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 "platform/image-encoders/skia/PNGImageEncoder.h" 33 34 #include "SkBitmap.h" 35 #include "SkColorPriv.h" 36 #include "SkUnPreMultiply.h" 37 #include "platform/geometry/IntSize.h" 38 #include "platform/graphics/ImageBuffer.h" 39 extern "C" { 40 #include "png.h" 41 } 42 43 namespace blink { 44 45 static void writeOutput(png_structp png, png_bytep data, png_size_t size) 46 { 47 static_cast<Vector<unsigned char>*>(png_get_io_ptr(png))->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(IntSize imageSize, unsigned char* inputPixels, bool premultiplied, Vector<unsigned char>* output) 72 { 73 imageSize.clampNegativeToZero(); 74 Vector<unsigned char> row; 75 76 png_struct* png = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0); 77 png_info* info = png_create_info_struct(png); 78 if (!png || !info || setjmp(png_jmpbuf(png))) { 79 png_destroy_write_struct(png ? &png : 0, info ? &info : 0); 80 return false; 81 } 82 83 // Optimize compression for speed. 84 // The parameters are the same as what libpng uses by default for RGB and RGBA images, except: 85 // - the zlib compression level is 3 instead of 6, to avoid the lazy Ziv-Lempel match searching; 86 // - the delta filter is 1 ("sub") instead of 5 ("all"), to reduce the filter computations. 87 // The zlib memory level (8) and strategy (Z_FILTERED) will be set inside libpng. 88 // 89 // Avoid the zlib strategies Z_HUFFMAN_ONLY or Z_RLE. 90 // Although they are the fastest for poorly-compressible images (e.g. photographs), 91 // they are very slow for highly-compressible images (e.g. text, drawings or business graphics). 92 png_set_compression_level(png, 3); 93 png_set_filter(png, PNG_FILTER_TYPE_BASE, PNG_FILTER_SUB); 94 95 png_set_write_fn(png, output, writeOutput, 0); 96 png_set_IHDR(png, info, imageSize.width(), imageSize.height(), 97 8, PNG_COLOR_TYPE_RGB_ALPHA, 0, 0, 0); 98 png_write_info(png, info); 99 100 unsigned char* pixels = inputPixels; 101 row.resize(imageSize.width() * sizeof(SkPMColor)); 102 const size_t pixelRowStride = imageSize.width() * 4; 103 for (int y = 0; y < imageSize.height(); ++y) { 104 if (premultiplied) { 105 preMultipliedBGRAtoRGBA(pixels, imageSize.width(), row.data()); 106 png_write_row(png, row.data()); 107 } else 108 png_write_row(png, pixels); 109 pixels += pixelRowStride; 110 } 111 112 png_write_end(png, info); 113 png_destroy_write_struct(&png, &info); 114 return true; 115 } 116 117 bool PNGImageEncoder::encode(const SkBitmap& bitmap, Vector<unsigned char>* output) 118 { 119 SkAutoLockPixels bitmapLock(bitmap); 120 121 if (bitmap.colorType() != kN32_SkColorType || !bitmap.getPixels()) 122 return false; // Only support 32 bit/pixel skia bitmaps. 123 124 return encodePixels(IntSize(bitmap.width(), bitmap.height()), static_cast<unsigned char*>(bitmap.getPixels()), true, output); 125 } 126 127 bool PNGImageEncoder::encode(const ImageDataBuffer& imageData, Vector<unsigned char>* output) 128 { 129 return encodePixels(imageData.size(), imageData.data(), false, output); 130 } 131 132 } // namespace blink 133
