1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/mobile/android/base/favicons/decoders/IconDirectoryEntry.java Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,201 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.6 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +package org.mozilla.gecko.favicons.decoders;
1.9 +
1.10 +/**
1.11 + * Representation of an ICO file ICONDIRENTRY structure.
1.12 + */
1.13 +public class IconDirectoryEntry implements Comparable<IconDirectoryEntry> {
1.14 +
1.15 + public static int maxBPP;
1.16 +
1.17 + int width;
1.18 + int height;
1.19 + int paletteSize;
1.20 + int bitsPerPixel;
1.21 + int payloadSize;
1.22 + int payloadOffset;
1.23 + boolean payloadIsPNG;
1.24 +
1.25 + // Tracks the index in the Icon Directory of this entry. Useful only for pruning.
1.26 + int index;
1.27 + boolean isErroneous;
1.28 +
1.29 + public IconDirectoryEntry(int width, int height, int paletteSize, int bitsPerPixel, int payloadSize, int payloadOffset, boolean payloadIsPNG) {
1.30 + this.width = width;
1.31 + this.height = height;
1.32 + this.paletteSize = paletteSize;
1.33 + this.bitsPerPixel = bitsPerPixel;
1.34 + this.payloadSize = payloadSize;
1.35 + this.payloadOffset = payloadOffset;
1.36 + this.payloadIsPNG = payloadIsPNG;
1.37 + }
1.38 +
1.39 + /**
1.40 + * Method to get a dummy Icon Directory Entry with the Erroneous bit set.
1.41 + *
1.42 + * @return An erroneous placeholder Icon Directory Entry.
1.43 + */
1.44 + public static IconDirectoryEntry getErroneousEntry() {
1.45 + IconDirectoryEntry ret = new IconDirectoryEntry(-1, -1, -1, -1, -1, -1, false);
1.46 + ret.isErroneous = true;
1.47 +
1.48 + return ret;
1.49 + }
1.50 +
1.51 + /**
1.52 + * Create an IconDirectoryEntry object from a byte[]. Interprets the buffer starting at the given
1.53 + * offset as an IconDirectoryEntry and returns the result.
1.54 + *
1.55 + * @param buffer Byte array containing the icon directory entry to decode.
1.56 + * @param regionOffset Offset into the byte array of the valid region of the buffer.
1.57 + * @param regionLength Length of the valid region in the buffer.
1.58 + * @param entryOffset Offset of the icon directory entry to decode within the buffer.
1.59 + * @return An IconDirectoryEntry object representing the entry specified, or null if the entry
1.60 + * is obviously invalid.
1.61 + */
1.62 + public static IconDirectoryEntry createFromBuffer(byte[] buffer, int regionOffset, int regionLength, int entryOffset) {
1.63 + // Verify that the reserved field is really zero.
1.64 + if (buffer[entryOffset + 3] != 0) {
1.65 + return getErroneousEntry();
1.66 + }
1.67 +
1.68 + // Verify that the entry points to a region that actually exists in the buffer, else bin it.
1.69 + int fieldPtr = entryOffset + 8;
1.70 + int entryLength = (buffer[fieldPtr] & 0xFF) |
1.71 + (buffer[fieldPtr + 1] & 0xFF) << 8 |
1.72 + (buffer[fieldPtr + 2] & 0xFF) << 16 |
1.73 + (buffer[fieldPtr + 3] & 0xFF) << 24;
1.74 +
1.75 + // Advance to the offset field.
1.76 + fieldPtr += 4;
1.77 +
1.78 + int payloadOffset = (buffer[fieldPtr] & 0xFF) |
1.79 + (buffer[fieldPtr + 1] & 0xFF) << 8 |
1.80 + (buffer[fieldPtr + 2] & 0xFF) << 16 |
1.81 + (buffer[fieldPtr + 3] & 0xFF) << 24;
1.82 +
1.83 + // Fail if the entry describes a region outside the buffer.
1.84 + if (payloadOffset < 0 || entryLength < 0 || payloadOffset + entryLength > regionOffset + regionLength) {
1.85 + return getErroneousEntry();
1.86 + }
1.87 +
1.88 + // Extract the image dimensions.
1.89 + int imageWidth = buffer[entryOffset] & 0xFF;
1.90 + int imageHeight = buffer[entryOffset+1] & 0xFF;
1.91 +
1.92 + // Because Microsoft, a size value of zero represents an image size of 256.
1.93 + if (imageWidth == 0) {
1.94 + imageWidth = 256;
1.95 + }
1.96 +
1.97 + if (imageHeight == 0) {
1.98 + imageHeight = 256;
1.99 + }
1.100 +
1.101 + // If the image uses a colour palette, this is the number of colours, otherwise this is zero.
1.102 + int paletteSize = buffer[entryOffset + 2] & 0xFF;
1.103 +
1.104 + // The plane count - usually 0 or 1. When > 1, taken as multiplier on bitsPerPixel.
1.105 + int colorPlanes = buffer[entryOffset + 4] & 0xFF;
1.106 +
1.107 + int bitsPerPixel = (buffer[entryOffset + 6] & 0xFF) |
1.108 + (buffer[entryOffset + 7] & 0xFF) << 8;
1.109 +
1.110 + if (colorPlanes > 1) {
1.111 + bitsPerPixel *= colorPlanes;
1.112 + }
1.113 +
1.114 + // Look for PNG magic numbers at the start of the payload.
1.115 + boolean payloadIsPNG = FaviconDecoder.bufferStartsWith(buffer, FaviconDecoder.ImageMagicNumbers.PNG.value, regionOffset + payloadOffset);
1.116 +
1.117 + return new IconDirectoryEntry(imageWidth, imageHeight, paletteSize, bitsPerPixel, entryLength, payloadOffset, payloadIsPNG);
1.118 + }
1.119 +
1.120 + /**
1.121 + * Get the number of bytes from the start of the ICO file to the beginning of this entry.
1.122 + */
1.123 + public int getOffset() {
1.124 + return ICODecoder.ICO_HEADER_LENGTH_BYTES + (index * ICODecoder.ICO_ICONDIRENTRY_LENGTH_BYTES);
1.125 + }
1.126 +
1.127 + @Override
1.128 + public int compareTo(IconDirectoryEntry another) {
1.129 + if (width > another.width) {
1.130 + return 1;
1.131 + }
1.132 +
1.133 + if (width < another.width) {
1.134 + return -1;
1.135 + }
1.136 +
1.137 + // Where both images exceed the max BPP, take the smaller of the two BPP values.
1.138 + if (bitsPerPixel >= maxBPP && another.bitsPerPixel >= maxBPP) {
1.139 + if (bitsPerPixel < another.bitsPerPixel) {
1.140 + return 1;
1.141 + }
1.142 +
1.143 + if (bitsPerPixel > another.bitsPerPixel) {
1.144 + return -1;
1.145 + }
1.146 + }
1.147 +
1.148 + // Otherwise, take the larger of the BPP values.
1.149 + if (bitsPerPixel > another.bitsPerPixel) {
1.150 + return 1;
1.151 + }
1.152 +
1.153 + if (bitsPerPixel < another.bitsPerPixel) {
1.154 + return -1;
1.155 + }
1.156 +
1.157 + // Prefer large palettes.
1.158 + if (paletteSize > another.paletteSize) {
1.159 + return 1;
1.160 + }
1.161 +
1.162 + if (paletteSize < another.paletteSize) {
1.163 + return -1;
1.164 + }
1.165 +
1.166 + // Prefer smaller payloads.
1.167 + if (payloadSize < another.payloadSize) {
1.168 + return 1;
1.169 + }
1.170 +
1.171 + if (payloadSize > another.payloadSize) {
1.172 + return -1;
1.173 + }
1.174 +
1.175 + // If all else fails, prefer PNGs over BMPs. They tend to be smaller.
1.176 + if (payloadIsPNG && !another.payloadIsPNG) {
1.177 + return 1;
1.178 + }
1.179 +
1.180 + if (!payloadIsPNG && another.payloadIsPNG) {
1.181 + return -1;
1.182 + }
1.183 +
1.184 + return 0;
1.185 + }
1.186 +
1.187 + public static void setMaxBPP(int maxBPP) {
1.188 + IconDirectoryEntry.maxBPP = maxBPP;
1.189 + }
1.190 +
1.191 + @Override
1.192 + public String toString() {
1.193 + return "IconDirectoryEntry{" +
1.194 + "\nwidth=" + width +
1.195 + ", \nheight=" + height +
1.196 + ", \npaletteSize=" + paletteSize +
1.197 + ", \nbitsPerPixel=" + bitsPerPixel +
1.198 + ", \npayloadSize=" + payloadSize +
1.199 + ", \npayloadOffset=" + payloadOffset +
1.200 + ", \npayloadIsPNG=" + payloadIsPNG +
1.201 + ", \nindex=" + index +
1.202 + '}';
1.203 + }
1.204 +}
