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32 #include "platform/image-encoders/skia/JPEGImageEncoder.h"
35 #include "SkColorPriv.h"
36 #include "platform/geometry/IntSize.h"
37 #include "platform/graphics/ImageBuffer.h"
40 #include <stdio.h> // jpeglib.h needs stdio.h FILE
46 struct JPEGOutputBuffer : public jpeg_destination_mgr {
47 Vector<unsigned char>* output;
48 Vector<unsigned char> buffer;
51 static void prepareOutput(j_compress_ptr cinfo)
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();
60 static boolean writeOutput(j_compress_ptr cinfo)
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();
69 static void finishOutput(j_compress_ptr cinfo)
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);
76 static void handleError(j_common_ptr common)
78 jmp_buf* jumpBufferPtr = static_cast<jmp_buf*>(common->client_data);
79 longjmp(*jumpBufferPtr, -1);
82 static void preMultipliedBGRAtoRGB(const unsigned char* pixels, unsigned pixelCount, unsigned char* output)
84 const SkPMColor* input = reinterpret_cast_ptr<const SkPMColor*>(pixels);
85 for (; pixelCount-- > 0; ++input) {
86 *output++ = SkGetPackedR32(*input);
87 *output++ = SkGetPackedG32(*input);
88 *output++ = SkGetPackedB32(*input);
92 static void RGBAtoRGB(const unsigned char* pixels, unsigned pixelCount, unsigned char* output)
94 for (; pixelCount-- > 0; pixels += 4) {
95 // Do source-over composition on black.
96 unsigned char alpha = pixels[3];
98 *output++ = SkMulDiv255Round(pixels[0], alpha);
99 *output++ = SkMulDiv255Round(pixels[1], alpha);
100 *output++ = SkMulDiv255Round(pixels[2], alpha);
102 *output++ = pixels[0];
103 *output++ = pixels[1];
104 *output++ = pixels[2];
109 static void disableSubsamplingForHighQuality(jpeg_compress_struct* cinfo, int quality)
114 for (int i = 0; i < MAX_COMPONENTS; ++i) {
115 cinfo->comp_info[i].h_samp_factor = 1;
116 cinfo->comp_info[i].v_samp_factor = 1;
120 static bool encodePixels(IntSize imageSize, unsigned char* inputPixels, bool premultiplied, int quality, Vector<unsigned char>* output)
122 JPEGOutputBuffer destination;
123 destination.output = output;
126 jpeg_compress_struct cinfo;
127 jpeg_error_mgr error;
128 cinfo.err = jpeg_std_error(&error);
129 error.error_exit = handleError;
131 cinfo.client_data = &jumpBuffer;
133 if (setjmp(jumpBuffer)) {
134 jpeg_destroy_compress(&cinfo);
138 jpeg_create_compress(&cinfo);
139 cinfo.dest = &destination;
140 cinfo.dest->init_destination = prepareOutput;
141 cinfo.dest->empty_output_buffer = writeOutput;
142 cinfo.dest->term_destination = finishOutput;
144 imageSize.clampNegativeToZero();
145 cinfo.image_height = imageSize.height();
146 cinfo.image_width = imageSize.width();
148 #if defined(JCS_EXTENSIONS)
150 cinfo.in_color_space = SK_B32_SHIFT ? JCS_EXT_RGBX : JCS_EXT_BGRX;
152 cinfo.input_components = 4;
154 jpeg_set_defaults(&cinfo);
155 jpeg_set_quality(&cinfo, quality, TRUE);
156 disableSubsamplingForHighQuality(&cinfo, quality);
157 jpeg_start_compress(&cinfo, TRUE);
159 unsigned char* pixels = inputPixels;
160 const size_t pixelRowStride = cinfo.image_width * 4;
161 while (cinfo.next_scanline < cinfo.image_height) {
162 jpeg_write_scanlines(&cinfo, &pixels, 1);
163 pixels += pixelRowStride;
166 jpeg_finish_compress(&cinfo);
167 jpeg_destroy_compress(&cinfo);
172 cinfo.in_color_space = JCS_RGB;
173 cinfo.input_components = 3;
175 void (*extractRowRGB)(const unsigned char*, unsigned, unsigned char* output);
176 extractRowRGB = &RGBAtoRGB;
178 extractRowRGB = &preMultipliedBGRAtoRGB;
180 jpeg_set_defaults(&cinfo);
181 jpeg_set_quality(&cinfo, quality, TRUE);
182 disableSubsamplingForHighQuality(&cinfo, quality);
183 jpeg_start_compress(&cinfo, TRUE);
185 unsigned char* pixels = inputPixels;
186 row.resize(cinfo.image_width * cinfo.input_components);
187 const size_t pixelRowStride = cinfo.image_width * 4;
188 while (cinfo.next_scanline < cinfo.image_height) {
189 JSAMPLE* rowData = row.data();
190 extractRowRGB(pixels, cinfo.image_width, rowData);
191 jpeg_write_scanlines(&cinfo, &rowData, 1);
192 pixels += pixelRowStride;
195 jpeg_finish_compress(&cinfo);
196 jpeg_destroy_compress(&cinfo);
200 bool JPEGImageEncoder::encode(const SkBitmap& bitmap, int quality, Vector<unsigned char>* output)
202 SkAutoLockPixels bitmapLock(bitmap);
204 if (bitmap.colorType() != kN32_SkColorType || !bitmap.getPixels())
205 return false; // Only support 32 bit/pixel skia bitmaps.
207 return encodePixels(IntSize(bitmap.width(), bitmap.height()), static_cast<unsigned char *>(bitmap.getPixels()), true, quality, output);
210 bool JPEGImageEncoder::encode(const ImageDataBuffer& imageData, int quality, Vector<unsigned char>* output)
212 return encodePixels(imageData.size(), imageData.data(), false, quality, output);