ui/gfx/codec/png_codec_unittest.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <stddef.h>
#include <stdint.h>

#include <algorithm>
#include <cmath>

#include "base/logging.h"
#include "base/macros.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "third_party/libpng/png.h"
#include "third_party/skia/include/core/SkBitmap.h"
#include "third_party/skia/include/core/SkColorPriv.h"
#include "third_party/skia/include/core/SkUnPreMultiply.h"
#include "third_party/zlib/zlib.h"
#include "ui/gfx/codec/png_codec.h"
#include "ui/gfx/geometry/size.h"
#include "ui/gfx/skia_util.h"

namespace gfx {

namespace {

void MakeRGBImage(int w, int h, std::vector<unsigned char>* data) {
  data->resize(w * h * 3);
  for (int y = 0; y < h; y++) {
    for (int x = 0; x < w; x++) {
      unsigned char* org_px = &(*data)[(y * w + x) * 3];
      org_px[0] = x * 3;      // r
      org_px[1] = x * 3 + 1;  // g
      org_px[2] = x * 3 + 2;  // b
    }
  }
}

// Set use_transparency to write data into the alpha channel, otherwise it will
// be filled with 0xff. With the alpha channel stripped, this should yield the
// same image as MakeRGBImage above, so the code below can make reference
// images for conversion testing.
void MakeRGBAImage(int w, int h, bool use_transparency,
                   std::vector<unsigned char>* data) {
  data->resize(w * h * 4);
  for (int y = 0; y < h; y++) {
    for (int x = 0; x < w; x++) {
      unsigned char* org_px = &(*data)[(y * w + x) * 4];
      org_px[0] = x * 3;      // r
      org_px[1] = x * 3 + 1;  // g
      org_px[2] = x * 3 + 2;  // b
      if (use_transparency)
        org_px[3] = x*3 + 3;  // a
      else
        org_px[3] = 0xFF;     // a (opaque)
    }
  }
}

// Creates a palette-based image.
void MakePaletteImage(int w, int h,
                      std::vector<unsigned char>* data,
                      std::vector<png_color>* palette,
                      std::vector<unsigned char>* trans_chunk = 0) {
  data->resize(w * h);
  palette->resize(w);
  for (int i = 0; i < w; ++i) {
    png_color& color = (*palette)[i];
    color.red = i * 3;
    color.green = color.red + 1;
    color.blue = color.red + 2;
  }
  for (int y = 0; y < h; y++) {
    for (int x = 0; x < w; x++) {
      (*data)[y * w + x] = x;  // palette index
    }
  }
  if (trans_chunk) {
    trans_chunk->resize(palette->size());
    for (std::size_t i = 0; i < trans_chunk->size(); ++i) {
      (*trans_chunk)[i] = i % 256;
    }
  }
}

// Creates a grayscale image without an alpha channel.
void MakeGrayscaleImage(int w, int h,
                        std::vector<unsigned char>* data) {
  data->resize(w * h);
  for (int y = 0; y < h; y++) {
    for (int x = 0; x < w; x++) {
      (*data)[y * w + x] = x;  // gray value
    }
  }
}

// Creates a grayscale image with an alpha channel.
void MakeGrayscaleAlphaImage(int w, int h,
                             std::vector<unsigned char>* data) {
  data->resize(w * h * 2);
  for (int y = 0; y < h; y++) {
    for (int x = 0; x < w; x++) {
      unsigned char* px = &(*data)[(y * w + x) * 2];
      px[0] = x;        // gray value
      px[1] = x % 256;  // alpha
    }
  }
}

// User write function (to be passed to libpng by EncodeImage) which writes
// into a buffer instead of to a file.
void WriteImageData(png_structp png_ptr,
                    png_bytep data,
                    png_size_t length) {
  std::vector<unsigned char>& v =
      *static_cast<std::vector<unsigned char>*>(png_get_io_ptr(png_ptr));
  v.resize(v.size() + length);
  memcpy(&v[v.size() - length], data, length);
}

// User flush function; goes with WriteImageData, above.
void FlushImageData(png_structp /*png_ptr*/) {
}

// Libpng user error function which allows us to print libpng errors using
// Chrome's logging facilities instead of stderr.
void LogLibPNGError(png_structp png_ptr,
                    png_const_charp error_msg) {
  DLOG(ERROR) << "libpng encode error: " << error_msg;
  longjmp(png_jmpbuf(png_ptr), 1);
}

// Goes with LogLibPNGError, above.
void LogLibPNGWarning(png_structp png_ptr,
                      png_const_charp warning_msg) {
  DLOG(ERROR) << "libpng encode warning: " << warning_msg;
}

// Color types supported by EncodeImage. Required because neither libpng nor
// PNGCodec::Encode supports all of the required values.
enum ColorType {
  COLOR_TYPE_GRAY = PNG_COLOR_TYPE_GRAY,
  COLOR_TYPE_GRAY_ALPHA = PNG_COLOR_TYPE_GRAY_ALPHA,
  COLOR_TYPE_PALETTE = PNG_COLOR_TYPE_PALETTE,
  COLOR_TYPE_RGB = PNG_COLOR_TYPE_RGB,
  COLOR_TYPE_RGBA = PNG_COLOR_TYPE_RGBA,
  COLOR_TYPE_BGR,
  COLOR_TYPE_BGRA
};

// PNG encoder used for testing. Required because PNGCodec::Encode doesn't do
// interlaced, palette-based, or grayscale images, but PNGCodec::Decode is
// actually asked to decode these types of images by Chrome.
bool EncodeImage(const std::vector<unsigned char>& input,
                 const int width,
                 const int height,
                 ColorType output_color_type,
                 std::vector<unsigned char>* output,
                 const int interlace_type = PNG_INTERLACE_NONE,
                 std::vector<png_color>* palette = 0,
                 std::vector<unsigned char>* palette_alpha = 0) {
  DCHECK(output);

  int input_rowbytes = 0;
  int transforms = PNG_TRANSFORM_IDENTITY;

  switch (output_color_type) {
    case COLOR_TYPE_GRAY:
      input_rowbytes = width;
      break;
    case COLOR_TYPE_GRAY_ALPHA:
      input_rowbytes = width * 2;
      break;
    case COLOR_TYPE_PALETTE:
      if (!palette)
        return false;
      input_rowbytes = width;
      break;
    case COLOR_TYPE_RGB:
      input_rowbytes = width * 3;
      break;
    case COLOR_TYPE_RGBA:
      input_rowbytes = width * 4;
      break;
    case COLOR_TYPE_BGR:
      input_rowbytes = width * 3;
      output_color_type = static_cast<ColorType>(PNG_COLOR_TYPE_RGB);
      transforms |= PNG_TRANSFORM_BGR;
      break;
    case COLOR_TYPE_BGRA:
      input_rowbytes = width * 4;
      output_color_type = static_cast<ColorType>(PNG_COLOR_TYPE_RGBA);
      transforms |= PNG_TRANSFORM_BGR;
      break;
  };

  png_struct* png_ptr =
      png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
  if (!png_ptr)
    return false;
  png_infop info_ptr = png_create_info_struct(png_ptr);
  if (!info_ptr) {
    png_destroy_write_struct(&png_ptr, NULL);
    return false;
  }

  std::vector<png_bytep> row_pointers(height);
  for (int y = 0 ; y < height; ++y) {
    row_pointers[y] = const_cast<unsigned char*>(&input[y * input_rowbytes]);
  }

  if (setjmp(png_jmpbuf(png_ptr))) {
    png_destroy_write_struct(&png_ptr, &info_ptr);
    return false;
  }

  png_set_error_fn(png_ptr, NULL, LogLibPNGError, LogLibPNGWarning);
  png_set_rows(png_ptr, info_ptr, &row_pointers[0]);
  png_set_write_fn(png_ptr, output, WriteImageData, FlushImageData);
  png_set_IHDR(png_ptr, info_ptr, width, height, 8, output_color_type,
               interlace_type, PNG_COMPRESSION_TYPE_DEFAULT,
               PNG_FILTER_TYPE_DEFAULT);
  if (output_color_type == COLOR_TYPE_PALETTE) {
    png_set_PLTE(png_ptr, info_ptr, &palette->front(), palette->size());
    if (palette_alpha) {
      unsigned char* alpha_data = &palette_alpha->front();
      size_t alpha_size = palette_alpha->size();
      png_set_tRNS(png_ptr, info_ptr, alpha_data, alpha_size, NULL);
    }
  }

  png_write_png(png_ptr, info_ptr, transforms, NULL);

  png_destroy_write_struct(&png_ptr, &info_ptr);
  return true;
}

}  // namespace

// Returns true if each channel of the given two colors are "close." This is
// used for comparing colors where rounding errors may cause off-by-one.
bool ColorsClose(uint32_t a, uint32_t b) {
  return abs(static_cast<int>(SkColorGetB(a) - SkColorGetB(b))) < 2 &&
         abs(static_cast<int>(SkColorGetG(a) - SkColorGetG(b))) < 2 &&
         abs(static_cast<int>(SkColorGetR(a) - SkColorGetR(b))) < 2 &&
         abs(static_cast<int>(SkColorGetA(a) - SkColorGetA(b))) < 2;
}

// Returns true if the RGB components are "close."
bool NonAlphaColorsClose(uint32_t a, uint32_t b) {
  return abs(static_cast<int>(SkColorGetB(a) - SkColorGetB(b))) < 2 &&
         abs(static_cast<int>(SkColorGetG(a) - SkColorGetG(b))) < 2 &&
         abs(static_cast<int>(SkColorGetR(a) - SkColorGetR(b))) < 2;
}

// Returns true if the BGRA 32-bit SkColor specified by |a| is equivalent to the
// 8-bit Gray color specified by |b|.
bool BGRAGrayEqualsA8Gray(uint32_t a, uint8_t b) {
  return SkColorGetB(a) == b && SkColorGetG(a) ==  b &&
         SkColorGetR(a) == b && SkColorGetA(a) == 255;
}

void MakeTestBGRASkBitmap(int w, int h, SkBitmap* bmp) {
  bmp->allocN32Pixels(w, h);

  uint32_t* src_data = bmp->getAddr32(0, 0);
  for (int i = 0; i < w * h; i++)
    src_data[i] = SkPreMultiplyARGB(i % 255, i % 250, i % 245, i % 240);
}

void MakeTestA8SkBitmap(int w, int h, SkBitmap* bmp) {
  bmp->allocPixels(SkImageInfo::MakeA8(w, h));

  uint8_t* src_data = bmp->getAddr8(0, 0);
  for (int i = 0; i < w * h; i++)
    src_data[i] = i % 255;
}

TEST(PNGCodec, EncodeDecodeRGB) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeRGBImage(w, h, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(PNGCodec::Encode(&original[0], PNGCodec::FORMAT_RGB,
                               Size(w, h), w * 3, false,
                               std::vector<PNGCodec::Comment>(),
                               &encoded));

  // decode, it should have the same size as the original
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGB, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(original.size(), decoded.size());

  // Images must be equal
  ASSERT_TRUE(original == decoded);
}

TEST(PNGCodec, EncodeDecodeRGBA) {
  const int w = 20, h = 20;

  // create an image with known values, a must be opaque because it will be
  // lost during encoding
  std::vector<unsigned char> original;
  MakeRGBAImage(w, h, true, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(PNGCodec::Encode(&original[0], PNGCodec::FORMAT_RGBA,
                               Size(w, h), w * 4, false,
                               std::vector<PNGCodec::Comment>(),
                               &encoded));

  // decode, it should have the same size as the original
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGBA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(original.size(), decoded.size());

  // Images must be exactly equal
  ASSERT_TRUE(original == decoded);
}

TEST(PNGCodec, EncodeDecodeBGRA) {
  const int w = 20, h = 20;

  // Create an image with known values, alpha must be opaque because it will be
  // lost during encoding.
  std::vector<unsigned char> original;
  MakeRGBAImage(w, h, true, &original);

  // Encode.
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(PNGCodec::Encode(&original[0], PNGCodec::FORMAT_BGRA,
                               Size(w, h), w * 4, false,
                               std::vector<PNGCodec::Comment>(),
                               &encoded));

  // Decode, it should have the same size as the original.
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_BGRA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(original.size(), decoded.size());

  // Images must be exactly equal.
  ASSERT_TRUE(original == decoded);
}

TEST(PNGCodec, DecodePalette) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  std::vector<png_color> original_palette;
  std::vector<unsigned char> original_trans_chunk;
  MakePaletteImage(w, h, &original, &original_palette, &original_trans_chunk);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_PALETTE,
                          &encoded,
                          PNG_INTERLACE_NONE,
                          &original_palette,
                          &original_trans_chunk));

  // decode
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGBA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), w * h * 4U);

  // Images must be equal
  for (int y = 0; y < h; ++y) {
    for (int x = 0; x < w; ++x) {
      unsigned char palette_pixel = original[y * w + x];
      png_color& palette_color = original_palette[palette_pixel];
      int alpha = original_trans_chunk[palette_pixel];
      unsigned char* rgba_pixel = &decoded[(y * w + x) * 4];

      EXPECT_EQ(palette_color.red, rgba_pixel[0]);
      EXPECT_EQ(palette_color.green, rgba_pixel[1]);
      EXPECT_EQ(palette_color.blue, rgba_pixel[2]);
      EXPECT_EQ(alpha, rgba_pixel[3]);
    }
  }
}

TEST(PNGCodec, DecodePaletteDiscardAlpha) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  std::vector<png_color> original_palette;
  std::vector<unsigned char> original_trans_chunk;
  MakePaletteImage(w, h, &original, &original_palette, &original_trans_chunk);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_PALETTE,
                          &encoded,
                          PNG_INTERLACE_NONE,
                          &original_palette,
                          &original_trans_chunk));

  // decode
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGB, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), w * h * 3U);

  // Images must be equal
  for (int y = 0; y < h; ++y) {
    for (int x = 0; x < w; ++x) {
      unsigned char palette_pixel = original[y * w + x];
      png_color& palette_color = original_palette[palette_pixel];
      unsigned char* rgba_pixel = &decoded[(y * w + x) * 3];

      EXPECT_EQ(palette_color.red, rgba_pixel[0]);
      EXPECT_EQ(palette_color.green, rgba_pixel[1]);
      EXPECT_EQ(palette_color.blue, rgba_pixel[2]);
    }
  }
}

TEST(PNGCodec, DecodeInterlacedPalette) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  std::vector<png_color> original_palette;
  std::vector<unsigned char> original_trans_chunk;
  MakePaletteImage(w, h, &original, &original_palette, &original_trans_chunk);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_PALETTE,
                          &encoded,
                          PNG_INTERLACE_ADAM7,
                          &original_palette,
                          &original_trans_chunk));

  // decode
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGBA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), w * h * 4U);

  // Images must be equal
  for (int y = 0; y < h; ++y) {
    for (int x = 0; x < w; ++x) {
      unsigned char palette_pixel = original[y * w + x];
      png_color& palette_color = original_palette[palette_pixel];
      int alpha = original_trans_chunk[palette_pixel];
      unsigned char* rgba_pixel = &decoded[(y * w + x) * 4];

      EXPECT_EQ(palette_color.red, rgba_pixel[0]);
      EXPECT_EQ(palette_color.green, rgba_pixel[1]);
      EXPECT_EQ(palette_color.blue, rgba_pixel[2]);
      EXPECT_EQ(alpha, rgba_pixel[3]);
    }
  }
}

TEST(PNGCodec, DecodeGrayscale) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeGrayscaleImage(w, h, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original, w, h, COLOR_TYPE_GRAY, &encoded));

  // decode
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGB, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), original.size() * 3);

  // Images must be equal
  for (int y = 0; y < h; ++y) {
    for (int x = 0; x < w; ++x) {
      unsigned char gray_pixel = original[(y * w + x)];
      unsigned char* rgba_pixel = &decoded[(y * w + x) * 3];
      EXPECT_EQ(rgba_pixel[0], gray_pixel);
      EXPECT_EQ(rgba_pixel[1], gray_pixel);
      EXPECT_EQ(rgba_pixel[2], gray_pixel);
    }
  }
}

TEST(PNGCodec, DecodeGrayscaleWithAlpha) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeGrayscaleAlphaImage(w, h, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_GRAY_ALPHA,
                          &encoded));

  // decode
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGBA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), original.size() * 2);

  // Images must be equal
  for (int y = 0; y < h; ++y) {
    for (int x = 0; x < w; ++x) {
      unsigned char* gray_pixel = &original[(y * w + x) * 2];
      unsigned char* rgba_pixel = &decoded[(y * w + x) * 4];
      EXPECT_EQ(rgba_pixel[0], gray_pixel[0]);
      EXPECT_EQ(rgba_pixel[1], gray_pixel[0]);
      EXPECT_EQ(rgba_pixel[2], gray_pixel[0]);
      EXPECT_EQ(rgba_pixel[3], gray_pixel[1]);
    }
  }
}

TEST(PNGCodec, DecodeGrayscaleWithAlphaDiscardAlpha) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeGrayscaleAlphaImage(w, h, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_GRAY_ALPHA,
                          &encoded));

  // decode
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGB, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), w * h * 3U);

  // Images must be equal
  for (int y = 0; y < h; ++y) {
    for (int x = 0; x < w; ++x) {
      unsigned char* gray_pixel = &original[(y * w + x) * 2];
      unsigned char* rgba_pixel = &decoded[(y * w + x) * 3];
      EXPECT_EQ(rgba_pixel[0], gray_pixel[0]);
      EXPECT_EQ(rgba_pixel[1], gray_pixel[0]);
      EXPECT_EQ(rgba_pixel[2], gray_pixel[0]);
    }
  }
}

TEST(PNGCodec, DecodeInterlacedGrayscale) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeGrayscaleImage(w, h, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_GRAY,
                          &encoded,
                          PNG_INTERLACE_ADAM7));

  // decode
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGBA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), original.size() * 4);

  // Images must be equal
  for (int y = 0; y < h; ++y) {
    for (int x = 0; x < w; ++x) {
      unsigned char gray_pixel = original[(y * w + x)];
      unsigned char* rgba_pixel = &decoded[(y * w + x) * 4];
      EXPECT_EQ(rgba_pixel[0], gray_pixel);
      EXPECT_EQ(rgba_pixel[1], gray_pixel);
      EXPECT_EQ(rgba_pixel[2], gray_pixel);
      EXPECT_EQ(rgba_pixel[3], 0xFF);
    }
  }
}

TEST(PNGCodec, DecodeInterlacedGrayscaleWithAlpha) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeGrayscaleAlphaImage(w, h, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_GRAY_ALPHA,
                          &encoded,
                          PNG_INTERLACE_ADAM7));

  // decode
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGBA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), original.size() * 2);

  // Images must be equal
  for (int y = 0; y < h; ++y) {
    for (int x = 0; x < w; ++x) {
      unsigned char* gray_pixel = &original[(y * w + x) * 2];
      unsigned char* rgba_pixel = &decoded[(y * w + x) * 4];
      EXPECT_EQ(rgba_pixel[0], gray_pixel[0]);
      EXPECT_EQ(rgba_pixel[1], gray_pixel[0]);
      EXPECT_EQ(rgba_pixel[2], gray_pixel[0]);
      EXPECT_EQ(rgba_pixel[3], gray_pixel[1]);
    }
  }
}

TEST(PNGCodec, DecodeInterlacedRGB) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeRGBImage(w, h, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_RGB,
                          &encoded,
                          PNG_INTERLACE_ADAM7));

  // decode, it should have the same size as the original
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGB, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(original.size(), decoded.size());

  // Images must be equal
  ASSERT_EQ(original, decoded);
}

TEST(PNGCodec, DecodeInterlacedRGBA) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeRGBAImage(w, h, false, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_RGBA,
                          &encoded,
                          PNG_INTERLACE_ADAM7));

  // decode, it should have the same size as the original
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGBA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(original.size(), decoded.size());

  // Images must be equal
  ASSERT_EQ(original, decoded);
}

TEST(PNGCodec, DecodeInterlacedRGBADiscardAlpha) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeRGBAImage(w, h, false, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_RGBA,
                          &encoded,
                          PNG_INTERLACE_ADAM7));

  // decode
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGB, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), w * h * 3U);

  // Images must be equal
  for (int x = 0; x < w; x++) {
    for (int y = 0; y < h; y++) {
      unsigned char* orig_px = &original[(y * w + x) * 4];
      unsigned char* dec_px = &decoded[(y * w + x) * 3];
      EXPECT_EQ(dec_px[0], orig_px[0]);
      EXPECT_EQ(dec_px[1], orig_px[1]);
      EXPECT_EQ(dec_px[2], orig_px[2]);
    }
  }
}

TEST(PNGCodec, DecodeInterlacedBGR) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeRGBImage(w, h, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_BGR,
                          &encoded,
                          PNG_INTERLACE_ADAM7));

  // decode, it should have the same size as the original
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_BGRA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(decoded.size(), w * h * 4U);

  // Images must be equal
  for (int x = 0; x < w; x++) {
    for (int y = 0; y < h; y++) {
      unsigned char* orig_px = &original[(y * w + x) * 3];
      unsigned char* dec_px = &decoded[(y * w + x) * 4];
      EXPECT_EQ(dec_px[0], orig_px[0]);
      EXPECT_EQ(dec_px[1], orig_px[1]);
      EXPECT_EQ(dec_px[2], orig_px[2]);
    }
  }
}

TEST(PNGCodec, DecodeInterlacedBGRA) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeRGBAImage(w, h, false, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_BGRA,
                          &encoded,
                          PNG_INTERLACE_ADAM7));

  // decode, it should have the same size as the original
  std::vector<unsigned char> decoded;
  int outw, outh;
  ASSERT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_BGRA, &decoded,
                               &outw, &outh));
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(original.size(), decoded.size());

  // Images must be equal
  ASSERT_EQ(original, decoded);
}

// Not encoding an interlaced PNG from SkBitmap because we don't do it
// anywhere, and the ability to do that requires more code changes.
TEST(PNGCodec, DecodeInterlacedRGBtoSkBitmap) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeRGBImage(w, h, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_RGB,
                          &encoded,
                          PNG_INTERLACE_ADAM7));

  // Decode the encoded string.
  SkBitmap decoded_bitmap;
  ASSERT_TRUE(PNGCodec::Decode(&encoded.front(), encoded.size(),
                               &decoded_bitmap));

  for (int x = 0; x < w; x++) {
    for (int y = 0; y < h; y++) {
      const unsigned char* original_pixel = &original[(y * w + x) * 3];
      const uint32_t original_pixel_sk = SkPackARGB32(0xFF,
                                                      original_pixel[0],
                                                      original_pixel[1],
                                                      original_pixel[2]);
      const uint32_t decoded_pixel = decoded_bitmap.getAddr32(0, y)[x];
      EXPECT_EQ(original_pixel_sk, decoded_pixel);
    }
  }
}

TEST(PNGCodec, DecodeInterlacedRGBAtoSkBitmap) {
  const int w = 20, h = 20;

  // create an image with known values
  std::vector<unsigned char> original;
  MakeRGBAImage(w, h, false, &original);

  // encode
  std::vector<unsigned char> encoded;
  ASSERT_TRUE(EncodeImage(original,
                          w, h,
                          COLOR_TYPE_RGBA,
                          &encoded,
                          PNG_INTERLACE_ADAM7));

  // Decode the encoded string.
  SkBitmap decoded_bitmap;
  ASSERT_TRUE(PNGCodec::Decode(&encoded.front(), encoded.size(),
                               &decoded_bitmap));

  for (int x = 0; x < w; x++) {
    for (int y = 0; y < h; y++) {
      const unsigned char* original_pixel = &original[(y * w + x) * 4];
      const uint32_t original_pixel_sk = SkPackARGB32(original_pixel[3],
                                                      original_pixel[0],
                                                      original_pixel[1],
                                                      original_pixel[2]);
      const uint32_t decoded_pixel = decoded_bitmap.getAddr32(0, y)[x];
      EXPECT_EQ(original_pixel_sk, decoded_pixel);
    }
  }
}

// Test that corrupted data decompression causes failures.
TEST(PNGCodec, DecodeCorrupted) {
  int w = 20, h = 20;

  // Make some random data (an uncompressed image).
  std::vector<unsigned char> original;
  MakeRGBImage(w, h, &original);

  // It should fail when given non-JPEG compressed data.
  std::vector<unsigned char> output;
  int outw, outh;
  EXPECT_FALSE(PNGCodec::Decode(&original[0], original.size(),
                                PNGCodec::FORMAT_RGB, &output,
                                &outw, &outh));

  // Make some compressed data.
  std::vector<unsigned char> compressed;
  ASSERT_TRUE(PNGCodec::Encode(&original[0], PNGCodec::FORMAT_RGB,
                               Size(w, h), w * 3, false,
                               std::vector<PNGCodec::Comment>(),
                               &compressed));

  // Try decompressing a truncated version.
  EXPECT_FALSE(PNGCodec::Decode(&compressed[0], compressed.size() / 2,
                                PNGCodec::FORMAT_RGB, &output,
                                &outw, &outh));

  // Corrupt it and try decompressing that.
  for (int i = 10; i < 30; i++)
    compressed[i] = i;
  EXPECT_FALSE(PNGCodec::Decode(&compressed[0], compressed.size(),
                                PNGCodec::FORMAT_RGB, &output,
                                &outw, &outh));
}

TEST(PNGCodec, StripAddAlpha) {
  const int w = 20, h = 20;

  // These should be the same except one has a 0xff alpha channel.
  std::vector<unsigned char> original_rgb;
  MakeRGBImage(w, h, &original_rgb);
  std::vector<unsigned char> original_rgba;
  MakeRGBAImage(w, h, false, &original_rgba);

  // Encode RGBA data as RGB.
  std::vector<unsigned char> encoded;
  EXPECT_TRUE(PNGCodec::Encode(&original_rgba[0], PNGCodec::FORMAT_RGBA,
                               Size(w, h), w * 4, true,
                               std::vector<PNGCodec::Comment>(),
                               &encoded));

  // Decode the RGB to RGBA.
  std::vector<unsigned char> decoded;
  int outw, outh;
  EXPECT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGBA, &decoded,
                               &outw, &outh));

  // Decoded and reference should be the same (opaque alpha).
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(original_rgba.size(), decoded.size());
  ASSERT_EQ(original_rgba, decoded);

  // Encode RGBA to RGBA.
  EXPECT_TRUE(PNGCodec::Encode(&original_rgba[0], PNGCodec::FORMAT_RGBA,
                               Size(w, h), w * 4, false,
                               std::vector<PNGCodec::Comment>(),
                               &encoded));

  // Decode the RGBA to RGB.
  EXPECT_TRUE(PNGCodec::Decode(&encoded[0], encoded.size(),
                               PNGCodec::FORMAT_RGB, &decoded,
                               &outw, &outh));

  // It should be the same as our non-alpha-channel reference.
  ASSERT_EQ(w, outw);
  ASSERT_EQ(h, outh);
  ASSERT_EQ(original_rgb.size(), decoded.size());
  ASSERT_EQ(original_rgb, decoded);
}

TEST(PNGCodec, EncodeBGRASkBitmapStridePadded) {
  const int kWidth = 20;
  const int kHeight = 20;
  const int kPaddedWidth = 32;
  const int kBytesPerPixel = 4;
  const int kPaddedSize = kPaddedWidth * kHeight;
  const int kRowBytes = kPaddedWidth * kBytesPerPixel;

  SkImageInfo info = SkImageInfo::MakeN32Premul(kWidth, kHeight);
  SkBitmap original_bitmap;
  original_bitmap.setInfo(info, kRowBytes);
  original_bitmap.allocPixels();

  // Write data over the source bitmap.
  // We write on the pad area here too.
  // The encoder should ignore the pad area.
  uint32_t* src_data = original_bitmap.getAddr32(0, 0);
  for (int i = 0; i < kPaddedSize; i++) {
    src_data[i] = SkPreMultiplyARGB(i % 255, i % 250, i % 245, i % 240);
  }

  // Encode the bitmap.
  std::vector<unsigned char> encoded;
  PNGCodec::EncodeBGRASkBitmap(original_bitmap, false, &encoded);

  // Decode the encoded string.
  SkBitmap decoded_bitmap;
  EXPECT_TRUE(PNGCodec::Decode(&encoded.front(), encoded.size(),
                               &decoded_bitmap));

  // Compare the original bitmap and the output bitmap. We use ColorsClose
  // as SkBitmaps are considered to be pre-multiplied, the unpremultiplication
  // (in Encode) and repremultiplication (in Decode) can be lossy.
  for (int x = 0; x < kWidth; x++) {
    for (int y = 0; y < kHeight; y++) {
      uint32_t original_pixel = original_bitmap.getAddr32(0, y)[x];
      uint32_t decoded_pixel = decoded_bitmap.getAddr32(0, y)[x];
      EXPECT_TRUE(ColorsClose(original_pixel, decoded_pixel));
    }
  }
}

TEST(PNGCodec, EncodeBGRASkBitmap) {
  const int w = 20, h = 20;

  SkBitmap original_bitmap;
  MakeTestBGRASkBitmap(w, h, &original_bitmap);

  // Encode the bitmap.
  std::vector<unsigned char> encoded;
  PNGCodec::EncodeBGRASkBitmap(original_bitmap, false, &encoded);

  // Decode the encoded string.
  SkBitmap decoded_bitmap;
  EXPECT_TRUE(PNGCodec::Decode(&encoded.front(), encoded.size(),
                               &decoded_bitmap));

  // Compare the original bitmap and the output bitmap. We use ColorsClose
  // as SkBitmaps are considered to be pre-multiplied, the unpremultiplication
  // (in Encode) and repremultiplication (in Decode) can be lossy.
  for (int x = 0; x < w; x++) {
    for (int y = 0; y < h; y++) {
      uint32_t original_pixel = original_bitmap.getAddr32(0, y)[x];
      uint32_t decoded_pixel = decoded_bitmap.getAddr32(0, y)[x];
      EXPECT_TRUE(ColorsClose(original_pixel, decoded_pixel));
    }
  }
}

TEST(PNGCodec, EncodeA8SkBitmap) {
  const int w = 20, h = 20;

  SkBitmap original_bitmap;
  MakeTestA8SkBitmap(w, h, &original_bitmap);

  // Encode the bitmap.
  std::vector<unsigned char> encoded;
  EXPECT_TRUE(PNGCodec::EncodeA8SkBitmap(original_bitmap, &encoded));

  // Decode the encoded string.
  SkBitmap decoded_bitmap;
  EXPECT_TRUE(PNGCodec::Decode(&encoded.front(), encoded.size(),
                               &decoded_bitmap));

  for (int x = 0; x < w; x++) {
    for (int y = 0; y < h; y++) {
      uint8_t original_pixel = *original_bitmap.getAddr8(x, y);
      uint32_t decoded_pixel = *decoded_bitmap.getAddr32(x, y);
      EXPECT_TRUE(BGRAGrayEqualsA8Gray(decoded_pixel, original_pixel));
    }
  }
}

TEST(PNGCodec, EncodeBGRASkBitmapDiscardTransparency) {
  const int w = 20, h = 20;

  SkBitmap original_bitmap;
  MakeTestBGRASkBitmap(w, h, &original_bitmap);

  // Encode the bitmap.
  std::vector<unsigned char> encoded;
  PNGCodec::EncodeBGRASkBitmap(original_bitmap, true, &encoded);

  // Decode the encoded string.
  SkBitmap decoded_bitmap;
  EXPECT_TRUE(PNGCodec::Decode(&encoded.front(), encoded.size(),
                               &decoded_bitmap));

  // Compare the original bitmap and the output bitmap. We need to
  // unpremultiply original_pixel, as the decoded bitmap doesn't have an alpha
  // channel.
  for (int x = 0; x < w; x++) {
    for (int y = 0; y < h; y++) {
      uint32_t original_pixel = original_bitmap.getAddr32(0, y)[x];
      uint32_t unpremultiplied =
          SkUnPreMultiply::PMColorToColor(original_pixel);
      uint32_t decoded_pixel = decoded_bitmap.getAddr32(0, y)[x];
      uint32_t unpremultiplied_decoded =
          SkUnPreMultiply::PMColorToColor(decoded_pixel);

      EXPECT_TRUE(NonAlphaColorsClose(unpremultiplied, unpremultiplied_decoded))
          << "Original_pixel: ("
          << SkColorGetR(unpremultiplied) << ", "
          << SkColorGetG(unpremultiplied) << ", "
          << SkColorGetB(unpremultiplied) << "), "
          << "Decoded pixel: ("
          << SkColorGetR(unpremultiplied_decoded) << ", "
          << SkColorGetG(unpremultiplied_decoded) << ", "
          << SkColorGetB(unpremultiplied_decoded) << ")";
    }
  }
}

TEST(PNGCodec, EncodeWithComment) {
  const int w = 10, h = 10;

  std::vector<unsigned char> original;
  MakeRGBImage(w, h, &original);

  std::vector<unsigned char> encoded;
  std::vector<PNGCodec::Comment> comments;
  comments.push_back(PNGCodec::Comment("key", "text"));
  comments.push_back(PNGCodec::Comment("test", "something"));
  comments.push_back(PNGCodec::Comment("have some", "spaces in both"));
  EXPECT_TRUE(PNGCodec::Encode(&original[0], PNGCodec::FORMAT_RGB,
                               Size(w, h), w * 3, false, comments, &encoded));

  // Each chunk is of the form length (4 bytes), chunk type (tEXt), data,
  // checksum (4 bytes).  Make sure we find all of them in the encoded
  // results.
  const unsigned char kExpected1[] =
      "\x00\x00\x00\x08tEXtkey\x00text\x9e\xe7\x66\x51";
  const unsigned char kExpected2[] =
      "\x00\x00\x00\x0etEXttest\x00something\x29\xba\xef\xac";
  const unsigned char kExpected3[] =
      "\x00\x00\x00\x18tEXthave some\x00spaces in both\x8d\x69\x34\x2d";

  EXPECT_NE(std::search(encoded.begin(), encoded.end(), kExpected1,
                        kExpected1 + arraysize(kExpected1)),
            encoded.end());
  EXPECT_NE(std::search(encoded.begin(), encoded.end(), kExpected2,
                        kExpected2 + arraysize(kExpected2)),
            encoded.end());
  EXPECT_NE(std::search(encoded.begin(), encoded.end(), kExpected3,
                        kExpected3 + arraysize(kExpected3)),
            encoded.end());
}

TEST(PNGCodec, EncodeDecodeWithVaryingCompressionLevels) {
  const int w = 20, h = 20;

  // create an image with known values, a must be opaque because it will be
  // lost during encoding
  SkBitmap original_bitmap;
  MakeTestBGRASkBitmap(w, h, &original_bitmap);

  // encode
  std::vector<unsigned char> encoded_normal;
  EXPECT_TRUE(
      PNGCodec::EncodeBGRASkBitmap(original_bitmap, false, &encoded_normal));

  std::vector<unsigned char> encoded_fast;
  EXPECT_TRUE(
      PNGCodec::FastEncodeBGRASkBitmap(original_bitmap, false, &encoded_fast));

  // Make sure the different compression settings actually do something; the
  // sizes should be different.
  EXPECT_NE(encoded_normal.size(), encoded_fast.size());

  // decode, they should be identical to the original.
  SkBitmap decoded;
  EXPECT_TRUE(
      PNGCodec::Decode(&encoded_normal[0], encoded_normal.size(), &decoded));
  EXPECT_TRUE(BitmapsAreEqual(decoded, original_bitmap));

  EXPECT_TRUE(
      PNGCodec::Decode(&encoded_fast[0], encoded_fast.size(), &decoded));
  EXPECT_TRUE(BitmapsAreEqual(decoded, original_bitmap));
}


}  // namespace gfx