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/*******************************************************************************
* Copyright (c) 2000, 2011 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
*******************************************************************************/
package org.eclipse.swt.internal.image;
import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
class PngIhdrChunk extends PngChunk {
static final int IHDR_DATA_LENGTH = 13;
static final int WIDTH_DATA_OFFSET = DATA_OFFSET + 0;
static final int HEIGHT_DATA_OFFSET = DATA_OFFSET + 4;
static final int BIT_DEPTH_OFFSET = DATA_OFFSET + 8;
static final int COLOR_TYPE_OFFSET = DATA_OFFSET + 9;
static final int COMPRESSION_METHOD_OFFSET = DATA_OFFSET + 10;
static final int FILTER_METHOD_OFFSET = DATA_OFFSET + 11;
static final int INTERLACE_METHOD_OFFSET = DATA_OFFSET + 12;
static final byte COLOR_TYPE_GRAYSCALE = 0;
static final byte COLOR_TYPE_RGB = 2;
static final byte COLOR_TYPE_PALETTE = 3;
static final byte COLOR_TYPE_GRAYSCALE_WITH_ALPHA = 4;
static final byte COLOR_TYPE_RGB_WITH_ALPHA = 6;
static final int INTERLACE_METHOD_NONE = 0;
static final int INTERLACE_METHOD_ADAM7 = 1;
static final int FILTER_NONE = 0;
static final int FILTER_SUB = 1;
static final int FILTER_UP = 2;
static final int FILTER_AVERAGE = 3;
static final int FILTER_PAETH = 4;
static final byte[] ValidBitDepths = {1, 2, 4, 8, 16};
static final byte[] ValidColorTypes = {0, 2, 3, 4, 6};
int width, height;
byte bitDepth, colorType, compressionMethod, filterMethod, interlaceMethod;
PngIhdrChunk(int width, int height, byte bitDepth, byte colorType, byte compressionMethod, byte filterMethod, byte interlaceMethod) {
super(IHDR_DATA_LENGTH);
setType(TYPE_IHDR);
setWidth(width);
setHeight(height);
setBitDepth(bitDepth);
setColorType(colorType);
setCompressionMethod(compressionMethod);
setFilterMethod(filterMethod);
setInterlaceMethod(interlaceMethod);
setCRC(computeCRC());
}
/**
* Construct a PNGChunk using the reference bytes
* given.
*/
PngIhdrChunk(byte[] reference) {
super(reference);
if (reference.length <= IHDR_DATA_LENGTH) SWT.error(SWT.ERROR_INVALID_IMAGE);
width = getInt32(WIDTH_DATA_OFFSET);
height = getInt32(HEIGHT_DATA_OFFSET);
bitDepth = reference[BIT_DEPTH_OFFSET];
colorType = reference[COLOR_TYPE_OFFSET];
compressionMethod = reference[COMPRESSION_METHOD_OFFSET];
filterMethod = reference[FILTER_METHOD_OFFSET];
interlaceMethod = reference[INTERLACE_METHOD_OFFSET];
}
int getChunkType() {
return CHUNK_IHDR;
}
/**
* Get the image's width in pixels.
*/
int getWidth() {
return width;
}
/**
* Set the image's width in pixels.
*/
void setWidth(int value) {
setInt32(WIDTH_DATA_OFFSET, value);
width = value;
}
/**
* Get the image's height in pixels.
*/
int getHeight() {
return height;
}
/**
* Set the image's height in pixels.
*/
void setHeight(int value) {
setInt32(HEIGHT_DATA_OFFSET, value);
height = value;
}
/**
* Get the image's bit depth.
* This is limited to the values 1, 2, 4, 8, or 16.
*/
byte getBitDepth() {
return bitDepth;
}
/**
* Set the image's bit depth.
* This is limited to the values 1, 2, 4, 8, or 16.
*/
void setBitDepth(byte value) {
reference[BIT_DEPTH_OFFSET] = value;
bitDepth = value;
}
/**
* Get the image's color type.
* This is limited to the values:
* 0 - Grayscale image.
* 2 - RGB triple.
* 3 - Palette.
* 4 - Grayscale with Alpha channel.
* 6 - RGB with Alpha channel.
*/
byte getColorType() {
return colorType;
}
/**
* Set the image's color type.
* This is limited to the values:
* 0 - Grayscale image.
* 2 - RGB triple.
* 3 - Palette.
* 4 - Grayscale with Alpha channel.
* 6 - RGB with Alpha channel.
*/
void setColorType(byte value) {
reference[COLOR_TYPE_OFFSET] = value;
colorType = value;
}
/**
* Get the image's compression method.
* This value must be 0.
*/
byte getCompressionMethod() {
return compressionMethod;
}
/**
* Set the image's compression method.
* This value must be 0.
*/
void setCompressionMethod(byte value) {
reference[COMPRESSION_METHOD_OFFSET] = value;
compressionMethod = value;
}
/**
* Get the image's filter method.
* This value must be 0.
*/
byte getFilterMethod() {
return filterMethod;
}
/**
* Set the image's filter method.
* This value must be 0.
*/
void setFilterMethod(byte value) {
reference[FILTER_METHOD_OFFSET] = value;
filterMethod = value;
}
/**
* Get the image's interlace method.
* This value is limited to:
* 0 - No interlacing used.
* 1 - Adam7 interlacing used.
*/
byte getInterlaceMethod() {
return interlaceMethod;
}
/**
* Set the image's interlace method.
* This value is limited to:
* 0 - No interlacing used.
* 1 - Adam7 interlacing used.
*/
void setInterlaceMethod(byte value) {
reference[INTERLACE_METHOD_OFFSET] = value;
interlaceMethod = value;
}
/**
* Answer whether the chunk is a valid IHDR chunk.
*/
void validate(PngFileReadState readState, PngIhdrChunk headerChunk) {
// An IHDR chunk is invalid if any other chunk has
// been read.
if (readState.readIHDR
|| readState.readPLTE
|| readState.readIDAT
|| readState.readIEND)
{
SWT.error(SWT.ERROR_INVALID_IMAGE);
} else {
readState.readIHDR = true;
}
super.validate(readState, headerChunk);
if (length != IHDR_DATA_LENGTH) SWT.error(SWT.ERROR_INVALID_IMAGE);
if (compressionMethod != 0) SWT.error(SWT.ERROR_INVALID_IMAGE);
if (interlaceMethod != INTERLACE_METHOD_NONE &&
interlaceMethod != INTERLACE_METHOD_ADAM7) {
SWT.error(SWT.ERROR_INVALID_IMAGE);
}
boolean colorTypeIsValid = false;
for (int i = 0; i < ValidColorTypes.length; i++) {
if (ValidColorTypes[i] == colorType) {
colorTypeIsValid = true;
break;
}
}
if (!colorTypeIsValid) SWT.error(SWT.ERROR_INVALID_IMAGE);
boolean bitDepthIsValid = false;
for (int i = 0; i < ValidBitDepths.length; i++) {
if (ValidBitDepths[i] == bitDepth) {
bitDepthIsValid = true;
break;
}
}
if (!bitDepthIsValid) SWT.error(SWT.ERROR_INVALID_IMAGE);
if ((colorType == COLOR_TYPE_RGB
|| colorType == COLOR_TYPE_RGB_WITH_ALPHA
|| colorType == COLOR_TYPE_GRAYSCALE_WITH_ALPHA)
&& bitDepth < 8)
{
SWT.error(SWT.ERROR_INVALID_IMAGE);
}
if (colorType == COLOR_TYPE_PALETTE && bitDepth > 8) {
SWT.error(SWT.ERROR_INVALID_IMAGE);
}
}
String getColorTypeString() {
switch (colorType) {
case COLOR_TYPE_GRAYSCALE: return "Grayscale";
case COLOR_TYPE_RGB: return "RGB";
case COLOR_TYPE_PALETTE: return "Palette";
case COLOR_TYPE_GRAYSCALE_WITH_ALPHA: return "Grayscale with Alpha";
case COLOR_TYPE_RGB_WITH_ALPHA: return "RGB with Alpha";
default: return "Unknown - " + colorType;
}
}
String getFilterMethodString() {
switch (filterMethod) {
case FILTER_NONE: return "None";
case FILTER_SUB: return "Sub";
case FILTER_UP: return "Up";
case FILTER_AVERAGE: return "Average";
case FILTER_PAETH: return "Paeth";
default: return "Unknown";
}
}
String getInterlaceMethodString() {
switch (interlaceMethod) {
case INTERLACE_METHOD_NONE: return "Not Interlaced";
case INTERLACE_METHOD_ADAM7: return "Interlaced - ADAM7";
default: return "Unknown";
}
}
void contributeToString(StringBuffer buffer) {
buffer.append("\n\tWidth: ");
buffer.append(width);
buffer.append("\n\tHeight: ");
buffer.append(height);
buffer.append("\n\tBit Depth: ");
buffer.append(bitDepth);
buffer.append("\n\tColor Type: ");
buffer.append(getColorTypeString());
buffer.append("\n\tCompression Method: ");
buffer.append(compressionMethod);
buffer.append("\n\tFilter Method: ");
buffer.append(getFilterMethodString());
buffer.append("\n\tInterlace Method: ");
buffer.append(getInterlaceMethodString());
}
boolean getMustHavePalette() {
return colorType == COLOR_TYPE_PALETTE;
}
boolean getCanHavePalette() {
return colorType != COLOR_TYPE_GRAYSCALE &&
colorType != COLOR_TYPE_GRAYSCALE_WITH_ALPHA;
}
/**
* Answer the pixel size in bits based on the color type
* and bit depth.
*/
int getBitsPerPixel() {
switch (colorType) {
case COLOR_TYPE_RGB_WITH_ALPHA:
return 4 * bitDepth;
case COLOR_TYPE_RGB:
return 3 * bitDepth;
case COLOR_TYPE_GRAYSCALE_WITH_ALPHA:
return 2 * bitDepth;
case COLOR_TYPE_GRAYSCALE:
case COLOR_TYPE_PALETTE:
return bitDepth;
default:
SWT.error(SWT.ERROR_INVALID_IMAGE);
return 0;
}
}
/**
* Answer the pixel size in bits based on the color type
* and bit depth.
*/
int getSwtBitsPerPixel() {
switch (colorType) {
case COLOR_TYPE_RGB_WITH_ALPHA:
case COLOR_TYPE_RGB:
case COLOR_TYPE_GRAYSCALE_WITH_ALPHA:
return 24;
case COLOR_TYPE_GRAYSCALE:
case COLOR_TYPE_PALETTE:
return Math.min(bitDepth, 8);
default:
SWT.error(SWT.ERROR_INVALID_IMAGE);
return 0;
}
}
int getFilterByteOffset() {
if (bitDepth < 8) return 1;
return getBitsPerPixel() / 8;
}
boolean usesDirectColor() {
switch (colorType) {
case COLOR_TYPE_GRAYSCALE:
case COLOR_TYPE_GRAYSCALE_WITH_ALPHA:
case COLOR_TYPE_RGB:
case COLOR_TYPE_RGB_WITH_ALPHA:
return true;
default:
return false;
}
}
PaletteData createGrayscalePalette() {
int depth = Math.min(bitDepth, 8);
int max = (1 << depth) - 1;
int delta = 255 / max;
int gray = 0;
RGB[] rgbs = new RGB[max + 1];
for (int i = 0; i <= max; i++) {
rgbs[i] = new RGB(gray, gray, gray);
gray += delta;
}
return new PaletteData(rgbs);
}
PaletteData getPaletteData() {
switch (colorType) {
case COLOR_TYPE_GRAYSCALE:
return createGrayscalePalette();
case COLOR_TYPE_GRAYSCALE_WITH_ALPHA:
case COLOR_TYPE_RGB:
case COLOR_TYPE_RGB_WITH_ALPHA:
return new PaletteData(0xFF0000, 0xFF00, 0xFF);
default:
return null;
}
}
}
