| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.imaging.formats.icns; |
| |
| class Rle24Compression |
| { |
| public static byte[] decompress(int width, int height, byte[] data) |
| { |
| final int pixelCount = width * height; |
| final byte[] result = new byte[4 * pixelCount]; |
| |
| // Several ICNS parsers advance by 4 bytes here: |
| // http://code.google.com/p/icns2png/ - when the width is >= 128 |
| // http://icns.sourceforge.net/ - when those 4 bytes are all zero |
| // |
| // A scan of all .icns files on MacOS shows that |
| // all 128x128 images indeed start with 4 zeroes, |
| // while all smaller images don't. |
| // However it is dangerous to assume |
| // that 4 initial zeroes always need to be skipped, |
| // because they could encode valid pixels on smaller images. |
| // So always skip on 128x128, and never skip on anything else. |
| int dataPos = 0; |
| if (width >= 128 && height >= 128) |
| dataPos = 4; |
| |
| // argb, band by band in 3 passes, with no alpha |
| for (int band = 1; band <= 3; band++) |
| { |
| int remaining = pixelCount; |
| int resultPos = 0; |
| while (remaining > 0) |
| { |
| if ((data[dataPos] & 0x80) != 0) |
| { |
| int count = (0xff & data[dataPos]) - 125; |
| for (int i = 0; i < count; i++) |
| result[band + 4*(resultPos++)] = data[dataPos + 1]; |
| dataPos += 2; |
| remaining -= count; |
| } |
| else |
| { |
| int count = (0xff & data[dataPos]) + 1; |
| dataPos++; |
| for (int i = 0; i < count; i++) |
| result[band + 4*(resultPos++)] = data[dataPos++]; |
| remaining -= count; |
| } |
| } |
| } |
| return result; |
| } |
| } |