// Copyright 2014 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 "android_webview/browser/hardware_renderer.h"

#include "android_webview/browser/aw_gl_surface.h"
#include "android_webview/browser/deferred_gpu_command_service.h"
#include "android_webview/browser/parent_output_surface.h"
#include "android_webview/browser/shared_renderer_state.h"
#include "android_webview/public/browser/draw_gl.h"
#include "base/auto_reset.h"
#include "base/debug/trace_event.h"
#include "base/strings/string_number_conversions.h"
#include "cc/layers/delegated_frame_provider.h"
#include "cc/layers/delegated_renderer_layer.h"
#include "cc/layers/layer.h"
#include "cc/output/compositor_frame.h"
#include "cc/output/output_surface.h"
#include "cc/trees/layer_tree_host.h"
#include "cc/trees/layer_tree_settings.h"
#include "gpu/command_buffer/client/gl_in_process_context.h"
#include "gpu/command_buffer/common/gles2_cmd_utils.h"
#include "ui/gfx/frame_time.h"
#include "ui/gfx/geometry/rect_conversions.h"
#include "ui/gfx/geometry/rect_f.h"
#include "ui/gfx/transform.h"
#include "ui/gl/gl_bindings.h"
#include "webkit/common/gpu/context_provider_in_process.h"
#include "webkit/common/gpu/webgraphicscontext3d_in_process_command_buffer_impl.h"

namespace android_webview {

namespace {

using webkit::gpu::WebGraphicsContext3DInProcessCommandBufferImpl;
using webkit::gpu::WebGraphicsContext3DImpl;

scoped_refptr<cc::ContextProvider> CreateContext(
    scoped_refptr<gfx::GLSurface> surface,
    scoped_refptr<gpu::InProcessCommandBuffer::Service> service) {
  const gfx::GpuPreference gpu_preference = gfx::PreferDiscreteGpu;

  blink::WebGraphicsContext3D::Attributes attributes;
  attributes.antialias = false;
  attributes.depth = false;
  attributes.stencil = false;
  attributes.shareResources = true;
  attributes.noAutomaticFlushes = true;
  gpu::gles2::ContextCreationAttribHelper attribs_for_gles2;
  WebGraphicsContext3DImpl::ConvertAttributes(
      attributes, &attribs_for_gles2);
  attribs_for_gles2.lose_context_when_out_of_memory = true;

  scoped_ptr<gpu::GLInProcessContext> context(gpu::GLInProcessContext::Create(
      service,
      surface,
      surface->IsOffscreen(),
      gfx::kNullAcceleratedWidget,
      surface->GetSize(),
      NULL /* share_context */,
      false /* share_resources */,
      attribs_for_gles2,
      gpu_preference,
      gpu::GLInProcessContextSharedMemoryLimits()));
  DCHECK(context.get());

  return webkit::gpu::ContextProviderInProcess::Create(
      WebGraphicsContext3DInProcessCommandBufferImpl::WrapContext(
          context.Pass(), attributes),
      "Parent-Compositor");
}

}  // namespace

HardwareRenderer::HardwareRenderer(SharedRendererState* state)
    : shared_renderer_state_(state),
      last_egl_context_(eglGetCurrentContext()),
      width_(0),
      height_(0),
      stencil_enabled_(false),
      viewport_clip_valid_for_dcheck_(false),
      gl_surface_(new AwGLSurface),
      root_layer_(cc::Layer::Create()),
      resource_collection_(new cc::DelegatedFrameResourceCollection),
      output_surface_(NULL) {
  DCHECK(last_egl_context_);

  resource_collection_->SetClient(this);

  cc::LayerTreeSettings settings;

  // Should be kept in sync with compositor_impl_android.cc.
  settings.allow_antialiasing = false;
  settings.highp_threshold_min = 2048;

  // Webview does not own the surface so should not clear it.
  settings.should_clear_root_render_pass = false;

  // TODO(enne): Update this this compositor to use a synchronous scheduler.
  settings.single_thread_proxy_scheduler = false;

  layer_tree_host_ =
      cc::LayerTreeHost::CreateSingleThreaded(this, this, NULL, settings, NULL);
  layer_tree_host_->SetRootLayer(root_layer_);
  layer_tree_host_->SetLayerTreeHostClientReady();
  layer_tree_host_->set_has_transparent_background(true);
}

HardwareRenderer::~HardwareRenderer() {
  SetFrameData();

  // Must reset everything before |resource_collection_| to ensure all
  // resources are returned before resetting |resource_collection_| client.
  layer_tree_host_.reset();
  root_layer_ = NULL;
  delegated_layer_ = NULL;
  frame_provider_ = NULL;
#if DCHECK_IS_ON
  // Check collection is empty.
  cc::ReturnedResourceArray returned_resources;
  resource_collection_->TakeUnusedResourcesForChildCompositor(
      &returned_resources);
  DCHECK_EQ(0u, returned_resources.size());
#endif  // DCHECK_IS_ON

  resource_collection_->SetClient(NULL);

  // Reset draw constraints.
  shared_renderer_state_->UpdateDrawConstraints(
      ParentCompositorDrawConstraints());
}

void HardwareRenderer::DidBeginMainFrame() {
  // This is called after OutputSurface is created, but before the impl frame
  // starts. We set the draw constraints here.
  DCHECK(output_surface_);
  DCHECK(viewport_clip_valid_for_dcheck_);
  output_surface_->SetExternalStencilTest(stencil_enabled_);
  output_surface_->SetDrawConstraints(viewport_, clip_);
}

void HardwareRenderer::CommitFrame() {
  scroll_offset_ = shared_renderer_state_->GetScrollOffset();
  if (committed_frame_.get()) {
    TRACE_EVENT_INSTANT0("android_webview",
                         "EarlyOut_PreviousFrameUnconsumed",
                         TRACE_EVENT_SCOPE_THREAD);
    return;
  }

  committed_frame_ = shared_renderer_state_->PassCompositorFrame();
  // Happens with empty global visible rect.
  if (!committed_frame_.get())
    return;

  DCHECK(!committed_frame_->gl_frame_data);
  DCHECK(!committed_frame_->software_frame_data);

  // DelegatedRendererLayerImpl applies the inverse device_scale_factor of the
  // renderer frame, assuming that the browser compositor will scale
  // it back up to device scale.  But on Android we put our browser layers in
  // physical pixels and set our browser CC device_scale_factor to 1, so this
  // suppresses the transform.
  committed_frame_->delegated_frame_data->device_scale_factor = 1.0f;
}

void HardwareRenderer::SetFrameData() {
  if (!committed_frame_.get())
    return;

  scoped_ptr<cc::CompositorFrame> frame = committed_frame_.Pass();
  gfx::Size frame_size =
      frame->delegated_frame_data->render_pass_list.back()->output_rect.size();
  bool size_changed = frame_size != frame_size_;
  frame_size_ = frame_size;

  if (!frame_provider_ || size_changed) {
    if (delegated_layer_) {
      delegated_layer_->RemoveFromParent();
    }

    frame_provider_ = new cc::DelegatedFrameProvider(
        resource_collection_.get(), frame->delegated_frame_data.Pass());

    delegated_layer_ = cc::DelegatedRendererLayer::Create(frame_provider_);
    delegated_layer_->SetBounds(frame_size_);
    delegated_layer_->SetIsDrawable(true);

    root_layer_->AddChild(delegated_layer_);
  } else {
    frame_provider_->SetFrameData(frame->delegated_frame_data.Pass());
  }
}

void HardwareRenderer::DrawGL(bool stencil_enabled,
                              int framebuffer_binding_ext,
                              AwDrawGLInfo* draw_info) {
  TRACE_EVENT0("android_webview", "HardwareRenderer::DrawGL");

  // We need to watch if the current Android context has changed and enforce
  // a clean-up in the compositor.
  EGLContext current_context = eglGetCurrentContext();
  DCHECK(current_context) << "DrawGL called without EGLContext";

  // TODO(boliu): Handle context loss.
  if (last_egl_context_ != current_context)
    DLOG(WARNING) << "EGLContextChanged";

  SetFrameData();
  if (shared_renderer_state_->ForceCommit()) {
    CommitFrame();
    SetFrameData();
  }

  gfx::Transform transform(gfx::Transform::kSkipInitialization);
  transform.matrix().setColMajorf(draw_info->transform);
  transform.Translate(scroll_offset_.x(), scroll_offset_.y());

  // Need to post the new transform matrix back to child compositor
  // because there is no onDraw during a Render Thread animation, and child
  // compositor might not have the tiles rasterized as the animation goes on.
  ParentCompositorDrawConstraints draw_constraints(
      draw_info->is_layer, transform, gfx::Rect(viewport_));

  draw_constraints_ = draw_constraints;
  shared_renderer_state_->PostExternalDrawConstraintsToChildCompositor(
      draw_constraints);

  if (!delegated_layer_.get())
    return;

  viewport_.SetSize(draw_info->width, draw_info->height);
  layer_tree_host_->SetViewportSize(viewport_);
  clip_.SetRect(draw_info->clip_left,
                draw_info->clip_top,
                draw_info->clip_right - draw_info->clip_left,
                draw_info->clip_bottom - draw_info->clip_top);
  stencil_enabled_ = stencil_enabled;

  delegated_layer_->SetTransform(transform);

  gl_surface_->SetBackingFrameBufferObject(framebuffer_binding_ext);
  {
    base::AutoReset<bool> frame_resetter(&viewport_clip_valid_for_dcheck_,
                                         true);
    layer_tree_host_->SetNeedsRedrawRect(clip_);
    layer_tree_host_->Composite(gfx::FrameTime::Now());
  }
  gl_surface_->ResetBackingFrameBufferObject();
}

void HardwareRenderer::RequestNewOutputSurface(bool fallback) {
  // Android webview does not support losing output surface.
  DCHECK(!fallback);
  scoped_refptr<cc::ContextProvider> context_provider =
      CreateContext(gl_surface_,
                    DeferredGpuCommandService::GetInstance());
  scoped_ptr<ParentOutputSurface> output_surface_holder(
      new ParentOutputSurface(context_provider));
  output_surface_ = output_surface_holder.get();
  layer_tree_host_->SetOutputSurface(
      output_surface_holder.PassAs<cc::OutputSurface>());
}

void HardwareRenderer::UnusedResourcesAreAvailable() {
  cc::ReturnedResourceArray returned_resources;
  resource_collection_->TakeUnusedResourcesForChildCompositor(
      &returned_resources);
  shared_renderer_state_->InsertReturnedResources(returned_resources);
}

}  // namespace android_webview