/*
 * 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 "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,
                          SkBitmap::Config pref, 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;
};

/* our source struct for directing jpeg to our stream object
*/
struct sk_source_mgr : jpeg_source_mgr {
    sk_source_mgr(SkStream* stream, SkImageDecoder* decoder);

    SkStream*   fStream;
    const void* fMemoryBase;
    size_t      fMemoryBaseSize;
    SkImageDecoder* fDecoder;
    enum {
        kBufferSize = 1024
    };
    char    fBuffer[kBufferSize];
};

/* 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;
};

static void sk_init_source(j_decompress_ptr cinfo) {
    sk_source_mgr*  src = (sk_source_mgr*)cinfo->src;
    src->next_input_byte = (const JOCTET*)src->fBuffer;
    src->bytes_in_buffer = 0;
}

static boolean sk_fill_input_buffer(j_decompress_ptr cinfo) {
    sk_source_mgr* src = (sk_source_mgr*)cinfo->src;
    if (src->fDecoder != NULL && src->fDecoder->shouldCancelDecode()) {
        return FALSE;
    }
    size_t bytes = src->fStream->read(src->fBuffer, sk_source_mgr::kBufferSize);
    // note that JPEG is happy with less than the full read,
    // as long as the result is non-zero
    if (bytes == 0) {
        return FALSE;
    }

    src->next_input_byte = (const JOCTET*)src->fBuffer;
    src->bytes_in_buffer = bytes;
    return TRUE;
}

static void sk_skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
    SkASSERT(num_bytes > 0);

    sk_source_mgr*  src = (sk_source_mgr*)cinfo->src;

    long bytesToSkip = num_bytes - src->bytes_in_buffer;

    // check if the skip amount exceeds the current buffer
    if (bytesToSkip > 0) {
        size_t bytes = src->fStream->skip(bytesToSkip);
        if (bytes != (size_t)bytesToSkip) {
//            SkDebugf("xxxxxxxxxxxxxx failure to skip request %d actual %d\n", bytesToSkip, bytes);
            cinfo->err->error_exit((j_common_ptr)cinfo);
        }
        src->next_input_byte = (const JOCTET*)src->fBuffer;
        src->bytes_in_buffer = 0;
    } else {
        src->next_input_byte += num_bytes;
        src->bytes_in_buffer -= num_bytes;
    }
}

static boolean sk_resync_to_restart(j_decompress_ptr cinfo, int desired) {
    sk_source_mgr*  src = (sk_source_mgr*)cinfo->src;

    // what is the desired param for???

    if (!src->fStream->rewind()) {
        SkDebugf("xxxxxxxxxxxxxx failure to rewind\n");
        cinfo->err->error_exit((j_common_ptr)cinfo);
        return FALSE;
    }
    src->next_input_byte = (const JOCTET*)src->fBuffer;
    src->bytes_in_buffer = 0;
    return TRUE;
}

static void sk_term_source(j_decompress_ptr /*cinfo*/) {}

///////////////////////////////////////////////////////////////////////////////

static void skmem_init_source(j_decompress_ptr cinfo) {
    sk_source_mgr*  src = (sk_source_mgr*)cinfo->src;
    src->next_input_byte = (const JOCTET*)src->fMemoryBase;
    src->bytes_in_buffer = src->fMemoryBaseSize;
}

static boolean skmem_fill_input_buffer(j_decompress_ptr cinfo) {
    SkDebugf("xxxxxxxxxxxxxx skmem_fill_input_buffer called\n");
    return FALSE;
}

static void skmem_skip_input_data(j_decompress_ptr cinfo, long num_bytes) {
    sk_source_mgr*  src = (sk_source_mgr*)cinfo->src;
//    SkDebugf("xxxxxxxxxxxxxx skmem_skip_input_data called %d\n", num_bytes);
    src->next_input_byte = (const JOCTET*)((const char*)src->next_input_byte + num_bytes);
    src->bytes_in_buffer -= num_bytes;
}

static boolean skmem_resync_to_restart(j_decompress_ptr cinfo, int desired) {
    SkDebugf("xxxxxxxxxxxxxx skmem_resync_to_restart called\n");
    return TRUE;
}

static void skmem_term_source(j_decompress_ptr /*cinfo*/) {}

#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

///////////////////////////////////////////////////////////////////////////////

sk_source_mgr::sk_source_mgr(SkStream* stream, SkImageDecoder* decoder) : fStream(stream) {
    fDecoder = decoder;
    const void* baseAddr = stream->getMemoryBase();
    if (baseAddr && false) {
        fMemoryBase = baseAddr;
        fMemoryBaseSize = stream->getLength();
        
        init_source = skmem_init_source;
        fill_input_buffer = skmem_fill_input_buffer;
        skip_input_data = skmem_skip_input_data;
        resync_to_restart = skmem_resync_to_restart;
        term_source = skmem_term_source;
    } else {
        fMemoryBase = NULL;
        fMemoryBaseSize = 0;

        init_source = sk_init_source;
        fill_input_buffer = sk_fill_input_buffer;
        skip_input_data = sk_skip_input_data;
        resync_to_restart = sk_resync_to_restart;
        term_source = sk_term_source;
    }
//    SkDebugf("**************** use memorybase %p %d\n", fMemoryBase, fMemoryBaseSize);
}

#include <setjmp.h>

struct sk_error_mgr : jpeg_error_mgr {
    jmp_buf fJmpBuf;
};

static void sk_error_exit(j_common_ptr cinfo) {
    sk_error_mgr* error = (sk_error_mgr*)cinfo->err;

    (*error->output_message) (cinfo);

    /* Let the memory manager delete any temp files before we die */
    jpeg_destroy(cinfo);

    longjmp(error->fJmpBuf, -1);
}

///////////////////////////////////////////////////////////////////////////////

/*  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,
                                  SkBitmap::Config prefConfig, Mode mode) {
#ifdef TIME_DECODE
    AutoTimeMillis atm("JPEG Decode");
#endif

    SkAutoMalloc  srcStorage;
    JPEGAutoClean autoClean;

    jpeg_decompress_struct  cinfo;
    sk_error_mgr            sk_err;
    sk_source_mgr           sk_stream(stream, this);

    cinfo.err = jpeg_std_error(&sk_err);
    sk_err.error_exit = sk_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 = prefConfig;
    // if no user preference, see what the device recommends
    if (config == SkBitmap::kNo_Config)
        config = SkImageDecoder::GetDeviceConfig();

    // 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;
    }
}

struct sk_destination_mgr : jpeg_destination_mgr {
    sk_destination_mgr(SkWStream* stream);

    SkWStream*  fStream;

    enum {
        kBufferSize = 1024
    };
    uint8_t fBuffer[kBufferSize];
};

static void sk_init_destination(j_compress_ptr cinfo) {
    sk_destination_mgr* dest = (sk_destination_mgr*)cinfo->dest;

    dest->next_output_byte = dest->fBuffer;
    dest->free_in_buffer = sk_destination_mgr::kBufferSize;
}

static boolean sk_empty_output_buffer(j_compress_ptr cinfo) {
    sk_destination_mgr* dest = (sk_destination_mgr*)cinfo->dest;

//  if (!dest->fStream->write(dest->fBuffer, sk_destination_mgr::kBufferSize - dest->free_in_buffer))
    if (!dest->fStream->write(dest->fBuffer, sk_destination_mgr::kBufferSize)) {
        ERREXIT(cinfo, JERR_FILE_WRITE);
        return false;
    }

    dest->next_output_byte = dest->fBuffer;
    dest->free_in_buffer = sk_destination_mgr::kBufferSize;
    return TRUE;
}

static void sk_term_destination (j_compress_ptr cinfo) {
    sk_destination_mgr* dest = (sk_destination_mgr*)cinfo->dest;

    size_t size = sk_destination_mgr::kBufferSize - dest->free_in_buffer;
    if (size > 0) {
        if (!dest->fStream->write(dest->fBuffer, size)) {
            ERREXIT(cinfo, JERR_FILE_WRITE);
            return;
        }
    }
    dest->fStream->flush();
}

sk_destination_mgr::sk_destination_mgr(SkWStream* stream)
        : fStream(stream) {
    this->init_destination = sk_init_destination;
    this->empty_output_buffer = sk_empty_output_buffer;
    this->term_destination = sk_term_destination;
}

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;
        sk_error_mgr            sk_err;
        sk_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 = sk_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);