author Ryan VanderMeulen <>
Mon, 14 Apr 2014 16:16:18 -0400
changeset 196901 376496720a0e662039298fcfdde08ff911e23695
parent 196893 fa82f32d0c397317d19c92a60538b4562f8bed0f
child 197215 b54fdf8bb4860ced8f64b7540485157b69ebed11
permissions -rw-r--r--
Backed out changesets ddbac34527fe and fa82f32d0c39 (bug 991812) for B2G bustage. CLOSED TREE

/* -*- Mode: C++; tab-width: 20; 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 */


#include "Units.h"                      // for LayerPoint, etc
#include "mozilla/layers/LayerManagerComposite.h"  // for LayerManagerComposite
#include "gfx3DMatrix.h"                // for gfx3DMatrix
#include "mozilla/Attributes.h"         // for MOZ_DELETE, MOZ_FINAL, etc
#include "mozilla/RefPtr.h"             // for RefCounted
#include "mozilla/TimeStamp.h"          // for TimeStamp
#include "mozilla/dom/ScreenOrientation.h"  // for ScreenOrientation
#include "mozilla/gfx/BasePoint.h"      // for BasePoint
#include "mozilla/layers/LayersMessages.h"  // for TargetConfig
#include "nsAutoPtr.h"                  // for nsRefPtr
#include "nsISupportsImpl.h"            // for LayerManager::AddRef, etc

namespace mozilla {
namespace layers {

class AsyncPanZoomController;
class Layer;
class LayerManagerComposite;
class AutoResolveRefLayers;

// Represents (affine) transforms that are calculated from a content view.
struct ViewTransform {
  ViewTransform(LayerPoint aTranslation = LayerPoint(),
                ParentLayerToScreenScale aScale = ParentLayerToScreenScale())
    : mTranslation(aTranslation)
    , mScale(aScale)

  operator gfx3DMatrix() const
      gfx3DMatrix::Translation(mTranslation.x, mTranslation.y, 0) *
      gfx3DMatrix::ScalingMatrix(mScale.scale, mScale.scale, 1);

  bool operator==(const ViewTransform& rhs) const {
    return mTranslation == rhs.mTranslation && mScale == rhs.mScale;

  bool operator!=(const ViewTransform& rhs) const {
    return !(*this == rhs);

  LayerPoint mTranslation;
  ParentLayerToScreenScale mScale;

 * Manage async composition effects. This class is only used with OMTC and only
 * lives on the compositor thread. It is a layer on top of the layer manager
 * (LayerManagerComposite) which deals with elements of composition which are
 * usually dealt with by dom or layout when main thread rendering, but which can
 * short circuit that stuff to directly affect layers as they are composited,
 * for example, off-main thread animation, async video, async pan/zoom.
class AsyncCompositionManager MOZ_FINAL : public RefCounted<AsyncCompositionManager>
  friend class AutoResolveRefLayers;
  AsyncCompositionManager(LayerManagerComposite* aManager)
    : mLayerManager(aManager)
    , mIsFirstPaint(false)
    , mLayersUpdated(false)
    , mReadyForCompose(true)

   * This forces the is-first-paint flag to true. This is intended to
   * be called by the widget code when it loses its viewport information
   * (or for whatever reason wants to refresh the viewport information).
   * The information refresh happens because the compositor will call
   * SetFirstPaintViewport on the next frame of composition.
  void ForceIsFirstPaint() { mIsFirstPaint = true; }

  // Sample transforms for layer trees.  Return true to request
  // another animation frame.
  bool TransformShadowTree(TimeStamp aCurrentFrame);

  // Calculates the correct rotation and applies the transform to
  // our layer manager
  void ComputeRotation();

  // Call after updating our layer tree.
  void Updated(bool isFirstPaint, const TargetConfig& aTargetConfig)
    mIsFirstPaint |= isFirstPaint;
    mLayersUpdated = true;
    mTargetConfig = aTargetConfig;

  bool RequiresReorientation(mozilla::dom::ScreenOrientation aOrientation)
    return mTargetConfig.orientation() != aOrientation;

  // True if the underlying layer tree is ready to be composited.
  bool ReadyForCompose() { return mReadyForCompose; }

  // Returns true if the next composition will be the first for a
  // particular document.
  bool IsFirstPaint() { return mIsFirstPaint; }

  void TransformScrollableLayer(Layer* aLayer);
  // Return true if an AsyncPanZoomController content transform was
  // applied for |aLayer|.  *aWantNextFrame is set to true if the
  // controller wants another animation frame.
  bool ApplyAsyncContentTransformToTree(TimeStamp aCurrentFrame, Layer* aLayer,
                                        bool* aWantNextFrame);
   * Update the shadow transform for aLayer assuming that is a scrollbar,
   * so that it stays in sync with the content that is being scrolled by APZ.
  void ApplyAsyncTransformToScrollbar(TimeStamp aCurrentFrame, ContainerLayer* aLayer);

  void SetFirstPaintViewport(const LayerIntPoint& aOffset,
                             const CSSToLayerScale& aZoom,
                             const CSSRect& aCssPageRect);
  void SetPageRect(const CSSRect& aCssPageRect);
  void SyncViewportInfo(const LayerIntRect& aDisplayPort,
                        const CSSToLayerScale& aDisplayResolution,
                        bool aLayersUpdated,
                        ScreenPoint& aScrollOffset,
                        CSSToScreenScale& aScale,
                        LayerMargin& aFixedLayerMargins,
                        ScreenPoint& aOffset);
  void SyncFrameMetrics(const ScreenPoint& aScrollOffset,
                        float aZoom,
                        const CSSRect& aCssPageRect,
                        bool aLayersUpdated,
                        const CSSRect& aDisplayPort,
                        const CSSToLayerScale& aDisplayResolution,
                        bool aIsFirstPaint,
                        LayerMargin& aFixedLayerMargins,
                        ScreenPoint& aOffset);

   * Adds a translation to the transform of any fixed position (whose parent
   * layer is not fixed) or sticky position layer descendant of
   * aTransformedSubtreeRoot. The translation is chosen so that the layer's
   * anchor point relative to aTransformedSubtreeRoot's parent layer is the same
   * as it was when aTransformedSubtreeRoot's GetLocalTransform() was
   * aPreviousTransformForRoot. For sticky position layers, the translation is
   * further intersected with the layer's sticky scroll ranges.
   * This function will also adjust layers so that the given content document
   * fixed position margins will be respected during asynchronous panning and
   * zooming.
  void AlignFixedAndStickyLayers(Layer* aLayer, Layer* aTransformedSubtreeRoot,
                                 const gfx::Matrix4x4& aPreviousTransformForRoot,
                                 const LayerMargin& aFixedLayerMargins);

   * For reach RefLayer in our layer tree, look up its referent and connect it
   * to the layer tree, if found.
  void ResolveRefLayers();
   * Detaches all referents resolved by ResolveRefLayers.
   * Assumes that mLayerManager->GetRoot() and mTargetConfig have not changed
   * since ResolveRefLayers was called.
  void DetachRefLayers();

  TargetConfig mTargetConfig;
  CSSRect mContentRect;

  nsRefPtr<LayerManagerComposite> mLayerManager;
  // When this flag is set, the next composition will be the first for a
  // particular document (i.e. the document displayed on the screen will change).
  // This happens when loading a new page or switching tabs. We notify the
  // front-end (e.g. Java on Android) about this so that it take the new page
  // size and zoom into account when providing us with the next view transform.
  bool mIsFirstPaint;

  // This flag is set during a layers update, so that the first composition
  // after a layers update has it set. It is cleared after that first composition.
  bool mLayersUpdated;

  bool mReadyForCompose;

class MOZ_STACK_CLASS AutoResolveRefLayers {
  AutoResolveRefLayers(AsyncCompositionManager* aManager) : mManager(aManager)
    if (mManager) {

    if (mManager) {

  AsyncCompositionManager* mManager;

  AutoResolveRefLayers(const AutoResolveRefLayers&) MOZ_DELETE;
  AutoResolveRefLayers& operator=(const AutoResolveRefLayers&) MOZ_DELETE;

} // layers
} // mozilla