text: // Copyright 2016 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 "gpu/command_buffer/client/gl_helper.h"
  
  #include <GLES2/gl2.h>
  #include <GLES2/gl2ext.h>
  #include <GLES2/gl2extchromium.h>
  
  #include <algorithm>
  #include <cmath>
  #include <string>
  #include <tuple>
  #include <utility>
  #include <vector>
  
  #include "base/bind.h"
  #include "base/memory/ref_counted_memory.h"
  #include "base/numerics/ranges.h"
  #include "base/run_loop.h"
  #include "base/stl_util.h"
  #include "base/strings/stringprintf.h"
  #include "base/synchronization/waitable_event.h"
  #include "base/threading/thread_task_runner_handle.h"
  #include "base/time/time.h"
  #include "build/build_config.h"
  #include "components/viz/test/test_gpu_service_holder.h"
  #include "gpu/command_buffer/client/gl_helper_scaling.h"
  #include "gpu/command_buffer/client/gles2_implementation.h"
  #include "gpu/command_buffer/client/shared_memory_limits.h"
  #include "gpu/ipc/gl_in_process_context.h"
  #include "testing/gtest/include/gtest/gtest.h"
  #include "third_party/skia/include/core/SkBitmap.h"
  
  #if !defined(OS_ANDROID)
  
  namespace gpu {
  
  namespace {
  
  GLHelper::ScalerQuality kQualities[] = {
      GLHelper::SCALER_QUALITY_BEST,
      GLHelper::SCALER_QUALITY_GOOD,
      GLHelper::SCALER_QUALITY_FAST,
  };
  
  const char* kQualityNames[] = {
      "best",
      "good",
      "fast",
  };
  
  }  // namespace
  
  class GLHelperTest : public testing::Test {
   protected:
    void SetUp() override {
      ContextCreationAttribs attributes;
      attributes.alpha_size = 8;
      attributes.depth_size = 24;
      attributes.red_size = 8;
      attributes.green_size = 8;
      attributes.blue_size = 8;
      attributes.stencil_size = 8;
      attributes.samples = 4;
      attributes.sample_buffers = 1;
      attributes.bind_generates_resource = false;
  
      context_ = std::make_unique<GLInProcessContext>();
      auto result = context_->Initialize(
          viz::TestGpuServiceHolder::GetInstance()->task_executor(),
          nullptr,            /* surface */
          true,               /* offscreen */
          kNullSurfaceHandle, /* window */
          attributes, SharedMemoryLimits(),
          nullptr, /* gpu_memory_buffer_manager */
          nullptr, /* image_factory */
          nullptr, /* gpu_task_scheduler */
          nullptr, /* display_compositor_memory_and_task_controller_on_gpu */
          base::ThreadTaskRunnerHandle::Get());
      DCHECK_EQ(result, ContextResult::kSuccess);
      gl_ = context_->GetImplementation();
      ContextSupport* support = context_->GetImplementation();
  
      helper_.reset(new GLHelper(gl_, support));
      helper_scaling_.reset(new GLHelperScaling(gl_, helper_.get()));
    }
  
    void TearDown() override {
      helper_scaling_.reset(nullptr);
      helper_.reset(nullptr);
      context_.reset(nullptr);
    }
  
    // Bicubic filter kernel function.
    static float Bicubic(float x) {
      const float a = -0.5;
      x = std::abs(x);
      float x2 = x * x;
      float x3 = x2 * x;
      if (x <= 1) {
        return (a + 2) * x3 - (a + 3) * x2 + 1;
      } else if (x < 2) {
        return a * x3 - 5 * a * x2 + 8 * a * x - 4 * a;
      } else {
        return 0.0f;
      }
    }
  
    // Look up a single channel value. Works for 4-channel and single channel
    // bitmaps.  Clamp x/y.
    int Channel(SkBitmap* pixels, int x, int y, int c) {
      if (pixels->bytesPerPixel() == 4) {
        uint32_t* data =
            pixels->getAddr32(base::ClampToRange(x, 0, pixels->width() - 1),
                              base::ClampToRange(y, 0, pixels->height() - 1));
        return (*data) >> (c * 8) & 0xff;
      } else {
        DCHECK_EQ(pixels->bytesPerPixel(), 1);
        DCHECK_EQ(c, 0);
        return *pixels->getAddr8(base::ClampToRange(x, 0, pixels->width() - 1),
                                 base::ClampToRange(y, 0, pixels->height() - 1));
      }
    }
  
    // Set a single channel value. Works for 4-channel and single channel
    // bitmaps.  Clamp x/y.
    void SetChannel(SkBitmap* pixels, int x, int y, int c, int v) {
      DCHECK_GE(x, 0);
      DCHECK_GE(y, 0);
      DCHECK_LT(x, pixels->width());
      DCHECK_LT(y, pixels->height());
      if (pixels->bytesPerPixel() == 4) {
        uint32_t* data = pixels->getAddr32(x, y);
        v = base::ClampToRange(v, 0, 255);
        *data = (*data & ~(0xffu << (c * 8))) | (v << (c * 8));
      } else {
        DCHECK_EQ(pixels->bytesPerPixel(), 1);
        DCHECK_EQ(c, 0);
        uint8_t* data = pixels->getAddr8(x, y);
        v = base::ClampToRange(v, 0, 255);
        *data = v;
      }
    }
  
    // Print all the R, G, B or A values from an SkBitmap in a
    // human-readable format.
    void PrintChannel(SkBitmap* pixels, int c) {
      for (int y = 0; y < pixels->height(); y++) {
        std::string formatted;
        for (int x = 0; x < pixels->width(); x++) {
          formatted.append(base::StringPrintf("%3d, ", Channel(pixels, x, y, c)));
        }
        LOG(ERROR) << formatted;
      }
    }
  
    // Print out the individual steps of a scaler pipeline.
    std::string PrintStages(
        const std::vector<GLHelperScaling::ScalerStage>& scaler_stages) {
      std::string ret;
      for (size_t i = 0; i < scaler_stages.size(); i++) {
        ret.append(base::StringPrintf(
            "%dx%d -> %dx%d ", scaler_stages[i].scale_from.x(),
            scaler_stages[i].scale_from.y(), scaler_stages[i].scale_to.x(),
            scaler_stages[i].scale_to.y()));
        bool xy_matters = false;
        switch (scaler_stages[i].shader) {
          case GLHelperScaling::SHADER_BILINEAR:
            ret.append("bilinear");
            break;
          case GLHelperScaling::SHADER_BILINEAR2:
            ret.append("bilinear2");
            xy_matters = true;
            break;
          case GLHelperScaling::SHADER_BILINEAR3:
            ret.append("bilinear3");
            xy_matters = true;
            break;
          case GLHelperScaling::SHADER_BILINEAR4:
            ret.append("bilinear4");
            xy_matters = true;
            break;
          case GLHelperScaling::SHADER_BILINEAR2X2:
            ret.append("bilinear2x2");
            break;
          case GLHelperScaling::SHADER_BICUBIC_UPSCALE:
            ret.append("bicubic upscale");
            xy_matters = true;
            break;
          case GLHelperScaling::SHADER_BICUBIC_HALF_1D:
            ret.append("bicubic 1/2");
            xy_matters = true;
            break;
          case GLHelperScaling::SHADER_PLANAR:
            ret.append("planar");
            break;
          case GLHelperScaling::SHADER_YUV_MRT_PASS1:
            ret.append("rgb2yuv pass 1");
            break;
          case GLHelperScaling::SHADER_YUV_MRT_PASS2:
            ret.append("rgb2yuv pass 2");
            break;
        }
  
        if (xy_matters) {
          if (scaler_stages[i].scale_x) {
            ret.append(" X");
          } else {
            ret.append(" Y");
          }
        }
        ret.append("\n");
      }
      return ret;
    }
  
    bool CheckScale(double scale, int samples, bool already_scaled) {
      // 1:1 is valid if there is one sample.
      if (samples == 1 && scale == 1.0) {
        return true;
      }
      // Is it an exact down-scale (50%, 25%, etc.?)
      if (scale == 2.0 * samples) {
        return true;
      }
      // Upscales, only valid if we haven't already scaled in this dimension.
      if (!already_scaled) {
        // Is it a valid bilinear upscale?
        if (samples == 1 && scale <= 1.0) {
          return true;
        }
        // Multi-sample upscale-downscale combination?
        if (scale > samples / 2.0 && scale < samples) {
          return true;
        }
      }
      return false;
    }
  
    // Make sure that the stages of the scaler pipeline are sane.
    void ValidateScalerStages(
        GLHelper::ScalerQuality quality,
        const std::vector<GLHelperScaling::ScalerStage>& scaler_stages,
        const gfx::Vector2d& overall_scale_from,
        const gfx::Vector2d& overall_scale_to,
        const std::string& message) {
      bool previous_error = HasFailure();
  
      // Used to verify that up-scales are not attempted after some
      // other scale.
      bool scaled_x = false;
      bool scaled_y = false;
  
      double combined_x_scale = 1.0;
      double combined_y_scale = 1.0;
      for (size_t i = 0; i < scaler_stages.size(); i++) {
        // Note: 2.0 means scaling down by 50%
        double x_scale = static_cast<double>(scaler_stages[i].scale_from.x()) /
                         static_cast<double>(scaler_stages[i].scale_to.x());
        combined_x_scale *= x_scale;
        double y_scale = static_cast<double>(scaler_stages[i].scale_from.y()) /
                         static_cast<double>(scaler_stages[i].scale_to.y());
        combined_y_scale *= y_scale;
  
        int x_samples = 0;
        int y_samples = 0;
  
        // Codify valid scale operations.
        switch (scaler_stages[i].shader) {
          case GLHelperScaling::SHADER_PLANAR:
          case GLHelperScaling::SHADER_YUV_MRT_PASS1:
          case GLHelperScaling::SHADER_YUV_MRT_PASS2:
            EXPECT_TRUE(false) << "Invalid shader.";
            break;
  
          case GLHelperScaling::SHADER_BILINEAR:
            if (quality != GLHelper::SCALER_QUALITY_FAST) {
              x_samples = 1;
              y_samples = 1;
            }
            break;
          case GLHelperScaling::SHADER_BILINEAR2:
            x_samples = 2;
            y_samples = 1;
            break;
          case GLHelperScaling::SHADER_BILINEAR3:
            x_samples = 3;
            y_samples = 1;
            break;
          case GLHelperScaling::SHADER_BILINEAR4:
            x_samples = 4;
            y_samples = 1;
            break;
          case GLHelperScaling::SHADER_BILINEAR2X2:
            x_samples = 2;
            y_samples = 2;
            break;
          case GLHelperScaling::SHADER_BICUBIC_UPSCALE:
            if (scaler_stages[i].scale_x) {
              EXPECT_LT(x_scale, 1.0);
              EXPECT_EQ(y_scale, 1.0);
            } else {
              EXPECT_EQ(x_scale, 1.0);
              EXPECT_LT(y_scale, 1.0);
            }
            break;
          case GLHelperScaling::SHADER_BICUBIC_HALF_1D:
            if (scaler_stages[i].scale_x) {
              EXPECT_EQ(x_scale, 2.0);
              EXPECT_EQ(y_scale, 1.0);
            } else {
              EXPECT_EQ(x_scale, 1.0);
              EXPECT_EQ(y_scale, 2.0);
            }
            break;
        }
  
        if (!scaler_stages[i].scale_x) {
          std::swap(x_samples, y_samples);
        }
  
        if (x_samples) {
          EXPECT_TRUE(CheckScale(x_scale, x_samples, scaled_x))
              << "x_scale = " << x_scale;
        }
        if (y_samples) {
          EXPECT_TRUE(CheckScale(y_scale, y_samples, scaled_y))
              << "y_scale = " << y_scale;
        }
  
        if (x_scale != 1.0) {
          scaled_x = true;
        }
        if (y_scale != 1.0) {
          scaled_y = true;
        }
      }
  
      const double expected_x_scale =
          static_cast<double>(overall_scale_from.x()) /
          static_cast<double>(overall_scale_to.x());
      const double expected_y_scale =
          static_cast<double>(overall_scale_from.y()) /
          static_cast<double>(overall_scale_to.y());
      EXPECT_NEAR(expected_x_scale, combined_x_scale, 1e-9);
      EXPECT_NEAR(expected_y_scale, combined_y_scale, 1e-9);
  
      if (HasFailure() && !previous_error) {
        LOG(ERROR) << "Invalid scaler stages: " << message;
        LOG(ERROR) << "Scaler stages:";
        LOG(ERROR) << PrintStages(scaler_stages);
      }
    }
  
    // Compares two bitmaps taking color types into account. Checks whether each
    // component of each pixel is no more than |maxdiff| apart. If bitmaps are not
    // similar enough, prints out |truth|, |other|, |source|, |scaler_stages|
    // and |message|.
    void Compare(SkBitmap* truth,
                 SkBitmap* other,
                 int maxdiff,
                 SkBitmap* source,
                 const std::vector<GLHelperScaling::ScalerStage>& scaler_stages,
                 std::string message) {
      EXPECT_EQ(truth->width(), other->width());
      EXPECT_EQ(truth->height(), other->height());
      bool swizzle = (truth->colorType() == kRGBA_8888_SkColorType &&
                      other->colorType() == kBGRA_8888_SkColorType) ||
                     (truth->colorType() == kBGRA_8888_SkColorType &&
                      other->colorType() == kRGBA_8888_SkColorType);
      EXPECT_TRUE(swizzle || truth->colorType() == other->colorType());
      int bpp = truth->bytesPerPixel();
      for (int x = 0; x < truth->width(); x++) {
        for (int y = 0; y < truth->height(); y++) {
          for (int c = 0; c < bpp; c++) {
            int a = Channel(truth, x, y, c);
            // swizzle when comparing if needed
            int b = swizzle && (c == 0 || c == 2)
                        ? Channel(other, x, y, (c + 2) & 2)
                        : Channel(other, x, y, c);
            EXPECT_NEAR(a, b, maxdiff)
                << " x=" << x << " y=" << y << " c=" << c << " " << message;
            if (std::abs(a - b) > maxdiff) {
              LOG(ERROR) << "-------expected--------";
              for (int i = 0; i < bpp; i++) {
                LOG(ERROR) << "Channel " << i << ":";
                PrintChannel(truth, i);
              }
              LOG(ERROR) << "-------actual--------";
              for (int i = 0; i < bpp; i++) {
                LOG(ERROR) << "Channel " << i << ":";
                PrintChannel(other, i);
              }
              if (source) {
                LOG(ERROR) << "-------original--------";
                for (int i = 0; i < source->bytesPerPixel(); i++) {
                  LOG(ERROR) << "Channel " << i << ":";
                  PrintChannel(source, i);
                }
              }
              LOG(ERROR) << "-----Scaler stages------";
              LOG(ERROR) << PrintStages(scaler_stages);
              return;
            }
          }
        }
      }
    }
  
    // Get a single R, G, B or A value as a float.
    float ChannelAsFloat(SkBitmap* pixels, int x, int y, int c) {
      return Channel(pixels, x, y, c) / 255.0;
    }
  
    // Works like a GL_LINEAR lookup on an SkBitmap.
    float Bilinear(SkBitmap* pixels, float x, float y, int c) {
      x -= 0.5;
      y -= 0.5;
      int base_x = static_cast<int>(floorf(x));
      int base_y = static_cast<int>(floorf(y));
      x -= base_x;
      y -= base_y;
      return (ChannelAsFloat(pixels, base_x, base_y, c) * (1 - x) * (1 - y) +
              ChannelAsFloat(pixels, base_x + 1, base_y, c) * x * (1 - y) +
              ChannelAsFloat(pixels, base_x, base_y + 1, c) * (1 - x) * y +
              ChannelAsFloat(pixels, base_x + 1, base_y + 1, c) * x * y);
    }
  
    // Very slow bicubic / bilinear scaler for reference.
    void ScaleSlow(SkBitmap* input,
                   const gfx::Rect& source_rect,
                   GLHelper::ScalerQuality quality,
                   SkBitmap* output) {
      float xscale = static_cast<float>(source_rect.width()) / output->width();
      float yscale = static_cast<float>(source_rect.height()) / output->height();
      float clamped_xscale = xscale < 1.0 ? 1.0 : 1.0 / xscale;
      float clamped_yscale = yscale < 1.0 ? 1.0 : 1.0 / yscale;
      for (int dst_y = 0; dst_y < output->height(); dst_y++) {
        for (int dst_x = 0; dst_x < output->width(); dst_x++) {
          for (int channel = 0; channel < 4; channel++) {
            float dst_x_in_src = source_rect.x() + (dst_x + 0.5f) * xscale;
            float dst_y_in_src = source_rect.y() + (dst_y + 0.5f) * yscale;
  
            float value = 0.0f;
            float sum = 0.0f;
            switch (quality) {
              case GLHelper::SCALER_QUALITY_BEST:
                for (int src_y = source_rect.y() - 10;
                     src_y < source_rect.bottom() + 10; ++src_y) {
                  float coeff_y =
                      Bicubic((src_y + 0.5f - dst_y_in_src) * clamped_yscale);
                  if (coeff_y == 0.0f) {
                    continue;
                  }
                  for (int src_x = source_rect.x() - 10;
                       src_x < source_rect.right() + 10; ++src_x) {
                    float coeff =
                        coeff_y *
                        Bicubic((src_x + 0.5f - dst_x_in_src) * clamped_xscale);
                    if (coeff == 0.0f) {
                      continue;
                    }
                    sum += coeff;
                    float c = ChannelAsFloat(input, src_x, src_y, channel);
                    value += c * coeff;
                  }
                }
                break;
  
              case GLHelper::SCALER_QUALITY_GOOD: {
                int xshift = 0, yshift = 0;
                while ((output->width() << xshift) < source_rect.width()) {
                  xshift++;
                }
                while ((output->height() << yshift) < source_rect.height()) {
                  yshift++;
                }
                int xmag = 1 << xshift;
                int ymag = 1 << yshift;
                if (xmag == 4 && output->width() * 3 >= source_rect.width()) {
                  xmag = 3;
                }
                if (ymag == 4 && output->height() * 3 >= source_rect.height()) {
                  ymag = 3;
                }
                for (int x = 0; x < xmag; x++) {
                  for (int y = 0; y < ymag; y++) {
                    value += Bilinear(input,
                                      source_rect.x() + (dst_x * xmag + x + 0.5) *
                                                            xscale / xmag,
                                      source_rect.y() + (dst_y * ymag + y + 0.5) *
                                                            yscale / ymag,
                                      channel);
                    sum += 1.0;
                  }
                }
                break;
              }
  
              case GLHelper::SCALER_QUALITY_FAST:
                value = Bilinear(input, dst_x_in_src, dst_y_in_src, channel);
                sum = 1.0;
            }
            value /= sum;
            SetChannel(output, dst_x, dst_y, channel,
                       static_cast<int>(value * 255.0f + 0.5f));
          }
        }
      }
    }
  
    void FlipSKBitmap(SkBitmap* bitmap) {
      int bpp = bitmap->bytesPerPixel();
      DCHECK(bpp == 4 || bpp == 1);
      int top_line = 0;
      int bottom_line = bitmap->height() - 1;
      while (top_line < bottom_line) {
        for (int x = 0; x < bitmap->width(); x++) {
          bpp == 4 ? std::swap(*bitmap->getAddr32(x, top_line),
                               *bitmap->getAddr32(x, bottom_line))
                   : std::swap(*bitmap->getAddr8(x, top_line),
                               *bitmap->getAddr8(x, bottom_line));
        }
        top_line++;
        bottom_line--;
      }
    }
  
    // gl_helper scales recursively, so we'll need to do that
    // in the reference implementation too.
    void ScaleSlowRecursive(SkBitmap* input,
                            const gfx::Rect& source_rect,
                            GLHelper::ScalerQuality quality,
                            SkBitmap* output) {
      if (quality == GLHelper::SCALER_QUALITY_FAST ||
          quality == GLHelper::SCALER_QUALITY_GOOD) {
        ScaleSlow(input, source_rect, quality, output);
        return;
      }
  
      float xscale = static_cast<float>(output->width()) / source_rect.width();
  
      // This corresponds to all the operations we can do directly.
      float yscale = static_cast<float>(output->height()) / source_rect.height();
      if ((xscale == 1.0f && yscale == 1.0f) ||
          (xscale == 0.5f && yscale == 1.0f) ||
          (xscale == 1.0f && yscale == 0.5f) ||
          (xscale >= 1.0f && yscale == 1.0f) ||
          (xscale == 1.0f && yscale >= 1.0f)) {
        ScaleSlow(input, source_rect, quality, output);
        return;
      }
  
      // Now we break the problem down into smaller pieces, using the
      // operations available.
      int xtmp = source_rect.width();
      int ytmp = source_rect.height();
  
      if (output->height() != source_rect.height()) {
        ytmp = output->height();
        while (ytmp < source_rect.height() && ytmp * 2 != source_rect.height()) {
          ytmp += ytmp;
        }
      } else {
        xtmp = output->width();
        while (xtmp < source_rect.width() && xtmp * 2 != source_rect.width()) {
          xtmp += xtmp;
        }
      }
  
      // Note: The following does not account for scaler overscan. This was
      // attempted, but then unit test run time increased by a factor of 30!
      SkBitmap tmp;
      tmp.allocN32Pixels(xtmp, ytmp);
  
      ScaleSlowRecursive(input, source_rect, quality, &tmp);
      ScaleSlowRecursive(&tmp, gfx::Rect(0, 0, xtmp, ytmp), quality, output);
    }
  
    // Creates an RGBA SkBitmap with one of the pre-programmed test patterns. The
    // pattern starts at the given |origin|. For positions to the left or above
    // that point, values are filled-in corresponding to GL_CLAMP_TO_EDGE
    // behavior. This is because the reference scaler does not properly account
    // for overscan.
    std::unique_ptr<SkBitmap> CreateTestBitmap(const gfx::Size& size,
                                               const gfx::Point& origin,
                                               int test_pattern) {
      std::unique_ptr<SkBitmap> bitmap(new SkBitmap);
      bitmap->allocPixels(SkImageInfo::Make(size.width(), size.height(),
                                            kRGBA_8888_SkColorType,
                                            kPremul_SkAlphaType));
  
      for (int x = 0; x < size.width(); ++x) {
        for (int y = 0; y < size.height(); ++y) {
          const int s = std::max(0, x - origin.x());
          const int t = std::max(0, y - origin.y());
          switch (test_pattern) {
            case 0:  // Smooth test pattern
              SetChannel(bitmap.get(), x, y, 0, s * 10);
              SetChannel(bitmap.get(), x, y, 0, t == 0 ? s * 50 : s * 10);
              SetChannel(bitmap.get(), x, y, 1, t * 10);
              SetChannel(bitmap.get(), x, y, 2, (s + t) * 10);
              SetChannel(bitmap.get(), x, y, 3, 255);
              break;
            case 1:  // Small blocks
              SetChannel(bitmap.get(), x, y, 0, s & 1 ? 255 : 0);
              SetChannel(bitmap.get(), x, y, 1, t & 1 ? 255 : 0);
              SetChannel(bitmap.get(), x, y, 2, (s + t) & 1 ? 255 : 0);
              SetChannel(bitmap.get(), x, y, 3, 255);
              break;
            case 2:  // Medium blocks
              SetChannel(bitmap.get(), x, y, 0, 10 + s / 2 * 50);
              SetChannel(bitmap.get(), x, y, 1, 10 + t / 3 * 50);
              SetChannel(bitmap.get(), x, y, 2, (s + t) / 5 * 50 + 5);
              SetChannel(bitmap.get(), x, y, 3, 255);
              break;
          }
        }
      }
      return bitmap;
    }
  
    // Scaling test: Create a test image, scale it using GLHelperScaling
    // and a reference implementation and compare the results.
    void TestScale(const gfx::Rect& source_rect,
                   const gfx::Size& scaled_size,
                   int test_pattern,
                   size_t quality_index,
                   bool flip_output) {
      // The source texture is meant to be the contents of a framebuffer. Thus, it
      // includes (0,0), and all the way out to the lower-right corner of the
      // |source_rect|.
      const gfx::Size framebuffer_size(source_rect.right(), source_rect.bottom());
      std::unique_ptr<SkBitmap> input_pixels =
          CreateTestBitmap(framebuffer_size, source_rect.origin(), test_pattern);
      GLuint src_texture;
      gl_->GenTextures(1, &src_texture);
      gl_->BindTexture(GL_TEXTURE_2D, src_texture);
      gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, framebuffer_size.width(),
                      framebuffer_size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE,
                      input_pixels->getPixels());
  
      std::string message = base::StringPrintf(
          "source rect: %s "
          "output size: %s "
          "pattern: %d quality: %s %s",
          source_rect.ToString().c_str(), scaled_size.ToString().c_str(),
          test_pattern, kQualityNames[quality_index],
          flip_output ? "flipout" : "noflipout");
  
      std::vector<GLHelperScaling::ScalerStage> stages;
      const auto scale_from =
          gfx::Vector2d(source_rect.width(), source_rect.height());
      const auto scale_to =
          gfx::Vector2d(scaled_size.width(), scaled_size.height());
      helper_scaling_->ComputeScalerStages(kQualities[quality_index], scale_from,
                                           scale_to, false, flip_output, false,
                                           &stages);
      ValidateScalerStages(kQualities[quality_index], stages, scale_from,
                           scale_to, message);
  
      // Scale the source texture, producing the results in a new output
      // texture.
      std::unique_ptr<GLHelper::ScalerInterface> scaler =
          helper_->CreateScaler(kQualities[quality_index], scale_from, scale_to,
                                false, flip_output, false);
      ASSERT_FALSE(scaler->IsSamplingFlippedSource());
      ASSERT_EQ(flip_output, scaler->IsFlippingOutput());
      GLuint dst_texture = 0;
      gl_->GenTextures(1, &dst_texture);
      gl_->BindTexture(GL_TEXTURE_2D, dst_texture);
      gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, scaled_size.width(),
                      scaled_size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE,
                      nullptr);
      scaler->Scale(src_texture, framebuffer_size, source_rect.OffsetFromOrigin(),
                    dst_texture, gfx::Rect(scaled_size));
  
      SkBitmap output_pixels;
      output_pixels.allocPixels(
          SkImageInfo::Make(scaled_size.width(), scaled_size.height(),
                            kRGBA_8888_SkColorType, kPremul_SkAlphaType));
  
      EXPECT_TRUE(
          ReadBackTexture(dst_texture, scaled_size,
                          static_cast<unsigned char*>(output_pixels.getPixels()),
                          kRGBA_8888_SkColorType));
      if (flip_output) {
        // Flip the pixels back.
        FlipSKBitmap(&output_pixels);
      }
  
      // If the bitmap shouldn't have changed - compare against input.
      if (source_rect == gfx::Rect(scaled_size)) {
        Compare(input_pixels.get(), &output_pixels, 0, nullptr, stages,
                message + " comparing against input");
        return;
      }
  
      // Now scale the bitmap using the reference implementation.
      SkBitmap truth_pixels;
      truth_pixels.allocPixels(
          SkImageInfo::Make(scaled_size.width(), scaled_size.height(),
                            kRGBA_8888_SkColorType, kPremul_SkAlphaType));
      ScaleSlowRecursive(input_pixels.get(), source_rect,
                         kQualities[quality_index], &truth_pixels);
  
      // Compare the results produced by the two implementations. Note that the
      // reference implementation does not fully account for overscan (see
      // comment in ScaleSlowRecursive()), and so the the maxdiff must be
      // increased when the bicubic scaler is being used.
      const int maxdiff = 2 + (quality_index == 0 ? (2 * stages.size()) : 0);
      Compare(&truth_pixels, &output_pixels, maxdiff, input_pixels.get(), stages,
              message + " comparing against scaled");
  
      gl_->DeleteTextures(1, &src_texture);
      gl_->DeleteTextures(1, &dst_texture);
    }
  
    // Scaling patching test: Scale an entire source image, and then scale various
    // subsets of the source image; and then confirm that the pixels in the
    // subsets exactly match their corresponding ones in the whole. This is
    // critical for use cases where the scaler only needs to render the changed
    // region of a source image.
    void TestScalePatching(const gfx::Vector2d& scale_from,
                           const gfx::Vector2d& scale_to,
                           int test_pattern,
                           size_t quality_index,
                           bool flipped_source) {
      // Generate a source texture representing copied-from-framebuffer content
      // with a test pattern that is twice the size of the "from" vector.
      const gfx::Size framebuffer_size(scale_from.x() * 2, scale_from.y() * 2);
      std::unique_ptr<SkBitmap> test_bitmap =
          CreateTestBitmap(framebuffer_size, gfx::Point(), test_pattern);
      if (flipped_source)
        FlipSKBitmap(test_bitmap.get());
      GLuint src_texture;
      gl_->GenTextures(1, &src_texture);
      gl_->BindTexture(GL_TEXTURE_2D, src_texture);
      gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, framebuffer_size.width(),
                      framebuffer_size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE,
                      test_bitmap->getPixels());
  
      const std::unique_ptr<GLHelper::ScalerInterface> scaler =
          helper_->CreateScaler(kQualities[quality_index], scale_from, scale_to,
                                flipped_source, false, false);
      ASSERT_EQ(flipped_source, scaler->IsSamplingFlippedSource());
      ASSERT_FALSE(scaler->IsFlippingOutput());
      // Note: These scaler stages are only being computed here for the benefit
      // Compare()'s error output messaging, below.
      std::vector<GLHelperScaling::ScalerStage> stages;
      helper_scaling_->ComputeScalerStages(kQualities[quality_index], scale_from,
                                           scale_to, flipped_source, false, false,
                                           &stages);
  
      // First, produce the entire output image, a full scan of the source to
      // produce all the output pixels. The output image is twice the size of the
      // "to" vector.
      GLuint dst_texture;
      gl_->GenTextures(1, &dst_texture);
      gl_->BindTexture(GL_TEXTURE_2D, dst_texture);
      const gfx::Size entire_output_size(scale_to.x() * 2, scale_to.y() * 2);
      gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, entire_output_size.width(),
                      entire_output_size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE,
                      nullptr);
      scaler->Scale(src_texture, framebuffer_size, gfx::Vector2dF(), dst_texture,
                    gfx::Rect(entire_output_size));
      SkBitmap entire_output;
      entire_output.allocPixels(SkImageInfo::Make(
          entire_output_size.width(), entire_output_size.height(),
          kRGBA_8888_SkColorType, kPremul_SkAlphaType));
  
      EXPECT_TRUE(
          ReadBackTexture(dst_texture, entire_output_size,
                          static_cast<unsigned char*>(entire_output.getPixels()),
                          kRGBA_8888_SkColorType));
  
      const std::string human_readable_test_params = base::StringPrintf(
          "scale from: %s "
          "scale to: %s "
          "pattern: %d quality: %s %s",
          scale_from.ToString().c_str(), scale_to.ToString().c_str(),
          test_pattern, kQualityNames[quality_index],
          flipped_source ? "flippedsource" : "");
  
      // Check the entire output image against the reference implementation.
      SkBitmap entire_output_ref;
      entire_output_ref.allocPixels(SkImageInfo::Make(
          entire_output_size.width(), entire_output_size.height(),
          kRGBA_8888_SkColorType, kPremul_SkAlphaType));
      ScaleSlowRecursive(test_bitmap.get(), gfx::Rect(framebuffer_size),
                         kQualities[quality_index], &entire_output_ref);
      Compare(&entire_output_ref, &entire_output, 2, test_bitmap.get(), stages,
              human_readable_test_params + " ENTIRE OUTPUT");
      if (HasFailure())
        return;
  
      // Now, produce patches at various offsets and compare to the pixels in
      // |entire_output|.
      const gfx::Size patch_size(scale_to.x(), scale_to.y());
      gl_->BindTexture(GL_TEXTURE_2D, dst_texture);
      gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, patch_size.width(),
                      patch_size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
      for (int xoffset = 0; xoffset < scale_to.x(); ++xoffset) {
        for (int yoffset = 0; yoffset < scale_to.y(); ++yoffset) {
          const gfx::Rect patch_rect(gfx::Point(xoffset, yoffset), patch_size);
  
          // First method of producing a patch: Scale from the same source texture
          // and just provide an offset output Rect.
          scaler->Scale(src_texture, framebuffer_size, gfx::Vector2dF(),
                        dst_texture, patch_rect);
          SkBitmap patch_output;
          patch_output.allocPixels(
              SkImageInfo::Make(patch_size.width(), patch_size.height(),
                                kRGBA_8888_SkColorType, kPremul_SkAlphaType));
          EXPECT_TRUE(ReadBackTexture(
              dst_texture, patch_size,
              static_cast<unsigned char*>(patch_output.getPixels()),
              kRGBA_8888_SkColorType));
          SkBitmap expected;
          SkIRect expected_subrect{patch_rect.x(), patch_rect.y(),
                                   patch_rect.right(), patch_rect.bottom()};
          if (flipped_source) {
            expected_subrect.fTop = entire_output.height() - patch_rect.bottom();
            expected_subrect.fBottom = entire_output.height() - patch_rect.y();
          }
          ASSERT_TRUE(entire_output.extractSubset(&expected, expected_subrect));
          Compare(&expected, &patch_output, 2, test_bitmap.get(), stages,
                  "METHOD1 " + human_readable_test_params +
                      " patch rect: " + patch_rect.ToString());
          if (HasFailure())
            return;
  
          // Second method of producing a patch: First copy just the "region of
          // influence" of the source texture, then produced a scaled image from
          // that.
          gfx::Rect sampling_rect;
          gfx::Vector2dF offset;
          scaler->ComputeRegionOfInfluence(framebuffer_size, gfx::Vector2dF(),
                                           patch_rect, &sampling_rect, &offset);
          // TODO(crbug.com/775740): Only test offsets having whole-numbered
          // coordinates until the scalers can account for the other case.
          if (offset.x() == std::floor(offset.x()) &&
              offset.y() == std::floor(offset.y())) {
            GLuint src_subset_texture;
            gl_->GenTextures(1, &src_subset_texture);
            gl_->BindTexture(GL_TEXTURE_2D, src_subset_texture);
            gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, sampling_rect.width(),
                            sampling_rect.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE,
                            nullptr);
            gl_->CopySubTextureCHROMIUM(
                src_texture, 0 /* source_level */, GL_TEXTURE_2D,
                src_subset_texture, 0 /* dest_level */, 0 /* xoffset */,
                0 /* yoffset */, sampling_rect.x(), sampling_rect.y(),
                sampling_rect.width(), sampling_rect.height(), false, false,
                false);
            scaler->Scale(src_subset_texture, sampling_rect.size(), offset,
                          dst_texture, gfx::Rect(patch_size));
            gl_->DeleteTextures(1, &src_subset_texture);
            EXPECT_TRUE(ReadBackTexture(
                dst_texture, patch_size,
                static_cast<unsigned char*>(patch_output.getPixels()),
                kRGBA_8888_SkColorType));
            Compare(&expected, &patch_output, 2, test_bitmap.get(), stages,
                    "METHOD2 " + human_readable_test_params +
                        " patch rect: " + patch_rect.ToString());
            if (HasFailure())
              return;
          }
        }
      }
  
      gl_->DeleteTextures(1, &src_texture);
      gl_->DeleteTextures(1, &dst_texture);
    }
  
    // Create a scaling pipeline and check that it is made up of
    // valid scaling operations.
    void TestScalerPipeline(size_t quality,
                            int xsize,
                            int ysize,
                            int dst_xsize,
                            int dst_ysize) {
      std::vector<GLHelperScaling::ScalerStage> stages;
      helper_scaling_->ComputeScalerStages(
          kQualities[quality], gfx::Vector2d(xsize, ysize),
          gfx::Vector2d(dst_xsize, dst_ysize), false, false, false, &stages);
      ValidateScalerStages(kQualities[quality], stages,
                           gfx::Vector2d(xsize, ysize),
                           gfx::Vector2d(dst_xsize, dst_ysize),
                           base::StringPrintf("input size: %dx%d "
                                              "output size: %dx%d "
                                              "quality: %s",
                                              xsize, ysize, dst_xsize, dst_ysize,
                                              kQualityNames[quality]));
    }
  
    // Create a scaling pipeline and make sure that the steps
    // are exactly the steps we expect.
    void CheckPipeline(GLHelper::ScalerQuality quality,
                       int xsize,
                       int ysize,
                       int dst_xsize,
                       int dst_ysize,
                       const std::string& description) {
      std::vector<GLHelperScaling::ScalerStage> stages;
      helper_scaling_->ComputeScalerStages(quality, gfx::Vector2d(xsize, ysize),
                                           gfx::Vector2d(dst_xsize, dst_ysize),
                                           false, false, false, &stages);
      ValidateScalerStages(GLHelper::SCALER_QUALITY_GOOD, stages,
                           gfx::Vector2d(xsize, ysize),
                           gfx::Vector2d(dst_xsize, dst_ysize), "");
      EXPECT_EQ(PrintStages(stages), description);
    }
  
    void DrawGridToBitmap(int w,
                          int h,
                          SkColor background_color,
                          SkColor grid_color,
                          int grid_pitch,
                          int grid_width,
                          const SkBitmap& bmp) {
      ASSERT_GT(grid_pitch, 0);
      ASSERT_GT(grid_width, 0);
      ASSERT_NE(background_color, grid_color);
  
      for (int y = 0; y < h; ++y) {
        bool y_on_grid = ((y % grid_pitch) < grid_width);
  
        for (int x = 0; x < w; ++x) {
          bool on_grid = (y_on_grid || ((x % grid_pitch) < grid_width));
  
          *bmp.getAddr32(x, y) = (on_grid ? grid_color : background_color);
        }
      }
    }
  
    void DrawCheckerToBitmap(int w,
                             int h,
                             SkColor color1,
                             SkColor color2,
                             int rect_w,
                             int rect_h,
                             const SkBitmap& bmp) {
      ASSERT_GT(rect_w, 0);
      ASSERT_GT(rect_h, 0);
      ASSERT_NE(color1, color2);
  
      for (int y = 0; y < h; ++y) {
        bool y_bit = (((y / rect_h) & 0x1) == 0);
  
        for (int x = 0; x < w; ++x) {
          bool x_bit = (((x / rect_w) & 0x1) == 0);
  
          bool use_color2 = (x_bit != y_bit);  // xor
          *bmp.getAddr32(x, y) = (use_color2 ? color2 : color1);
        }
      }
    }
  
    bool ColorComponentsClose(SkColor component1, SkColor component2) {
      int c1 = static_cast<int>(component1);
      int c2 = static_cast<int>(component2);
      return (std::abs(c1 - c2) == 0);
    }
  
    bool ColorsClose(SkColor color1, SkColor color2) {
      bool red = ColorComponentsClose(SkColorGetR(color1), SkColorGetR(color2));
      bool green = ColorComponentsClose(SkColorGetG(color1), SkColorGetG(color2));
      bool blue = ColorComponentsClose(SkColorGetB(color1), SkColorGetB(color2));
      bool alpha = ColorComponentsClose(SkColorGetA(color1), SkColorGetA(color2));
      return red && blue && green && alpha;
    }
  
    bool IsEqual(const SkBitmap& bmp1, const SkBitmap& bmp2) {
      if (bmp1.isNull() && bmp2.isNull())
        return true;
      if (bmp1.width() != bmp2.width() || bmp1.height() != bmp2.height()) {
        LOG(ERROR) << "Bitmap geometry check failure";
        return false;
      }
      if (bmp1.colorType() != bmp2.colorType())
        return false;
  
      if (!bmp1.getPixels() || !bmp2.getPixels()) {
        LOG(ERROR) << "Empty Bitmap!";
        return false;
      }
      for (int y = 0; y < bmp1.height(); ++y) {
        for (int x = 0; x < bmp1.width(); ++x) {
          if (!ColorsClose(bmp1.getColor(x, y), bmp2.getColor(x, y))) {
            LOG(ERROR) << "Bitmap color comparison failure";
            return false;
          }
        }
      }
      return true;
    }
  
    void BindAndAttachTextureWithPixels(GLuint src_texture,
                                        SkColorType color_type,
                                        const gfx::Size& src_size,
                                        const SkBitmap& input_pixels) {
      gl_->BindTexture(GL_TEXTURE_2D, src_texture);
      const GLenum format =
          (color_type == kBGRA_8888_SkColorType) ? GL_BGRA_EXT : GL_RGBA;
      gl_->TexImage2D(GL_TEXTURE_2D, 0, format, src_size.width(),
                      src_size.height(), 0, format, GL_UNSIGNED_BYTE,
                      input_pixels.getPixels());
    }
  
    bool ReadBackTexture(GLuint src_texture,
                         const gfx::Size& src_size,
                         unsigned char* pixels,
                         SkColorType color_type) {
      DCHECK(color_type == kRGBA_8888_SkColorType ||
             color_type == kBGRA_8888_SkColorType);
      base::RunLoop run_loop;
      bool success = false;
      GLenum format;
      if (color_type == kRGBA_8888_SkColorType)
        format = GL_RGBA;
      else
        format = GL_BGRA_EXT;
  
      helper_->ReadbackTextureAsync(
          src_texture, GL_TEXTURE_2D, src_size, pixels, format,
          base::BindOnce(
              [](bool* success, base::OnceClosure callback, bool result) {
                *success = result;
                std::move(callback).Run();
              },
              &success, run_loop.QuitClosure()));
      run_loop.Run();
      return success;
    }
  
    // Test basic format readback.
    bool TestTextureFormatReadback(const gfx::Size& src_size,
                                   SkColorType color_type) {
      SkImageInfo info = SkImageInfo::Make(src_size.width(), src_size.height(),
                                           color_type, kPremul_SkAlphaType);
      GLuint src_texture;
      gl_->GenTextures(1, &src_texture);
      SkBitmap input_pixels;
      input_pixels.allocPixels(info);
      // Test Pattern-1, Fill with Plain color pattern.
      // Erase the input bitmap with red color.
      input_pixels.eraseColor(SK_ColorRED);
      BindAndAttachTextureWithPixels(src_texture, color_type, src_size,
                                     input_pixels);
      SkBitmap output_pixels;
      output_pixels.allocPixels(info);
      // Initialize the output bitmap with Green color.
      // When the readback is over output bitmap should have the red color.
      output_pixels.eraseColor(SK_ColorGREEN);
      uint8_t* pixels = static_cast<uint8_t*>(output_pixels.getPixels());
      if (!ReadBackTexture(src_texture, src_size, pixels, color_type) ||
          !IsEqual(input_pixels, output_pixels)) {
        LOG(ERROR) << "Bitmap comparison failure Pattern-1";
        return false;
      }
      const int rect_w = 10, rect_h = 4, src_grid_pitch = 10, src_grid_width = 4;
      const SkColor color1 = SK_ColorRED, color2 = SK_ColorBLUE;
      // Test Pattern-2, Fill with Grid Pattern.
      DrawGridToBitmap(src_size.width(), src_size.height(), color2, color1,
                       src_grid_pitch, src_grid_width, input_pixels);
      BindAndAttachTextureWithPixels(src_texture, color_type, src_size,
                                     input_pixels);
      if (!ReadBackTexture(src_texture, src_size, pixels, color_type) ||
          !IsEqual(input_pixels, output_pixels)) {
        LOG(ERROR) << "Bitmap comparison failure Pattern-2";
        return false;
      }
      // Test Pattern-3, Fill with CheckerBoard Pattern.
      DrawCheckerToBitmap(src_size.width(), src_size.height(), color1, color2,
                          rect_w, rect_h, input_pixels);
      BindAndAttachTextureWithPixels(src_texture, color_type, src_size,
                                     input_pixels);
      if (!ReadBackTexture(src_texture, src_size, pixels, color_type) ||
          !IsEqual(input_pixels, output_pixels)) {
        LOG(ERROR) << "Bitmap comparison failure Pattern-3";
        return false;
      }
      gl_->DeleteTextures(1, &src_texture);
      if (HasFailure()) {
        return false;
      }
      return true;
    }
  
    void TestAddOps(int src, int dst, bool scale_x, bool allow3) {
      base::circular_deque<GLHelperScaling::ScaleOp> ops;
      GLHelperScaling::ScaleOp::AddOps(src, dst, scale_x, allow3, &ops);
      // Scale factor 3 is a special case.
      // It is currently only allowed by itself.
      if (allow3 && dst * 3 >= src && dst * 2 < src) {
        EXPECT_EQ(ops[0].scale_factor, 3);
        EXPECT_EQ(ops.size(), 1U);
        EXPECT_EQ(ops[0].scale_x, scale_x);
        EXPECT_EQ(ops[0].scale_size, dst);
        return;
      }
  
      for (size_t i = 0; i < ops.size(); i++) {
        EXPECT_EQ(ops[i].scale_x, scale_x);
        if (i == 0) {
          // Only the first op is allowed to be a scale up.
          // (Scaling up *after* scaling down would make it fuzzy.)
          EXPECT_TRUE(ops[0].scale_factor == 0 || ops[0].scale_factor == 2);
        } else {
          // All other operations must be 50% downscales.
          EXPECT_EQ(ops[i].scale_factor, 2);
        }
      }
      // Check that the scale factors make sense and add up.
      int tmp = dst;
      for (int i = static_cast<int>(ops.size() - 1); i >= 0; i--) {
        EXPECT_EQ(tmp, ops[i].scale_size);
        if (ops[i].scale_factor == 0) {
          EXPECT_EQ(i, 0);
          EXPECT_GT(tmp, src);
          tmp = src;
        } else {
          tmp *= ops[i].scale_factor;
        }
      }
      EXPECT_EQ(tmp, src);
    }
  
    void CheckPipeline2(int xsize,
                        int ysize,
                        int dst_xsize,
                        int dst_ysize,
                        const std::string& description) {
      std::vector<GLHelperScaling::ScalerStage> stages;
      helper_scaling_->ConvertScalerOpsToScalerStages(
          GLHelper::SCALER_QUALITY_GOOD, gfx::Vector2d(xsize, ysize), &x_ops_,
          &y_ops_, &stages);
      EXPECT_EQ(x_ops_.size(), 0U);
      EXPECT_EQ(y_ops_.size(), 0U);
      ValidateScalerStages(GLHelper::SCALER_QUALITY_GOOD, stages,
                           gfx::Vector2d(xsize, ysize),
                           gfx::Vector2d(dst_xsize, dst_ysize), "");
      EXPECT_EQ(PrintStages(stages), description);
    }
  
    void CheckOptimizationsTest() {
      // Basic upscale. X and Y should be combined into one pass.
      x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 2000));
      y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 2000));
      CheckPipeline2(1024, 768, 2000, 2000, "1024x768 -> 2000x2000 bilinear\n");
  
      // X scaled 1/2, Y upscaled, should still be one pass.
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 512));
      y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 2000));
      CheckPipeline2(1024, 768, 512, 2000, "1024x768 -> 512x2000 bilinear\n");
  
      // X upscaled, Y scaled 1/2, one bilinear pass
      x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 2000));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 384));
      CheckPipeline2(1024, 768, 2000, 384, "1024x768 -> 2000x384 bilinear\n");
  
      // X scaled 1/2, Y scaled 1/2, one bilinear pass
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 512));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 384));
      CheckPipeline2(1024, 768, 512, 384, "1024x768 -> 512x384 bilinear\n");
  
      // X scaled 1/2, Y scaled to 60%, one bilinear2 pass.
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 50));
      y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
      CheckPipeline2(100, 100, 50, 60, "100x100 -> 50x60 bilinear2 Y\n");
  
      // X scaled to 60%, Y scaled 1/2, one bilinear2 pass.
      x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 120));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 60));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 50));
      CheckPipeline2(100, 100, 60, 50, "100x100 -> 60x50 bilinear2 X\n");
  
      // X scaled to 60%, Y scaled 60%, one bilinear2x2 pass.
      x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 120));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 60));
      y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
      CheckPipeline2(100, 100, 60, 60, "100x100 -> 60x60 bilinear2x2\n");
  
      // X scaled to 40%, Y scaled 40%, two bilinear3 passes.
      x_ops_.push_back(GLHelperScaling::ScaleOp(3, true, 40));
      y_ops_.push_back(GLHelperScaling::ScaleOp(3, false, 40));
      CheckPipeline2(100, 100, 40, 40,
                     "100x100 -> 100x40 bilinear3 Y\n"
                     "100x40 -> 40x40 bilinear3 X\n");
  
      // X scaled to 60%, Y scaled 40%
      x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 120));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 60));
      y_ops_.push_back(GLHelperScaling::ScaleOp(3, false, 40));
      CheckPipeline2(100, 100, 60, 40,
                     "100x100 -> 100x40 bilinear3 Y\n"
                     "100x40 -> 60x40 bilinear2 X\n");
  
      // X scaled to 40%, Y scaled 60%
      x_ops_.push_back(GLHelperScaling::ScaleOp(3, true, 40));
      y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
      CheckPipeline2(100, 100, 40, 60,
                     "100x100 -> 100x60 bilinear2 Y\n"
                     "100x60 -> 40x60 bilinear3 X\n");
  
      // X scaled to 30%, Y scaled 30%
      x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 120));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 60));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 30));
      y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 30));
      CheckPipeline2(100, 100, 30, 30,
                     "100x100 -> 100x30 bilinear4 Y\n"
                     "100x30 -> 30x30 bilinear4 X\n");
  
      // X scaled to 50%, Y scaled 30%
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 50));
      y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 30));
      CheckPipeline2(100, 100, 50, 30, "100x100 -> 50x30 bilinear4 Y\n");
  
      // X scaled to 150%, Y scaled 30%
      // Note that we avoid combinding X and Y passes
      // as that would probably be LESS efficient here.
      x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 150));
      y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 120));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 60));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 30));
      CheckPipeline2(100, 100, 150, 30,
                     "100x100 -> 100x30 bilinear4 Y\n"
                     "100x30 -> 150x30 bilinear\n");
  
      // X scaled to 1%, Y scaled 1%
      x_ops_.push_back(GLHelperScaling::ScaleOp(0, true, 128));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 64));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 32));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 16));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 8));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 4));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 2));
      x_ops_.push_back(GLHelperScaling::ScaleOp(2, true, 1));
      y_ops_.push_back(GLHelperScaling::ScaleOp(0, false, 128));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 64));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 32));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 16));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 8));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 4));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 2));
      y_ops_.push_back(GLHelperScaling::ScaleOp(2, false, 1));
      CheckPipeline2(100, 100, 1, 1,
                     "100x100 -> 100x32 bilinear4 Y\n"
                     "100x32 -> 100x4 bilinear4 Y\n"
                     "100x4 -> 64x1 bilinear2x2\n"
                     "64x1 -> 8x1 bilinear4 X\n"
                     "8x1 -> 1x1 bilinear4 X\n");
    }
  
    std::unique_ptr<GLInProcessContext> context_;
    gles2::GLES2Interface* gl_;
    std::unique_ptr<GLHelper> helper_;
    std::unique_ptr<GLHelperScaling> helper_scaling_;
    base::circular_deque<GLHelperScaling::ScaleOp> x_ops_, y_ops_;
  };
  
  class GLHelperPixelTest : public GLHelperTest {
   private:
    gl::DisableNullDrawGLBindings enable_pixel_output_;
  };
  
  TEST_F(GLHelperTest, RGBAASyncReadbackTest) {
    const int kTestSize = 64;
    bool result = TestTextureFormatReadback(gfx::Size(kTestSize, kTestSize),
                                            kRGBA_8888_SkColorType);
    EXPECT_EQ(result, true);
  }
  
  TEST_F(GLHelperTest, BGRAASyncReadbackTest) {
    const int kTestSize = 64;
    bool result = TestTextureFormatReadback(gfx::Size(kTestSize, kTestSize),
                                            kBGRA_8888_SkColorType);
    EXPECT_EQ(result, true);
  }
  
  int kRGBReadBackSizes[] = {3, 6, 16};
  
  class GLHelperPixelReadbackTest
      : public GLHelperPixelTest,
        public ::testing::WithParamInterface<std::tuple<unsigned int,
                                                        unsigned int,
                                                        unsigned int,
                                                        unsigned int,
                                                        unsigned int>> {};
  
  // Per pixel tests, all sizes are small so that we can print
  // out the generated bitmaps.
  TEST_P(GLHelperPixelReadbackTest, ScaleTest) {
    unsigned int q_index = std::get<0>(GetParam());
    unsigned int x = std::get<1>(GetParam());
    unsigned int y = std::get<2>(GetParam());
    unsigned int dst_x = std::get<3>(GetParam());
    unsigned int dst_y = std::get<4>(GetParam());
  
    for (int flip_output = 0; flip_output <= 1; ++flip_output) {
      for (int pattern = 0; pattern < 3; ++pattern) {
        for (int xoffset = 0; xoffset < 4; ++xoffset) {
          for (int yoffset = 0; yoffset < 4; ++yoffset) {
            TestScale(
                gfx::Rect(xoffset, yoffset, kRGBReadBackSizes[x],
                          kRGBReadBackSizes[y]),
                gfx::Size(kRGBReadBackSizes[dst_x], kRGBReadBackSizes[dst_y]),
                pattern, q_index, !!flip_output);
            if (HasFailure()) {
              return;
            }
          }
        }
      }
    }
  }
  
  // FLAKY: https://crbug.com/871799
  TEST_P(GLHelperPixelReadbackTest, DISABLED_ScalePatching) {
    for (int flipped_source = 0; flipped_source <= 1; ++flipped_source) {
      for (int pattern = 0; pattern < 3; ++pattern) {
        TestScalePatching(
            gfx::Vector2d(kRGBReadBackSizes[std::get<1>(GetParam())],
                          kRGBReadBackSizes[std::get<2>(GetParam())]),
            gfx::Vector2d(kRGBReadBackSizes[std::get<3>(GetParam())],
                          kRGBReadBackSizes[std::get<4>(GetParam())]),
            pattern, std::get<0>(GetParam()), !!flipped_source);
        if (HasFailure()) {
          return;
        }
      }
    }
  }
  
  INSTANTIATE_TEST_SUITE_P(
      All,
      GLHelperPixelReadbackTest,
      ::testing::Combine(
          ::testing::Range<unsigned int>(0, base::size(kQualities)),
          ::testing::Range<unsigned int>(0, base::size(kRGBReadBackSizes)),
          ::testing::Range<unsigned int>(0, base::size(kRGBReadBackSizes)),
          ::testing::Range<unsigned int>(0, base::size(kRGBReadBackSizes)),
          ::testing::Range<unsigned int>(0, base::size(kRGBReadBackSizes))));
  
  // Validate that all scaling generates valid pipelines.
  TEST_F(GLHelperTest, ValidateScalerPipelines) {
    int sizes[] = {7, 99, 128, 256, 512, 719, 720, 721, 1920, 2011, 3217, 4096};
    for (size_t q = 0; q < base::size(kQualities); q++) {
      for (size_t x = 0; x < base::size(sizes); x++) {
        for (size_t y = 0; y < base::size(sizes); y++) {
          for (size_t dst_x = 0; dst_x < base::size(sizes); dst_x++) {
            for (size_t dst_y = 0; dst_y < base::size(sizes); dst_y++) {
              TestScalerPipeline(q, sizes[x], sizes[y], sizes[dst_x],
                                 sizes[dst_y]);
              if (HasFailure()) {
                return;
              }
            }
          }
        }
      }
    }
  }
  
  // Make sure we don't create overly complicated pipelines
  // for a few common use cases.
  TEST_F(GLHelperTest, CheckSpecificPipelines) {
    // Upscale should be single pass.
    CheckPipeline(GLHelper::SCALER_QUALITY_GOOD, 1024, 700, 1280, 720,
                  "1024x700 -> 1280x720 bilinear\n");
    // Slight downscale should use BILINEAR2X2.
    CheckPipeline(GLHelper::SCALER_QUALITY_GOOD, 1280, 720, 1024, 700,
                  "1280x720 -> 1024x700 bilinear2x2\n");
    // Most common tab capture pipeline on the Pixel.
    // Should be using two BILINEAR3 passes.
    CheckPipeline(GLHelper::SCALER_QUALITY_GOOD, 2560, 1476, 1249, 720,
                  "2560x1476 -> 2560x720 bilinear3 Y\n"
                  "2560x720 -> 1249x720 bilinear3 X\n");
  }
  
  TEST_F(GLHelperTest, ScalerOpTest) {
    for (int allow3 = 0; allow3 <= 1; allow3++) {
      for (int dst = 1; dst < 2049; dst += 1 + (dst >> 3)) {
        for (int src = 1; src < 2049; src++) {
          TestAddOps(src, dst, allow3 == 1, (src & 1) == 1);
          if (HasFailure()) {
            LOG(ERROR) << "Failed for src=" << src << " dst=" << dst
                       << " allow3=" << allow3;
            return;
          }
        }
      }
    }
  }
  
  TEST_F(GLHelperTest, CheckOptimizations) {
    // Test in baseclass since it is friends with GLHelperScaling
    CheckOptimizationsTest();
  }
  
  }  // namespace gpu
  
  #endif  // OS_ANDROID
  