path: root/image/test/gtest/TestSurfaceSink.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "gtest/gtest.h"

#include "mozilla/gfx/2D.h"
#include "Common.h"
#include "Decoder.h"
#include "DecoderFactory.h"
#include "SourceBuffer.h"
#include "SurfacePipe.h"

using namespace mozilla;
using namespace mozilla::gfx;
using namespace mozilla::image;

enum class Orient
{
  NORMAL,
  FLIP_VERTICALLY
};

template <Orient Orientation, typename Func> void
WithSurfaceSink(Func aFunc)
{
  RefPtr<Decoder> decoder = CreateTrivialDecoder();
  ASSERT_TRUE(decoder != nullptr);

  const bool flipVertically = Orientation == Orient::FLIP_VERTICALLY;

  WithFilterPipeline(decoder, Forward<Func>(aFunc),
                     SurfaceConfig { decoder, 0, IntSize(100, 100),
                                     SurfaceFormat::B8G8R8A8, flipVertically });
}

template <typename Func> void
WithPalettedSurfaceSink(const IntRect& aFrameRect, Func aFunc)
{
  RefPtr<Decoder> decoder = CreateTrivialDecoder();
  ASSERT_TRUE(decoder != nullptr);

  WithFilterPipeline(decoder, Forward<Func>(aFunc),
                     PalettedSurfaceConfig { decoder, 0, IntSize(100, 100),
                                             aFrameRect, SurfaceFormat::B8G8R8A8,
                                             8, false });
}

void
ResetForNextPass(SurfaceFilter* aSink)
{
  aSink->ResetToFirstRow();
  EXPECT_FALSE(aSink->IsSurfaceFinished());
  Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
  EXPECT_TRUE(invalidRect.isNothing());
}

template <typename WriteFunc, typename CheckFunc> void
DoCheckIterativeWrite(SurfaceFilter* aSink,
                      WriteFunc aWriteFunc,
                      CheckFunc aCheckFunc)
{
  // Write the buffer to successive rows until every row of the surface
  // has been written.
  uint32_t row = 0;
  WriteState result = WriteState::NEED_MORE_DATA;
  while (result == WriteState::NEED_MORE_DATA) {
    result = aWriteFunc(row);
    ++row;
  }
  EXPECT_EQ(WriteState::FINISHED, result);
  EXPECT_EQ(100u, row);

  AssertCorrectPipelineFinalState(aSink,
                                  IntRect(0, 0, 100, 100),
                                  IntRect(0, 0, 100, 100));

  // Check that the generated image is correct.
  aCheckFunc();
}

template <typename WriteFunc> void
CheckIterativeWrite(Decoder* aDecoder,
                    SurfaceSink* aSink,
                    const IntRect& aOutputRect,
                    WriteFunc aWriteFunc)
{
  // Ignore the row passed to WriteFunc, since no callers use it.
  auto writeFunc = [&](uint32_t) {
    return aWriteFunc();
  };

  DoCheckIterativeWrite(aSink, writeFunc, [&]{
    CheckGeneratedImage(aDecoder, aOutputRect);
  });
}

template <typename WriteFunc> void
CheckPalettedIterativeWrite(Decoder* aDecoder,
                            PalettedSurfaceSink* aSink,
                            const IntRect& aOutputRect,
                            WriteFunc aWriteFunc)
{
  // Ignore the row passed to WriteFunc, since no callers use it.
  auto writeFunc = [&](uint32_t) {
    return aWriteFunc();
  };

  DoCheckIterativeWrite(aSink, writeFunc, [&]{
    CheckGeneratedPalettedImage(aDecoder, aOutputRect);
  });
}

TEST(ImageSurfaceSink, NullSurfaceSink)
{
  // Create the NullSurfaceSink.
  NullSurfaceSink sink;
  nsresult rv = sink.Configure(NullSurfaceConfig { });
  ASSERT_TRUE(NS_SUCCEEDED(rv));
  EXPECT_TRUE(!sink.IsValidPalettedPipe());

  // Ensure that we can't write anything.
  bool gotCalled = false;
  auto result = sink.WritePixels<uint32_t>([&]() {
    gotCalled = true;
    return AsVariant(BGRAColor::Green().AsPixel());
  });
  EXPECT_FALSE(gotCalled);
  EXPECT_EQ(WriteState::FINISHED, result);
  EXPECT_TRUE(sink.IsSurfaceFinished());
  Maybe<SurfaceInvalidRect> invalidRect = sink.TakeInvalidRect();
  EXPECT_TRUE(invalidRect.isNothing());

  uint32_t source = BGRAColor::Red().AsPixel();
  result = sink.WriteBuffer(&source);
  EXPECT_EQ(WriteState::FINISHED, result);
  EXPECT_TRUE(sink.IsSurfaceFinished());
  invalidRect = sink.TakeInvalidRect();
  EXPECT_TRUE(invalidRect.isNothing());

  result = sink.WriteBuffer(&source, 0, 1);
  EXPECT_EQ(WriteState::FINISHED, result);
  EXPECT_TRUE(sink.IsSurfaceFinished());
  invalidRect = sink.TakeInvalidRect();
  EXPECT_TRUE(invalidRect.isNothing());

  result = sink.WriteEmptyRow();
  EXPECT_EQ(WriteState::FINISHED, result);
  EXPECT_TRUE(sink.IsSurfaceFinished());
  invalidRect = sink.TakeInvalidRect();
  EXPECT_TRUE(invalidRect.isNothing());

  result = sink.WriteUnsafeComputedRow<uint32_t>([&](uint32_t* aRow,
                                                     uint32_t aLength) {
    gotCalled = true;
    for (uint32_t col = 0; col < aLength; ++col, ++aRow) {
      *aRow = BGRAColor::Red().AsPixel();
    }
  });
  EXPECT_FALSE(gotCalled);
  EXPECT_EQ(WriteState::FINISHED, result);
  EXPECT_TRUE(sink.IsSurfaceFinished());
  invalidRect = sink.TakeInvalidRect();
  EXPECT_TRUE(invalidRect.isNothing());

  // Attempt to advance to the next row and make sure nothing changes.
  sink.AdvanceRow();
  EXPECT_TRUE(sink.IsSurfaceFinished());
  invalidRect = sink.TakeInvalidRect();
  EXPECT_TRUE(invalidRect.isNothing());

  // Attempt to advance to the next pass and make sure nothing changes.
  sink.ResetToFirstRow();
  EXPECT_TRUE(sink.IsSurfaceFinished());
  invalidRect = sink.TakeInvalidRect();
  EXPECT_TRUE(invalidRect.isNothing());
}

TEST(ImageSurfaceSink, SurfaceSinkInitialization)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    // Check initial state.
    EXPECT_FALSE(aSink->IsSurfaceFinished());
    Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
    EXPECT_TRUE(invalidRect.isNothing());

    // Check that the surface is zero-initialized. We verify this by calling
    // CheckGeneratedImage() and telling it that we didn't write to the surface
    // anyway (i.e., we wrote to the empty rect); it will then expect the entire
    // surface to be transparent, which is what it should be if it was
    // zero-initialied.
    CheckGeneratedImage(aDecoder, IntRect(0, 0, 0, 0));
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWritePixels)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    CheckWritePixels(aDecoder, aSink);
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWritePixelsFinish)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    // Write nothing into the surface; just finish immediately.
    uint32_t count = 0;
    auto result = aSink->WritePixels<uint32_t>([&]() {
      count++;
      return AsVariant(WriteState::FINISHED);
    });
    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(1u, count);

    AssertCorrectPipelineFinalState(aSink,
                                    IntRect(0, 0, 100, 100),
                                    IntRect(0, 0, 100, 100));

    // Attempt to write more and make sure that nothing gets written.
    count = 0;
    result = aSink->WritePixels<uint32_t>([&]() {
      count++;
      return AsVariant(BGRAColor::Red().AsPixel());
    });
    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(0u, count);
    EXPECT_TRUE(aSink->IsSurfaceFinished());

    // Check that the generated image is correct.
    RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
    RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();
    EXPECT_TRUE(IsSolidColor(surface, BGRAColor::Transparent()));
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWritePixelsEarlyExit)
{
  auto checkEarlyExit =
    [](Decoder* aDecoder, SurfaceSink* aSink, WriteState aState) {
    // Write half a row of green pixels and then exit early with |aState|. If
    // the lambda keeps getting called, we'll write red pixels, which will cause
    // the test to fail.
    uint32_t count = 0;
    auto result = aSink->WritePixels<uint32_t>([&]() -> NextPixel<uint32_t> {
      if (count == 50) {
        return AsVariant(aState);
      }
      return count++ < 50 ? AsVariant(BGRAColor::Green().AsPixel())
                          : AsVariant(BGRAColor::Red().AsPixel());
    });

    EXPECT_EQ(aState, result);
    EXPECT_EQ(50u, count);
    CheckGeneratedImage(aDecoder, IntRect(0, 0, 50, 1));

    if (aState != WriteState::FINISHED) {
      // We should still be able to write more at this point.
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Verify that we can resume writing. We'll finish up the same row.
      count = 0;
      result = aSink->WritePixels<uint32_t>([&]() -> NextPixel<uint32_t> {
        if (count == 50) {
          return AsVariant(WriteState::NEED_MORE_DATA);
        }
        ++count;
        return AsVariant(BGRAColor::Green().AsPixel());
      });

      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(50u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());
      CheckGeneratedImage(aDecoder, IntRect(0, 0, 100, 1));

      return;
    }

    // We should've finished the surface at this point.
    AssertCorrectPipelineFinalState(aSink,
                                    IntRect(0, 0, 100, 100),
                                    IntRect(0, 0, 100, 100));

    // Attempt to write more and make sure that nothing gets written.
    count = 0;
    result = aSink->WritePixels<uint32_t>([&]{
      count++;
      return AsVariant(BGRAColor::Red().AsPixel());
    });

    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(0u, count);
    EXPECT_TRUE(aSink->IsSurfaceFinished());

    // Check that the generated image is still correct.
    CheckGeneratedImage(aDecoder, IntRect(0, 0, 50, 1));
  };

  WithSurfaceSink<Orient::NORMAL>([&](Decoder* aDecoder, SurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::NEED_MORE_DATA);
  });

  WithSurfaceSink<Orient::NORMAL>([&](Decoder* aDecoder, SurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::FAILURE);
  });

  WithSurfaceSink<Orient::NORMAL>([&](Decoder* aDecoder, SurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::FINISHED);
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWritePixelsToRow)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    // Write the first 99 rows of our 100x100 surface and verify that even
    // though our lambda will yield pixels forever, only one row is written per
    // call to WritePixelsToRow().
    for (int row = 0; row < 99; ++row) {
      uint32_t count = 0;
      WriteState result = aSink->WritePixelsToRow<uint32_t>([&]{
        ++count;
        return AsVariant(BGRAColor::Green().AsPixel());
      });

      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(100u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
      EXPECT_TRUE(invalidRect.isSome());
      EXPECT_EQ(IntRect(0, row, 100, 1), invalidRect->mInputSpaceRect);
      EXPECT_EQ(IntRect(0, row, 100, 1), invalidRect->mOutputSpaceRect);

      CheckGeneratedImage(aDecoder, IntRect(0, 0, 100, row + 1));
    }

    // Write the final line, which should finish the surface.
    uint32_t count = 0;
    WriteState result = aSink->WritePixelsToRow<uint32_t>([&]{
      ++count;
      return AsVariant(BGRAColor::Green().AsPixel());
    });

    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(100u, count);

    // Note that the final invalid rect we expect here is only the last row;
    // that's because we called TakeInvalidRect() repeatedly in the loop above.
    AssertCorrectPipelineFinalState(aSink,
                                    IntRect(0, 99, 100, 1),
                                    IntRect(0, 99, 100, 1));

    // Check that the generated image is correct.
    CheckGeneratedImage(aDecoder, IntRect(0, 0, 100, 100));

    // Attempt to write more and make sure that nothing gets written.
    count = 0;
    result = aSink->WritePixelsToRow<uint32_t>([&]{
      count++;
      return AsVariant(BGRAColor::Red().AsPixel());
    });

    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(0u, count);
    EXPECT_TRUE(aSink->IsSurfaceFinished());

    // Check that the generated image is still correct.
    CheckGeneratedImage(aDecoder, IntRect(0, 0, 100, 100));
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWritePixelsToRowEarlyExit)
{
  auto checkEarlyExit =
    [](Decoder* aDecoder, SurfaceSink* aSink, WriteState aState) {
    // Write half a row of green pixels and then exit early with |aState|. If
    // the lambda keeps getting called, we'll write red pixels, which will cause
    // the test to fail.
    uint32_t count = 0;
    auto result = aSink->WritePixelsToRow<uint32_t>([&]() -> NextPixel<uint32_t> {
      if (count == 50) {
        return AsVariant(aState);
      }
      return count++ < 50 ? AsVariant(BGRAColor::Green().AsPixel())
                          : AsVariant(BGRAColor::Red().AsPixel());
    });

    EXPECT_EQ(aState, result);
    EXPECT_EQ(50u, count);
    CheckGeneratedImage(aDecoder, IntRect(0, 0, 50, 1));

    if (aState != WriteState::FINISHED) {
      // We should still be able to write more at this point.
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Verify that we can resume the same row and still stop at the end.
      count = 0;
      WriteState result = aSink->WritePixelsToRow<uint32_t>([&]{
        ++count;
        return AsVariant(BGRAColor::Green().AsPixel());
      });

      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(50u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());
      CheckGeneratedImage(aDecoder, IntRect(0, 0, 100, 1));

      return;
    }

    // We should've finished the surface at this point.
    AssertCorrectPipelineFinalState(aSink,
                                    IntRect(0, 0, 100, 100),
                                    IntRect(0, 0, 100, 100));

    // Attempt to write more and make sure that nothing gets written.
    count = 0;
    result = aSink->WritePixelsToRow<uint32_t>([&]{
      count++;
      return AsVariant(BGRAColor::Red().AsPixel());
    });

    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(0u, count);
    EXPECT_TRUE(aSink->IsSurfaceFinished());

    // Check that the generated image is still correct.
    CheckGeneratedImage(aDecoder, IntRect(0, 0, 50, 1));
  };

  WithSurfaceSink<Orient::NORMAL>([&](Decoder* aDecoder, SurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::NEED_MORE_DATA);
  });

  WithSurfaceSink<Orient::NORMAL>([&](Decoder* aDecoder, SurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::FAILURE);
  });

  WithSurfaceSink<Orient::NORMAL>([&](Decoder* aDecoder, SurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::FINISHED);
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWriteBuffer)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    // Create a green buffer the same size as one row of the surface (which is 100x100),
    // containing 60 pixels of green in the middle and 20 transparent pixels on
    // either side.
    uint32_t buffer[100];
    for (int i = 0; i < 100; ++i) {
      buffer[i] = 20 <= i && i < 80 ? BGRAColor::Green().AsPixel()
                                    : BGRAColor::Transparent().AsPixel();
    }

    // Write the buffer to every row of the surface and check that the generated
    // image is correct.
    CheckIterativeWrite(aDecoder, aSink, IntRect(20, 0, 60, 100), [&]{
      return aSink->WriteBuffer(buffer);
    });
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWriteBufferPartialRow)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    // Create a buffer the same size as one row of the surface, containing all
    // green pixels.
    uint32_t buffer[100];
    for (int i = 0; i < 100; ++i) {
      buffer[i] = BGRAColor::Green().AsPixel();
    }

    // Write the buffer to the middle 60 pixels of every row of the surface and
    // check that the generated image is correct.
    CheckIterativeWrite(aDecoder, aSink, IntRect(20, 0, 60, 100), [&]{
      return aSink->WriteBuffer(buffer, 20, 60);
    });
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWriteBufferPartialRowStartColOverflow)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    // Create a buffer the same size as one row of the surface, containing all
    // green pixels.
    uint32_t buffer[100];
    for (int i = 0; i < 100; ++i) {
      buffer[i] = BGRAColor::Green().AsPixel();
    }

    {
      // Write the buffer to successive rows until every row of the surface
      // has been written. We place the start column beyond the end of the row,
      // which will prevent us from writing anything, so we check that the
      // generated image is entirely transparent.
      CheckIterativeWrite(aDecoder, aSink, IntRect(0, 0, 0, 0), [&]{
        return aSink->WriteBuffer(buffer, 100, 100);
      });
    }

    ResetForNextPass(aSink);

    {
      // Write the buffer to successive rows until every row of the surface
      // has been written. We use column 50 as the start column, but we still
      // write the buffer, which means we overflow the right edge of the surface
      // by 50 pixels. We check that the left half of the generated image is
      // transparent and the right half is green.
      CheckIterativeWrite(aDecoder, aSink, IntRect(50, 0, 50, 100), [&]{
        return aSink->WriteBuffer(buffer, 50, 100);
      });
    }
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWriteBufferPartialRowBufferOverflow)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    // Create a buffer twice as large as a row of the surface. The first half
    // (which is as large as a row of the image) will contain green pixels,
    // while the second half will contain red pixels.
    uint32_t buffer[200];
    for (int i = 0; i < 200; ++i) {
      buffer[i] = i < 100 ? BGRAColor::Green().AsPixel()
                          : BGRAColor::Red().AsPixel();
    }

    {
      // Write the buffer to successive rows until every row of the surface has
      // been written. The buffer extends 100 pixels to the right of a row of
      // the surface, but bounds checking will prevent us from overflowing the
      // buffer. We check that the generated image is entirely green since the
      // pixels on the right side of the buffer shouldn't have been written to
      // the surface.
      CheckIterativeWrite(aDecoder, aSink, IntRect(0, 0, 100, 100), [&]{
        return aSink->WriteBuffer(buffer, 0, 200);
      });
    }

    ResetForNextPass(aSink);

    {
      // Write from the buffer to the middle of each row of the surface. That
      // means that the left side of each row should be transparent, since we
      // didn't write anything there. A buffer overflow would cause us to write
      // buffer contents into the left side of each row. We check that the
      // generated image is transparent on the left side and green on the right.
      CheckIterativeWrite(aDecoder, aSink, IntRect(50, 0, 50, 100), [&]{
        return aSink->WriteBuffer(buffer, 50, 200);
      });
    }
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWriteBufferFromNullSource)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    // Calling WriteBuffer() with a null pointer should fail without making any
    // changes to the surface.
    uint32_t* nullBuffer = nullptr;
    WriteState result = aSink->WriteBuffer(nullBuffer);

    EXPECT_EQ(WriteState::FAILURE, result);
    EXPECT_FALSE(aSink->IsSurfaceFinished());
    Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
    EXPECT_TRUE(invalidRect.isNothing());

    // Check that nothing got written to the surface.
    CheckGeneratedImage(aDecoder, IntRect(0, 0, 0, 0));
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWriteEmptyRow)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    {
      // Write an empty row to each row of the surface. We check that the
      // generated image is entirely transparent.
      CheckIterativeWrite(aDecoder, aSink, IntRect(0, 0, 0, 0), [&]{
        return aSink->WriteEmptyRow();
      });
    }

    ResetForNextPass(aSink);

    {
      // Write a partial row before we begin calling WriteEmptyRow(). We check
      // that the generated image is entirely transparent, which is to be
      // expected since WriteEmptyRow() overwrites the current row even if some
      // data has already been written to it.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() -> NextPixel<uint32_t> {
        if (count == 50) {
          return AsVariant(WriteState::NEED_MORE_DATA);
        }
        ++count;
        return AsVariant(BGRAColor::Green().AsPixel());
      });

      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(50u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      CheckIterativeWrite(aDecoder, aSink, IntRect(0, 0, 0, 0), [&]{
        return aSink->WriteEmptyRow();
      });
    }

    ResetForNextPass(aSink);

    {
      // Create a buffer the same size as one row of the surface, containing all
      // green pixels.
      uint32_t buffer[100];
      for (int i = 0; i < 100; ++i) {
        buffer[i] = BGRAColor::Green().AsPixel();
      }

      // Write an empty row to the middle 60 rows of the surface. The first 20
      // and last 20 rows will be green. (We need to use DoCheckIterativeWrite()
      // here because we need a custom function to check the output, since it
      // can't be described by a simple rect.)
      auto writeFunc = [&](uint32_t aRow) {
        if (aRow < 20 || aRow >= 80) {
          return aSink->WriteBuffer(buffer);
        } else {
          return aSink->WriteEmptyRow();
        }
      };

      auto checkFunc = [&]{
        RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
        RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();

        EXPECT_TRUE(RowsAreSolidColor(surface, 0, 20, BGRAColor::Green()));
        EXPECT_TRUE(RowsAreSolidColor(surface, 20, 60, BGRAColor::Transparent()));
        EXPECT_TRUE(RowsAreSolidColor(surface, 80, 20, BGRAColor::Green()));
      };

      DoCheckIterativeWrite(aSink, writeFunc, checkFunc);
    }
  });
}

TEST(ImageSurfaceSink, SurfaceSinkWriteUnsafeComputedRow)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    // Create a green buffer the same size as one row of the surface.
    uint32_t buffer[100];
    for (int i = 0; i < 100; ++i) {
      buffer[i] = BGRAColor::Green().AsPixel();
    }

    // Write the buffer to successive rows until every row of the surface
    // has been written. We only write to the right half of each row, so we
    // check that the left side of the generated image is transparent and the
    // right side is green.
    CheckIterativeWrite(aDecoder, aSink, IntRect(50, 0, 50, 100), [&]{
      return aSink->WriteUnsafeComputedRow<uint32_t>([&](uint32_t* aRow,
                                                         uint32_t aLength) {
        EXPECT_EQ(100u, aLength );
        memcpy(aRow + 50, buffer, 50 * sizeof(uint32_t));
      });
    });
  });
}

TEST(ImageSurfaceSink, SurfaceSinkProgressivePasses)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    {
      // Fill the image with a first pass of red.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() {
        ++count;
        return AsVariant(BGRAColor::Red().AsPixel());
      });
      EXPECT_EQ(WriteState::FINISHED, result);
      EXPECT_EQ(100u * 100u, count);

      AssertCorrectPipelineFinalState(aSink,
                                      IntRect(0, 0, 100, 100),
                                      IntRect(0, 0, 100, 100));

      // Check that the generated image is correct.
      RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
      RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();
      EXPECT_TRUE(IsSolidColor(surface, BGRAColor::Red()));
    }

    {
      ResetForNextPass(aSink);

      // Check that the generated image is still the first pass image.
      RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
      RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();
      EXPECT_TRUE(IsSolidColor(surface, BGRAColor::Red()));
    }

    {
      // Fill the image with a second pass of green.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() {
        ++count;
        return AsVariant(BGRAColor::Green().AsPixel());
      });
      EXPECT_EQ(WriteState::FINISHED, result);
      EXPECT_EQ(100u * 100u, count);

      AssertCorrectPipelineFinalState(aSink,
                                      IntRect(0, 0, 100, 100),
                                      IntRect(0, 0, 100, 100));

      // Check that the generated image is correct.
      RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
      RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();
      EXPECT_TRUE(IsSolidColor(surface, BGRAColor::Green()));
    }
  });
}

TEST(ImageSurfaceSink, SurfaceSinkInvalidRect)
{
  WithSurfaceSink<Orient::NORMAL>([](Decoder* aDecoder, SurfaceSink* aSink) {
    {
      // Write one row.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() -> NextPixel<uint32_t> {
        if (count == 100) {
          return AsVariant(WriteState::NEED_MORE_DATA);
        }
        count++;
        return AsVariant(BGRAColor::Green().AsPixel());
      });
      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(100u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Assert that we have the right invalid rect.
      Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
      EXPECT_TRUE(invalidRect.isSome());
      EXPECT_EQ(IntRect(0, 0, 100, 1), invalidRect->mInputSpaceRect);
      EXPECT_EQ(IntRect(0, 0, 100, 1), invalidRect->mOutputSpaceRect);
    }

    {
      // Write eight rows.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() -> NextPixel<uint32_t> {
        if (count == 100 * 8) {
          return AsVariant(WriteState::NEED_MORE_DATA);
        }
        count++;
        return AsVariant(BGRAColor::Green().AsPixel());
      });
      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(100u * 8u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Assert that we have the right invalid rect.
      Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
      EXPECT_TRUE(invalidRect.isSome());
      EXPECT_EQ(IntRect(0, 1, 100, 8), invalidRect->mInputSpaceRect);
      EXPECT_EQ(IntRect(0, 1, 100, 8), invalidRect->mOutputSpaceRect);
    }

    {
      // Write the left half of one row.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() -> NextPixel<uint32_t> {
        if (count == 50) {
          return AsVariant(WriteState::NEED_MORE_DATA);
        }
        count++;
        return AsVariant(BGRAColor::Green().AsPixel());
      });
      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(50u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Assert that we don't have an invalid rect, since the invalid rect only
      // gets updated when a row gets completed.
      Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
      EXPECT_TRUE(invalidRect.isNothing());
    }

    {
      // Write the right half of the same row.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() -> NextPixel<uint32_t> {
        if (count == 50) {
          return AsVariant(WriteState::NEED_MORE_DATA);
        }
        count++;
        return AsVariant(BGRAColor::Green().AsPixel());
      });
      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(50u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Assert that we have the right invalid rect, which will include both the
      // left and right halves of this row now that we've completed it.
      Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
      EXPECT_TRUE(invalidRect.isSome());
      EXPECT_EQ(IntRect(0, 9, 100, 1), invalidRect->mInputSpaceRect);
      EXPECT_EQ(IntRect(0, 9, 100, 1), invalidRect->mOutputSpaceRect);
    }

    {
      // Write no rows.
      auto result = aSink->WritePixels<uint32_t>([&]() {
        return AsVariant(WriteState::NEED_MORE_DATA);
      });
      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Assert that we don't have an invalid rect.
      Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
      EXPECT_TRUE(invalidRect.isNothing());
    }

    {
      // Fill the rest of the image.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() {
        count++;
        return AsVariant(BGRAColor::Green().AsPixel());
      });
      EXPECT_EQ(WriteState::FINISHED, result);
      EXPECT_EQ(100u * 90u, count);
      EXPECT_TRUE(aSink->IsSurfaceFinished());

      // Assert that we have the right invalid rect.
      Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
      EXPECT_TRUE(invalidRect.isSome());
      EXPECT_EQ(IntRect(0, 10, 100, 90), invalidRect->mInputSpaceRect);
      EXPECT_EQ(IntRect(0, 10, 100, 90), invalidRect->mOutputSpaceRect);

      // Check that the generated image is correct.
      RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
      RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();
      EXPECT_TRUE(IsSolidColor(surface, BGRAColor::Green()));
    }
  });
}

TEST(ImageSurfaceSink, SurfaceSinkFlipVertically)
{
  WithSurfaceSink<Orient::FLIP_VERTICALLY>([](Decoder* aDecoder,
                                              SurfaceSink* aSink) {
    {
      // Fill the image with a first pass of red.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() {
        ++count;
        return AsVariant(BGRAColor::Red().AsPixel());
      });
      EXPECT_EQ(WriteState::FINISHED, result);
      EXPECT_EQ(100u * 100u, count);

      AssertCorrectPipelineFinalState(aSink,
                                      IntRect(0, 0, 100, 100),
                                      IntRect(0, 0, 100, 100));

      // Check that the generated image is correct.
      RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
      RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();
      EXPECT_TRUE(IsSolidColor(surface, BGRAColor::Red()));
    }

    {
      ResetForNextPass(aSink);

      // Check that the generated image is still the first pass image.
      RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
      RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();
      EXPECT_TRUE(IsSolidColor(surface, BGRAColor::Red()));
    }

    {
      // Fill 25 rows of the image with green and make sure everything is OK.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() -> NextPixel<uint32_t> {
        if (count == 25 * 100) {
          return AsVariant(WriteState::NEED_MORE_DATA);
        }
        count++;
        return AsVariant(BGRAColor::Green().AsPixel());
      });
      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(25u * 100u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Assert that we have the right invalid rect, which should include the
      // *bottom* (since we're flipping vertically) 25 rows of the image.
      Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
      EXPECT_TRUE(invalidRect.isSome());
      EXPECT_EQ(IntRect(0, 75, 100, 25), invalidRect->mInputSpaceRect);
      EXPECT_EQ(IntRect(0, 75, 100, 25), invalidRect->mOutputSpaceRect);

      // Check that the generated image is correct.
      RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
      RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();
      EXPECT_TRUE(RowsAreSolidColor(surface, 0, 75, BGRAColor::Red()));
      EXPECT_TRUE(RowsAreSolidColor(surface, 75, 25, BGRAColor::Green()));
    }

    {
      // Fill the rest of the image with a second pass of green.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint32_t>([&]() {
        ++count;
        return AsVariant(BGRAColor::Green().AsPixel());
      });
      EXPECT_EQ(WriteState::FINISHED, result);
      EXPECT_EQ(75u * 100u, count);

      AssertCorrectPipelineFinalState(aSink,
                                      IntRect(0, 0, 100, 75),
                                      IntRect(0, 0, 100, 75));

      // Check that the generated image is correct.
      RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
      RefPtr<SourceSurface> surface = currentFrame->GetSourceSurface();
      EXPECT_TRUE(IsSolidColor(surface, BGRAColor::Green()));
    }
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkInitialization)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    // Check initial state.
    EXPECT_FALSE(aSink->IsSurfaceFinished());
    Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
    EXPECT_TRUE(invalidRect.isNothing());

    // Check that the paletted image data is zero-initialized.
    RawAccessFrameRef currentFrame = aDecoder->GetCurrentFrameRef();
    uint8_t* imageData = nullptr;
    uint32_t imageLength = 0;
    currentFrame->GetImageData(&imageData, &imageLength);
    ASSERT_TRUE(imageData != nullptr);
    ASSERT_EQ(100u * 100u, imageLength);
    for (uint32_t i = 0; i < imageLength; ++i) {
      ASSERT_EQ(uint8_t(0), imageData[i]);
    }
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsFor0_0_100_100)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    CheckPalettedWritePixels(aDecoder, aSink);
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsFor25_25_50_50)
{
  WithPalettedSurfaceSink(IntRect(25, 25, 50, 50),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    CheckPalettedWritePixels(aDecoder, aSink,
                             /* aOutputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputWriteRect = */ Some(IntRect(25, 25, 50, 50)),
                             /* aOutputWriteRect = */ Some(IntRect(25, 25, 50, 50)));
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsForMinus25_Minus25_50_50)
{
  WithPalettedSurfaceSink(IntRect(-25, -25, 50, 50),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    CheckPalettedWritePixels(aDecoder, aSink,
                             /* aOutputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputWriteRect = */ Some(IntRect(-25, -25, 50, 50)),
                             /* aOutputWriteRect = */ Some(IntRect(-25, -25, 50, 50)));
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsFor75_Minus25_50_50)
{
  WithPalettedSurfaceSink(IntRect(75, -25, 50, 50),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    CheckPalettedWritePixels(aDecoder, aSink,
                             /* aOutputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputWriteRect = */ Some(IntRect(75, -25, 50, 50)),
                             /* aOutputWriteRect = */ Some(IntRect(75, -25, 50, 50)));
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsForMinus25_75_50_50)
{
  WithPalettedSurfaceSink(IntRect(-25, 75, 50, 50),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    CheckPalettedWritePixels(aDecoder, aSink,
                             /* aOutputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputWriteRect = */ Some(IntRect(-25, 75, 50, 50)),
                             /* aOutputWriteRect = */ Some(IntRect(-25, 75, 50, 50)));
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsFor75_75_50_50)
{
  WithPalettedSurfaceSink(IntRect(75, 75, 50, 50),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    CheckPalettedWritePixels(aDecoder, aSink,
                             /* aOutputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputRect = */ Some(IntRect(0, 0, 50, 50)),
                             /* aInputWriteRect = */ Some(IntRect(75, 75, 50, 50)),
                             /* aOutputWriteRect = */ Some(IntRect(75, 75, 50, 50)));
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsFinish)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    // Write nothing into the surface; just finish immediately.
    uint32_t count = 0;
    auto result = aSink->WritePixels<uint8_t>([&]{
      count++;
      return AsVariant(WriteState::FINISHED);
    });
    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(1u, count);

    AssertCorrectPipelineFinalState(aSink,
                                    IntRect(0, 0, 100, 100),
                                    IntRect(0, 0, 100, 100));

    // Attempt to write more and make sure that nothing gets written.
    count = 0;
    result = aSink->WritePixels<uint8_t>([&]() {
      count++;
      return AsVariant(uint8_t(128));
    });
    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(0u, count);
    EXPECT_TRUE(aSink->IsSurfaceFinished());

    // Check that the generated image is correct.
    EXPECT_TRUE(IsSolidPalettedColor(aDecoder, 0));
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsEarlyExit)
{
  auto checkEarlyExit =
    [](Decoder* aDecoder, PalettedSurfaceSink* aSink, WriteState aState) {
    // Write half a row of green pixels and then exit early with |aState|. If
    // the lambda keeps getting called, we'll write red pixels, which will cause
    // the test to fail.
    uint32_t count = 0;
    auto result = aSink->WritePixels<uint8_t>([&]() -> NextPixel<uint8_t> {
      if (count == 50) {
        return AsVariant(aState);
      }
      return count++ < 50 ? AsVariant(uint8_t(255)) : AsVariant(uint8_t(128));
    });

    EXPECT_EQ(aState, result);
    EXPECT_EQ(50u, count);
    CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 50, 1));

    if (aState != WriteState::FINISHED) {
      // We should still be able to write more at this point.
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Verify that we can resume writing. We'll finish up the same row.
      count = 0;
      result = aSink->WritePixels<uint8_t>([&]() -> NextPixel<uint8_t> {
        if (count == 50) {
          return AsVariant(WriteState::NEED_MORE_DATA);
        }
        ++count;
        return AsVariant(uint8_t(255));
      });

      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(50u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());
      CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 100, 1));

      return;
    }

    // We should've finished the surface at this point.
    AssertCorrectPipelineFinalState(aSink,
                                    IntRect(0, 0, 100, 100),
                                    IntRect(0, 0, 100, 100));

    // Attempt to write more and make sure that nothing gets written.
    count = 0;
    result = aSink->WritePixels<uint8_t>([&]{
      count++;
      return AsVariant(uint8_t(128));
    });

    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(0u, count);
    EXPECT_TRUE(aSink->IsSurfaceFinished());

    // Check that the generated image is still correct.
    CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 50, 1));
  };

  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [&](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::NEED_MORE_DATA);
  });

  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [&](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::FAILURE);
  });

  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [&](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::FINISHED);
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsToRow)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    // Write the first 99 rows of our 100x100 surface and verify that even
    // though our lambda will yield pixels forever, only one row is written per
    // call to WritePixelsToRow().
    for (int row = 0; row < 99; ++row) {
      uint32_t count = 0;
      WriteState result = aSink->WritePixelsToRow<uint8_t>([&]{
        ++count;
        return AsVariant(uint8_t(255));
      });

      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(100u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
      EXPECT_TRUE(invalidRect.isSome());
      EXPECT_EQ(IntRect(0, row, 100, 1), invalidRect->mInputSpaceRect);
      EXPECT_EQ(IntRect(0, row, 100, 1), invalidRect->mOutputSpaceRect);

      CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 100, row + 1));
    }

    // Write the final line, which should finish the surface.
    uint32_t count = 0;
    WriteState result = aSink->WritePixelsToRow<uint8_t>([&]{
      ++count;
      return AsVariant(uint8_t(255));
    });

    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(100u, count);

    // Note that the final invalid rect we expect here is only the last row;
    // that's because we called TakeInvalidRect() repeatedly in the loop above.
    AssertCorrectPipelineFinalState(aSink,
                                    IntRect(0, 99, 100, 1),
                                    IntRect(0, 99, 100, 1));

    // Check that the generated image is correct.
    CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 100, 100));

    // Attempt to write more and make sure that nothing gets written.
    count = 0;
    result = aSink->WritePixelsToRow<uint8_t>([&]{
      count++;
      return AsVariant(uint8_t(128));
    });

    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(0u, count);
    EXPECT_TRUE(aSink->IsSurfaceFinished());

    // Check that the generated image is still correct.
    CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 100, 100));
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWritePixelsToRowEarlyExit)
{
  auto checkEarlyExit =
    [](Decoder* aDecoder, PalettedSurfaceSink* aSink, WriteState aState) {
    // Write half a row of 255s and then exit early with |aState|. If the lambda
    // keeps getting called, we'll write 128s, which will cause the test to
    // fail.
    uint32_t count = 0;
    auto result = aSink->WritePixelsToRow<uint8_t>([&]() -> NextPixel<uint8_t> {
      if (count == 50) {
        return AsVariant(aState);
      }
      return count++ < 50 ? AsVariant(uint8_t(255))
                          : AsVariant(uint8_t(128));
    });

    EXPECT_EQ(aState, result);
    EXPECT_EQ(50u, count);
    CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 50, 1));

    if (aState != WriteState::FINISHED) {
      // We should still be able to write more at this point.
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      // Verify that we can resume the same row and still stop at the end.
      count = 0;
      WriteState result = aSink->WritePixelsToRow<uint8_t>([&]{
        ++count;
        return AsVariant(uint8_t(255));
      });

      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(50u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());
      CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 100, 1));

      return;
    }

    // We should've finished the surface at this point.
    AssertCorrectPipelineFinalState(aSink,
                                    IntRect(0, 0, 100, 100),
                                    IntRect(0, 0, 100, 100));

    // Attempt to write more and make sure that nothing gets written.
    count = 0;
    result = aSink->WritePixelsToRow<uint8_t>([&]{
      count++;
      return AsVariant(uint8_t(128));
    });

    EXPECT_EQ(WriteState::FINISHED, result);
    EXPECT_EQ(0u, count);
    EXPECT_TRUE(aSink->IsSurfaceFinished());

    // Check that the generated image is still correct.
    CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 50, 1));
  };

  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [&](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::NEED_MORE_DATA);
  });

  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [&](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::FAILURE);
  });

  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                  [&](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    checkEarlyExit(aDecoder, aSink, WriteState::FINISHED);
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWriteBuffer)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    // Create a buffer the same size as one row of the surface (which is 100x100),
    // containing 60 pixels of 255 in the middle and 20 transparent pixels of 0 on
    // either side.
    uint8_t buffer[100];
    for (int i = 0; i < 100; ++i) {
      buffer[i] = 20 <= i && i < 80 ? 255 : 0;
    }

    // Write the buffer to every row of the surface and check that the generated
    // image is correct.
    CheckPalettedIterativeWrite(aDecoder, aSink, IntRect(20, 0, 60, 100), [&]{
      return aSink->WriteBuffer(buffer);
    });
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWriteBufferPartialRow)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    // Create a buffer the same size as one row of the surface, containing all
    // 255 pixels.
    uint8_t buffer[100];
    for (int i = 0; i < 100; ++i) {
      buffer[i] = 255;
    }

    // Write the buffer to the middle 60 pixels of every row of the surface and
    // check that the generated image is correct.
    CheckPalettedIterativeWrite(aDecoder, aSink, IntRect(20, 0, 60, 100), [&]{
      return aSink->WriteBuffer(buffer, 20, 60);
    });
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWriteBufferPartialRowStartColOverflow)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    // Create a buffer the same size as one row of the surface, containing all
    // 255 pixels.
    uint8_t buffer[100];
    for (int i = 0; i < 100; ++i) {
      buffer[i] = 255;
    }

    {
      // Write the buffer to successive rows until every row of the surface
      // has been written. We place the start column beyond the end of the row,
      // which will prevent us from writing anything, so we check that the
      // generated image is entirely 0.
      CheckPalettedIterativeWrite(aDecoder, aSink, IntRect(0, 0, 0, 0), [&]{
        return aSink->WriteBuffer(buffer, 100, 100);
      });
    }

    ResetForNextPass(aSink);

    {
      // Write the buffer to successive rows until every row of the surface
      // has been written. We use column 50 as the start column, but we still
      // write the buffer, which means we overflow the right edge of the surface
      // by 50 pixels. We check that the left half of the generated image is
      // 0 and the right half is 255.
      CheckPalettedIterativeWrite(aDecoder, aSink, IntRect(50, 0, 50, 100), [&]{
        return aSink->WriteBuffer(buffer, 50, 100);
      });
    }
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWriteBufferPartialRowBufferOverflow)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    // Create a buffer twice as large as a row of the surface. The first half
    // (which is as large as a row of the image) will contain 255 pixels,
    // while the second half will contain 128 pixels.
    uint8_t buffer[200];
    for (int i = 0; i < 200; ++i) {
      buffer[i] = i < 100 ? 255 : 128;
    }

    {
      // Write the buffer to successive rows until every row of the surface has
      // been written. The buffer extends 100 pixels to the right of a row of
      // the surface, but bounds checking will prevent us from overflowing the
      // buffer. We check that the generated image is entirely 255 since the
      // pixels on the right side of the buffer shouldn't have been written to
      // the surface.
      CheckPalettedIterativeWrite(aDecoder, aSink, IntRect(0, 0, 100, 100), [&]{
        return aSink->WriteBuffer(buffer, 0, 200);
      });
    }

    ResetForNextPass(aSink);

    {
      // Write from the buffer to the middle of each row of the surface. That
      // means that the left side of each row should be 0, since we didn't write
      // anything there. A buffer overflow would cause us to write buffer
      // contents into the left side of each row. We check that the generated
      // image is 0 on the left side and 255 on the right.
      CheckPalettedIterativeWrite(aDecoder, aSink, IntRect(50, 0, 50, 100), [&]{
        return aSink->WriteBuffer(buffer, 50, 200);
      });
    }
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWriteBufferFromNullSource)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    // Calling WriteBuffer() with a null pointer should fail without making any
    // changes to the surface.
    uint8_t* nullBuffer = nullptr;
    WriteState result = aSink->WriteBuffer(nullBuffer);

    EXPECT_EQ(WriteState::FAILURE, result);
    EXPECT_FALSE(aSink->IsSurfaceFinished());
    Maybe<SurfaceInvalidRect> invalidRect = aSink->TakeInvalidRect();
    EXPECT_TRUE(invalidRect.isNothing());

    // Check that nothing got written to the surface.
    CheckGeneratedPalettedImage(aDecoder, IntRect(0, 0, 0, 0));
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWriteEmptyRow)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    {
      // Write an empty row to each row of the surface. We check that the
      // generated image is entirely 0.
      CheckPalettedIterativeWrite(aDecoder, aSink, IntRect(0, 0, 0, 0), [&]{
        return aSink->WriteEmptyRow();
      });
    }

    ResetForNextPass(aSink);

    {
      // Write a partial row before we begin calling WriteEmptyRow(). We check
      // that the generated image is entirely 0, which is to be expected since
      // WriteEmptyRow() overwrites the current row even if some data has
      // already been written to it.
      uint32_t count = 0;
      auto result = aSink->WritePixels<uint8_t>([&]() -> NextPixel<uint8_t> {
        if (count == 50) {
          return AsVariant(WriteState::NEED_MORE_DATA);
        }
        ++count;
        return AsVariant(uint8_t(255));
      });

      EXPECT_EQ(WriteState::NEED_MORE_DATA, result);
      EXPECT_EQ(50u, count);
      EXPECT_FALSE(aSink->IsSurfaceFinished());

      CheckPalettedIterativeWrite(aDecoder, aSink, IntRect(0, 0, 0, 0), [&]{
        return aSink->WriteEmptyRow();
      });
    }

    ResetForNextPass(aSink);

    {
      // Create a buffer the same size as one row of the surface, containing all
      // 255 pixels.
      uint8_t buffer[100];
      for (int i = 0; i < 100; ++i) {
        buffer[i] = 255;
      }

      // Write an empty row to the middle 60 rows of the surface. The first 20
      // and last 20 rows will be 255. (We need to use DoCheckIterativeWrite()
      // here because we need a custom function to check the output, since it
      // can't be described by a simple rect.)
      auto writeFunc = [&](uint32_t aRow) {
        if (aRow < 20 || aRow >= 80) {
          return aSink->WriteBuffer(buffer);
        } else {
          return aSink->WriteEmptyRow();
        }
      };

      auto checkFunc = [&]{
        EXPECT_TRUE(PalettedRowsAreSolidColor(aDecoder, 0, 20, 255));
        EXPECT_TRUE(PalettedRowsAreSolidColor(aDecoder, 20, 60, 0));
        EXPECT_TRUE(PalettedRowsAreSolidColor(aDecoder, 80, 20, 255));
      };

      DoCheckIterativeWrite(aSink, writeFunc, checkFunc);
    }
  });
}

TEST(ImageSurfaceSink, PalettedSurfaceSinkWriteUnsafeComputedRow)
{
  WithPalettedSurfaceSink(IntRect(0, 0, 100, 100),
                          [](Decoder* aDecoder, PalettedSurfaceSink* aSink) {
    // Create an all-255 buffer the same size as one row of the surface.
    uint8_t buffer[100];
    for (int i = 0; i < 100; ++i) {
      buffer[i] = 255;
    }

    // Write the buffer to successive rows until every row of the surface has
    // been written. We only write to the right half of each row, so we check
    // that the left side of the generated image is 0 and the right side is 255.
    CheckPalettedIterativeWrite(aDecoder, aSink, IntRect(50, 0, 50, 100), [&]{
      return aSink->WriteUnsafeComputedRow<uint8_t>([&](uint8_t* aRow,
                                                        uint32_t aLength) {
        EXPECT_EQ(100u, aLength );
        memcpy(aRow + 50, buffer, 50 * sizeof(uint8_t));
      });
    });
  });
}