gecko-dev/dom/canvas/OffscreenCanvas.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim:set ts=2 sw=2 sts=2 et cindent: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include "OffscreenCanvas.h"
#include "mozilla/dom/DOMPrefs.h"
#include "mozilla/dom/OffscreenCanvasBinding.h"
#include "mozilla/dom/WorkerPrivate.h"
#include "mozilla/dom/WorkerScope.h"
#include "mozilla/layers/AsyncCanvasRenderer.h"
#include "mozilla/layers/CanvasClient.h"
#include "mozilla/layers/ImageBridgeChild.h"
#include "mozilla/Telemetry.h"
#include "CanvasRenderingContext2D.h"
#include "CanvasUtils.h"
#include "GLScreenBuffer.h"
#include "WebGL1Context.h"
#include "WebGL2Context.h"
namespace mozilla {
namespace dom {
OffscreenCanvasCloneData::OffscreenCanvasCloneData(layers::AsyncCanvasRenderer* aRenderer,
uint32_t aWidth, uint32_t aHeight,
layers::LayersBackend aCompositorBackend,
bool aNeutered, bool aIsWriteOnly)
: mRenderer(aRenderer)
, mWidth(aWidth)
, mHeight(aHeight)
, mCompositorBackendType(aCompositorBackend)
, mNeutered(aNeutered)
, mIsWriteOnly(aIsWriteOnly)
{
}
OffscreenCanvasCloneData::~OffscreenCanvasCloneData()
{
}
OffscreenCanvas::OffscreenCanvas(nsIGlobalObject* aGlobal,
uint32_t aWidth,
uint32_t aHeight,
layers::LayersBackend aCompositorBackend,
layers::AsyncCanvasRenderer* aRenderer)
: DOMEventTargetHelper(aGlobal)
, mAttrDirty(false)
, mNeutered(false)
, mIsWriteOnly(false)
, mWidth(aWidth)
, mHeight(aHeight)
, mCompositorBackendType(aCompositorBackend)
, mCanvasRenderer(aRenderer)
{}
OffscreenCanvas::~OffscreenCanvas()
{
ClearResources();
}
JSObject*
OffscreenCanvas::WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto)
{
return OffscreenCanvasBinding::Wrap(aCx, this, aGivenProto);
}
/* static */ already_AddRefed<OffscreenCanvas>
OffscreenCanvas::Constructor(const GlobalObject& aGlobal,
uint32_t aWidth,
uint32_t aHeight,
ErrorResult& aRv)
{
nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
RefPtr<OffscreenCanvas> offscreenCanvas =
new OffscreenCanvas(global, aWidth, aHeight,
layers::LayersBackend::LAYERS_NONE, nullptr);
return offscreenCanvas.forget();
}
void
OffscreenCanvas::ClearResources()
{
if (mCanvasClient) {
mCanvasClient->Clear();
if (mCanvasRenderer) {
nsCOMPtr<nsISerialEventTarget> activeTarget = mCanvasRenderer->GetActiveEventTarget();
MOZ_RELEASE_ASSERT(activeTarget, "GFX: failed to get active event target.");
bool current;
activeTarget->IsOnCurrentThread(&current);
MOZ_RELEASE_ASSERT(current, "GFX: active thread is not current thread.");
mCanvasRenderer->SetCanvasClient(nullptr);
mCanvasRenderer->mContext = nullptr;
mCanvasRenderer->mGLContext = nullptr;
mCanvasRenderer->ResetActiveEventTarget();
}
mCanvasClient = nullptr;
}
}
already_AddRefed<nsISupports>
OffscreenCanvas::GetContext(JSContext* aCx,
const nsAString& aContextId,
JS::Handle<JS::Value> aContextOptions,
ErrorResult& aRv)
{
if (mNeutered) {
aRv.Throw(NS_ERROR_FAILURE);
return nullptr;
}
// We only support WebGL in workers for now
CanvasContextType contextType;
if (!CanvasUtils::GetCanvasContextType(aContextId, &contextType)) {
aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
return nullptr;
}
if (!(contextType == CanvasContextType::WebGL1 ||
contextType == CanvasContextType::WebGL2 ||
contextType == CanvasContextType::ImageBitmap))
{
aRv.Throw(NS_ERROR_NOT_IMPLEMENTED);
return nullptr;
}
already_AddRefed<nsISupports> result =
CanvasRenderingContextHelper::GetContext(aCx,
aContextId,
aContextOptions,
aRv);
if (!mCurrentContext) {
return nullptr;
}
if (mCanvasRenderer) {
if (contextType == CanvasContextType::WebGL1 ||
contextType == CanvasContextType::WebGL2) {
WebGLContext* webGL = static_cast<WebGLContext*>(mCurrentContext.get());
gl::GLContext* gl = webGL->GL();
mCanvasRenderer->mContext = mCurrentContext;
mCanvasRenderer->SetActiveEventTarget();
mCanvasRenderer->mGLContext = gl;
mCanvasRenderer->SetIsAlphaPremultiplied(webGL->IsPremultAlpha() || !gl->Caps().alpha);
if (RefPtr<ImageBridgeChild> imageBridge = ImageBridgeChild::GetSingleton()) {
TextureFlags flags = TextureFlags::ORIGIN_BOTTOM_LEFT;
mCanvasClient = imageBridge->CreateCanvasClient(CanvasClient::CanvasClientTypeShSurf, flags);
mCanvasRenderer->SetCanvasClient(mCanvasClient);
gl::GLScreenBuffer* screen = gl->Screen();
gl::SurfaceCaps caps = screen->mCaps;
auto forwarder = mCanvasClient->GetForwarder();
UniquePtr<gl::SurfaceFactory> factory =
gl::GLScreenBuffer::CreateFactory(gl, caps, forwarder, flags);
if (factory)
screen->Morph(Move(factory));
}
}
}
return result;
}
already_AddRefed<nsICanvasRenderingContextInternal>
OffscreenCanvas::CreateContext(CanvasContextType aContextType)
{
RefPtr<nsICanvasRenderingContextInternal> ret =
CanvasRenderingContextHelper::CreateContext(aContextType);
ret->SetOffscreenCanvas(this);
return ret.forget();
}
void
OffscreenCanvas::CommitFrameToCompositor()
{
if (!mCanvasRenderer) {
// This offscreen canvas doesn't associate to any HTML canvas element.
// So, just bail out.
return;
}
// The attributes has changed, we have to notify main
// thread to change canvas size.
if (mAttrDirty) {
if (mCanvasRenderer) {
mCanvasRenderer->SetWidth(mWidth);
mCanvasRenderer->SetHeight(mHeight);
mCanvasRenderer->NotifyElementAboutAttributesChanged();
}
mAttrDirty = false;
}
if (mCurrentContext) {
static_cast<WebGLContext*>(mCurrentContext.get())->PresentScreenBuffer();
}
if (mCanvasRenderer && mCanvasRenderer->mGLContext) {
mCanvasRenderer->NotifyElementAboutInvalidation();
ImageBridgeChild::GetSingleton()->
UpdateAsyncCanvasRenderer(mCanvasRenderer);
}
}
OffscreenCanvasCloneData*
OffscreenCanvas::ToCloneData()
{
return new OffscreenCanvasCloneData(mCanvasRenderer, mWidth, mHeight,
mCompositorBackendType, mNeutered, mIsWriteOnly);
}
already_AddRefed<ImageBitmap>
OffscreenCanvas::TransferToImageBitmap(ErrorResult& aRv)
{
nsCOMPtr<nsIGlobalObject> globalObject = GetGlobalObject();
RefPtr<ImageBitmap> result = ImageBitmap::CreateFromOffscreenCanvas(globalObject, *this, aRv);
if (aRv.Failed()) {
return nullptr;
}
// TODO: Clear the content?
return result.forget();
}
already_AddRefed<Promise>
OffscreenCanvas::ToBlob(JSContext* aCx,
const nsAString& aType,
JS::Handle<JS::Value> aParams,
ErrorResult& aRv)
{
// do a trust check if this is a write-only canvas
if (mIsWriteOnly) {
aRv.Throw(NS_ERROR_DOM_SECURITY_ERR);
return nullptr;
}
nsCOMPtr<nsIGlobalObject> global = GetGlobalObject();
RefPtr<Promise> promise = Promise::Create(global, aRv);
if (aRv.Failed()) {
return nullptr;
}
// Encoder callback when encoding is complete.
class EncodeCallback : public EncodeCompleteCallback
{
public:
EncodeCallback(nsIGlobalObject* aGlobal, Promise* aPromise)
: mGlobal(aGlobal)
, mPromise(aPromise) {}
// This is called on main thread.
nsresult ReceiveBlob(already_AddRefed<Blob> aBlob) override
{
RefPtr<Blob> blob = aBlob;
if (mPromise) {
RefPtr<Blob> newBlob = Blob::Create(mGlobal, blob->Impl());
mPromise->MaybeResolve(newBlob);
}
mGlobal = nullptr;
mPromise = nullptr;
return NS_OK;
}
nsCOMPtr<nsIGlobalObject> mGlobal;
RefPtr<Promise> mPromise;
};
RefPtr<EncodeCompleteCallback> callback =
new EncodeCallback(global, promise);
// TODO: Can we obtain the context and document here somehow
// so that we can decide when usePlaceholder should be true/false?
// See https://trac.torproject.org/18599
// For now, we always return a placeholder if fingerprinting resistance is on.
bool usePlaceholder = nsContentUtils::ShouldResistFingerprinting();
CanvasRenderingContextHelper::ToBlob(aCx, global, callback, aType, aParams,
usePlaceholder, aRv);
return promise.forget();
}
already_AddRefed<gfx::SourceSurface>
OffscreenCanvas::GetSurfaceSnapshot(gfxAlphaType* const aOutAlphaType)
{
if (!mCurrentContext) {
return nullptr;
}
return mCurrentContext->GetSurfaceSnapshot(aOutAlphaType);
}
nsCOMPtr<nsIGlobalObject>
OffscreenCanvas::GetGlobalObject()
{
if (NS_IsMainThread()) {
return GetParentObject();
}
dom::WorkerPrivate* workerPrivate = dom::GetCurrentThreadWorkerPrivate();
return workerPrivate->GlobalScope();
}
/* static */ already_AddRefed<OffscreenCanvas>
OffscreenCanvas::CreateFromCloneData(nsIGlobalObject* aGlobal, OffscreenCanvasCloneData* aData)
{
MOZ_ASSERT(aData);
RefPtr<OffscreenCanvas> wc =
new OffscreenCanvas(aGlobal, aData->mWidth, aData->mHeight,
aData->mCompositorBackendType, aData->mRenderer);
if (aData->mNeutered) {
wc->SetNeutered();
}
return wc.forget();
}
/* static */ bool
OffscreenCanvas::PrefEnabledOnWorkerThread(JSContext* aCx, JSObject* aObj)
{
if (NS_IsMainThread()) {
return true;
}
return DOMPrefs::OffscreenCanvasEnabled(aCx, aObj);
}
NS_IMPL_CYCLE_COLLECTION_INHERITED(OffscreenCanvas, DOMEventTargetHelper, mCurrentContext)
NS_IMPL_ADDREF_INHERITED(OffscreenCanvas, DOMEventTargetHelper)
NS_IMPL_RELEASE_INHERITED(OffscreenCanvas, DOMEventTargetHelper)
NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(OffscreenCanvas)
NS_INTERFACE_MAP_ENTRY(nsISupports)
NS_INTERFACE_MAP_END_INHERITING(DOMEventTargetHelper)
} // namespace dom
} // namespace mozilla