1 /* 2 * Copyright (c) 2010, Google Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are 6 * met: 7 * 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above 11 * copyright notice, this list of conditions and the following disclaimer 12 * in the documentation and/or other materials provided with the 13 * distribution. 14 * * Neither the name of Google Inc. nor the names of its 15 * contributors may be used to endorse or promote products derived from 16 * this software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include "config.h" 32 #include "PNGImageEncoder.h" 33 34 #include "ImageData.h" 35 #include "IntSize.h" 36 #include "SkBitmap.h" 37 #include "SkColorPriv.h" 38 #include "SkUnPreMultiply.h" 39 extern "C" { 40 #include "png.h" 41 } 42 43 namespace WebCore { 44 45 static void writeOutput(png_structp png, png_bytep data, png_size_t size) 46 { 47 static_cast<Vector<unsigned char>*>(png->io_ptr)->append(data, size); 48 } 49 50 static void preMultipliedBGRAtoRGBA(const void* pixels, int pixelCount, unsigned char* output) 51 { 52 static const SkUnPreMultiply::Scale* scale = SkUnPreMultiply::GetScaleTable(); 53 const SkPMColor* input = static_cast<const SkPMColor*>(pixels); 54 55 for (; pixelCount-- > 0; ++input) { 56 const unsigned alpha = SkGetPackedA32(*input); 57 if ((alpha != 0) && (alpha != 255)) { 58 *output++ = SkUnPreMultiply::ApplyScale(scale[alpha], SkGetPackedR32(*input)); 59 *output++ = SkUnPreMultiply::ApplyScale(scale[alpha], SkGetPackedG32(*input)); 60 *output++ = SkUnPreMultiply::ApplyScale(scale[alpha], SkGetPackedB32(*input)); 61 *output++ = alpha; 62 } else { 63 *output++ = SkGetPackedR32(*input); 64 *output++ = SkGetPackedG32(*input); 65 *output++ = SkGetPackedB32(*input); 66 *output++ = alpha; 67 } 68 } 69 } 70 71 static bool encodePixels(const IntSize& inputSize, unsigned char* inputPixels, 72 bool premultiplied, Vector<unsigned char>* output) 73 { 74 IntSize imageSize(inputSize); 75 imageSize.clampNegativeToZero(); 76 Vector<unsigned char> row; 77 78 png_struct* png = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0); 79 png_info* info = png_create_info_struct(png); 80 if (!png || !info || setjmp(png_jmpbuf(png))) { 81 png_destroy_write_struct(png ? &png : 0, info ? &info : 0); 82 return false; 83 } 84 85 // Optimize compression for speed. 86 // The parameters are the same as what libpng uses by default for RGB and RGBA images, except: 87 // - the zlib compression level is 3 instead of 6, to avoid the lazy Ziv-Lempel match searching; 88 // - the delta filter is 1 ("sub") instead of 5 ("all"), to reduce the filter computations. 89 // The zlib memory level (8) and strategy (Z_FILTERED) will be set inside libpng. 90 // 91 // Avoid the zlib strategies Z_HUFFMAN_ONLY or Z_RLE. 92 // Although they are the fastest for poorly-compressible images (e.g. photographs), 93 // they are very slow for highly-compressible images (e.g. text, drawings or business graphics). 94 png_set_compression_level(png, 3); 95 png_set_filter(png, PNG_FILTER_TYPE_BASE, PNG_FILTER_SUB); 96 97 png_set_write_fn(png, output, writeOutput, 0); 98 png_set_IHDR(png, info, imageSize.width(), imageSize.height(), 99 8, PNG_COLOR_TYPE_RGB_ALPHA, 0, 0, 0); 100 png_write_info(png, info); 101 102 unsigned char* pixels = inputPixels; 103 row.resize(imageSize.width() * sizeof(SkPMColor)); 104 for (int y = 0; y < imageSize.height(); ++y) { 105 if (premultiplied) { 106 preMultipliedBGRAtoRGBA(pixels, imageSize.width(), row.data()); 107 png_write_row(png, row.data()); 108 } else 109 png_write_row(png, pixels); 110 pixels += imageSize.width() * 4; 111 } 112 113 png_write_end(png, info); 114 png_destroy_write_struct(&png, &info); 115 return true; 116 } 117 118 bool PNGImageEncoder::encode(const SkBitmap& bitmap, Vector<unsigned char>* output) 119 { 120 if (bitmap.config() != SkBitmap::kARGB_8888_Config) 121 return false; // Only support ARGB 32 bpp skia bitmaps. 122 123 SkAutoLockPixels bitmapLock(bitmap); 124 IntSize imageSize(bitmap.width(), bitmap.height()); 125 return encodePixels(imageSize, static_cast<unsigned char*>(bitmap.getPixels()), true, output); 126 } 127 128 bool PNGImageEncoder::encode(const ImageData& bitmap, Vector<unsigned char>* output) 129 { 130 return encodePixels(bitmap.size(), bitmap.data()->data()->data(), false, output); 131 } 132 133 } // namespace WebCore 134
