src/images/SkImageDecoder_libwebp.cpp - skia - Git at Google

 /*
  * Copyright 2010, 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 "SkScaledBitmapSampler.h"
 #include "SkStream.h"
 #include "SkTemplates.h"
 #include "SkUtils.h"

 // A WebP decoder only, on top of (subset of) libwebp
 // For more information on WebP image format, and libwebp library, see:
 //   http://code.google.com/speed/webp/
 //   http://www.webmproject.org/code/#libwebp_webp_image_decoder_library
 //   http://review.webmproject.org/gitweb?p=libwebp.git

 #include <stdio.h>
 extern "C" {
 // If moving libwebp out of skia source tree, path for webp headers must be
 // updated accordingly. Here, we enforce using local copy in webp sub-directory.
 #include "webp/decode.h"
 #include "webp/encode.h"
 }

 // this enables timing code to report milliseconds for a decode
 //#define TIME_DECODE

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

 // Define VP8 I/O on top of Skia stream

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

 static const size_t WEBP_VP8_HEADER_SIZE = 64;
 static const size_t WEBP_IDECODE_BUFFER_SZ = (1 << 16);

 // Parse headers of RIFF container, and check for valid Webp (VP8) content.
 static bool webp_parse_header(SkStream* stream, int* width, int* height, int* alpha) {
     unsigned char buffer[WEBP_VP8_HEADER_SIZE];
     size_t bytesToRead = WEBP_VP8_HEADER_SIZE;
     size_t totalBytesRead = 0;
     do {
         unsigned char* dst = buffer + totalBytesRead;
         const size_t bytesRead = stream->read(dst, bytesToRead);
         if (0 == bytesRead) {
             // Could not read any bytes. Check to see if we are at the end (exit
             // condition), and continue reading if not. Important for streams
             // that do not have all the data ready.
             continue;
         }
         bytesToRead -= bytesRead;
         totalBytesRead += bytesRead;
         SkASSERT(bytesToRead + totalBytesRead == WEBP_VP8_HEADER_SIZE);
     } while (!stream->isAtEnd() && bytesToRead > 0);

     WebPBitstreamFeatures features;
     VP8StatusCode status = WebPGetFeatures(buffer, totalBytesRead, &features);
     if (VP8_STATUS_OK != status) {
         return false; // Invalid WebP file.
     }
     *width = features.width;
     *height = features.height;
     *alpha = features.has_alpha;

     // sanity check for image size that's about to be decoded.
     {
         int64_t size = sk_64_mul(*width, *height);
         if (!sk_64_isS32(size)) {
             return false;
         }
         // now check that if we are 4-bytes per pixel, we also don't overflow
         if (sk_64_asS32(size) > (0x7FFFFFFF >> 2)) {
             return false;
         }
     }
     return true;
 }

 class SkWEBPImageDecoder: public SkImageDecoder {
 public:
     SkWEBPImageDecoder() {
         fInputStream = NULL;
         fOrigWidth = 0;
         fOrigHeight = 0;
         fHasAlpha = 0;
     }
     virtual ~SkWEBPImageDecoder() {
         SkSafeUnref(fInputStream);
     }

     virtual Format getFormat() const SK_OVERRIDE {
         return kWEBP_Format;
     }

 protected:
     virtual bool onBuildTileIndex(SkStreamRewindable *stream, int *width, int *height) SK_OVERRIDE;
     virtual bool onDecodeSubset(SkBitmap* bitmap, const SkIRect& rect) SK_OVERRIDE;
     virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;

 private:
     /**
      *  Called when determining the output config to request to webp.
      *  If the image does not have alpha, there is no need to premultiply.
      *  If the caller wants unpremultiplied colors, that is respected.
      */
     bool shouldPremultiply() const {
         return SkToBool(fHasAlpha) && !this->getRequireUnpremultipliedColors();
     }

     bool setDecodeConfig(SkBitmap* decodedBitmap, int width, int height);

     SkStream* fInputStream;
     int fOrigWidth;
     int fOrigHeight;
     int fHasAlpha;

     typedef SkImageDecoder INHERITED;
 };

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

 #ifdef TIME_DECODE

 #include "SkTime.h"

 class AutoTimeMillis {
 public:
     AutoTimeMillis(const char label[]) :
         fLabel(label) {
         if (NULL == fLabel) {
             fLabel = "";
         }
         fNow = SkTime::GetMSecs();
     }
     ~AutoTimeMillis() {
         SkDebugf("---- Time (ms): %s %d\n", fLabel, SkTime::GetMSecs() - fNow);
     }
 private:
     const char* fLabel;
     SkMSec fNow;
 };

 #endif

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

 // 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 SkBitmap& bm, const char msg[]) {
     SkDEBUGF(("libwebp error %s [%d %d]", msg, bm.width(), bm.height()));
     return false; // must always return false
 }

 static WEBP_CSP_MODE webp_decode_mode(const SkBitmap* decodedBitmap, bool premultiply) {
     WEBP_CSP_MODE mode = MODE_LAST;
     const SkColorType ct = decodedBitmap->colorType();

     if (ct == kN32_SkColorType) {
         #if SK_PMCOLOR_BYTE_ORDER(B,G,R,A)
             mode = premultiply ? MODE_bgrA : MODE_BGRA;
         #elif SK_PMCOLOR_BYTE_ORDER(R,G,B,A)
             mode = premultiply ? MODE_rgbA : MODE_RGBA;
         #else
             #error "Skia uses BGRA or RGBA byte order"
         #endif
     } else if (ct == kARGB_4444_SkColorType) {
         mode = premultiply ? MODE_rgbA_4444 : MODE_RGBA_4444;
     } else if (ct == kRGB_565_SkColorType) {
         mode = MODE_RGB_565;
     }
     SkASSERT(MODE_LAST != mode);
     return mode;
 }

 // Incremental WebP image decoding. Reads input buffer of 64K size iteratively
 // and decodes this block to appropriate color-space as per config object.
 static bool webp_idecode(SkStream* stream, WebPDecoderConfig* config) {
     WebPIDecoder* idec = WebPIDecode(NULL, 0, config);
     if (NULL == idec) {
         WebPFreeDecBuffer(&config->output);
         return false;
     }

     if (!stream->rewind()) {
         SkDebugf("Failed to rewind webp stream!");
         return false;
     }
     const size_t readBufferSize = stream->hasLength() ?
             SkTMin(stream->getLength(), WEBP_IDECODE_BUFFER_SZ) : WEBP_IDECODE_BUFFER_SZ;
     SkAutoMalloc srcStorage(readBufferSize);
     unsigned char* input = (uint8_t*)srcStorage.get();
     if (NULL == input) {
         WebPIDelete(idec);
         WebPFreeDecBuffer(&config->output);
         return false;
     }

     bool success = true;
     VP8StatusCode status = VP8_STATUS_SUSPENDED;
     do {
         const size_t bytesRead = stream->read(input, readBufferSize);
         if (0 == bytesRead) {
             success = false;
             break;
         }

         status = WebPIAppend(idec, input, bytesRead);
         if (VP8_STATUS_OK != status && VP8_STATUS_SUSPENDED != status) {
             success = false;
             break;
         }
     } while (VP8_STATUS_OK != status);
     srcStorage.free();
     WebPIDelete(idec);
     WebPFreeDecBuffer(&config->output);

     return success;
 }

 static bool webp_get_config_resize(WebPDecoderConfig* config,
                                    SkBitmap* decodedBitmap,
                                    int width, int height, bool premultiply) {
     WEBP_CSP_MODE mode = webp_decode_mode(decodedBitmap, premultiply);
     if (MODE_LAST == mode) {
         return false;
     }

     if (0 == WebPInitDecoderConfig(config)) {
         return false;
     }

     config->output.colorspace = mode;
     config->output.u.RGBA.rgba = (uint8_t*)decodedBitmap->getPixels();
     config->output.u.RGBA.stride = (int) decodedBitmap->rowBytes();
     config->output.u.RGBA.size = decodedBitmap->getSize();
     config->output.is_external_memory = 1;

     if (width != decodedBitmap->width() || height != decodedBitmap->height()) {
         config->options.use_scaling = 1;
         config->options.scaled_width = decodedBitmap->width();
         config->options.scaled_height = decodedBitmap->height();
     }

     return true;
 }

 static bool webp_get_config_resize_crop(WebPDecoderConfig* config,
                                         SkBitmap* decodedBitmap,
                                         const SkIRect& region, bool premultiply) {

     if (!webp_get_config_resize(config, decodedBitmap, region.width(),
                                 region.height(), premultiply)) {
       return false;
     }

     config->options.use_cropping = 1;
     config->options.crop_left = region.fLeft;
     config->options.crop_top = region.fTop;
     config->options.crop_width = region.width();
     config->options.crop_height = region.height();

     return true;
 }

 bool SkWEBPImageDecoder::setDecodeConfig(SkBitmap* decodedBitmap, int width, int height) {
     SkColorType colorType = this->getPrefColorType(k32Bit_SrcDepth, SkToBool(fHasAlpha));

     // YUV converter supports output in RGB565, RGBA4444 and RGBA8888 formats.
     if (fHasAlpha) {
         if (colorType != kARGB_4444_SkColorType) {
             colorType = kN32_SkColorType;
         }
     } else {
         if (colorType != kRGB_565_SkColorType && colorType != kARGB_4444_SkColorType) {
             colorType = kN32_SkColorType;
         }
     }

 #ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER
     if (!this->chooseFromOneChoice(colorType, width, height)) {
         return false;
     }
 #endif

     SkAlphaType alphaType = kOpaque_SkAlphaType;
     if (SkToBool(fHasAlpha)) {
         if (this->getRequireUnpremultipliedColors()) {
             alphaType = kUnpremul_SkAlphaType;
         } else {
             alphaType = kPremul_SkAlphaType;
         }
     }
     return decodedBitmap->setInfo(SkImageInfo::Make(width, height, colorType, alphaType));
 }

 bool SkWEBPImageDecoder::onBuildTileIndex(SkStreamRewindable* stream,
                                           int *width, int *height) {
     int origWidth, origHeight, hasAlpha;
     if (!webp_parse_header(stream, &origWidth, &origHeight, &hasAlpha)) {
         return false;
     }

     if (!stream->rewind()) {
         SkDebugf("Failed to rewind webp stream!");
         return false;
     }

     *width = origWidth;
     *height = origHeight;

     SkRefCnt_SafeAssign(this->fInputStream, stream);
     this->fOrigWidth = origWidth;
     this->fOrigHeight = origHeight;
     this->fHasAlpha = hasAlpha;

     return true;
 }

 static bool is_config_compatible(const SkBitmap& bitmap) {
     const SkColorType ct = bitmap.colorType();
     return ct == kARGB_4444_SkColorType || ct == kRGB_565_SkColorType || ct == kN32_SkColorType;
 }

 bool SkWEBPImageDecoder::onDecodeSubset(SkBitmap* decodedBitmap,
                                         const SkIRect& region) {
     SkIRect rect = SkIRect::MakeWH(fOrigWidth, fOrigHeight);

     if (!rect.intersect(region)) {
         // If the requested region is entirely outsides the image, return false
         return false;
     }

     const int sampleSize = this->getSampleSize();
     SkScaledBitmapSampler sampler(rect.width(), rect.height(), sampleSize);
     const int width = sampler.scaledWidth();
     const int height = sampler.scaledHeight();

     // The image can be decoded directly to decodedBitmap if
     //   1. the region is within the image range
     //   2. bitmap's config is compatible
     //   3. bitmap's size is same as the required region (after sampled)
     bool directDecode = (rect == region) &&
                         (decodedBitmap->isNull() ||
                          (is_config_compatible(*decodedBitmap) &&
                          (decodedBitmap->width() == width) &&
                          (decodedBitmap->height() == height)));

     SkBitmap tmpBitmap;
     SkBitmap *bitmap = decodedBitmap;

     if (!directDecode) {
         bitmap = &tmpBitmap;
     }

     if (bitmap->isNull()) {
         if (!setDecodeConfig(bitmap, width, height)) {
             return false;
         }
         // alloc from native heap if it is a temp bitmap. (prevent GC)
         bool allocResult = (bitmap == decodedBitmap)
                                ? allocPixelRef(bitmap, NULL)
                                : bitmap->allocPixels();
         if (!allocResult) {
             return return_false(*decodedBitmap, "allocPixelRef");
         }
 #ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER
     } else {
         // This is also called in setDecodeConfig in above block.
         // i.e., when bitmap->isNull() is true.
         if (!chooseFromOneChoice(bitmap->colorType(), width, height)) {
             return false;
         }
 #endif
     }

     SkAutoLockPixels alp(*bitmap);
     WebPDecoderConfig config;
     if (!webp_get_config_resize_crop(&config, bitmap, rect,
                                      this->shouldPremultiply())) {
         return false;
     }

     // Decode the WebP image data stream using WebP incremental decoding for
     // the specified cropped image-region.
     if (!webp_idecode(this->fInputStream, &config)) {
         return false;
     }

     if (!directDecode) {
         cropBitmap(decodedBitmap, bitmap, sampleSize, region.x(), region.y(),
                    region.width(), region.height(), rect.x(), rect.y());
     }
     return true;
 }

 bool SkWEBPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap,
                                   Mode mode) {
 #ifdef TIME_DECODE
     AutoTimeMillis atm("WEBP Decode");
 #endif

     int origWidth, origHeight, hasAlpha;
     if (!webp_parse_header(stream, &origWidth, &origHeight, &hasAlpha)) {
         return false;
     }
     this->fHasAlpha = hasAlpha;

     const int sampleSize = this->getSampleSize();
     SkScaledBitmapSampler sampler(origWidth, origHeight, sampleSize);
     if (!setDecodeConfig(decodedBitmap, sampler.scaledWidth(),
                          sampler.scaledHeight())) {
         return false;
     }

     // If only bounds are requested, done
     if (SkImageDecoder::kDecodeBounds_Mode == mode) {
         return true;
     }

     if (!this->allocPixelRef(decodedBitmap, NULL)) {
         return return_false(*decodedBitmap, "allocPixelRef");
     }

     SkAutoLockPixels alp(*decodedBitmap);

     WebPDecoderConfig config;
     if (!webp_get_config_resize(&config, decodedBitmap, origWidth, origHeight,
                                 this->shouldPremultiply())) {
         return false;
     }

     // Decode the WebP image data stream using WebP incremental decoding.
     return webp_idecode(stream, &config);
 }

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

 #include "SkUnPreMultiply.h"

 typedef void (*ScanlineImporter)(const uint8_t* in, uint8_t* out, int width,
                                  const SkPMColor* SK_RESTRICT ctable);

 static void ARGB_8888_To_RGB(const uint8_t* in, uint8_t* rgb, int width,
                              const SkPMColor*) {
   const uint32_t* SK_RESTRICT src = (const uint32_t*)in;
   for (int i = 0; i < width; ++i) {
       const uint32_t c = *src++;
       rgb[0] = SkGetPackedR32(c);
       rgb[1] = SkGetPackedG32(c);
       rgb[2] = SkGetPackedB32(c);
       rgb += 3;
   }
 }

 static void ARGB_8888_To_RGBA(const uint8_t* in, uint8_t* rgb, int width,
                               const SkPMColor*) {
   const uint32_t* SK_RESTRICT src = (const uint32_t*)in;
   const SkUnPreMultiply::Scale* SK_RESTRICT table =
       SkUnPreMultiply::GetScaleTable();
   for (int i = 0; i < width; ++i) {
       const uint32_t c = *src++;
       uint8_t a = SkGetPackedA32(c);
       uint8_t r = SkGetPackedR32(c);
       uint8_t g = SkGetPackedG32(c);
       uint8_t b = SkGetPackedB32(c);
       if (0 != a && 255 != a) {
         SkUnPreMultiply::Scale scale = table[a];
         r = SkUnPreMultiply::ApplyScale(scale, r);
         g = SkUnPreMultiply::ApplyScale(scale, g);
         b = SkUnPreMultiply::ApplyScale(scale, b);
       }
       rgb[0] = r;
       rgb[1] = g;
       rgb[2] = b;
       rgb[3] = a;
       rgb += 4;
   }
 }

 static void RGB_565_To_RGB(const uint8_t* in, uint8_t* rgb, int width,
                            const SkPMColor*) {
   const uint16_t* SK_RESTRICT src = (const uint16_t*)in;
   for (int i = 0; i < width; ++i) {
       const uint16_t c = *src++;
       rgb[0] = SkPacked16ToR32(c);
       rgb[1] = SkPacked16ToG32(c);
       rgb[2] = SkPacked16ToB32(c);
       rgb += 3;
   }
 }

 static void ARGB_4444_To_RGB(const uint8_t* in, uint8_t* rgb, int width,
                              const SkPMColor*) {
   const SkPMColor16* SK_RESTRICT src = (const SkPMColor16*)in;
   for (int i = 0; i < width; ++i) {
       const SkPMColor16 c = *src++;
       rgb[0] = SkPacked4444ToR32(c);
       rgb[1] = SkPacked4444ToG32(c);
       rgb[2] = SkPacked4444ToB32(c);
       rgb += 3;
   }
 }

 static void ARGB_4444_To_RGBA(const uint8_t* in, uint8_t* rgb, int width,
                               const SkPMColor*) {
   const SkPMColor16* SK_RESTRICT src = (const SkPMColor16*)in;
   const SkUnPreMultiply::Scale* SK_RESTRICT table =
       SkUnPreMultiply::GetScaleTable();
   for (int i = 0; i < width; ++i) {
       const SkPMColor16 c = *src++;
       uint8_t a = SkPacked4444ToA32(c);
       uint8_t r = SkPacked4444ToR32(c);
       uint8_t g = SkPacked4444ToG32(c);
       uint8_t b = SkPacked4444ToB32(c);
       if (0 != a && 255 != a) {
         SkUnPreMultiply::Scale scale = table[a];
         r = SkUnPreMultiply::ApplyScale(scale, r);
         g = SkUnPreMultiply::ApplyScale(scale, g);
         b = SkUnPreMultiply::ApplyScale(scale, b);
       }
       rgb[0] = r;
       rgb[1] = g;
       rgb[2] = b;
       rgb[3] = a;
       rgb += 4;
   }
 }

 static void Index8_To_RGB(const uint8_t* in, uint8_t* rgb, int width,
                           const SkPMColor* SK_RESTRICT ctable) {
   const uint8_t* SK_RESTRICT src = (const uint8_t*)in;
   for (int i = 0; i < width; ++i) {
       const uint32_t c = ctable[*src++];
       rgb[0] = SkGetPackedR32(c);
       rgb[1] = SkGetPackedG32(c);
       rgb[2] = SkGetPackedB32(c);
       rgb += 3;
   }
 }

 static ScanlineImporter ChooseImporter(SkColorType ct, bool  hasAlpha, int*  bpp) {
     switch (ct) {
         case kN32_SkColorType:
             if (hasAlpha) {
                 *bpp = 4;
                 return ARGB_8888_To_RGBA;
             } else {
                 *bpp = 3;
                 return ARGB_8888_To_RGB;
             }
         case kARGB_4444_SkColorType:
             if (hasAlpha) {
                 *bpp = 4;
                 return ARGB_4444_To_RGBA;
             } else {
                 *bpp = 3;
                 return ARGB_4444_To_RGB;
             }
         case kRGB_565_SkColorType:
             *bpp = 3;
             return RGB_565_To_RGB;
         case kIndex_8_SkColorType:
             *bpp = 3;
             return Index8_To_RGB;
         default:
             return NULL;
     }
 }

 static int stream_writer(const uint8_t* data, size_t data_size,
                          const WebPPicture* const picture) {
   SkWStream* const stream = (SkWStream*)picture->custom_ptr;
   return stream->write(data, data_size) ? 1 : 0;
 }

 class SkWEBPImageEncoder : public SkImageEncoder {
 protected:
     virtual bool onEncode(SkWStream* stream, const SkBitmap& bm, int quality) SK_OVERRIDE;

 private:
     typedef SkImageEncoder INHERITED;
 };

 bool SkWEBPImageEncoder::onEncode(SkWStream* stream, const SkBitmap& bm,
                                   int quality) {
     const bool hasAlpha = !bm.isOpaque();
     int bpp = -1;
     const ScanlineImporter scanline_import = ChooseImporter(bm.colorType(), hasAlpha, &bpp);
     if (NULL == scanline_import) {
         return false;
     }
     if (-1 == bpp) {
         return false;
     }

     SkAutoLockPixels alp(bm);
     SkAutoLockColors ctLocker;
     if (NULL == bm.getPixels()) {
         return false;
     }

     WebPConfig webp_config;
     if (!WebPConfigPreset(&webp_config, WEBP_PRESET_DEFAULT, (float) quality)) {
         return false;
     }

     WebPPicture pic;
     WebPPictureInit(&pic);
     pic.width = bm.width();
     pic.height = bm.height();
     pic.writer = stream_writer;
     pic.custom_ptr = (void*)stream;

     const SkPMColor* colors = ctLocker.lockColors(bm);
     const uint8_t* src = (uint8_t*)bm.getPixels();
     const int rgbStride = pic.width * bpp;

     // Import (for each scanline) the bit-map image (in appropriate color-space)
     // to RGB color space.
     uint8_t* rgb = new uint8_t[rgbStride * pic.height];
     for (int y = 0; y < pic.height; ++y) {
         scanline_import(src + y * bm.rowBytes(), rgb + y * rgbStride,
                         pic.width, colors);
     }

     bool ok;
     if (bpp == 3) {
         ok = SkToBool(WebPPictureImportRGB(&pic, rgb, rgbStride));
     } else {
         ok = SkToBool(WebPPictureImportRGBA(&pic, rgb, rgbStride));
     }
     delete[] rgb;

     ok = ok && WebPEncode(&webp_config, &pic);
     WebPPictureFree(&pic);

     return ok;
 }


 ///////////////////////////////////////////////////////////////////////////////
 DEFINE_DECODER_CREATOR(WEBPImageDecoder);
 DEFINE_ENCODER_CREATOR(WEBPImageEncoder);
 ///////////////////////////////////////////////////////////////////////////////

 static SkImageDecoder* sk_libwebp_dfactory(SkStreamRewindable* stream) {
     int width, height, hasAlpha;
     if (!webp_parse_header(stream, &width, &height, &hasAlpha)) {
         return NULL;
     }

     // Magic matches, call decoder
     return SkNEW(SkWEBPImageDecoder);
 }

 static SkImageDecoder::Format get_format_webp(SkStreamRewindable* stream) {
     int width, height, hasAlpha;
     if (webp_parse_header(stream, &width, &height, &hasAlpha)) {
         return SkImageDecoder::kWEBP_Format;
     }
     return SkImageDecoder::kUnknown_Format;
 }

 static SkImageEncoder* sk_libwebp_efactory(SkImageEncoder::Type t) {
       return (SkImageEncoder::kWEBP_Type == t) ? SkNEW(SkWEBPImageEncoder) : NULL;
 }

 static SkImageDecoder_DecodeReg gDReg(sk_libwebp_dfactory);
 static SkImageDecoder_FormatReg gFormatReg(get_format_webp);
 static SkImageEncoder_EncodeReg gEReg(sk_libwebp_efactory);
	/*
	* Copyright 2010, 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 "SkScaledBitmapSampler.h"
	#include "SkStream.h"
	#include "SkTemplates.h"
	#include "SkUtils.h"

	// A WebP decoder only, on top of (subset of) libwebp
	// For more information on WebP image format, and libwebp library, see:
	// http://code.google.com/speed/webp/
	// http://www.webmproject.org/code/#libwebp_webp_image_decoder_library
	// http://review.webmproject.org/gitweb?p=libwebp.git

	#include <stdio.h>
	extern "C" {
	// If moving libwebp out of skia source tree, path for webp headers must be
	// updated accordingly. Here, we enforce using local copy in webp sub-directory.
	#include "webp/decode.h"
	#include "webp/encode.h"
	}

	// this enables timing code to report milliseconds for a decode
	//#define TIME_DECODE

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

	// Define VP8 I/O on top of Skia stream

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

	static const size_t WEBP_VP8_HEADER_SIZE = 64;
	static const size_t WEBP_IDECODE_BUFFER_SZ = (1 << 16);

	// Parse headers of RIFF container, and check for valid Webp (VP8) content.
	static bool webp_parse_header(SkStream* stream, int* width, int* height, int* alpha) {
	unsigned char buffer[WEBP_VP8_HEADER_SIZE];
	size_t bytesToRead = WEBP_VP8_HEADER_SIZE;
	size_t totalBytesRead = 0;
	do {
	unsigned char* dst = buffer + totalBytesRead;
	const size_t bytesRead = stream->read(dst, bytesToRead);
	if (0 == bytesRead) {
	// Could not read any bytes. Check to see if we are at the end (exit
	// condition), and continue reading if not. Important for streams
	// that do not have all the data ready.
	continue;
	}
	bytesToRead -= bytesRead;
	totalBytesRead += bytesRead;
	SkASSERT(bytesToRead + totalBytesRead == WEBP_VP8_HEADER_SIZE);
	} while (!stream->isAtEnd() && bytesToRead > 0);

	WebPBitstreamFeatures features;
	VP8StatusCode status = WebPGetFeatures(buffer, totalBytesRead, &features);
	if (VP8_STATUS_OK != status) {
	return false; // Invalid WebP file.
	}
	*width = features.width;
	*height = features.height;
	*alpha = features.has_alpha;

	// sanity check for image size that's about to be decoded.
	{
	int64_t size = sk_64_mul(width, height);
	if (!sk_64_isS32(size)) {
	return false;
	}
	// now check that if we are 4-bytes per pixel, we also don't overflow
	if (sk_64_asS32(size) > (0x7FFFFFFF >> 2)) {
	return false;
	}
	}
	return true;
	}

	class SkWEBPImageDecoder: public SkImageDecoder {
	public:
	SkWEBPImageDecoder() {
	fInputStream = NULL;
	fOrigWidth = 0;
	fOrigHeight = 0;
	fHasAlpha = 0;
	}
	virtual ~SkWEBPImageDecoder() {
	SkSafeUnref(fInputStream);
	}

	virtual Format getFormat() const SK_OVERRIDE {
	return kWEBP_Format;
	}

	protected:
	virtual bool onBuildTileIndex(SkStreamRewindable stream, int width, int *height) SK_OVERRIDE;
	virtual bool onDecodeSubset(SkBitmap* bitmap, const SkIRect& rect) SK_OVERRIDE;
	virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;

	private:
	/**
	* Called when determining the output config to request to webp.
	* If the image does not have alpha, there is no need to premultiply.
	* If the caller wants unpremultiplied colors, that is respected.
	*/
	bool shouldPremultiply() const {
	return SkToBool(fHasAlpha) && !this->getRequireUnpremultipliedColors();
	}

	bool setDecodeConfig(SkBitmap* decodedBitmap, int width, int height);

	SkStream* fInputStream;
	int fOrigWidth;
	int fOrigHeight;
	int fHasAlpha;

	typedef SkImageDecoder INHERITED;
	};

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

	#ifdef TIME_DECODE

	#include "SkTime.h"

	class AutoTimeMillis {
	public:
	AutoTimeMillis(const char label[]) :
	fLabel(label) {
	if (NULL == fLabel) {
	fLabel = "";
	}
	fNow = SkTime::GetMSecs();
	}
	~AutoTimeMillis() {
	SkDebugf("---- Time (ms): %s %d\n", fLabel, SkTime::GetMSecs() - fNow);
	}
	private:
	const char* fLabel;
	SkMSec fNow;
	};

	#endif

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

	// 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 SkBitmap& bm, const char msg[]) {
	SkDEBUGF(("libwebp error %s [%d %d]", msg, bm.width(), bm.height()));
	return false; // must always return false
	}

	static WEBP_CSP_MODE webp_decode_mode(const SkBitmap* decodedBitmap, bool premultiply) {
	WEBP_CSP_MODE mode = MODE_LAST;
	const SkColorType ct = decodedBitmap->colorType();

	if (ct == kN32_SkColorType) {
	#if SK_PMCOLOR_BYTE_ORDER(B,G,R,A)
	mode = premultiply ? MODE_bgrA : MODE_BGRA;
	#elif SK_PMCOLOR_BYTE_ORDER(R,G,B,A)
	mode = premultiply ? MODE_rgbA : MODE_RGBA;
	#else
	#error "Skia uses BGRA or RGBA byte order"
	#endif
	} else if (ct == kARGB_4444_SkColorType) {
	mode = premultiply ? MODE_rgbA_4444 : MODE_RGBA_4444;
	} else if (ct == kRGB_565_SkColorType) {
	mode = MODE_RGB_565;
	}
	SkASSERT(MODE_LAST != mode);
	return mode;
	}

	// Incremental WebP image decoding. Reads input buffer of 64K size iteratively
	// and decodes this block to appropriate color-space as per config object.
	static bool webp_idecode(SkStream* stream, WebPDecoderConfig* config) {
	WebPIDecoder* idec = WebPIDecode(NULL, 0, config);
	if (NULL == idec) {
	WebPFreeDecBuffer(&config->output);
	return false;
	}

	if (!stream->rewind()) {
	SkDebugf("Failed to rewind webp stream!");
	return false;
	}
	const size_t readBufferSize = stream->hasLength() ?
	SkTMin(stream->getLength(), WEBP_IDECODE_BUFFER_SZ) : WEBP_IDECODE_BUFFER_SZ;
	SkAutoMalloc srcStorage(readBufferSize);
	unsigned char* input = (uint8_t*)srcStorage.get();
	if (NULL == input) {
	WebPIDelete(idec);
	WebPFreeDecBuffer(&config->output);
	return false;
	}

	bool success = true;
	VP8StatusCode status = VP8_STATUS_SUSPENDED;
	do {
	const size_t bytesRead = stream->read(input, readBufferSize);
	if (0 == bytesRead) {
	success = false;
	break;
	}

	status = WebPIAppend(idec, input, bytesRead);
	if (VP8_STATUS_OK != status && VP8_STATUS_SUSPENDED != status) {
	success = false;
	break;
	}
	} while (VP8_STATUS_OK != status);
	srcStorage.free();
	WebPIDelete(idec);
	WebPFreeDecBuffer(&config->output);

	return success;
	}

	static bool webp_get_config_resize(WebPDecoderConfig* config,
	SkBitmap* decodedBitmap,
	int width, int height, bool premultiply) {
	WEBP_CSP_MODE mode = webp_decode_mode(decodedBitmap, premultiply);
	if (MODE_LAST == mode) {
	return false;
	}

	if (0 == WebPInitDecoderConfig(config)) {
	return false;
	}

	config->output.colorspace = mode;
	config->output.u.RGBA.rgba = (uint8_t*)decodedBitmap->getPixels();
	config->output.u.RGBA.stride = (int) decodedBitmap->rowBytes();
	config->output.u.RGBA.size = decodedBitmap->getSize();
	config->output.is_external_memory = 1;

	if (width != decodedBitmap->width() \|\| height != decodedBitmap->height()) {
	config->options.use_scaling = 1;
	config->options.scaled_width = decodedBitmap->width();
	config->options.scaled_height = decodedBitmap->height();
	}

	return true;
	}

	static bool webp_get_config_resize_crop(WebPDecoderConfig* config,
	SkBitmap* decodedBitmap,
	const SkIRect& region, bool premultiply) {

	if (!webp_get_config_resize(config, decodedBitmap, region.width(),
	region.height(), premultiply)) {
	return false;
	}

	config->options.use_cropping = 1;
	config->options.crop_left = region.fLeft;
	config->options.crop_top = region.fTop;
	config->options.crop_width = region.width();
	config->options.crop_height = region.height();

	return true;
	}

	bool SkWEBPImageDecoder::setDecodeConfig(SkBitmap* decodedBitmap, int width, int height) {
	SkColorType colorType = this->getPrefColorType(k32Bit_SrcDepth, SkToBool(fHasAlpha));

	// YUV converter supports output in RGB565, RGBA4444 and RGBA8888 formats.
	if (fHasAlpha) {
	if (colorType != kARGB_4444_SkColorType) {
	colorType = kN32_SkColorType;
	}
	} else {
	if (colorType != kRGB_565_SkColorType && colorType != kARGB_4444_SkColorType) {
	colorType = kN32_SkColorType;
	}
	}

	#ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER
	if (!this->chooseFromOneChoice(colorType, width, height)) {
	return false;
	}
	#endif

	SkAlphaType alphaType = kOpaque_SkAlphaType;
	if (SkToBool(fHasAlpha)) {
	if (this->getRequireUnpremultipliedColors()) {
	alphaType = kUnpremul_SkAlphaType;
	} else {
	alphaType = kPremul_SkAlphaType;
	}
	}
	return decodedBitmap->setInfo(SkImageInfo::Make(width, height, colorType, alphaType));
	}

	bool SkWEBPImageDecoder::onBuildTileIndex(SkStreamRewindable* stream,
	int width, int height) {
	int origWidth, origHeight, hasAlpha;
	if (!webp_parse_header(stream, &origWidth, &origHeight, &hasAlpha)) {
	return false;
	}

	if (!stream->rewind()) {
	SkDebugf("Failed to rewind webp stream!");
	return false;
	}

	*width = origWidth;
	*height = origHeight;

	SkRefCnt_SafeAssign(this->fInputStream, stream);
	this->fOrigWidth = origWidth;
	this->fOrigHeight = origHeight;
	this->fHasAlpha = hasAlpha;

	return true;
	}

	static bool is_config_compatible(const SkBitmap& bitmap) {
	const SkColorType ct = bitmap.colorType();
	return ct == kARGB_4444_SkColorType \|\| ct == kRGB_565_SkColorType \|\| ct == kN32_SkColorType;
	}

	bool SkWEBPImageDecoder::onDecodeSubset(SkBitmap* decodedBitmap,
	const SkIRect& region) {
	SkIRect rect = SkIRect::MakeWH(fOrigWidth, fOrigHeight);

	if (!rect.intersect(region)) {
	// If the requested region is entirely outsides the image, return false
	return false;
	}

	const int sampleSize = this->getSampleSize();
	SkScaledBitmapSampler sampler(rect.width(), rect.height(), sampleSize);
	const int width = sampler.scaledWidth();
	const int height = sampler.scaledHeight();

	// The image can be decoded directly to decodedBitmap if
	// 1. the region is within the image range
	// 2. bitmap's config is compatible
	// 3. bitmap's size is same as the required region (after sampled)
	bool directDecode = (rect == region) &&
	(decodedBitmap->isNull() \|\|
	(is_config_compatible(*decodedBitmap) &&
	(decodedBitmap->width() == width) &&
	(decodedBitmap->height() == height)));

	SkBitmap tmpBitmap;
	SkBitmap *bitmap = decodedBitmap;

	if (!directDecode) {
	bitmap = &tmpBitmap;
	}

	if (bitmap->isNull()) {
	if (!setDecodeConfig(bitmap, width, height)) {
	return false;
	}
	// alloc from native heap if it is a temp bitmap. (prevent GC)
	bool allocResult = (bitmap == decodedBitmap)
	? allocPixelRef(bitmap, NULL)
	: bitmap->allocPixels();
	if (!allocResult) {
	return return_false(*decodedBitmap, "allocPixelRef");
	}
	#ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER
	} else {
	// This is also called in setDecodeConfig in above block.
	// i.e., when bitmap->isNull() is true.
	if (!chooseFromOneChoice(bitmap->colorType(), width, height)) {
	return false;
	}
	#endif
	}

	SkAutoLockPixels alp(*bitmap);
	WebPDecoderConfig config;
	if (!webp_get_config_resize_crop(&config, bitmap, rect,
	this->shouldPremultiply())) {
	return false;
	}

	// Decode the WebP image data stream using WebP incremental decoding for
	// the specified cropped image-region.
	if (!webp_idecode(this->fInputStream, &config)) {
	return false;
	}

	if (!directDecode) {
	cropBitmap(decodedBitmap, bitmap, sampleSize, region.x(), region.y(),
	region.width(), region.height(), rect.x(), rect.y());
	}
	return true;
	}

	bool SkWEBPImageDecoder::onDecode(SkStream* stream, SkBitmap* decodedBitmap,
	Mode mode) {
	#ifdef TIME_DECODE
	AutoTimeMillis atm("WEBP Decode");
	#endif

	int origWidth, origHeight, hasAlpha;
	if (!webp_parse_header(stream, &origWidth, &origHeight, &hasAlpha)) {
	return false;
	}
	this->fHasAlpha = hasAlpha;

	const int sampleSize = this->getSampleSize();
	SkScaledBitmapSampler sampler(origWidth, origHeight, sampleSize);
	if (!setDecodeConfig(decodedBitmap, sampler.scaledWidth(),
	sampler.scaledHeight())) {
	return false;
	}

	// If only bounds are requested, done
	if (SkImageDecoder::kDecodeBounds_Mode == mode) {
	return true;
	}

	if (!this->allocPixelRef(decodedBitmap, NULL)) {
	return return_false(*decodedBitmap, "allocPixelRef");
	}

	SkAutoLockPixels alp(*decodedBitmap);

	WebPDecoderConfig config;
	if (!webp_get_config_resize(&config, decodedBitmap, origWidth, origHeight,
	this->shouldPremultiply())) {
	return false;
	}

	// Decode the WebP image data stream using WebP incremental decoding.
	return webp_idecode(stream, &config);
	}

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

	#include "SkUnPreMultiply.h"

	typedef void (ScanlineImporter)(const uint8_t in, uint8_t* out, int width,
	const SkPMColor* SK_RESTRICT ctable);

	static void ARGB_8888_To_RGB(const uint8_t* in, uint8_t* rgb, int width,
	const SkPMColor*) {
	const uint32_t* SK_RESTRICT src = (const uint32_t*)in;
	for (int i = 0; i < width; ++i) {
	const uint32_t c = *src++;
	rgb[0] = SkGetPackedR32(c);
	rgb[1] = SkGetPackedG32(c);
	rgb[2] = SkGetPackedB32(c);
	rgb += 3;
	}
	}

	static void ARGB_8888_To_RGBA(const uint8_t* in, uint8_t* rgb, int width,
	const SkPMColor*) {
	const uint32_t* SK_RESTRICT src = (const uint32_t*)in;
	const SkUnPreMultiply::Scale* SK_RESTRICT table =
	SkUnPreMultiply::GetScaleTable();
	for (int i = 0; i < width; ++i) {
	const uint32_t c = *src++;
	uint8_t a = SkGetPackedA32(c);
	uint8_t r = SkGetPackedR32(c);
	uint8_t g = SkGetPackedG32(c);
	uint8_t b = SkGetPackedB32(c);
	if (0 != a && 255 != a) {
	SkUnPreMultiply::Scale scale = table[a];
	r = SkUnPreMultiply::ApplyScale(scale, r);
	g = SkUnPreMultiply::ApplyScale(scale, g);
	b = SkUnPreMultiply::ApplyScale(scale, b);
	}
	rgb[0] = r;
	rgb[1] = g;
	rgb[2] = b;
	rgb[3] = a;
	rgb += 4;
	}
	}

	static void RGB_565_To_RGB(const uint8_t* in, uint8_t* rgb, int width,
	const SkPMColor*) {
	const uint16_t* SK_RESTRICT src = (const uint16_t*)in;
	for (int i = 0; i < width; ++i) {
	const uint16_t c = *src++;
	rgb[0] = SkPacked16ToR32(c);
	rgb[1] = SkPacked16ToG32(c);
	rgb[2] = SkPacked16ToB32(c);
	rgb += 3;
	}
	}

	static void ARGB_4444_To_RGB(const uint8_t* in, uint8_t* rgb, int width,
	const SkPMColor*) {
	const SkPMColor16* SK_RESTRICT src = (const SkPMColor16*)in;
	for (int i = 0; i < width; ++i) {
	const SkPMColor16 c = *src++;
	rgb[0] = SkPacked4444ToR32(c);
	rgb[1] = SkPacked4444ToG32(c);
	rgb[2] = SkPacked4444ToB32(c);
	rgb += 3;
	}
	}

	static void ARGB_4444_To_RGBA(const uint8_t* in, uint8_t* rgb, int width,
	const SkPMColor*) {
	const SkPMColor16* SK_RESTRICT src = (const SkPMColor16*)in;
	const SkUnPreMultiply::Scale* SK_RESTRICT table =
	SkUnPreMultiply::GetScaleTable();
	for (int i = 0; i < width; ++i) {
	const SkPMColor16 c = *src++;
	uint8_t a = SkPacked4444ToA32(c);
	uint8_t r = SkPacked4444ToR32(c);
	uint8_t g = SkPacked4444ToG32(c);
	uint8_t b = SkPacked4444ToB32(c);
	if (0 != a && 255 != a) {
	SkUnPreMultiply::Scale scale = table[a];
	r = SkUnPreMultiply::ApplyScale(scale, r);
	g = SkUnPreMultiply::ApplyScale(scale, g);
	b = SkUnPreMultiply::ApplyScale(scale, b);
	}
	rgb[0] = r;
	rgb[1] = g;
	rgb[2] = b;
	rgb[3] = a;
	rgb += 4;
	}
	}

	static void Index8_To_RGB(const uint8_t* in, uint8_t* rgb, int width,
	const SkPMColor* SK_RESTRICT ctable) {
	const uint8_t* SK_RESTRICT src = (const uint8_t*)in;
	for (int i = 0; i < width; ++i) {
	const uint32_t c = ctable[*src++];
	rgb[0] = SkGetPackedR32(c);
	rgb[1] = SkGetPackedG32(c);
	rgb[2] = SkGetPackedB32(c);
	rgb += 3;
	}
	}

	static ScanlineImporter ChooseImporter(SkColorType ct, bool hasAlpha, int* bpp) {
	switch (ct) {
	case kN32_SkColorType:
	if (hasAlpha) {
	*bpp = 4;
	return ARGB_8888_To_RGBA;
	} else {
	*bpp = 3;
	return ARGB_8888_To_RGB;
	}
	case kARGB_4444_SkColorType:
	if (hasAlpha) {
	*bpp = 4;
	return ARGB_4444_To_RGBA;
	} else {
	*bpp = 3;
	return ARGB_4444_To_RGB;
	}
	case kRGB_565_SkColorType:
	*bpp = 3;
	return RGB_565_To_RGB;
	case kIndex_8_SkColorType:
	*bpp = 3;
	return Index8_To_RGB;
	default:
	return NULL;
	}
	}

	static int stream_writer(const uint8_t* data, size_t data_size,
	const WebPPicture* const picture) {
	SkWStream* const stream = (SkWStream*)picture->custom_ptr;
	return stream->write(data, data_size) ? 1 : 0;
	}

	class SkWEBPImageEncoder : public SkImageEncoder {
	protected:
	virtual bool onEncode(SkWStream* stream, const SkBitmap& bm, int quality) SK_OVERRIDE;

	private:
	typedef SkImageEncoder INHERITED;
	};

	bool SkWEBPImageEncoder::onEncode(SkWStream* stream, const SkBitmap& bm,
	int quality) {
	const bool hasAlpha = !bm.isOpaque();
	int bpp = -1;
	const ScanlineImporter scanline_import = ChooseImporter(bm.colorType(), hasAlpha, &bpp);
	if (NULL == scanline_import) {
	return false;
	}
	if (-1 == bpp) {
	return false;
	}

	SkAutoLockPixels alp(bm);
	SkAutoLockColors ctLocker;
	if (NULL == bm.getPixels()) {
	return false;
	}

	WebPConfig webp_config;
	if (!WebPConfigPreset(&webp_config, WEBP_PRESET_DEFAULT, (float) quality)) {
	return false;
	}

	WebPPicture pic;
	WebPPictureInit(&pic);
	pic.width = bm.width();
	pic.height = bm.height();
	pic.writer = stream_writer;
	pic.custom_ptr = (void*)stream;

	const SkPMColor* colors = ctLocker.lockColors(bm);
	const uint8_t* src = (uint8_t*)bm.getPixels();
	const int rgbStride = pic.width * bpp;

	// Import (for each scanline) the bit-map image (in appropriate color-space)
	// to RGB color space.
	uint8_t* rgb = new uint8_t[rgbStride * pic.height];
	for (int y = 0; y < pic.height; ++y) {
	scanline_import(src + y * bm.rowBytes(), rgb + y * rgbStride,
	pic.width, colors);
	}

	bool ok;
	if (bpp == 3) {
	ok = SkToBool(WebPPictureImportRGB(&pic, rgb, rgbStride));
	} else {
	ok = SkToBool(WebPPictureImportRGBA(&pic, rgb, rgbStride));
	}
	delete[] rgb;

	ok = ok && WebPEncode(&webp_config, &pic);
	WebPPictureFree(&pic);

	return ok;
	}


	///////////////////////////////////////////////////////////////////////////////
	DEFINE_DECODER_CREATOR(WEBPImageDecoder);
	DEFINE_ENCODER_CREATOR(WEBPImageEncoder);
	///////////////////////////////////////////////////////////////////////////////

	static SkImageDecoder* sk_libwebp_dfactory(SkStreamRewindable* stream) {
	int width, height, hasAlpha;
	if (!webp_parse_header(stream, &width, &height, &hasAlpha)) {
	return NULL;
	}

	// Magic matches, call decoder
	return SkNEW(SkWEBPImageDecoder);
	}

	static SkImageDecoder::Format get_format_webp(SkStreamRewindable* stream) {
	int width, height, hasAlpha;
	if (webp_parse_header(stream, &width, &height, &hasAlpha)) {
	return SkImageDecoder::kWEBP_Format;
	}
	return SkImageDecoder::kUnknown_Format;
	}

	static SkImageEncoder* sk_libwebp_efactory(SkImageEncoder::Type t) {
	return (SkImageEncoder::kWEBP_Type == t) ? SkNEW(SkWEBPImageEncoder) : NULL;
	}

	static SkImageDecoder_DecodeReg gDReg(sk_libwebp_dfactory);
	static SkImageDecoder_FormatReg gFormatReg(get_format_webp);
	static SkImageEncoder_EncodeReg gEReg(sk_libwebp_efactory);