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      1 /*
      2  * Copyright 2014 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #include "SkColorPriv.h"
      9 #include "SkImageDecoder.h"
     10 #include "SkScaledBitmapSampler.h"
     11 #include "SkStream.h"
     12 #include "SkStreamHelpers.h"
     13 #include "SkTypes.h"
     14 
     15 #include "etc1.h"
     16 
     17 class SkPKMImageDecoder : public SkImageDecoder {
     18 public:
     19     SkPKMImageDecoder() { }
     20 
     21     virtual Format getFormat() const SK_OVERRIDE {
     22         return kPKM_Format;
     23     }
     24 
     25 protected:
     26     virtual Result onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;
     27 
     28 private:
     29     typedef SkImageDecoder INHERITED;
     30 };
     31 
     32 /////////////////////////////////////////////////////////////////////////////////////////
     33 
     34 SkImageDecoder::Result SkPKMImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
     35     SkAutoMalloc autoMal;
     36     const size_t length = CopyStreamToStorage(&autoMal, stream);
     37     if (0 == length) {
     38         return kFailure;
     39     }
     40 
     41     unsigned char* buf = (unsigned char*)autoMal.get();
     42 
     43     // Make sure original PKM header is there...
     44     SkASSERT(etc1_pkm_is_valid(buf));
     45 
     46     const unsigned short width = etc1_pkm_get_width(buf);
     47     const unsigned short height = etc1_pkm_get_height(buf);
     48 
     49 #ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER
     50     // should we allow the Chooser (if present) to pick a config for us???
     51     if (!this->chooseFromOneChoice(kN32_SkColorType, width, height)) {
     52         return kFailure;
     53     }
     54 #endif
     55 
     56     // Setup the sampler...
     57     SkScaledBitmapSampler sampler(width, height, this->getSampleSize());
     58 
     59     // Set the config...
     60     bm->setInfo(SkImageInfo::MakeN32(sampler.scaledWidth(), sampler.scaledHeight(),
     61                                      kOpaque_SkAlphaType));
     62     if (SkImageDecoder::kDecodeBounds_Mode == mode) {
     63         return kSuccess;
     64     }
     65 
     66     if (!this->allocPixelRef(bm, NULL)) {
     67         return kFailure;
     68     }
     69 
     70     // Lock the pixels, since we're about to write to them...
     71     SkAutoLockPixels alp(*bm);
     72 
     73     if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
     74         return kFailure;
     75     }
     76 
     77     // Advance buffer past the header
     78     buf += ETC_PKM_HEADER_SIZE;
     79 
     80     // ETC1 Data is encoded as RGB pixels, so we should extract it as such
     81     int nPixels = width * height;
     82     SkAutoMalloc outRGBData(nPixels * 3);
     83     etc1_byte *outRGBDataPtr = reinterpret_cast<etc1_byte *>(outRGBData.get());
     84 
     85     // Decode ETC1
     86     if (etc1_decode_image(buf, outRGBDataPtr, width, height, 3, width*3)) {
     87         return kFailure;
     88     }
     89 
     90     // Set each of the pixels...
     91     const int srcRowBytes = width * 3;
     92     const int dstHeight = sampler.scaledHeight();
     93     const uint8_t *srcRow = reinterpret_cast<uint8_t *>(outRGBDataPtr);
     94     srcRow += sampler.srcY0() * srcRowBytes;
     95     for (int y = 0; y < dstHeight; ++y) {
     96         sampler.next(srcRow);
     97         srcRow += sampler.srcDY() * srcRowBytes;
     98     }
     99 
    100     return kSuccess;
    101 }
    102 
    103 /////////////////////////////////////////////////////////////////////////////////////////
    104 DEFINE_DECODER_CREATOR(PKMImageDecoder);
    105 /////////////////////////////////////////////////////////////////////////////////////////
    106 
    107 static bool is_pkm(SkStreamRewindable* stream) {
    108     // Read the PKM header and make sure it's valid.
    109     unsigned char buf[ETC_PKM_HEADER_SIZE];
    110     if (stream->read((void*)buf, ETC_PKM_HEADER_SIZE) != ETC_PKM_HEADER_SIZE) {
    111         return false;
    112     }
    113 
    114     return SkToBool(etc1_pkm_is_valid(buf));
    115 }
    116 
    117 static SkImageDecoder* sk_libpkm_dfactory(SkStreamRewindable* stream) {
    118     if (is_pkm(stream)) {
    119         return SkNEW(SkPKMImageDecoder);
    120     }
    121     return NULL;
    122 }
    123 
    124 static SkImageDecoder_DecodeReg gReg(sk_libpkm_dfactory);
    125 
    126 static SkImageDecoder::Format get_format_pkm(SkStreamRewindable* stream) {
    127     if (is_pkm(stream)) {
    128         return SkImageDecoder::kPKM_Format;
    129     }
    130     return SkImageDecoder::kUnknown_Format;
    131 }
    132 
    133 static SkImageDecoder_FormatReg gFormatReg(get_format_pkm);
    134