third_party/WebKit/Source/platform/image-encoders/skia/JPEGImageEncoder.cpp

   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/JPEGImageEncoder.h"
  33
  34 #include "SkColorPriv.h"
  35 #include "platform/geometry/IntSize.h"
  36 #include "platform/graphics/ImageBuffer.h"
  37
  38 extern "C" {
  39 #include <setjmp.h>
  40 #include <stdio.h> // jpeglib.h needs stdio.h FILE
  41 #include "jpeglib.h"
  42 }
  43
  44 namespace blink {
  45
  46 struct JPEGOutputBuffer : public jpeg_destination_mgr {
  47     Vector<unsigned char>* output;
  48     Vector<unsigned char> buffer;
  49 };
  50
  51 static void prepareOutput(j_compress_ptr cinfo)
  52 {
  53     JPEGOutputBuffer* out = static_cast<JPEGOutputBuffer*>(cinfo->dest);
  54     const size_t internalBufferSize = 8192;
  55     out->buffer.resize(internalBufferSize);
  56     out->next_output_byte = out->buffer.data();
  57     out->free_in_buffer = out->buffer.size();
  58 }
  59
  60 static boolean writeOutput(j_compress_ptr cinfo)
  61 {
  62     JPEGOutputBuffer* out = static_cast<JPEGOutputBuffer*>(cinfo->dest);
  63     out->output->append(out->buffer.data(), out->buffer.size());
  64     out->next_output_byte = out->buffer.data();
  65     out->free_in_buffer = out->buffer.size();
  66     return TRUE;
  67 }
  68
  69 static void finishOutput(j_compress_ptr cinfo)
  70 {
  71     JPEGOutputBuffer* out = static_cast<JPEGOutputBuffer*>(cinfo->dest);
  72     const size_t size = out->buffer.size() - out->free_in_buffer;
  73     out->output->append(out->buffer.data(), size);
  74 }
  75
  76 static void handleError(j_common_ptr common)
  77 {
  78     jmp_buf* jumpBufferPtr = static_cast<jmp_buf*>(common->client_data);
  79     longjmp(*jumpBufferPtr, -1);
  80 }
  81
  82 static void RGBAtoRGB(const unsigned char* pixels, unsigned pixelCount, unsigned char* output)
  83 {
  84     // Per <canvas> spec, composite the input image pixels source-over on black.
  85
  86     for (; pixelCount-- > 0; pixels += 4) {
  87         unsigned char alpha = pixels[3];
  88         if (alpha != 255) {
  89             *output++ = SkMulDiv255Round(pixels[0], alpha);
  90             *output++ = SkMulDiv255Round(pixels[1], alpha);
  91             *output++ = SkMulDiv255Round(pixels[2], alpha);
  92         } else {
  93             *output++ = pixels[0];
  94             *output++ = pixels[1];
  95             *output++ = pixels[2];
  96         }
  97     }
  98 }
  99
 100 static void disableSubsamplingForHighQuality(jpeg_compress_struct* cinfo, int quality)
 101 {
 102     if (quality < 100)
 103         return;
 104
 105     for (int i = 0; i < MAX_COMPONENTS; ++i) {
 106         cinfo->comp_info[i].h_samp_factor = 1;
 107         cinfo->comp_info[i].v_samp_factor = 1;
 108     }
 109 }
 110
 111 static bool encodePixels(IntSize imageSize, const unsigned char* inputPixels, int quality, Vector<unsigned char>* output)
 112 {
 113     if (imageSize.width() <= 0 || imageSize.height() <= 0)
 114         return false;
 115
 116     JPEGOutputBuffer destination;
 117     destination.output = output;
 118     Vector<JSAMPLE> row;
 119
 120     jpeg_compress_struct cinfo;
 121     jpeg_error_mgr error;
 122     cinfo.err = jpeg_std_error(&error);
 123     error.error_exit = handleError;
 124     jmp_buf jumpBuffer;
 125     cinfo.client_data = &jumpBuffer;
 126
 127     if (setjmp(jumpBuffer)) {
 128         jpeg_destroy_compress(&cinfo);
 129         return false;
 130     }
 131
 132     jpeg_create_compress(&cinfo);
 133     cinfo.dest = &destination;
 134     cinfo.dest->init_destination = prepareOutput;
 135     cinfo.dest->empty_output_buffer = writeOutput;
 136     cinfo.dest->term_destination = finishOutput;
 137
 138     cinfo.image_height = imageSize.height();
 139     cinfo.image_width = imageSize.width();
 140     cinfo.in_color_space = JCS_RGB;
 141     cinfo.input_components = 3;
 142
 143     jpeg_set_defaults(&cinfo);
 144     jpeg_set_quality(&cinfo, quality, TRUE);
 145     disableSubsamplingForHighQuality(&cinfo, quality);
 146     jpeg_start_compress(&cinfo, TRUE);
 147
 148     unsigned char* pixels = const_cast<unsigned char*>(inputPixels);
 149     row.resize(cinfo.image_width * cinfo.input_components);
 150     const size_t pixelRowStride = cinfo.image_width * 4;
 151     while (cinfo.next_scanline < cinfo.image_height) {
 152         JSAMPLE* rowData = row.data();
 153         RGBAtoRGB(pixels, cinfo.image_width, rowData);
 154         jpeg_write_scanlines(&cinfo, &rowData, 1);
 155         pixels += pixelRowStride;
 156     }
 157
 158     jpeg_finish_compress(&cinfo);
 159     jpeg_destroy_compress(&cinfo);
 160     return true;
 161 }
 162
 163 bool JPEGImageEncoder::encode(const ImageDataBuffer& imageData, int quality, Vector<unsigned char>* output)
 164 {
 165     if (!imageData.pixels())
 166         return false;
 167
 168     return encodePixels(IntSize(imageData.width(), imageData.height()), imageData.pixels(), quality, output);
 169 }
 170
 171 } // namespace blink