| /* |
| * Copyright 2007, The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #include "SkImageDecoder.h" |
| #include "SkImageEncoder.h" |
| #include "SkJpegUtility.h" |
| #include "SkColorPriv.h" |
| #include "SkDither.h" |
| #include "SkScaledBitmapSampler.h" |
| #include "SkStream.h" |
| #include "SkTemplates.h" |
| #include "SkUtils.h" |
| |
| #include <stdio.h> |
| extern "C" { |
| #include "jpeglib.h" |
| #include "jerror.h" |
| } |
| |
| #ifdef ANDROID |
| #include <cutils/properties.h> |
| |
| // Key to lookup the size of memory buffer set in system property |
| static const char KEY_MEM_CAP[] = "ro.media.dec.jpeg.memcap"; |
| #endif |
| |
| // this enables timing code to report milliseconds for an encode |
| //#define TIME_ENCODE |
| //#define TIME_DECODE |
| |
| // this enables our rgb->yuv code, which is faster than libjpeg on ARM |
| // disable for the moment, as we have some glitches when width != multiple of 4 |
| #define WE_CONVERT_TO_YUV |
| |
| ////////////////////////////////////////////////////////////////////////// |
| ////////////////////////////////////////////////////////////////////////// |
| |
| class SkJPEGImageDecoder : public SkImageDecoder { |
| public: |
| virtual Format getFormat() const { |
| return kJPEG_Format; |
| } |
| |
| protected: |
| virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode); |
| }; |
| |
| ////////////////////////////////////////////////////////////////////////// |
| |
| #include "SkTime.h" |
| |
| class AutoTimeMillis { |
| public: |
| AutoTimeMillis(const char label[]) : fLabel(label) { |
| if (!fLabel) { |
| fLabel = ""; |
| } |
| fNow = SkTime::GetMSecs(); |
| } |
| ~AutoTimeMillis() { |
| SkDebugf("---- Time (ms): %s %d\n", fLabel, SkTime::GetMSecs() - fNow); |
| } |
| private: |
| const char* fLabel; |
| SkMSec fNow; |
| }; |
| |
| /* Automatically clean up after throwing an exception */ |
| class JPEGAutoClean { |
| public: |
| JPEGAutoClean(): cinfo_ptr(NULL) {} |
| ~JPEGAutoClean() { |
| if (cinfo_ptr) { |
| jpeg_destroy_decompress(cinfo_ptr); |
| } |
| } |
| void set(jpeg_decompress_struct* info) { |
| cinfo_ptr = info; |
| } |
| private: |
| jpeg_decompress_struct* cinfo_ptr; |
| }; |
| |
| #ifdef ANDROID |
| /* Check if the memory cap property is set. |
| If so, use the memory size for jpeg decode. |
| */ |
| static void overwrite_mem_buffer_size(j_decompress_ptr cinfo) { |
| int len = 0; |
| char value[PROPERTY_VALUE_MAX]; |
| int memCap; |
| |
| len = property_get(KEY_MEM_CAP, value, ""); |
| if (len > 0 && sscanf(value, "%d", &memCap) == 1) { |
| cinfo->mem->max_memory_to_use = memCap; |
| } |
| } |
| #endif |
| |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| /* If we need to better match the request, we might examine the image and |
| output dimensions, and determine if the downsampling jpeg provided is |
| not sufficient. If so, we can recompute a modified sampleSize value to |
| make up the difference. |
| |
| To skip this additional scaling, just set sampleSize = 1; below. |
| */ |
| static int recompute_sampleSize(int sampleSize, |
| const jpeg_decompress_struct& cinfo) { |
| return sampleSize * cinfo.output_width / cinfo.image_width; |
| } |
| |
| static bool valid_output_dimensions(const jpeg_decompress_struct& cinfo) { |
| /* These are initialized to 0, so if they have non-zero values, we assume |
| they are "valid" (i.e. have been computed by libjpeg) |
| */ |
| return cinfo.output_width != 0 && cinfo.output_height != 0; |
| } |
| |
| static bool skip_src_rows(jpeg_decompress_struct* cinfo, void* buffer, |
| int count) { |
| for (int i = 0; i < count; i++) { |
| JSAMPLE* rowptr = (JSAMPLE*)buffer; |
| int row_count = jpeg_read_scanlines(cinfo, &rowptr, 1); |
| if (row_count != 1) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| // This guy exists just to aid in debugging, as it allows debuggers to just |
| // set a break-point in one place to see all error exists. |
| static bool return_false(const jpeg_decompress_struct& cinfo, |
| const SkBitmap& bm, const char msg[]) { |
| #if 0 |
| SkDebugf("libjpeg error %d <%s> from %s [%d %d]", cinfo.err->msg_code, |
| cinfo.err->jpeg_message_table[cinfo.err->msg_code], msg, |
| bm.width(), bm.height()); |
| #endif |
| return false; // must always return false |
| } |
| |
| bool SkJPEGImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) { |
| #ifdef TIME_DECODE |
| AutoTimeMillis atm("JPEG Decode"); |
| #endif |
| |
| SkAutoMalloc srcStorage; |
| JPEGAutoClean autoClean; |
| |
| jpeg_decompress_struct cinfo; |
| skjpeg_error_mgr sk_err; |
| skjpeg_source_mgr sk_stream(stream, this); |
| |
| cinfo.err = jpeg_std_error(&sk_err); |
| sk_err.error_exit = skjpeg_error_exit; |
| |
| // All objects need to be instantiated before this setjmp call so that |
| // they will be cleaned up properly if an error occurs. |
| if (setjmp(sk_err.fJmpBuf)) { |
| return return_false(cinfo, *bm, "setjmp"); |
| } |
| |
| jpeg_create_decompress(&cinfo); |
| autoClean.set(&cinfo); |
| |
| #ifdef ANDROID |
| overwrite_mem_buffer_size(&cinfo); |
| #endif |
| |
| //jpeg_stdio_src(&cinfo, file); |
| cinfo.src = &sk_stream; |
| |
| int status = jpeg_read_header(&cinfo, true); |
| if (status != JPEG_HEADER_OK) { |
| return return_false(cinfo, *bm, "read_header"); |
| } |
| |
| /* Try to fulfill the requested sampleSize. Since jpeg can do it (when it |
| can) much faster that we, just use their num/denom api to approximate |
| the size. |
| */ |
| int sampleSize = this->getSampleSize(); |
| |
| cinfo.dct_method = JDCT_IFAST; |
| cinfo.scale_num = 1; |
| cinfo.scale_denom = sampleSize; |
| |
| /* this gives about 30% performance improvement. In theory it may |
| reduce the visual quality, in practice I'm not seeing a difference |
| */ |
| cinfo.do_fancy_upsampling = 0; |
| |
| /* this gives another few percents */ |
| cinfo.do_block_smoothing = 0; |
| |
| /* default format is RGB */ |
| cinfo.out_color_space = JCS_RGB; |
| |
| SkBitmap::Config config = this->getPrefConfig(k32Bit_SrcDepth, false); |
| // only these make sense for jpegs |
| if (config != SkBitmap::kARGB_8888_Config && |
| config != SkBitmap::kARGB_4444_Config && |
| config != SkBitmap::kRGB_565_Config) { |
| config = SkBitmap::kARGB_8888_Config; |
| } |
| |
| #ifdef ANDROID_RGB |
| cinfo.dither_mode = JDITHER_NONE; |
| if (config == SkBitmap::kARGB_8888_Config) { |
| cinfo.out_color_space = JCS_RGBA_8888; |
| } else if (config == SkBitmap::kRGB_565_Config) { |
| if (sampleSize == 1) { |
| // SkScaledBitmapSampler can't handle RGB_565 yet, |
| // so don't even try. |
| cinfo.out_color_space = JCS_RGB_565; |
| if (this->getDitherImage()) { |
| cinfo.dither_mode = JDITHER_ORDERED; |
| } |
| } |
| } |
| #endif |
| |
| if (sampleSize == 1 && mode == SkImageDecoder::kDecodeBounds_Mode) { |
| bm->setConfig(config, cinfo.image_width, cinfo.image_height); |
| bm->setIsOpaque(true); |
| return true; |
| } |
| |
| /* image_width and image_height are the original dimensions, available |
| after jpeg_read_header(). To see the scaled dimensions, we have to call |
| jpeg_start_decompress(), and then read output_width and output_height. |
| */ |
| if (!jpeg_start_decompress(&cinfo)) { |
| /* If we failed here, we may still have enough information to return |
| to the caller if they just wanted (subsampled bounds). If sampleSize |
| was 1, then we would have already returned. Thus we just check if |
| we're in kDecodeBounds_Mode, and that we have valid output sizes. |
| |
| One reason to fail here is that we have insufficient stream data |
| to complete the setup. However, output dimensions seem to get |
| computed very early, which is why this special check can pay off. |
| */ |
| if (SkImageDecoder::kDecodeBounds_Mode == mode && |
| valid_output_dimensions(cinfo)) { |
| SkScaledBitmapSampler smpl(cinfo.output_width, cinfo.output_height, |
| recompute_sampleSize(sampleSize, cinfo)); |
| bm->setConfig(config, smpl.scaledWidth(), smpl.scaledHeight()); |
| bm->setIsOpaque(true); |
| return true; |
| } else { |
| return return_false(cinfo, *bm, "start_decompress"); |
| } |
| } |
| sampleSize = recompute_sampleSize(sampleSize, cinfo); |
| |
| // should we allow the Chooser (if present) to pick a config for us??? |
| if (!this->chooseFromOneChoice(config, cinfo.output_width, |
| cinfo.output_height)) { |
| return return_false(cinfo, *bm, "chooseFromOneChoice"); |
| } |
| |
| #ifdef ANDROID_RGB |
| /* short-circuit the SkScaledBitmapSampler when possible, as this gives |
| a significant performance boost. |
| */ |
| if (sampleSize == 1 && |
| ((config == SkBitmap::kARGB_8888_Config && |
| cinfo.out_color_space == JCS_RGBA_8888) || |
| (config == SkBitmap::kRGB_565_Config && |
| cinfo.out_color_space == JCS_RGB_565))) |
| { |
| bm->setConfig(config, cinfo.output_width, cinfo.output_height); |
| bm->setIsOpaque(true); |
| if (SkImageDecoder::kDecodeBounds_Mode == mode) { |
| return true; |
| } |
| if (!this->allocPixelRef(bm, NULL)) { |
| return return_false(cinfo, *bm, "allocPixelRef"); |
| } |
| SkAutoLockPixels alp(*bm); |
| JSAMPLE* rowptr = (JSAMPLE*)bm->getPixels(); |
| INT32 const bpr = bm->rowBytes(); |
| |
| while (cinfo.output_scanline < cinfo.output_height) { |
| int row_count = jpeg_read_scanlines(&cinfo, &rowptr, 1); |
| // if row_count == 0, then we didn't get a scanline, so abort. |
| // if we supported partial images, we might return true in this case |
| if (0 == row_count) { |
| return return_false(cinfo, *bm, "read_scanlines"); |
| } |
| if (this->shouldCancelDecode()) { |
| return return_false(cinfo, *bm, "shouldCancelDecode"); |
| } |
| rowptr += bpr; |
| } |
| jpeg_finish_decompress(&cinfo); |
| return true; |
| } |
| #endif |
| |
| // check for supported formats |
| SkScaledBitmapSampler::SrcConfig sc; |
| if (3 == cinfo.out_color_components && JCS_RGB == cinfo.out_color_space) { |
| sc = SkScaledBitmapSampler::kRGB; |
| #ifdef ANDROID_RGB |
| } else if (JCS_RGBA_8888 == cinfo.out_color_space) { |
| sc = SkScaledBitmapSampler::kRGBX; |
| //} else if (JCS_RGB_565 == cinfo.out_color_space) { |
| // sc = SkScaledBitmapSampler::kRGB_565; |
| #endif |
| } else if (1 == cinfo.out_color_components && |
| JCS_GRAYSCALE == cinfo.out_color_space) { |
| sc = SkScaledBitmapSampler::kGray; |
| } else { |
| return return_false(cinfo, *bm, "jpeg colorspace"); |
| } |
| |
| SkScaledBitmapSampler sampler(cinfo.output_width, cinfo.output_height, |
| sampleSize); |
| |
| bm->setConfig(config, sampler.scaledWidth(), sampler.scaledHeight()); |
| // jpegs are always opauqe (i.e. have no per-pixel alpha) |
| bm->setIsOpaque(true); |
| |
| if (SkImageDecoder::kDecodeBounds_Mode == mode) { |
| return true; |
| } |
| if (!this->allocPixelRef(bm, NULL)) { |
| return return_false(cinfo, *bm, "allocPixelRef"); |
| } |
| |
| SkAutoLockPixels alp(*bm); |
| if (!sampler.begin(bm, sc, this->getDitherImage())) { |
| return return_false(cinfo, *bm, "sampler.begin"); |
| } |
| |
| uint8_t* srcRow = (uint8_t*)srcStorage.alloc(cinfo.output_width * 4); |
| |
| // Possibly skip initial rows [sampler.srcY0] |
| if (!skip_src_rows(&cinfo, srcRow, sampler.srcY0())) { |
| return return_false(cinfo, *bm, "skip rows"); |
| } |
| |
| // now loop through scanlines until y == bm->height() - 1 |
| for (int y = 0;; y++) { |
| JSAMPLE* rowptr = (JSAMPLE*)srcRow; |
| int row_count = jpeg_read_scanlines(&cinfo, &rowptr, 1); |
| if (0 == row_count) { |
| return return_false(cinfo, *bm, "read_scanlines"); |
| } |
| if (this->shouldCancelDecode()) { |
| return return_false(cinfo, *bm, "shouldCancelDecode"); |
| } |
| |
| sampler.next(srcRow); |
| if (bm->height() - 1 == y) { |
| // we're done |
| break; |
| } |
| |
| if (!skip_src_rows(&cinfo, srcRow, sampler.srcDY() - 1)) { |
| return return_false(cinfo, *bm, "skip rows"); |
| } |
| } |
| |
| // we formally skip the rest, so we don't get a complaint from libjpeg |
| if (!skip_src_rows(&cinfo, srcRow, |
| cinfo.output_height - cinfo.output_scanline)) { |
| return return_false(cinfo, *bm, "skip rows"); |
| } |
| jpeg_finish_decompress(&cinfo); |
| |
| // SkDebugf("------------------- bm2 size %d [%d %d] %d\n", bm->getSize(), bm->width(), bm->height(), bm->config()); |
| return true; |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #include "SkColorPriv.h" |
| |
| // taken from jcolor.c in libjpeg |
| #if 0 // 16bit - precise but slow |
| #define CYR 19595 // 0.299 |
| #define CYG 38470 // 0.587 |
| #define CYB 7471 // 0.114 |
| |
| #define CUR -11059 // -0.16874 |
| #define CUG -21709 // -0.33126 |
| #define CUB 32768 // 0.5 |
| |
| #define CVR 32768 // 0.5 |
| #define CVG -27439 // -0.41869 |
| #define CVB -5329 // -0.08131 |
| |
| #define CSHIFT 16 |
| #else // 8bit - fast, slightly less precise |
| #define CYR 77 // 0.299 |
| #define CYG 150 // 0.587 |
| #define CYB 29 // 0.114 |
| |
| #define CUR -43 // -0.16874 |
| #define CUG -85 // -0.33126 |
| #define CUB 128 // 0.5 |
| |
| #define CVR 128 // 0.5 |
| #define CVG -107 // -0.41869 |
| #define CVB -21 // -0.08131 |
| |
| #define CSHIFT 8 |
| #endif |
| |
| static void rgb2yuv_32(uint8_t dst[], SkPMColor c) { |
| int r = SkGetPackedR32(c); |
| int g = SkGetPackedG32(c); |
| int b = SkGetPackedB32(c); |
| |
| int y = ( CYR*r + CYG*g + CYB*b ) >> CSHIFT; |
| int u = ( CUR*r + CUG*g + CUB*b ) >> CSHIFT; |
| int v = ( CVR*r + CVG*g + CVB*b ) >> CSHIFT; |
| |
| dst[0] = SkToU8(y); |
| dst[1] = SkToU8(u + 128); |
| dst[2] = SkToU8(v + 128); |
| } |
| |
| static void rgb2yuv_4444(uint8_t dst[], U16CPU c) { |
| int r = SkGetPackedR4444(c); |
| int g = SkGetPackedG4444(c); |
| int b = SkGetPackedB4444(c); |
| |
| int y = ( CYR*r + CYG*g + CYB*b ) >> (CSHIFT - 4); |
| int u = ( CUR*r + CUG*g + CUB*b ) >> (CSHIFT - 4); |
| int v = ( CVR*r + CVG*g + CVB*b ) >> (CSHIFT - 4); |
| |
| dst[0] = SkToU8(y); |
| dst[1] = SkToU8(u + 128); |
| dst[2] = SkToU8(v + 128); |
| } |
| |
| static void rgb2yuv_16(uint8_t dst[], U16CPU c) { |
| int r = SkGetPackedR16(c); |
| int g = SkGetPackedG16(c); |
| int b = SkGetPackedB16(c); |
| |
| int y = ( 2*CYR*r + CYG*g + 2*CYB*b ) >> (CSHIFT - 2); |
| int u = ( 2*CUR*r + CUG*g + 2*CUB*b ) >> (CSHIFT - 2); |
| int v = ( 2*CVR*r + CVG*g + 2*CVB*b ) >> (CSHIFT - 2); |
| |
| dst[0] = SkToU8(y); |
| dst[1] = SkToU8(u + 128); |
| dst[2] = SkToU8(v + 128); |
| } |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| typedef void (*WriteScanline)(uint8_t* SK_RESTRICT dst, |
| const void* SK_RESTRICT src, int width, |
| const SkPMColor* SK_RESTRICT ctable); |
| |
| static void Write_32_YUV(uint8_t* SK_RESTRICT dst, |
| const void* SK_RESTRICT srcRow, int width, |
| const SkPMColor*) { |
| const uint32_t* SK_RESTRICT src = (const uint32_t*)srcRow; |
| while (--width >= 0) { |
| #ifdef WE_CONVERT_TO_YUV |
| rgb2yuv_32(dst, *src++); |
| #else |
| uint32_t c = *src++; |
| dst[0] = SkGetPackedR32(c); |
| dst[1] = SkGetPackedG32(c); |
| dst[2] = SkGetPackedB32(c); |
| #endif |
| dst += 3; |
| } |
| } |
| |
| static void Write_4444_YUV(uint8_t* SK_RESTRICT dst, |
| const void* SK_RESTRICT srcRow, int width, |
| const SkPMColor*) { |
| const SkPMColor16* SK_RESTRICT src = (const SkPMColor16*)srcRow; |
| while (--width >= 0) { |
| #ifdef WE_CONVERT_TO_YUV |
| rgb2yuv_4444(dst, *src++); |
| #else |
| SkPMColor16 c = *src++; |
| dst[0] = SkPacked4444ToR32(c); |
| dst[1] = SkPacked4444ToG32(c); |
| dst[2] = SkPacked4444ToB32(c); |
| #endif |
| dst += 3; |
| } |
| } |
| |
| static void Write_16_YUV(uint8_t* SK_RESTRICT dst, |
| const void* SK_RESTRICT srcRow, int width, |
| const SkPMColor*) { |
| const uint16_t* SK_RESTRICT src = (const uint16_t*)srcRow; |
| while (--width >= 0) { |
| #ifdef WE_CONVERT_TO_YUV |
| rgb2yuv_16(dst, *src++); |
| #else |
| uint16_t c = *src++; |
| dst[0] = SkPacked16ToR32(c); |
| dst[1] = SkPacked16ToG32(c); |
| dst[2] = SkPacked16ToB32(c); |
| #endif |
| dst += 3; |
| } |
| } |
| |
| static void Write_Index_YUV(uint8_t* SK_RESTRICT dst, |
| const void* SK_RESTRICT srcRow, int width, |
| const SkPMColor* SK_RESTRICT ctable) { |
| const uint8_t* SK_RESTRICT src = (const uint8_t*)srcRow; |
| while (--width >= 0) { |
| #ifdef WE_CONVERT_TO_YUV |
| rgb2yuv_32(dst, ctable[*src++]); |
| #else |
| uint32_t c = ctable[*src++]; |
| dst[0] = SkGetPackedR32(c); |
| dst[1] = SkGetPackedG32(c); |
| dst[2] = SkGetPackedB32(c); |
| #endif |
| dst += 3; |
| } |
| } |
| |
| static WriteScanline ChooseWriter(const SkBitmap& bm) { |
| switch (bm.config()) { |
| case SkBitmap::kARGB_8888_Config: |
| return Write_32_YUV; |
| case SkBitmap::kRGB_565_Config: |
| return Write_16_YUV; |
| case SkBitmap::kARGB_4444_Config: |
| return Write_4444_YUV; |
| case SkBitmap::kIndex8_Config: |
| return Write_Index_YUV; |
| default: |
| return NULL; |
| } |
| } |
| |
| class SkJPEGImageEncoder : public SkImageEncoder { |
| protected: |
| virtual bool onEncode(SkWStream* stream, const SkBitmap& bm, int quality) { |
| #ifdef TIME_ENCODE |
| AutoTimeMillis atm("JPEG Encode"); |
| #endif |
| |
| const WriteScanline writer = ChooseWriter(bm); |
| if (NULL == writer) { |
| return false; |
| } |
| |
| SkAutoLockPixels alp(bm); |
| if (NULL == bm.getPixels()) { |
| return false; |
| } |
| |
| jpeg_compress_struct cinfo; |
| skjpeg_error_mgr sk_err; |
| skjpeg_destination_mgr sk_wstream(stream); |
| |
| // allocate these before set call setjmp |
| SkAutoMalloc oneRow; |
| SkAutoLockColors ctLocker; |
| |
| cinfo.err = jpeg_std_error(&sk_err); |
| sk_err.error_exit = skjpeg_error_exit; |
| if (setjmp(sk_err.fJmpBuf)) { |
| return false; |
| } |
| jpeg_create_compress(&cinfo); |
| |
| cinfo.dest = &sk_wstream; |
| cinfo.image_width = bm.width(); |
| cinfo.image_height = bm.height(); |
| cinfo.input_components = 3; |
| #ifdef WE_CONVERT_TO_YUV |
| cinfo.in_color_space = JCS_YCbCr; |
| #else |
| cinfo.in_color_space = JCS_RGB; |
| #endif |
| cinfo.input_gamma = 1; |
| |
| jpeg_set_defaults(&cinfo); |
| jpeg_set_quality(&cinfo, quality, TRUE /* limit to baseline-JPEG values */); |
| cinfo.dct_method = JDCT_IFAST; |
| |
| jpeg_start_compress(&cinfo, TRUE); |
| |
| const int width = bm.width(); |
| uint8_t* oneRowP = (uint8_t*)oneRow.alloc(width * 3); |
| |
| const SkPMColor* colors = ctLocker.lockColors(bm); |
| const void* srcRow = bm.getPixels(); |
| |
| while (cinfo.next_scanline < cinfo.image_height) { |
| JSAMPROW row_pointer[1]; /* pointer to JSAMPLE row[s] */ |
| |
| writer(oneRowP, srcRow, width, colors); |
| row_pointer[0] = oneRowP; |
| (void) jpeg_write_scanlines(&cinfo, row_pointer, 1); |
| srcRow = (const void*)((const char*)srcRow + bm.rowBytes()); |
| } |
| |
| jpeg_finish_compress(&cinfo); |
| jpeg_destroy_compress(&cinfo); |
| |
| return true; |
| } |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #include "SkTRegistry.h" |
| |
| static SkImageDecoder* DFactory(SkStream* stream) { |
| static const char gHeader[] = { 0xFF, 0xD8, 0xFF }; |
| static const size_t HEADER_SIZE = sizeof(gHeader); |
| |
| char buffer[HEADER_SIZE]; |
| size_t len = stream->read(buffer, HEADER_SIZE); |
| |
| if (len != HEADER_SIZE) { |
| return NULL; // can't read enough |
| } |
| if (memcmp(buffer, gHeader, HEADER_SIZE)) { |
| return NULL; |
| } |
| return SkNEW(SkJPEGImageDecoder); |
| } |
| |
| static SkImageEncoder* EFactory(SkImageEncoder::Type t) { |
| return (SkImageEncoder::kJPEG_Type == t) ? SkNEW(SkJPEGImageEncoder) : NULL; |
| } |
| |
| static SkTRegistry<SkImageDecoder*, SkStream*> gDReg(DFactory); |
| static SkTRegistry<SkImageEncoder*, SkImageEncoder::Type> gEReg(EFactory); |
