src/third_party/skia/src/images/SkImageDecoder_pkm.cpp

   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 "SkStreamPriv.h"
  13 #include "SkTextureCompressor.h"
  14 #include "SkTypes.h"
  15
  16 #include "etc1.h"
  17
  18 class SkPKMImageDecoder : public SkImageDecoder {
  19 public:
  20     SkPKMImageDecoder() { }
  21
  22     virtual Format getFormat() const SK_OVERRIDE {
  23         return kPKM_Format;
  24     }
  25
  26 protected:
  27     virtual bool onDecode(SkStream* stream, SkBitmap* bm, Mode) SK_OVERRIDE;
  28
  29 private:
  30     typedef SkImageDecoder INHERITED;
  31 };
  32
  33 /////////////////////////////////////////////////////////////////////////////////////////
  34
  35 bool SkPKMImageDecoder::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
  36     SkAutoMalloc autoMal;
  37     const size_t length = SkCopyStreamToStorage(&autoMal, stream);
  38     if (0 == length) {
  39         return false;
  40     }
  41
  42     unsigned char* buf = (unsigned char*)autoMal.get();
  43
  44     // Make sure original PKM header is there...
  45     SkASSERT(etc1_pkm_is_valid(buf));
  46
  47     const unsigned short width = etc1_pkm_get_width(buf);
  48     const unsigned short height = etc1_pkm_get_height(buf);
  49
  50 #ifdef SK_SUPPORT_LEGACY_IMAGEDECODER_CHOOSER
  51     // should we allow the Chooser (if present) to pick a config for us???
  52     if (!this->chooseFromOneChoice(kN32_SkColorType, width, height)) {
  53         return false;
  54     }
  55 #endif
  56
  57     // Setup the sampler...
  58     SkScaledBitmapSampler sampler(width, height, this->getSampleSize());
  59
  60     // Set the config...
  61     bm->setInfo(SkImageInfo::MakeN32(sampler.scaledWidth(), sampler.scaledHeight(),
  62                                      kOpaque_SkAlphaType));
  63     if (SkImageDecoder::kDecodeBounds_Mode == mode) {
  64         return true;
  65     }
  66
  67     if (!this->allocPixelRef(bm, NULL)) {
  68         return false;
  69     }
  70
  71     // Lock the pixels, since we're about to write to them...
  72     SkAutoLockPixels alp(*bm);
  73
  74     if (!sampler.begin(bm, SkScaledBitmapSampler::kRGB, *this)) {
  75         return false;
  76     }
  77
  78     // Advance buffer past the header
  79     buf += ETC_PKM_HEADER_SIZE;
  80
  81     // ETC1 Data is encoded as RGB pixels, so we should extract it as such
  82     int nPixels = width * height;
  83     SkAutoMalloc outRGBData(nPixels * 3);
  84     uint8_t *outRGBDataPtr = reinterpret_cast<uint8_t *>(outRGBData.get());
  85
  86     // Decode ETC1
  87     if (!SkTextureCompressor::DecompressBufferFromFormat(
  88             outRGBDataPtr, width*3, buf, width, height, SkTextureCompressor::kETC1_Format)) {
  89         return false;
  90     }
  91
  92     // Set each of the pixels...
  93     const int srcRowBytes = width * 3;
  94     const int dstHeight = sampler.scaledHeight();
  95     const uint8_t *srcRow = reinterpret_cast<uint8_t *>(outRGBDataPtr);
  96     srcRow += sampler.srcY0() * srcRowBytes;
  97     for (int y = 0; y < dstHeight; ++y) {
  98         sampler.next(srcRow);
  99         srcRow += sampler.srcDY() * srcRowBytes;
 100     }
 101
 102     return true;
 103 }
 104
 105 /////////////////////////////////////////////////////////////////////////////////////////
 106 DEFINE_DECODER_CREATOR(PKMImageDecoder);
 107 /////////////////////////////////////////////////////////////////////////////////////////
 108
 109 static bool is_pkm(SkStreamRewindable* stream) {
 110     // Read the PKM header and make sure it's valid.
 111     unsigned char buf[ETC_PKM_HEADER_SIZE];
 112     if (stream->read((void*)buf, ETC_PKM_HEADER_SIZE) != ETC_PKM_HEADER_SIZE) {
 113         return false;
 114     }
 115
 116     return SkToBool(etc1_pkm_is_valid(buf));
 117 }
 118
 119 static SkImageDecoder* sk_libpkm_dfactory(SkStreamRewindable* stream) {
 120     if (is_pkm(stream)) {
 121         return SkNEW(SkPKMImageDecoder);
 122     }
 123     return NULL;
 124 }
 125
 126 static SkImageDecoder_DecodeReg gReg(sk_libpkm_dfactory);
 127
 128 static SkImageDecoder::Format get_format_pkm(SkStreamRewindable* stream) {
 129     if (is_pkm(stream)) {
 130         return SkImageDecoder::kPKM_Format;
 131     }
 132     return SkImageDecoder::kUnknown_Format;
 133 }
 134
 135 static SkImageDecoder_FormatReg gFormatReg(get_format_pkm);