1 files changed, 176 insertions, 0 deletions
diff --git a/gfx/ipc/CrossProcessPaint.h b/gfx/ipc/CrossProcessPaint.h
new file mode 100644
index 0000000000..8179b49b41
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+++ b/gfx/ipc/CrossProcessPaint.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/. */
+#ifndef _include_mozilla_gfx_ipc_CrossProcessPaint_h_
+#define _include_mozilla_gfx_ipc_CrossProcessPaint_h_
+
+#include "nsISupportsImpl.h"
+
+#include "mozilla/dom/ipc/IdType.h"
+#include "mozilla/gfx/Point.h"
+#include "mozilla/gfx/RecordedEvent.h"
+#include "mozilla/gfx/Rect.h"
+#include "mozilla/MozPromise.h"
+#include "mozilla/ipc/ByteBuf.h"
+#include "nsColor.h"
+#include "nsDataHashtable.h"
+#include "nsHashKeys.h"
+#include "nsRefPtrHashtable.h"
+#include "nsTHashtable.h"
+
+class nsIDocShell;
+
+namespace IPC {
+template <typename T>
+struct ParamTraits;
+}  // namespace IPC
+
+namespace mozilla {
+
+namespace dom {
+class DOMRect;
+class Promise;
+class WindowGlobalParent;
+}  // namespace dom
+
+namespace gfx {
+
+class CrossProcessPaint;
+
+enum class CrossProcessPaintFlags {
+  None = 0,
+  DrawView = 1 << 1,
+};
+
+MOZ_MAKE_ENUM_CLASS_BITWISE_OPERATORS(CrossProcessPaintFlags)
+
+/**
+ * A fragment of a paint of a cross process document tree.
+ */
+class PaintFragment final {
+ public:
+  /// Initializes an empty PaintFragment
+  PaintFragment() = default;
+
+  /**
+   * Creates a paint fragment by recording the draw commands and dependent tabs
+   * for a BrowsingContext.
+   *
+   * @param aBrowsingContext The frame to record.
+   * @param aRect The rectangle relative to the viewport to use. If no
+   *   rectangle is specified, then the whole viewport will be used.
+   * @param aScale The coordinate scale to use. The size of the resolved
+   *   surface will be `aRect.Size() * aScale`, with aScale clamped to
+   *   at least kMinPaintScale.
+   * @param aBackgroundColor The background color to use.
+   *
+   * @return A paint fragment. The paint fragment may be `empty` if rendering
+   *         was unable to be accomplished for some reason.
+   */
+  static PaintFragment Record(dom::BrowsingContext* aBc,
+                              const Maybe<IntRect>& aRect, float aScale,
+                              nscolor aBackgroundColor,
+                              CrossProcessPaintFlags aFlags);
+
+  /// Returns whether this paint fragment contains a valid recording.
+  bool IsEmpty() const;
+
+  PaintFragment(PaintFragment&&) = default;
+  PaintFragment& operator=(PaintFragment&&) = default;
+
+ protected:
+  friend struct mozilla::ipc::IPDLParamTraits<PaintFragment>;
+  friend CrossProcessPaint;
+
+  typedef mozilla::ipc::ByteBuf ByteBuf;
+
+  PaintFragment(IntSize, ByteBuf&&, nsTHashtable<nsUint64HashKey>&&);
+
+  IntSize mSize;
+  ByteBuf mRecording;
+  nsTHashtable<nsUint64HashKey> mDependencies;
+};
+
+/**
+ * An object for painting a cross process document tree.
+ */
+class CrossProcessPaint final {
+  NS_INLINE_DECL_REFCOUNTING(CrossProcessPaint);
+
+ public:
+  typedef nsRefPtrHashtable<nsUint64HashKey, RecordedDependentSurface>
+      ResolvedFragmentMap;
+  typedef MozPromise<ResolvedFragmentMap, nsresult, true> ResolvePromise;
+  /**
+   * Begin an asynchronous paint of a cross process document tree starting at
+   * a WindowGlobalParent. A maybe-async paint for the root WGP will be done,
+   * then async paints will be recursively queued for remote subframes. Once
+   * all subframes have been recorded, the final image will be resolved, and
+   * the promise will be resolved with a dom::ImageBitmap.
+   *
+   * @param aRoot The WindowGlobalParent to paint.
+   * @param aRect The rectangle relative to the viewport to use, or null to
+   *   render the whole viewport.
+   * @param aScale The coordinate scale to use. The size of the resolved
+   *   surface will be `aRect.Size() * aScale`, with aScale clamped to
+   *   at least kMinPaintScale. See the implementation for the current
+   *   minimum value.
+   * @param aBackgroundColor The background color to use.
+   * @param aPromise The promise to resolve with a dom::ImageBitmap.
+   *
+   * @returns Whether the paint was able to be initiated or not.
+   */
+  static bool Start(dom::WindowGlobalParent* aRoot, const dom::DOMRect* aRect,
+                    float aScale, nscolor aBackgroundColor,
+                    CrossProcessPaintFlags aFlags, dom::Promise* aPromise);
+
+  static RefPtr<ResolvePromise> Start(
+      nsTHashtable<nsUint64HashKey>&& aDependencies);
+
+  void ReceiveFragment(dom::WindowGlobalParent* aWGP,
+                       PaintFragment&& aFragment);
+  void LostFragment(dom::WindowGlobalParent* aWGP);
+
+ private:
+  typedef nsDataHashtable<nsUint64HashKey, PaintFragment> ReceivedFragmentMap;
+
+  CrossProcessPaint(float aScale, dom::TabId aRoot);
+  ~CrossProcessPaint();
+
+  void QueueDependencies(const nsTHashtable<nsUint64HashKey>& aDependencies);
+
+  void QueuePaint(
+      dom::WindowGlobalParent* aWGP, const Maybe<IntRect>& aRect,
+      nscolor aBackgroundColor = NS_RGBA(0, 0, 0, 0),
+      CrossProcessPaintFlags aFlags = CrossProcessPaintFlags::DrawView);
+
+  /// Clear the state of this paint so that it cannot be resolved or receive
+  /// any paint fragments.
+  void Clear(nsresult aStatus);
+
+  /// Returns if this paint has been cleared.
+  bool IsCleared() const;
+
+  /// Resolves the paint fragments if we have none pending and resolves the
+  /// promise.
+  void MaybeResolve();
+  nsresult ResolveInternal(dom::TabId aTabId, ResolvedFragmentMap* aResolved);
+
+  RefPtr<ResolvePromise> Init() {
+    MOZ_ASSERT(mPromise.IsEmpty());
+    return mPromise.Ensure(__func__);
+  }
+
+  MozPromiseHolder<ResolvePromise> mPromise;
+  dom::TabId mRoot;
+  float mScale;
+  uint32_t mPendingFragments;
+  ReceivedFragmentMap mReceivedFragments;
+};
+
+}  // namespace gfx
+}  // namespace mozilla
+
+#endif  // _include_mozilla_gfx_ipc_CrossProcessPaint_h_