third_party/WebKit/Source/core/offscreencanvas/OffscreenCanvas.cpp

// Copyright 2015 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 "core/offscreencanvas/OffscreenCanvas.h"

#include <memory>
#include <utility>

#include "core/css/CSSFontSelector.h"
#include "core/css/OffscreenFontSelector.h"
#include "core/css/StyleEngine.h"
#include "core/dom/ExceptionCode.h"
#include "core/execution_context/ExecutionContext.h"
#include "core/fileapi/Blob.h"
#include "core/html/canvas/CanvasAsyncBlobCreator.h"
#include "core/html/canvas/CanvasContextCreationAttributesCore.h"
#include "core/html/canvas/CanvasRenderingContext.h"
#include "core/html/canvas/CanvasRenderingContextFactory.h"
#include "core/html/canvas/ImageData.h"
#include "core/imagebitmap/ImageBitmap.h"
#include "core/origin_trials/origin_trials.h"
#include "core/workers/WorkerGlobalScope.h"
#include "gpu/config/gpu_feature_info.h"
#include "platform/graphics/CanvasResourceProvider.h"
#include "platform/graphics/Image.h"
#include "platform/graphics/OffscreenCanvasFrameDispatcherImpl.h"
#include "platform/graphics/StaticBitmapImage.h"
#include "platform/graphics/gpu/SharedGpuContext.h"
#include "platform/graphics/skia/SkiaUtils.h"
#include "platform/image-encoders/ImageEncoderUtils.h"
#include "platform/instrumentation/tracing/TraceEvent.h"
#include "platform/wtf/MathExtras.h"
#include "public/platform/Platform.h"
#include "third_party/skia/include/core/SkSurface.h"

namespace blink {

OffscreenCanvas::OffscreenCanvas(const IntSize& size) : size_(size) {}

OffscreenCanvas* OffscreenCanvas::Create(unsigned width, unsigned height) {
  return new OffscreenCanvas(
      IntSize(clampTo<int>(width), clampTo<int>(height)));
}

OffscreenCanvas::~OffscreenCanvas() = default;

void OffscreenCanvas::Dispose() {
  if (context_) {
    context_->DetachHost();
    context_ = nullptr;
  }
  if (commit_promise_resolver_) {
    // keepAliveWhilePending() guarantees the promise resolver is never
    // GC-ed before the OffscreenCanvas
    commit_promise_resolver_->Reject();
    commit_promise_resolver_.Clear();
  }
}

void OffscreenCanvas::setWidth(unsigned width) {
  IntSize new_size = size_;
  new_size.SetWidth(clampTo<int>(width));
  SetSize(new_size);
}

void OffscreenCanvas::setHeight(unsigned height) {
  IntSize new_size = size_;
  new_size.SetHeight(clampTo<int>(height));
  SetSize(new_size);
}

void OffscreenCanvas::SetSize(const IntSize& size) {
  if (context_) {
    if (context_->Is3d()) {
      if (size != size_)
        context_->Reshape(size.Width(), size.Height());
    } else if (context_->Is2d()) {
      context_->Reset();
      origin_clean_ = true;
    }
  }
  size_ = size;
  if (frame_dispatcher_) {
    frame_dispatcher_->Reshape(size_.Width(), size_.Height());
  }
  current_frame_damage_rect_ = SkIRect::MakeWH(size_.Width(), size_.Height());
}

void OffscreenCanvas::SetNeutered() {
  DCHECK(!context_);
  is_neutered_ = true;
  size_.SetWidth(0);
  size_.SetHeight(0);
}

ImageBitmap* OffscreenCanvas::transferToImageBitmap(
    ScriptState* script_state,
    ExceptionState& exception_state) {
  if (is_neutered_) {
    exception_state.ThrowDOMException(
        kInvalidStateError,
        "Cannot transfer an ImageBitmap from a detached OffscreenCanvas");
    return nullptr;
  }
  if (!context_) {
    exception_state.ThrowDOMException(kInvalidStateError,
                                      "Cannot transfer an ImageBitmap from an "
                                      "OffscreenCanvas with no context");
    return nullptr;
  }
  ImageBitmap* image = context_->TransferToImageBitmap(script_state);
  if (!image) {
    // Undocumented exception (not in spec)
    exception_state.ThrowDOMException(kV8Error, "Out of memory");
  }
  return image;
}

scoped_refptr<Image> OffscreenCanvas::GetSourceImageForCanvas(
    SourceImageStatus* status,
    AccelerationHint hint,
    const FloatSize& size) {
  if (!context_) {
    *status = kInvalidSourceImageStatus;
    sk_sp<SkSurface> surface =
        SkSurface::MakeRasterN32Premul(size_.Width(), size_.Height());
    return surface ? StaticBitmapImage::Create(surface->makeImageSnapshot())
                   : nullptr;
  }
  if (!size.Width() || !size.Height()) {
    *status = kZeroSizeCanvasSourceImageStatus;
    return nullptr;
  }
  scoped_refptr<Image> image = context_->GetImage(hint);
  if (!image)
    image = CreateTransparentImage(Size());
  *status = image ? kNormalSourceImageStatus : kInvalidSourceImageStatus;
  return image;
}

IntSize OffscreenCanvas::BitmapSourceSize() const {
  return size_;
}

ScriptPromise OffscreenCanvas::CreateImageBitmap(
    ScriptState* script_state,
    EventTarget&,
    Optional<IntRect> crop_rect,
    const ImageBitmapOptions& options) {
  return ImageBitmapSource::FulfillImageBitmap(
      script_state,
      IsPaintable() ? ImageBitmap::Create(this, crop_rect, options) : nullptr);
}

bool OffscreenCanvas::IsOpaque() const {
  if (!context_)
    return false;
  return !context_->CreationAttributes().alpha;
}

CanvasRenderingContext* OffscreenCanvas::GetCanvasRenderingContext(
    ExecutionContext* execution_context,
    const String& id,
    const CanvasContextCreationAttributesCore& attributes) {
  execution_context_ = execution_context;

  CanvasRenderingContext::ContextType context_type =
      CanvasRenderingContext::ContextTypeFromId(id);

  // Unknown type.
  if (context_type == CanvasRenderingContext::kContextTypeCount ||
      (context_type == CanvasRenderingContext::kContextXRPresent &&
       !OriginTrials::webXREnabled(execution_context)))
    return nullptr;

  CanvasRenderingContextFactory* factory =
      GetRenderingContextFactory(context_type);
  if (!factory)
    return nullptr;

  if (context_) {
    if (context_->GetContextType() != context_type) {
      factory->OnError(
          this, "OffscreenCanvas has an existing context of a different type");
      return nullptr;
    }
  } else {
    context_ = factory->Create(this, attributes);
  }

  return context_.Get();
}

OffscreenCanvas::ContextFactoryVector&
OffscreenCanvas::RenderingContextFactories() {
  DEFINE_STATIC_LOCAL(ContextFactoryVector, context_factories,
                      (CanvasRenderingContext::kContextTypeCount));
  return context_factories;
}

CanvasRenderingContextFactory* OffscreenCanvas::GetRenderingContextFactory(
    int type) {
  DCHECK_LT(type, CanvasRenderingContext::kContextTypeCount);
  return RenderingContextFactories()[type].get();
}

void OffscreenCanvas::RegisterRenderingContextFactory(
    std::unique_ptr<CanvasRenderingContextFactory> rendering_context_factory) {
  CanvasRenderingContext::ContextType type =
      rendering_context_factory->GetContextType();
  DCHECK_LT(type, CanvasRenderingContext::kContextTypeCount);
  DCHECK(!RenderingContextFactories()[type]);
  RenderingContextFactories()[type] = std::move(rendering_context_factory);
}

bool OffscreenCanvas::OriginClean() const {
  return origin_clean_ && !disable_reading_from_canvas_;
}

bool OffscreenCanvas::IsAccelerated() const {
  return context_ && context_->IsAccelerated();
}

OffscreenCanvasFrameDispatcher* OffscreenCanvas::GetOrCreateFrameDispatcher() {
  if (!frame_dispatcher_) {
    // The frame dispatcher connects the current thread of OffscreenCanvas
    // (either main or worker) to the browser process and remains unchanged
    // throughout the lifetime of this OffscreenCanvas.
    frame_dispatcher_ = std::make_unique<OffscreenCanvasFrameDispatcherImpl>(
        this, client_id_, sink_id_, placeholder_canvas_id_, size_.Width(),
        size_.Height());
  }
  return frame_dispatcher_.get();
}

void OffscreenCanvas::DiscardResourceProvider() {
  resource_provider_.reset();
  needs_matrix_clip_restore_ = true;
}

CanvasResourceProvider* OffscreenCanvas::GetOrCreateResourceProvider() {
  if (!resource_provider_) {
    bool is_accelerated_2d_canvas_blacklisted = true;
    if (SharedGpuContext::IsGpuCompositingEnabled()) {
      base::WeakPtr<WebGraphicsContext3DProviderWrapper>
          context_provider_wrapper = SharedGpuContext::ContextProviderWrapper();
      if (context_provider_wrapper) {
        const gpu::GpuFeatureInfo& gpu_feature_info =
            context_provider_wrapper->ContextProvider()->GetGpuFeatureInfo();
        if (gpu::kGpuFeatureStatusEnabled ==
            gpu_feature_info
                .status_values[gpu::GPU_FEATURE_TYPE_ACCELERATED_2D_CANVAS]) {
          is_accelerated_2d_canvas_blacklisted = false;
        }
      }
    }

    IntSize surface_size(width(), height());
    if (RuntimeEnabledFeatures::Accelerated2dCanvasEnabled() &&
        !is_accelerated_2d_canvas_blacklisted) {
      resource_provider_ = CanvasResourceProvider::Create(
          surface_size, CanvasResourceProvider::kAcceleratedResourceUsage,
          SharedGpuContext::ContextProviderWrapper(), 0,
          context_->ColorParams());
    }

    if (!resource_provider_ || !resource_provider_->IsValid()) {
      resource_provider_ = CanvasResourceProvider::Create(
          surface_size, CanvasResourceProvider::kSoftwareResourceUsage, nullptr,
          0, context_->ColorParams());
    }

    if (resource_provider_ && resource_provider_->IsValid()) {
      resource_provider_->Clear();
      // Always save an initial frame, to support resetting the top level matrix
      // and clip.
      resource_provider_->Canvas()->save();
    }

    if (resource_provider_ && needs_matrix_clip_restore_) {
      needs_matrix_clip_restore_ = false;
      context_->RestoreCanvasMatrixClipStack(resource_provider_->Canvas());
    }
  }

  return resource_provider_.get();
}

ScriptPromise OffscreenCanvas::Commit(scoped_refptr<StaticBitmapImage> image,
                                      const SkIRect& damage_rect,
                                      ScriptState* script_state,
                                      ExceptionState& exception_state) {
  TRACE_EVENT0("blink", "OffscreenCanvas::Commit");

  if (!HasPlaceholderCanvas()) {
    exception_state.ThrowDOMException(
        kInvalidStateError,
        "Commit() was called on a context whose "
        "OffscreenCanvas is not associated with a "
        "canvas element.");
    return exception_state.Reject(script_state);
  }

  GetOrCreateFrameDispatcher()->SetNeedsBeginFrame(true);

  if (!commit_promise_resolver_) {
    commit_promise_resolver_ = ScriptPromiseResolver::Create(script_state);
    commit_promise_resolver_->KeepAliveWhilePending();

    if (image) {
      // We defer the submission of commit frames at the end of JS task
      current_frame_ = std::move(image);
      // union of rects is necessary in case some frames are skipped.
      current_frame_damage_rect_.join(damage_rect);
      context_->NeedsFinalizeFrame();
    }
  } else if (image) {
    // Two possible scenarios:
    // 1. An override of m_currentFrame can happen when there are multiple
    // frames committed before JS task finishes. (m_currentFrame!=nullptr)
    // 2. The current frame has been dispatched but the promise is not
    // resolved yet. (m_currentFrame==nullptr)
    current_frame_ = std::move(image);
    current_frame_damage_rect_.join(damage_rect);
  }

  return commit_promise_resolver_->Promise();
}

void OffscreenCanvas::FinalizeFrame() {
  if (current_frame_) {
    // TODO(eseckler): OffscreenCanvas shouldn't dispatch CompositorFrames
    // without a prior BeginFrame.
    DoCommit();
  }
}

void OffscreenCanvas::DoCommit() {
  TRACE_EVENT0("blink", "OffscreenCanvas::DoCommit");
  double commit_start_time = WTF::CurrentTimeTicksInSeconds();
  DCHECK(current_frame_);
  GetOrCreateFrameDispatcher()->DispatchFrame(
      std::move(current_frame_), commit_start_time, current_frame_damage_rect_);
  current_frame_damage_rect_ = SkIRect::MakeEmpty();
}

void OffscreenCanvas::BeginFrame() {
  TRACE_EVENT0("blink", "OffscreenCanvas::BeginFrame");
  if (current_frame_) {
    // TODO(eseckler): beginFrame() shouldn't be used as confirmation of
    // CompositorFrame activation.
    // If we have an overdraw backlog, push the frame from the backlog
    // first and save the promise resolution for later.
    // Then we need to wait for one more frame time to resolve the existing
    // promise.
    DoCommit();
  } else if (commit_promise_resolver_) {
    commit_promise_resolver_->Resolve();
    commit_promise_resolver_.Clear();

    // We need to tell parent frame to stop sending signals on begin frame to
    // avoid overhead once we resolve the promise.
    GetOrCreateFrameDispatcher()->SetNeedsBeginFrame(false);
  }
}

ScriptPromise OffscreenCanvas::convertToBlob(ScriptState* script_state,
                                             const ImageEncodeOptions& options,
                                             ExceptionState& exception_state) {
  if (this->IsNeutered()) {
    exception_state.ThrowDOMException(kInvalidStateError,
                                      "OffscreenCanvas object is detached.");
    return exception_state.Reject(script_state);
  }

  if (!this->OriginClean()) {
    exception_state.ThrowSecurityError(
        "Tainted OffscreenCanvas may not be exported.");
    return exception_state.Reject(script_state);
  }

  if (!this->IsPaintable() || size_.IsEmpty()) {
    exception_state.ThrowDOMException(
        kIndexSizeError, "The size of the OffscreenCanvas is zero.");
    return exception_state.Reject(script_state);
  }

  if (!this->context_) {
    exception_state.ThrowDOMException(
        kInvalidStateError, "OffscreenCanvas object has no rendering contexts");
    return exception_state.Reject(script_state);
  }

  double start_time = WTF::CurrentTimeTicksInSeconds();
  scoped_refptr<StaticBitmapImage> snapshot =
      context_->GetImage(kPreferNoAcceleration);
  if (snapshot) {
    ScriptPromiseResolver* resolver =
        ScriptPromiseResolver::Create(script_state);
    String encoding_mime_type = ImageEncoderUtils::ToEncodingMimeType(
        options.type(), ImageEncoderUtils::kEncodeReasonConvertToBlobPromise);
    CanvasAsyncBlobCreator* async_creator = CanvasAsyncBlobCreator::Create(
        snapshot, encoding_mime_type, start_time,
        ExecutionContext::From(script_state), resolver);
    async_creator->ScheduleAsyncBlobCreation(options.quality());
    return resolver->Promise();
  } else {
    exception_state.ThrowDOMException(
        kNotReadableError, "Readback of the source image has failed.");
    return exception_state.Reject(script_state);
  }
}

FontSelector* OffscreenCanvas::GetFontSelector() {
  if (GetExecutionContext()->IsDocument()) {
    return ToDocument(execution_context_)->GetStyleEngine().GetFontSelector();
  }
  return ToWorkerGlobalScope(execution_context_)->GetFontSelector();
}

void OffscreenCanvas::Trace(blink::Visitor* visitor) {
  visitor->Trace(context_);
  visitor->Trace(execution_context_);
  visitor->Trace(commit_promise_resolver_);
  EventTargetWithInlineData::Trace(visitor);
}

}  // namespace blink