delay before displaying the next image
	 * in an animation (this field corresponds to the GIF89a
	 * Delay Time value).
	 */
	public int delayTime;

	/**
	 * Arbitrary channel width data to 8-bit conversion table.
	 */
	static final byte[][] ANY_TO_EIGHT = new byte[9][];
	static {
		for (int b = 0; b < 9; ++b) {
			byte[] data = ANY_TO_EIGHT[b] = new byte[1 << b];
			if (b == 0) continue;
			int inc = 0;
			for (int bit = 0x10000; (bit >>= b) != 0;) inc |= bit;
			for (int v = 0, p = 0; v < 0x10000; v+= inc) data[p++] = (byte)(v >> 8);
		}
	}
	static final byte[] ONE_TO_ONE_MAPPING = ANY_TO_EIGHT[8];

	/**
	 * Scaled 8x8 Bayer dither matrix.
	 */
	static final int[][] DITHER_MATRIX = {
		{ 0xfc0000, 0x7c0000, 0xdc0000, 0x5c0000, 0xf40000, 0x740000, 0xd40000, 0x540000 },
		{ 0x3c0000, 0xbc0000, 0x1c0000, 0x9c0000, 0x340000, 0xb40000, 0x140000, 0x940000 },
		{ 0xcc0000, 0x4c0000, 0xec0000, 0x6c0000, 0xc40000, 0x440000, 0xe40000, 0x640000 },
		{ 0x0c0000, 0x8c0000, 0x2c0000, 0xac0000, 0x040000, 0x840000, 0x240000, 0xa40000 },
		{ 0xf00000, 0x700000, 0xd00000, 0x500000, 0xf80000, 0x780000, 0xd80000, 0x580000 },
		{ 0x300000, 0xb00000, 0x100000, 0x900000, 0x380000, 0xb80000, 0x180000, 0x980000 },
		{ 0xc00000, 0x400000, 0xe00000, 0x600000, 0xc80000, 0x480000, 0xe80000, 0x680000 },
		{ 0x000000, 0x800000, 0x200000, 0xa00000, 0x080000, 0x880000, 0x280000, 0xa80000 }
	};

/**
 * Constructs a new, empty ImageData with the given width, height,
 * depth and palette. The data will be initialized to an (all zero)
 * array of the appropriate size.
 *
 * @param width the width of the image
 * @param height the height of the image
 * @param depth the depth of the image
 * @param palette the palette of the image (must not be null)
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the width or height is negative, or if the depth is not
 *        	one of 1, 2, 4, 8, 16, 24 or 32</li>
 *    <li>ERROR_NULL_ARGUMENT - if the palette is null</li>
 * </ul>
 */
public ImageData(int width, int height, int depth, PaletteData palette) {
	this(width, height, depth, palette,
		4, null, 0, null,
		null, -1, -1, SWT.IMAGE_UNDEFINED,
		0, 0, 0, 0);
}

/**
 * Constructs a new, empty ImageData with the given width, height,
 * depth, palette, scanlinePad and data.
 *
 * @param width the width of the image
 * @param height the height of the image
 * @param depth the depth of the image
 * @param palette the palette of the image
 * @param scanlinePad the padding of each line, in bytes
 * @param data the data of the image
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_INVALID_ARGUMENT - if the width or height is negative, or if the depth is not
 *        	one of 1, 2, 4, 8, 16, 24 or 32</li>
 *    <li>ERROR_NULL_ARGUMENT - if the palette or data is null</li>
 *    <li>ERROR_CANNOT_BE_ZERO - if the scanlinePad is zero</li>
 * </ul>
 */
public ImageData(int width, int height, int depth, PaletteData palette, int scanlinePad, byte[] data) {
	this(width, height, depth, palette,
		scanlinePad, checkData(data), 0, null,
		null, -1, -1, SWT.IMAGE_UNDEFINED,
		0, 0, 0, 0);
}

/**
 * Constructs an <code>ImageData</code> loaded from the specified
 * input stream. Throws an error if an error occurs while loading
 * the image, or if the image has an unsupported type.
 * <p>
 * This constructor is provided for convenience when loading a single
 * image only. If the stream contains multiple images, only the first
 * one will be loaded. To load multiple images, use 
 * <code>ImageLoader.load()</code>.
 * </p>
 *
 * @param stream the input stream to load the image from (must not be null)
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the stream is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_INVALID_IMAGE - if the image file contains invalid data</li>
 *    <li>ERROR_IO - if an IO error occurs while reading data</li>
 * </ul>
 *
 * @see ImageLoader#load(InputStream)
 */
public ImageData(InputStream stream) {
	ImageData[] data = new ImageLoader().load(stream);
	if (data.length < 1) SWT.error(SWT.ERROR_INVALID_IMAGE);
	ImageData i = data[0];
	setAllFields(
		i.width,
		i.height,
		i.depth,
		i.scanlinePad,
		i.bytesPerLine,
		i.data,
		i.palette,
		i.transparentPixel,
		i.maskData,
		i.maskPad,
		i.alphaData,
		i.alpha,
		i.type,
		i.x,
		i.y,
		i.disposalMethod,
		i.delayTime);
}

/**
 * Constructs an <code>ImageData</code> loaded from a file with the
 * specified name. Throws an error if an error occurs loading the
 * image, or if the image has an unsupported type.
 * <p>
 * This constructor is provided for convenience when loading a single
 * image only. If the file contains multiple images, only the first
 * one will be loaded. To load multiple images, use 
 * <code>ImageLoader.load()</code>.
 * </p>
 *
 * @param filename the name of the file to load the image from (must not be null)
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the file name is null</li>
 * </ul>
 * @exception SWTException <ul>
 *    <li>ERROR_INVALID_IMAGE - if the image file contains invalid data</li>
 *    <li>ERROR_IO if an IO error occurs while reading data</li>
 * </ul>
 */
public ImageData(String filename) {
	ImageData[] data = new ImageLoader().load(filename);
	if (data.length < 1) SWT.error(SWT.ERROR_INVALID_IMAGE);
	ImageData i = data[0];
	setAllFields(
		i.width,
		i.height,
		i.depth,
		i.scanlinePad,
		i.bytesPerLine,
		i.data,
		i.palette,
		i.transparentPixel,
		i.maskData,
		i.maskPad,
		i.alphaData,
		i.alpha,
		i.type,
		i.x,
		i.y,
		i.disposalMethod,
		i.delayTime);
}

/**
 * Prevents uninitialized instances from being created outside the package.
 */
ImageData() {
}

/**
 * Constructs an image data by giving values for all non-computable fields.
 * <p>
 * This method is for internal use, and is not described further.
 * </p>
 */
ImageData(
	int width, int height, int depth, PaletteData palette,
	int scanlinePad, byte[] data, int maskPad, byte[] maskData,
	byte[] alphaData, int alpha, int transparentPixel, int type,
	int x, int y, int disposalMethod, int delayTime)
{

	if (palette == null) SWT.error(SWT.ERROR_NULL_ARGUMENT);
	if (!(depth == 1 || depth == 2 || depth == 4 || depth == 8
		|| depth == 16 || depth == 24 || depth == 32)) {
		SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	if (width <= 0 || height <= 0) {
		SWT.error(SWT.ERROR_INVALID_ARGUMENT);
	}
	if (scanlinePad == 0) SWT.error (SWT.ERROR_CANNOT_BE_ZERO);

	int bytesPerLine = (((width * depth + 7) / 8) + (scanlinePad - 1))
		/ scanlinePad * scanlinePad;
	setAllFields(
		width,
		height,
		depth,
		scanlinePad,
		bytesPerLine,
		data != null ? data : new byte[bytesPerLine * height],
		palette,
		transparentPixel,
		maskData,
		maskPad,
		alphaData,
		alpha,
		type,
		x,
		y,
		disposalMethod,
		delayTime);
}

/**