| /******************************************************************************* |
| * Copyright (c) 2000, 2003 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 org.eclipse.swt.internal.Compatibility; |
| |
| class PngPlteChunk extends PngChunk { |
| |
| PngPlteChunk(byte[] reference){ |
| super(reference); |
| } |
| |
| /** |
| * Get the number of colors in this palette. |
| */ |
| int getPaletteSize() { |
| return getLength() / 3; |
| } |
| |
| /** |
| * Get a PaletteData object representing the colors |
| * stored in this PLTE chunk. |
| * The result should be cached as the PLTE chunk |
| * does not store the palette data created. |
| */ |
| PaletteData getPaletteData() { |
| RGB[] rgbs = new RGB[getPaletteSize()]; |
| // int start = DATA_OFFSET; |
| // int end = DATA_OFFSET + getLength(); |
| for (int i = 0; i < rgbs.length; i++) { |
| int offset = DATA_OFFSET + (i * 3); |
| int red = reference[offset] & 0xFF; |
| int green = reference[offset + 1] & 0xFF; |
| int blue = reference[offset + 2] & 0xFF; |
| rgbs[i] = new RGB(red, green, blue); |
| } |
| return new PaletteData(rgbs); |
| } |
| |
| /** |
| * Answer whether the chunk is a valid PLTE chunk. |
| */ |
| void validate(PngFileReadState readState, PngIhdrChunk headerChunk) { |
| // A PLTE chunk is invalid if no IHDR has been read or if any PLTE, |
| // IDAT, or IEND chunk has been read. |
| if (!readState.readIHDR |
| || readState.readPLTE |
| || readState.readTRNS |
| || readState.readBKGD |
| || readState.readIDAT |
| || readState.readIEND) |
| { |
| SWT.error(SWT.ERROR_INVALID_IMAGE); |
| } else { |
| readState.readPLTE = true; |
| } |
| |
| super.validate(readState, headerChunk); |
| |
| // Palettes cannot be included in grayscale images. |
| if (!headerChunk.getCanHavePalette()) SWT.error(SWT.ERROR_INVALID_IMAGE); |
| |
| // Palette chunks' data fields must be event multiples |
| // of 3. Each 3-byte group represents an RGB value. |
| if (getLength() % 3 != 0) SWT.error(SWT.ERROR_INVALID_IMAGE); |
| |
| // Palettes cannot have more entries than 2^bitDepth |
| // where bitDepth is the bit depth of the image given |
| // in the IHDR chunk. |
| if (Compatibility.pow2(headerChunk.getBitDepth()) < getPaletteSize()) { |
| SWT.error(SWT.ERROR_INVALID_IMAGE); |
| } |
| |
| // Palettes cannot have more than 256 entries. |
| if (256 < getPaletteSize()) SWT.error(SWT.ERROR_INVALID_IMAGE); |
| } |
| |
| void contributeToString(StringBuffer buffer) { |
| buffer.append("\n\tPalette size:"); |
| buffer.append(getPaletteSize()); |
| } |
| |
| } |