gecko-dev/dom/canvas/nsICanvasRenderingContextInternal.cpp

/* -*- Mode: C++; tab-width: 40; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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 "nsICanvasRenderingContextInternal.h"

#include "mozilla/dom/CanvasUtils.h"
#include "mozilla/dom/Document.h"
#include "mozilla/dom/Event.h"
#include "mozilla/dom/WorkerCommon.h"
#include "mozilla/dom/WorkerPrivate.h"
#include "mozilla/gfx/DrawTargetRecording.h"
#include "mozilla/ErrorResult.h"
#include "mozilla/PresShell.h"
#include "nsContentUtils.h"
#include "nsPIDOMWindow.h"
#include "nsRefreshDriver.h"

nsICanvasRenderingContextInternal::nsICanvasRenderingContextInternal() =
    default;

nsICanvasRenderingContextInternal::~nsICanvasRenderingContextInternal() =
    default;

mozilla::PresShell* nsICanvasRenderingContextInternal::GetPresShell() {
  if (mCanvasElement) {
    return mCanvasElement->OwnerDoc()->GetPresShell();
  }
  return nullptr;
}

nsIGlobalObject* nsICanvasRenderingContextInternal::GetParentObject() const {
  if (mCanvasElement) {
    return mCanvasElement->OwnerDoc()->GetScopeObject();
  }
  if (mOffscreenCanvas) {
    return mOffscreenCanvas->GetParentObject();
  }
  return nullptr;
}

nsIPrincipal* nsICanvasRenderingContextInternal::PrincipalOrNull() const {
  if (mCanvasElement) {
    return mCanvasElement->NodePrincipal();
  }
  if (mOffscreenCanvas) {
    nsIGlobalObject* global = mOffscreenCanvas->GetParentObject();
    if (global) {
      return global->PrincipalOrNull();
    }
  }
  return nullptr;
}

nsICookieJarSettings* nsICanvasRenderingContextInternal::GetCookieJarSettings()
    const {
  if (mCanvasElement) {
    return mCanvasElement->OwnerDoc()->CookieJarSettings();
  }

  // If there is an offscreen canvas, attempt to retrieve its owner window
  // and return the cookieJarSettings for the window's document, if available.
  if (mOffscreenCanvas) {
    nsCOMPtr<nsPIDOMWindowInner> win =
        do_QueryInterface(mOffscreenCanvas->GetOwnerGlobal());

    if (win) {
      return win->GetExtantDoc()->CookieJarSettings();
    }

    // If the owner window cannot be retrieved, check if there is a current
    // worker and return its cookie jar settings if available.
    mozilla::dom::WorkerPrivate* worker =
        mozilla::dom::GetCurrentThreadWorkerPrivate();

    if (worker) {
      return worker->CookieJarSettings();
    }
  }

  return nullptr;
}

void nsICanvasRenderingContextInternal::RemovePostRefreshObserver() {
  if (mRefreshDriver) {
    mRefreshDriver->RemovePostRefreshObserver(this);
    mRefreshDriver = nullptr;
  }
}

void nsICanvasRenderingContextInternal::AddPostRefreshObserverIfNecessary() {
  if (!GetPresShell() || !GetPresShell()->GetPresContext() ||
      !GetPresShell()->GetPresContext()->RefreshDriver()) {
    return;
  }
  mRefreshDriver = GetPresShell()->GetPresContext()->RefreshDriver();
  mRefreshDriver->AddPostRefreshObserver(this);
}

void nsICanvasRenderingContextInternal::DoSecurityCheck(
    nsIPrincipal* aPrincipal, bool aForceWriteOnly, bool aCORSUsed) {
  if (mCanvasElement) {
    mozilla::CanvasUtils::DoDrawImageSecurityCheck(mCanvasElement, aPrincipal,
                                                   aForceWriteOnly, aCORSUsed);
  } else if (mOffscreenCanvas) {
    mozilla::CanvasUtils::DoDrawImageSecurityCheck(mOffscreenCanvas, aPrincipal,
                                                   aForceWriteOnly, aCORSUsed);
  }
}

bool nsICanvasRenderingContextInternal::ShouldResistFingerprinting(
    mozilla::RFPTarget aTarget) const {
  if (mCanvasElement) {
    return mCanvasElement->OwnerDoc()->ShouldResistFingerprinting(aTarget);
  }
  if (mOffscreenCanvas) {
    return mOffscreenCanvas->ShouldResistFingerprinting(aTarget);
  }
  // Last resort, just check the global preference
  return nsContentUtils::ShouldResistFingerprinting("Fallback", aTarget);
}

bool nsICanvasRenderingContextInternal::DispatchEvent(
    const nsAString& eventName, mozilla::CanBubble aCanBubble,
    mozilla::Cancelable aIsCancelable) const {
  bool useDefaultHandler = true;

  if (mCanvasElement) {
    nsContentUtils::DispatchTrustedEvent(mCanvasElement->OwnerDoc(),
                                         mCanvasElement, eventName, aCanBubble,
                                         aIsCancelable, &useDefaultHandler);
  } else if (mOffscreenCanvas) {
    // OffscreenCanvas case
    auto event = mozilla::MakeRefPtr<mozilla::dom::Event>(mOffscreenCanvas,
                                                          nullptr, nullptr);
    event->InitEvent(eventName, aCanBubble, aIsCancelable);
    event->SetTrusted(true);
    useDefaultHandler = mOffscreenCanvas->DispatchEvent(
        *event, mozilla::dom::CallerType::System, mozilla::IgnoreErrors());
  }
  return useDefaultHandler;
}

already_AddRefed<mozilla::gfx::SourceSurface>
nsICanvasRenderingContextInternal::GetOptimizedSnapshot(
    mozilla::gfx::DrawTarget* aTarget, gfxAlphaType* out_alphaType) {
  if (aTarget &&
      aTarget->GetBackendType() == mozilla::gfx::BackendType::RECORDING) {
    if (auto* actor = SupportsSnapshotExternalCanvas()) {
      // If this snapshot is for a recording target, then try to avoid reading
      // back any data by using SnapshotExternalCanvas instead. This avoids
      // having sync interactions between GPU and content process.
      if (RefPtr<mozilla::gfx::SourceSurface> surf =
              static_cast<mozilla::gfx::DrawTargetRecording*>(aTarget)
                  ->SnapshotExternalCanvas(this, actor)) {
        if (out_alphaType) {
          *out_alphaType =
              GetIsOpaque() ? gfxAlphaType::Opaque : gfxAlphaType::Premult;
        }
        return surf.forget();
      }
    }
  }

  return GetSurfaceSnapshot(out_alphaType);
}