Revert of Introduce components/display_compositor

content/browser/compositor/gl_helper_scaling.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/compositor/gl_helper_scaling.h"
+
+#include <stddef.h>
+
+#include <deque>
+#include <string>
+#include <vector>
+
+#include "base/bind.h"
+#include "base/lazy_instance.h"
+#include "base/logging.h"
+#include "base/macros.h"
+#include "base/memory/ref_counted.h"
+#include "base/message_loop/message_loop.h"
+#include "base/time/time.h"
+#include "base/trace_event/trace_event.h"
+#include "gpu/command_buffer/client/gles2_interface.h"
+#include "third_party/skia/include/core/SkRegion.h"
+#include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/geometry/size.h"
+
+using gpu::gles2::GLES2Interface;
+
+namespace content {
+
+GLHelperScaling::GLHelperScaling(GLES2Interface* gl, GLHelper* helper)
+    : gl_(gl), helper_(helper), vertex_attributes_buffer_(gl_) {
+  InitBuffer();
+}
+
+GLHelperScaling::~GLHelperScaling() {}
+
+// Used to keep track of a generated shader program. The program
+// is passed in as text through Setup and is used by calling
+// UseProgram() with the right parameters. Note that |gl_|
+// and |helper_| are assumed to live longer than this program.
+class ShaderProgram : public base::RefCounted<ShaderProgram> {
+ public:
+  ShaderProgram(GLES2Interface* gl, GLHelper* helper)
+      : gl_(gl),
+        helper_(helper),
+        program_(gl_->CreateProgram()),
+        position_location_(-1),
+        texcoord_location_(-1),
+        src_subrect_location_(-1),
+        src_pixelsize_location_(-1),
+        dst_pixelsize_location_(-1),
+        scaling_vector_location_(-1),
+        color_weights_location_(-1) {}
+
+  // Compile shader program.
+  void Setup(const GLchar* vertex_shader_text,
+             const GLchar* fragment_shader_text);
+
+  // UseProgram must be called with GL_TEXTURE_2D bound to the
+  // source texture and GL_ARRAY_BUFFER bound to a vertex
+  // attribute buffer.
+  void UseProgram(const gfx::Size& src_size,
+                  const gfx::Rect& src_subrect,
+                  const gfx::Size& dst_size,
+                  bool scale_x,
+                  bool flip_y,
+                  GLfloat color_weights[4]);
+
+  bool Initialized() const { return position_location_ != -1; }
+
+ private:
+  friend class base::RefCounted<ShaderProgram>;
+  ~ShaderProgram() { gl_->DeleteProgram(program_); }
+
+  GLES2Interface* gl_;
+  GLHelper* helper_;
+
+  // A program for copying a source texture into a destination texture.
+  GLuint program_;
+
+  // The location of the position in the program.
+  GLint position_location_;
+  // The location of the texture coordinate in the program.
+  GLint texcoord_location_;
+  // The location of the source texture in the program.
+  GLint texture_location_;
+  // The location of the texture coordinate of
+  // the sub-rectangle in the program.
+  GLint src_subrect_location_;
+  // Location of size of source image in pixels.
+  GLint src_pixelsize_location_;
+  // Location of size of destination image in pixels.
+  GLint dst_pixelsize_location_;
+  // Location of vector for scaling direction.
+  GLint scaling_vector_location_;
+  // Location of color weights.
+  GLint color_weights_location_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShaderProgram);
+};
+
+// Implementation of a single stage in a scaler pipeline. If the pipeline has
+// multiple stages, it calls Scale() on the subscaler, then further scales the
+// output. Caches textures and framebuffers to avoid allocating/deleting
+// them once per frame, which can be expensive on some drivers.
+class ScalerImpl : public GLHelper::ScalerInterface,
+                   public GLHelperScaling::ShaderInterface {
+ public:
+  // |gl| and |copy_impl| are expected to live longer than this object.
+  // |src_size| is the size of the input texture in pixels.
+  // |dst_size| is the size of the output texutre in pixels.
+  // |src_subrect| is the portion of the src to copy to the output texture.
+  // If |scale_x| is true, we are scaling along the X axis, otherwise Y.
+  // If we are scaling in both X and Y, |scale_x| is ignored.
+  // If |vertically_flip_texture| is true, output will be upside-down.
+  // If |swizzle| is true, RGBA will be transformed into BGRA.
+  // |color_weights| are only used together with SHADER_PLANAR to specify
+  //   how to convert RGB colors into a single value.
+  ScalerImpl(GLES2Interface* gl,
+             GLHelperScaling* scaler_helper,
+             const GLHelperScaling::ScalerStage& scaler_stage,
+             ScalerImpl* subscaler,
+             const float* color_weights)
+      : gl_(gl),
+        scaler_helper_(scaler_helper),
+        spec_(scaler_stage),
+        intermediate_texture_(0),
+        dst_framebuffer_(gl),
+        subscaler_(subscaler) {
+    if (color_weights) {
+      color_weights_[0] = color_weights[0];
+      color_weights_[1] = color_weights[1];
+      color_weights_[2] = color_weights[2];
+      color_weights_[3] = color_weights[3];
+    } else {
+      color_weights_[0] = 0.0;
+      color_weights_[1] = 0.0;
+      color_weights_[2] = 0.0;
+      color_weights_[3] = 0.0;
+    }
+    shader_program_ =
+        scaler_helper_->GetShaderProgram(spec_.shader, spec_.swizzle);
+
+    if (subscaler_) {
+      intermediate_texture_ = 0u;
+      gl_->GenTextures(1, &intermediate_texture_);
+      ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_,
+                                                        intermediate_texture_);
+      gl_->TexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, spec_.src_size.width(),
+                      spec_.src_size.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE,
+                      NULL);
+    }
+  }
+
+  ~ScalerImpl() override {
+    if (intermediate_texture_) {
+      gl_->DeleteTextures(1, &intermediate_texture_);
+    }
+  }
+
+  // GLHelperShader::ShaderInterface implementation.
+  void Execute(GLuint source_texture,
+               const std::vector<GLuint>& dest_textures) override {
+    if (subscaler_) {
+      subscaler_->Scale(source_texture, intermediate_texture_);
+      source_texture = intermediate_texture_;
+    }
+
+    ScopedFramebufferBinder<GL_FRAMEBUFFER> framebuffer_binder(
+        gl_, dst_framebuffer_);
+    DCHECK_GT(dest_textures.size(), 0U);
+    std::unique_ptr<GLenum[]> buffers(new GLenum[dest_textures.size()]);
+    for (size_t t = 0; t < dest_textures.size(); t++) {
+      ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_, dest_textures[t]);
+      gl_->FramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + t,
+                                GL_TEXTURE_2D, dest_textures[t], 0);
+      buffers[t] = GL_COLOR_ATTACHMENT0 + t;
+    }
+    ScopedTextureBinder<GL_TEXTURE_2D> texture_binder(gl_, source_texture);
+
+    gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+    gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+    gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+    gl_->TexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+
+    ScopedBufferBinder<GL_ARRAY_BUFFER> buffer_binder(
+        gl_, scaler_helper_->vertex_attributes_buffer_);
+    shader_program_->UseProgram(spec_.src_size, spec_.src_subrect,
+                                spec_.dst_size, spec_.scale_x,
+                                spec_.vertically_flip_texture, color_weights_);
+    gl_->Viewport(0, 0, spec_.dst_size.width(), spec_.dst_size.height());
+
+    if (dest_textures.size() > 1) {
+      DCHECK_LE(static_cast<int>(dest_textures.size()),
+                scaler_helper_->helper_->MaxDrawBuffers());
+      gl_->DrawBuffersEXT(dest_textures.size(), buffers.get());
+    }
+    // Conduct texture mapping by drawing a quad composed of two triangles.
+    gl_->DrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    if (dest_textures.size() > 1) {
+      // Set the draw buffers back to not confuse others.
+      gl_->DrawBuffersEXT(1, &buffers[0]);
+    }
+  }
+
+  // GLHelper::ScalerInterface implementation.
+  void Scale(GLuint source_texture, GLuint dest_texture) override {
+    std::vector<GLuint> tmp(1);
+    tmp[0] = dest_texture;
+    Execute(source_texture, tmp);
+  }
+
+  const gfx::Size& SrcSize() override {
+    if (subscaler_) {
+      return subscaler_->SrcSize();
+    }
+    return spec_.src_size;
+  }
+  const gfx::Rect& SrcSubrect() override {
+    if (subscaler_) {
+      return subscaler_->SrcSubrect();
+    }
+    return spec_.src_subrect;
+  }
+  const gfx::Size& DstSize() override { return spec_.dst_size; }
+
+ private:
+  GLES2Interface* gl_;
+  GLHelperScaling* scaler_helper_;
+  GLHelperScaling::ScalerStage spec_;
+  GLfloat color_weights_[4];
+  GLuint intermediate_texture_;
+  scoped_refptr<ShaderProgram> shader_program_;
+  ScopedFramebuffer dst_framebuffer_;
+  std::unique_ptr<ScalerImpl> subscaler_;
+};
+
+GLHelperScaling::ScalerStage::ScalerStage(ShaderType shader_,
+                                          gfx::Size src_size_,
+                                          gfx::Rect src_subrect_,
+                                          gfx::Size dst_size_,
+                                          bool scale_x_,
+                                          bool vertically_flip_texture_,
+                                          bool swizzle_)
+    : shader(shader_),
+      src_size(src_size_),
+      src_subrect(src_subrect_),
+      dst_size(dst_size_),
+      scale_x(scale_x_),
+      vertically_flip_texture(vertically_flip_texture_),
+      swizzle(swizzle_) {}
+
+GLHelperScaling::ScalerStage::ScalerStage(const ScalerStage& other) = default;
+
+// The important inputs for this function is |x_ops| and
+// |y_ops|. They represent scaling operations to be done
+// on an imag of size |src_size|. If |quality| is SCALER_QUALITY_BEST,
+// then we will interpret these scale operations literally and we'll
+// create one scaler stage for each ScaleOp.  However, if |quality|
+// is SCALER_QUALITY_GOOD, then we can do a whole bunch of optimizations
+// by combining two or more ScaleOps in to a single scaler stage.
+// Normally we process ScaleOps from |y_ops| first and |x_ops| after
+// all |y_ops| are processed, but sometimes we can combine one or more
+// operation from both queues essentially for free. This is the reason
+// why |x_ops| and |y_ops| aren't just one single queue.
+void GLHelperScaling::ConvertScalerOpsToScalerStages(
+    GLHelper::ScalerQuality quality,
+    gfx::Size src_size,
+    gfx::Rect src_subrect,
+    const gfx::Size& dst_size,
+    bool vertically_flip_texture,
+    bool swizzle,
+    std::deque<GLHelperScaling::ScaleOp>* x_ops,
+    std::deque<GLHelperScaling::ScaleOp>* y_ops,
+    std::vector<ScalerStage>* scaler_stages) {
+  while (!x_ops->empty() || !y_ops->empty()) {
+    gfx::Size intermediate_size = src_subrect.size();
+    std::deque<ScaleOp>* current_queue = NULL;
+
+    if (!y_ops->empty()) {
+      current_queue = y_ops;
+    } else {
+      current_queue = x_ops;
+    }
+
+    ShaderType current_shader = SHADER_BILINEAR;
+    switch (current_queue->front().scale_factor) {
+      case 0:
+        if (quality == GLHelper::SCALER_QUALITY_BEST) {
+          current_shader = SHADER_BICUBIC_UPSCALE;
+        }
+        break;
+      case 2:
+        if (quality == GLHelper::SCALER_QUALITY_BEST) {
+          current_shader = SHADER_BICUBIC_HALF_1D;
+        }
+        break;
+      case 3:
+        DCHECK(quality != GLHelper::SCALER_QUALITY_BEST);
+        current_shader = SHADER_BILINEAR3;
+        break;
+      default:
+        NOTREACHED();
+    }
+    bool scale_x = current_queue->front().scale_x;
+    current_queue->front().UpdateSize(&intermediate_size);
+    current_queue->pop_front();
+
+    // Optimization: Sometimes we can combine 2-4 scaling operations into
+    // one operation.
+    if (quality == GLHelper::SCALER_QUALITY_GOOD) {
+      if (!current_queue->empty() && current_shader == SHADER_BILINEAR) {
+        // Combine two steps in the same dimension.
+        current_queue->front().UpdateSize(&intermediate_size);
+        current_queue->pop_front();
+        current_shader = SHADER_BILINEAR2;
+        if (!current_queue->empty()) {
+          // Combine three steps in the same dimension.
+          current_queue->front().UpdateSize(&intermediate_size);
+          current_queue->pop_front();
+          current_shader = SHADER_BILINEAR4;
+        }
+      }
+      // Check if we can combine some steps in the other dimension as well.
+      // Since all shaders currently use GL_LINEAR, we can easily scale up
+      // or scale down by exactly 2x at the same time as we do another
+      // operation. Currently, the following mergers are supported:
+      // * 1 bilinear Y-pass with 1 bilinear X-pass (up or down)
+      // * 2 bilinear Y-passes with 2 bilinear X-passes
+      // * 1 bilinear Y-pass with N bilinear X-pass
+      // * N bilinear Y-passes with 1 bilinear X-pass (down only)
+      // Measurements indicate that generalizing this for 3x3 and 4x4
+      // makes it slower on some platforms, such as the Pixel.
+      if (!scale_x && x_ops->size() > 0 && x_ops->front().scale_factor <= 2) {
+        int x_passes = 0;
+        if (current_shader == SHADER_BILINEAR2 && x_ops->size() >= 2) {
+          // 2y + 2x passes
+          x_passes = 2;
+          current_shader = SHADER_BILINEAR2X2;
+        } else if (current_shader == SHADER_BILINEAR) {
+          // 1y + Nx passes
+          scale_x = true;
+          switch (x_ops->size()) {
+            case 0:
+              NOTREACHED();
+            case 1:
+              if (x_ops->front().scale_factor == 3) {
+                current_shader = SHADER_BILINEAR3;
+              }
+              x_passes = 1;
+              break;
+            case 2:
+              x_passes = 2;
+              current_shader = SHADER_BILINEAR2;
+              break;
+            default:
+              x_passes = 3;
+              current_shader = SHADER_BILINEAR4;
+              break;
+          }
+        } else if (x_ops->front().scale_factor == 2) {
+          // Ny + 1x-downscale
+          x_passes = 1;
+        }
+
+        for (int i = 0; i < x_passes; i++) {
+          x_ops->front().UpdateSize(&intermediate_size);
+          x_ops->pop_front();
+        }
+      }
+    }
+
+    scaler_stages->push_back(ScalerStage(current_shader, src_size, src_subrect,
+                                         intermediate_size, scale_x,
+                                         vertically_flip_texture, swizzle));
+    src_size = intermediate_size;
+    src_subrect = gfx::Rect(intermediate_size);
+    vertically_flip_texture = false;
+    swizzle = false;
+  }
+}
+
+void GLHelperScaling::ComputeScalerStages(
+    GLHelper::ScalerQuality quality,
+    const gfx::Size& src_size,
+    const gfx::Rect& src_subrect,
+    const gfx::Size& dst_size,
+    bool vertically_flip_texture,
+    bool swizzle,
+    std::vector<ScalerStage>* scaler_stages) {
+  if (quality == GLHelper::SCALER_QUALITY_FAST ||
+      src_subrect.size() == dst_size) {
+    scaler_stages->push_back(ScalerStage(SHADER_BILINEAR, src_size, src_subrect,
+                                         dst_size, false,
+                                         vertically_flip_texture, swizzle));
+    return;
+  }
+
+  std::deque<GLHelperScaling::ScaleOp> x_ops, y_ops;
+  GLHelperScaling::ScaleOp::AddOps(src_subrect.width(), dst_size.width(), true,
+                                   quality == GLHelper::SCALER_QUALITY_GOOD,
+                                   &x_ops);
+  GLHelperScaling::ScaleOp::AddOps(
+      src_subrect.height(), dst_size.height(), false,
+      quality == GLHelper::SCALER_QUALITY_GOOD, &y_ops);
+
+  ConvertScalerOpsToScalerStages(quality, src_size, src_subrect, dst_size,
+                                 vertically_flip_texture, swizzle, &x_ops,
+                                 &y_ops, scaler_stages);
+}
+
+GLHelper::ScalerInterface* GLHelperScaling::CreateScaler(
+    GLHelper::ScalerQuality quality,
+    gfx::Size src_size,
+    gfx::Rect src_subrect,
+    const gfx::Size& dst_size,
+    bool vertically_flip_texture,
+    bool swizzle) {
+  std::vector<ScalerStage> scaler_stages;
+  ComputeScalerStages(quality, src_size, src_subrect, dst_size,
+                      vertically_flip_texture, swizzle, &scaler_stages);
+
+  ScalerImpl* ret = NULL;
+  for (unsigned int i = 0; i < scaler_stages.size(); i++) {
+    ret = new ScalerImpl(gl_, this, scaler_stages[i], ret, NULL);
+  }
+  return ret;
+}
+
+GLHelper::ScalerInterface* GLHelperScaling::CreatePlanarScaler(
+    const gfx::Size& src_size,
+    const gfx::Rect& src_subrect,
+    const gfx::Size& dst_size,
+    bool vertically_flip_texture,
+    bool swizzle,
+    const float color_weights[4]) {
+  ScalerStage stage(SHADER_PLANAR, src_size, src_subrect, dst_size, true,
+                    vertically_flip_texture, swizzle);
+  return new ScalerImpl(gl_, this, stage, NULL, color_weights);
+}
+
+GLHelperScaling::ShaderInterface* GLHelperScaling::CreateYuvMrtShader(
+    const gfx::Size& src_size,
+    const gfx::Rect& src_subrect,
+    const gfx::Size& dst_size,
+    bool vertically_flip_texture,
+    bool swizzle,
+    ShaderType shader) {
+  DCHECK(shader == SHADER_YUV_MRT_PASS1 || shader == SHADER_YUV_MRT_PASS2);
+  ScalerStage stage(shader, src_size, src_subrect, dst_size, true,
+                    vertically_flip_texture, swizzle);
+  return new ScalerImpl(gl_, this, stage, NULL, NULL);
+}
+
+const GLfloat GLHelperScaling::kVertexAttributes[] = {
+    -1.0f, -1.0f, 0.0f, 0.0f,  // vertex 0
+    1.0f,  -1.0f, 1.0f, 0.0f,  // vertex 1
+    -1.0f, 1.0f,  0.0f, 1.0f,  // vertex 2
+    1.0f,  1.0f,  1.0f, 1.0f,
+};  // vertex 3
+
+void GLHelperScaling::InitBuffer() {
+  ScopedBufferBinder<GL_ARRAY_BUFFER> buffer_binder(gl_,
+                                                    vertex_attributes_buffer_);
+  gl_->BufferData(GL_ARRAY_BUFFER, sizeof(kVertexAttributes), kVertexAttributes,
+                  GL_STATIC_DRAW);
+}
+
+scoped_refptr<ShaderProgram> GLHelperScaling::GetShaderProgram(ShaderType type,
+                                                               bool swizzle) {
+  ShaderProgramKeyType key(type, swizzle);
+  scoped_refptr<ShaderProgram>& cache_entry(shader_programs_[key]);
+  if (!cache_entry.get()) {
+    cache_entry = new ShaderProgram(gl_, helper_);
+    std::basic_string<GLchar> vertex_program;
+    std::basic_string<GLchar> fragment_program;
+    std::basic_string<GLchar> vertex_header;
+    std::basic_string<GLchar> fragment_directives;
+    std::basic_string<GLchar> fragment_header;
+    std::basic_string<GLchar> shared_variables;
+
+    vertex_header.append(
+        "precision highp float;\n"
+        "attribute vec2 a_position;\n"
+        "attribute vec2 a_texcoord;\n"
+        "uniform vec4 src_subrect;\n");
+
+    fragment_header.append(
+        "precision mediump float;\n"
+        "uniform sampler2D s_texture;\n");
+
+    vertex_program.append(
+        "  gl_Position = vec4(a_position, 0.0, 1.0);\n"
+        "  vec2 texcoord = src_subrect.xy + a_texcoord * src_subrect.zw;\n");
+
+    switch (type) {
+      case SHADER_BILINEAR:
+        shared_variables.append("varying vec2 v_texcoord;\n");
+        vertex_program.append("  v_texcoord = texcoord;\n");
+        fragment_program.append(
+            "  gl_FragColor = texture2D(s_texture, v_texcoord);\n");
+        break;
+
+      case SHADER_BILINEAR2:
+        // This is equivialent to two passes of the BILINEAR shader above.
+        // It can be used to scale an image down 1.0x-2.0x in either dimension,
+        // or exactly 4x.
+        shared_variables.append(
+            "varying vec4 v_texcoords;\n");  // 2 texcoords packed in one quad
+        vertex_header.append(
+            "uniform vec2 scaling_vector;\n"
+            "uniform vec2 dst_pixelsize;\n");
+        vertex_program.append(
+            "  vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
+            "  step /= 4.0;\n"
+            "  v_texcoords.xy = texcoord + step;\n"
+            "  v_texcoords.zw = texcoord - step;\n");
+
+        fragment_program.append(
+            "  gl_FragColor = (texture2D(s_texture, v_texcoords.xy) +\n"
+            "                  texture2D(s_texture, v_texcoords.zw)) / 2.0;\n");
+        break;
+
+      case SHADER_BILINEAR3:
+        // This is kind of like doing 1.5 passes of the BILINEAR shader.
+        // It can be used to scale an image down 1.5x-3.0x, or exactly 6x.
+        shared_variables.append(
+            "varying vec4 v_texcoords1;\n"  // 2 texcoords packed in one quad
+            "varying vec2 v_texcoords2;\n");
+        vertex_header.append(
+            "uniform vec2 scaling_vector;\n"
+            "uniform vec2 dst_pixelsize;\n");
+        vertex_program.append(
+            "  vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
+            "  step /= 3.0;\n"
+            "  v_texcoords1.xy = texcoord + step;\n"
+            "  v_texcoords1.zw = texcoord;\n"
+            "  v_texcoords2 = texcoord - step;\n");
+        fragment_program.append(
+            "  gl_FragColor = (texture2D(s_texture, v_texcoords1.xy) +\n"
+            "                  texture2D(s_texture, v_texcoords1.zw) +\n"
+            "                  texture2D(s_texture, v_texcoords2)) / 3.0;\n");
+        break;
+
+      case SHADER_BILINEAR4:
+        // This is equivialent to three passes of the BILINEAR shader above,
+        // It can be used to scale an image down 2.0x-4.0x or exactly 8x.
+        shared_variables.append("varying vec4 v_texcoords[2];\n");
+        vertex_header.append(
+            "uniform vec2 scaling_vector;\n"
+            "uniform vec2 dst_pixelsize;\n");
+        vertex_program.append(
+            "  vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
+            "  step /= 8.0;\n"
+            "  v_texcoords[0].xy = texcoord - step * 3.0;\n"
+            "  v_texcoords[0].zw = texcoord - step;\n"
+            "  v_texcoords[1].xy = texcoord + step;\n"
+            "  v_texcoords[1].zw = texcoord + step * 3.0;\n");
+        fragment_program.append(
+            "  gl_FragColor = (\n"
+            "      texture2D(s_texture, v_texcoords[0].xy) +\n"
+            "      texture2D(s_texture, v_texcoords[0].zw) +\n"
+            "      texture2D(s_texture, v_texcoords[1].xy) +\n"
+            "      texture2D(s_texture, v_texcoords[1].zw)) / 4.0;\n");
+        break;
+
+      case SHADER_BILINEAR2X2:
+        // This is equivialent to four passes of the BILINEAR shader above.
+        // Two in each dimension. It can be used to scale an image down
+        // 1.0x-2.0x in both X and Y directions. Or, it could be used to
+        // scale an image down by exactly 4x in both dimensions.
+        shared_variables.append("varying vec4 v_texcoords[2];\n");
+        vertex_header.append("uniform vec2 dst_pixelsize;\n");
+        vertex_program.append(
+            "  vec2 step = src_subrect.zw / 4.0 / dst_pixelsize;\n"
+            "  v_texcoords[0].xy = texcoord + vec2(step.x, step.y);\n"
+            "  v_texcoords[0].zw = texcoord + vec2(step.x, -step.y);\n"
+            "  v_texcoords[1].xy = texcoord + vec2(-step.x, step.y);\n"
+            "  v_texcoords[1].zw = texcoord + vec2(-step.x, -step.y);\n");
+        fragment_program.append(
+            "  gl_FragColor = (\n"
+            "      texture2D(s_texture, v_texcoords[0].xy) +\n"
+            "      texture2D(s_texture, v_texcoords[0].zw) +\n"
+            "      texture2D(s_texture, v_texcoords[1].xy) +\n"
+            "      texture2D(s_texture, v_texcoords[1].zw)) / 4.0;\n");
+        break;
+
+      case SHADER_BICUBIC_HALF_1D:
+        // This scales down texture by exactly half in one dimension.
+        // directions in one pass. We use bilinear lookup to reduce
+        // the number of texture reads from 8 to 4
+        shared_variables.append(
+            "const float CenterDist = 99.0 / 140.0;\n"
+            "const float LobeDist = 11.0 / 4.0;\n"
+            "const float CenterWeight = 35.0 / 64.0;\n"
+            "const float LobeWeight = -3.0 / 64.0;\n"
+            "varying vec4 v_texcoords[2];\n");
+        vertex_header.append(
+            "uniform vec2 scaling_vector;\n"
+            "uniform vec2 src_pixelsize;\n");
+        vertex_program.append(
+            "  vec2 step = src_subrect.zw * scaling_vector / src_pixelsize;\n"
+            "  v_texcoords[0].xy = texcoord - LobeDist * step;\n"
+            "  v_texcoords[0].zw = texcoord - CenterDist * step;\n"
+            "  v_texcoords[1].xy = texcoord + CenterDist * step;\n"
+            "  v_texcoords[1].zw = texcoord + LobeDist * step;\n");
+        fragment_program.append(
+            "  gl_FragColor = \n"
+            // Lobe pixels
+            "      (texture2D(s_texture, v_texcoords[0].xy) +\n"
+            "       texture2D(s_texture, v_texcoords[1].zw)) *\n"
+            "          LobeWeight +\n"
+            // Center pixels
+            "      (texture2D(s_texture, v_texcoords[0].zw) +\n"
+            "       texture2D(s_texture, v_texcoords[1].xy)) *\n"
+            "          CenterWeight;\n");
+        break;
+
+      case SHADER_BICUBIC_UPSCALE:
+        // When scaling up, we need 4 texture reads, but we can
+        // save some instructions because will know in which range of
+        // the bicubic function each call call to the bicubic function
+        // will be in.
+        // Also, when sampling the bicubic function like this, the sum
+        // is always exactly one, so we can skip normalization as well.
+        shared_variables.append("varying vec2 v_texcoord;\n");
+        vertex_program.append("  v_texcoord = texcoord;\n");
+        fragment_header.append(
+            "uniform vec2 src_pixelsize;\n"
+            "uniform vec2 scaling_vector;\n"
+            "const float a = -0.5;\n"
+            // This function is equivialent to calling the bicubic
+            // function with x-1, x, 1-x and 2-x
+            // (assuming 0 <= x < 1)
+            "vec4 filt4(float x) {\n"
+            "  return vec4(x * x * x, x * x, x, 1) *\n"
+            "         mat4(       a,      -2.0 * a,   a, 0.0,\n"
+            "               a + 2.0,      -a - 3.0, 0.0, 1.0,\n"
+            "              -a - 2.0, 3.0 + 2.0 * a,  -a, 0.0,\n"
+            "                    -a,             a, 0.0, 0.0);\n"
+            "}\n"
+            "mat4 pixels_x(vec2 pos, vec2 step) {\n"
+            "  return mat4(\n"
+            "      texture2D(s_texture, pos - step),\n"
+            "      texture2D(s_texture, pos),\n"
+            "      texture2D(s_texture, pos + step),\n"
+            "      texture2D(s_texture, pos + step * 2.0));\n"
+            "}\n");
+        fragment_program.append(
+            "  vec2 pixel_pos = v_texcoord * src_pixelsize - \n"
+            "      scaling_vector / 2.0;\n"
+            "  float frac = fract(dot(pixel_pos, scaling_vector));\n"
+            "  vec2 base = (floor(pixel_pos) + vec2(0.5)) / src_pixelsize;\n"
+            "  vec2 step = scaling_vector / src_pixelsize;\n"
+            "  gl_FragColor = pixels_x(base, step) * filt4(frac);\n");
+        break;
+
+      case SHADER_PLANAR:
+        // Converts four RGBA pixels into one pixel. Each RGBA
+        // pixel will be dot-multiplied with the color weights and
+        // then placed into a component of the output. This is used to
+        // convert RGBA textures into Y, U and V textures. We do this
+        // because single-component textures are not renderable on all
+        // architectures.
+        shared_variables.append("varying vec4 v_texcoords[2];\n");
+        vertex_header.append(
+            "uniform vec2 scaling_vector;\n"
+            "uniform vec2 dst_pixelsize;\n");
+        vertex_program.append(
+            "  vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
+            "  step /= 4.0;\n"
+            "  v_texcoords[0].xy = texcoord - step * 1.5;\n"
+            "  v_texcoords[0].zw = texcoord - step * 0.5;\n"
+            "  v_texcoords[1].xy = texcoord + step * 0.5;\n"
+            "  v_texcoords[1].zw = texcoord + step * 1.5;\n");
+        fragment_header.append("uniform vec4 color_weights;\n");
+        fragment_program.append(
+            "  gl_FragColor = color_weights * mat4(\n"
+            "    vec4(texture2D(s_texture, v_texcoords[0].xy).rgb, 1.0),\n"
+            "    vec4(texture2D(s_texture, v_texcoords[0].zw).rgb, 1.0),\n"
+            "    vec4(texture2D(s_texture, v_texcoords[1].xy).rgb, 1.0),\n"
+            "    vec4(texture2D(s_texture, v_texcoords[1].zw).rgb, 1.0));\n");
+        break;
+
+      case SHADER_YUV_MRT_PASS1:
+        // RGB24 to YV12 in two passes; writing two 8888 targets each pass.
+        //
+        // YV12 is full-resolution luma and half-resolution blue/red chroma.
+        //
+        //                  (original)
+        //    RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
+        //    RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
+        //    RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
+        //    RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
+        //    RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
+        //    RGBX RGBX RGBX RGBX RGBX RGBX RGBX RGBX
+        //      |
+        //      |      (y plane)    (temporary)
+        //      |      YYYY YYYY     UUVV UUVV
+        //      +--> { YYYY YYYY  +  UUVV UUVV }
+        //             YYYY YYYY     UUVV UUVV
+        //   First     YYYY YYYY     UUVV UUVV
+        //    pass     YYYY YYYY     UUVV UUVV
+        //             YYYY YYYY     UUVV UUVV
+        //                              |
+        //                              |  (u plane) (v plane)
+        //   Second                     |      UUUU   VVVV
+        //     pass                     +--> { UUUU + VVVV }
+        //                                     UUUU   VVVV
+        //
+        shared_variables.append("varying vec4 v_texcoords[2];\n");
+        vertex_header.append(
+            "uniform vec2 scaling_vector;\n"
+            "uniform vec2 dst_pixelsize;\n");
+        vertex_program.append(
+            "  vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
+            "  step /= 4.0;\n"
+            "  v_texcoords[0].xy = texcoord - step * 1.5;\n"
+            "  v_texcoords[0].zw = texcoord - step * 0.5;\n"
+            "  v_texcoords[1].xy = texcoord + step * 0.5;\n"
+            "  v_texcoords[1].zw = texcoord + step * 1.5;\n");
+        fragment_directives.append("#extension GL_EXT_draw_buffers : enable\n");
+        fragment_header.append(
+            "const vec3 kRGBtoY = vec3(0.257, 0.504, 0.098);\n"
+            "const float kYBias = 0.0625;\n"
+            // Divide U and V by two to compensate for averaging below.
+            "const vec3 kRGBtoU = vec3(-0.148, -0.291, 0.439) / 2.0;\n"
+            "const vec3 kRGBtoV = vec3(0.439, -0.368, -0.071) / 2.0;\n"
+            "const float kUVBias = 0.5;\n");
+        fragment_program.append(
+            "  vec3 pixel1 = texture2D(s_texture, v_texcoords[0].xy).rgb;\n"
+            "  vec3 pixel2 = texture2D(s_texture, v_texcoords[0].zw).rgb;\n"
+            "  vec3 pixel3 = texture2D(s_texture, v_texcoords[1].xy).rgb;\n"
+            "  vec3 pixel4 = texture2D(s_texture, v_texcoords[1].zw).rgb;\n"
+            "  vec3 pixel12 = pixel1 + pixel2;\n"
+            "  vec3 pixel34 = pixel3 + pixel4;\n"
+            "  gl_FragData[0] = vec4(dot(pixel1, kRGBtoY),\n"
+            "                        dot(pixel2, kRGBtoY),\n"
+            "                        dot(pixel3, kRGBtoY),\n"
+            "                        dot(pixel4, kRGBtoY)) + kYBias;\n"
+            "  gl_FragData[1] = vec4(dot(pixel12, kRGBtoU),\n"
+            "                        dot(pixel34, kRGBtoU),\n"
+            "                        dot(pixel12, kRGBtoV),\n"
+            "                        dot(pixel34, kRGBtoV)) + kUVBias;\n");
+        break;
+
+      case SHADER_YUV_MRT_PASS2:
+        // We're just sampling two pixels and unswizzling them.  There's
+        // no need to do vertical scaling with math, since bilinear
+        // interpolation in the sampler takes care of that.
+        shared_variables.append("varying vec4 v_texcoords;\n");
+        vertex_header.append(
+            "uniform vec2 scaling_vector;\n"
+            "uniform vec2 dst_pixelsize;\n");
+        vertex_program.append(
+            "  vec2 step = scaling_vector * src_subrect.zw / dst_pixelsize;\n"
+            "  step /= 2.0;\n"
+            "  v_texcoords.xy = texcoord - step * 0.5;\n"
+            "  v_texcoords.zw = texcoord + step * 0.5;\n");
+        fragment_directives.append("#extension GL_EXT_draw_buffers : enable\n");
+        fragment_program.append(
+            "  vec4 lo_uuvv = texture2D(s_texture, v_texcoords.xy);\n"
+            "  vec4 hi_uuvv = texture2D(s_texture, v_texcoords.zw);\n"
+            "  gl_FragData[0] = vec4(lo_uuvv.rg, hi_uuvv.rg);\n"
+            "  gl_FragData[1] = vec4(lo_uuvv.ba, hi_uuvv.ba);\n");
+        break;
+    }
+    if (swizzle) {
+      switch (type) {
+        case SHADER_YUV_MRT_PASS1:
+          fragment_program.append("  gl_FragData[0] = gl_FragData[0].bgra;\n");
+          break;
+        case SHADER_YUV_MRT_PASS2:
+          fragment_program.append("  gl_FragData[0] = gl_FragData[0].bgra;\n");
+          fragment_program.append("  gl_FragData[1] = gl_FragData[1].bgra;\n");
+          break;
+        default:
+          fragment_program.append("  gl_FragColor = gl_FragColor.bgra;\n");
+          break;
+      }
+    }
+
+    vertex_program = vertex_header + shared_variables + "void main() {\n" +
+                     vertex_program + "}\n";
+
+    fragment_program = fragment_directives + fragment_header +
+                       shared_variables + "void main() {\n" + fragment_program +
+                       "}\n";
+
+    cache_entry->Setup(vertex_program.c_str(), fragment_program.c_str());
+  }
+  return cache_entry;
+}
+
+void ShaderProgram::Setup(const GLchar* vertex_shader_text,
+                          const GLchar* fragment_shader_text) {
+  // Shaders to map the source texture to |dst_texture_|.
+  GLuint vertex_shader =
+      helper_->CompileShaderFromSource(vertex_shader_text, GL_VERTEX_SHADER);
+  if (vertex_shader == 0)
+    return;
+
+  gl_->AttachShader(program_, vertex_shader);
+  gl_->DeleteShader(vertex_shader);
+
+  GLuint fragment_shader = helper_->CompileShaderFromSource(
+      fragment_shader_text, GL_FRAGMENT_SHADER);
+  if (fragment_shader == 0)
+    return;
+  gl_->AttachShader(program_, fragment_shader);
+  gl_->DeleteShader(fragment_shader);
+
+  gl_->LinkProgram(program_);
+
+  GLint link_status = 0;
+  gl_->GetProgramiv(program_, GL_LINK_STATUS, &link_status);
+  if (!link_status)
+    return;
+
+  position_location_ = gl_->GetAttribLocation(program_, "a_position");
+  texcoord_location_ = gl_->GetAttribLocation(program_, "a_texcoord");
+  texture_location_ = gl_->GetUniformLocation(program_, "s_texture");
+  src_subrect_location_ = gl_->GetUniformLocation(program_, "src_subrect");
+  src_pixelsize_location_ = gl_->GetUniformLocation(program_, "src_pixelsize");
+  dst_pixelsize_location_ = gl_->GetUniformLocation(program_, "dst_pixelsize");
+  scaling_vector_location_ =
+      gl_->GetUniformLocation(program_, "scaling_vector");
+  color_weights_location_ = gl_->GetUniformLocation(program_, "color_weights");
+  // The only reason fetching these attribute locations should fail is
+  // if the context was spontaneously lost (i.e., because the GPU
+  // process crashed, perhaps deliberately for testing).
+  DCHECK(Initialized() || gl_->GetGraphicsResetStatusKHR() != GL_NO_ERROR);
+}
+
+void ShaderProgram::UseProgram(const gfx::Size& src_size,
+                               const gfx::Rect& src_subrect,
+                               const gfx::Size& dst_size,
+                               bool scale_x,
+                               bool flip_y,
+                               GLfloat color_weights[4]) {
+  gl_->UseProgram(program_);
+
+  // OpenGL defines the last parameter to VertexAttribPointer as type
+  // "const GLvoid*" even though it is actually an offset into the buffer
+  // object's data store and not a pointer to the client's address space.
+  const void* offsets[2] = {0,
+                            reinterpret_cast<const void*>(2 * sizeof(GLfloat))};
+
+  gl_->VertexAttribPointer(position_location_, 2, GL_FLOAT, GL_FALSE,
+                           4 * sizeof(GLfloat), offsets[0]);
+  gl_->EnableVertexAttribArray(position_location_);
+
+  gl_->VertexAttribPointer(texcoord_location_, 2, GL_FLOAT, GL_FALSE,
+                           4 * sizeof(GLfloat), offsets[1]);
+  gl_->EnableVertexAttribArray(texcoord_location_);
+
+  gl_->Uniform1i(texture_location_, 0);
+
+  // Convert |src_subrect| to texture coordinates.
+  GLfloat src_subrect_texcoord[] = {
+      static_cast<float>(src_subrect.x()) / src_size.width(),
+      static_cast<float>(src_subrect.y()) / src_size.height(),
+      static_cast<float>(src_subrect.width()) / src_size.width(),
+      static_cast<float>(src_subrect.height()) / src_size.height(),
+  };
+  if (flip_y) {
+    src_subrect_texcoord[1] += src_subrect_texcoord[3];
+    src_subrect_texcoord[3] *= -1.0;
+  }
+  gl_->Uniform4fv(src_subrect_location_, 1, src_subrect_texcoord);
+
+  gl_->Uniform2f(src_pixelsize_location_, src_size.width(), src_size.height());
+  gl_->Uniform2f(dst_pixelsize_location_, static_cast<float>(dst_size.width()),
+                 static_cast<float>(dst_size.height()));
+
+  gl_->Uniform2f(scaling_vector_location_, scale_x ? 1.0 : 0.0,
+                 scale_x ? 0.0 : 1.0);
+  gl_->Uniform4fv(color_weights_location_, 1, color_weights);
+}
+
+}  // namespace content