C++ LayerComposite::GetShadowClipRect方法代码示例

void
LayerManagerComposite::PostProcessLayers(Layer* aLayer,
                                         nsIntRegion& aOpaqueRegion,
                                         LayerIntRegion& aVisibleRegion,
                                         const Maybe<ParentLayerIntRect>& aClipFromAncestors)
{
  if (aLayer->Extend3DContext()) {
    // For layers participating 3D rendering context, their visible
    // region should be empty (invisible), so we pass through them
    // without doing anything.

    // Direct children of the establisher may have a clip, becaue the
    // item containing it; ex. of nsHTMLScrollFrame, may give it one.
    Maybe<ParentLayerIntRect> layerClip =
      aLayer->AsHostLayer()->GetShadowClipRect();
    Maybe<ParentLayerIntRect> ancestorClipForChildren =
      IntersectMaybeRects(layerClip, aClipFromAncestors);
    MOZ_ASSERT(!layerClip || !aLayer->Combines3DTransformWithAncestors(),
               "Only direct children of the establisher could have a clip");

    for (Layer* child = aLayer->GetLastChild();
         child;
         child = child->GetPrevSibling()) {
      PostProcessLayers(child, aOpaqueRegion, aVisibleRegion,
                        ancestorClipForChildren);
    }
    return;
  }

  nsIntRegion localOpaque;
  // Treat layers on the path to the root of the 3D rendering context as
  // a giant layer if it is a leaf.
  Matrix4x4 transform = GetAccTransformIn3DContext(aLayer);
  Matrix transform2d;
  Maybe<IntPoint> integerTranslation;
  // If aLayer has a simple transform (only an integer translation) then we
  // can easily convert aOpaqueRegion into pre-transform coordinates and include
  // that region.
  if (transform.Is2D(&transform2d)) {
    if (transform2d.IsIntegerTranslation()) {
      integerTranslation = Some(IntPoint::Truncate(transform2d.GetTranslation()));
      localOpaque = aOpaqueRegion;
      localOpaque.MoveBy(-*integerTranslation);
    }
  }

  // Compute a clip that's the combination of our layer clip with the clip
  // from our ancestors.
  LayerComposite* composite = static_cast<LayerComposite*>(aLayer->AsHostLayer());
  Maybe<ParentLayerIntRect> layerClip = composite->GetShadowClipRect();
  MOZ_ASSERT(!layerClip || !aLayer->Combines3DTransformWithAncestors(),
             "The layer with a clip should not participate "
             "a 3D rendering context");
  Maybe<ParentLayerIntRect> outsideClip =
    IntersectMaybeRects(layerClip, aClipFromAncestors);

  // Convert the combined clip into our pre-transform coordinate space, so
  // that it can later be intersected with our visible region.
  // If our transform is a perspective, there's no meaningful insideClip rect
  // we can compute (it would need to be a cone).
  Maybe<LayerIntRect> insideClip;
  if (outsideClip && !transform.HasPerspectiveComponent()) {
    Matrix4x4 inverse = transform;
    if (inverse.Invert()) {
      Maybe<LayerRect> insideClipFloat =
        UntransformBy(ViewAs<ParentLayerToLayerMatrix4x4>(inverse),
                      ParentLayerRect(*outsideClip),
                      LayerRect::MaxIntRect());
      if (insideClipFloat) {
        insideClipFloat->RoundOut();
        LayerIntRect insideClipInt;
        if (insideClipFloat->ToIntRect(&insideClipInt)) {
          insideClip = Some(insideClipInt);
        }
      }
    }
  }

  Maybe<ParentLayerIntRect> ancestorClipForChildren;
  if (insideClip) {
    ancestorClipForChildren =
      Some(ViewAs<ParentLayerPixel>(*insideClip, PixelCastJustification::MovingDownToChildren));
  }

  // Save the value of localOpaque, which currently stores the region obscured
  // by siblings (and uncles and such), before our descendants contribute to it.
  nsIntRegion obscured = localOpaque;

  // Recurse on our descendants, in front-to-back order. In this process:
  //  - Occlusions are computed for them, and they contribute to localOpaque.
  //  - They recalculate their visible regions, taking ancestorClipForChildren
  //    into account, and accumulate them into descendantsVisibleRegion.
  LayerIntRegion descendantsVisibleRegion;
  bool hasPreserve3DChild = false;
  for (Layer* child = aLayer->GetLastChild(); child; child = child->GetPrevSibling()) {
    PostProcessLayers(child, localOpaque, descendantsVisibleRegion, ancestorClipForChildren);
    if (child->Extend3DContext()) {
      hasPreserve3DChild = true;
    }
  }
//.........这里部分代码省略.........

// Go down shadow layer tree and apply transformations for scrollable layers.
static void
TransformShadowTree(nsDisplayListBuilder* aBuilder, nsFrameLoader* aFrameLoader,
                    nsIFrame* aFrame, Layer* aLayer,
                    const ViewTransform& aTransform,
                    float aTempScaleDiffX = 1.0,
                    float aTempScaleDiffY = 1.0)
{
  LayerComposite* shadow = aLayer->AsLayerComposite();
  shadow->SetShadowClipRect(aLayer->GetClipRect());
  shadow->SetShadowVisibleRegion(aLayer->GetVisibleRegion());
  shadow->SetShadowOpacity(aLayer->GetOpacity());

  const FrameMetrics* metrics = GetFrameMetrics(aLayer);

  gfx3DMatrix shadowTransform = aLayer->GetTransform();
  ViewTransform layerTransform = aTransform;

  if (metrics && metrics->IsScrollable()) {
    const ViewID scrollId = metrics->mScrollId;
    const nsContentView* view =
      aFrameLoader->GetCurrentRemoteFrame()->GetContentView(scrollId);
    NS_ABORT_IF_FALSE(view, "Array of views should be consistent with layer tree");
    const gfx3DMatrix& currentTransform = aLayer->GetTransform();

    const ViewConfig& config = view->GetViewConfig();
    // With temporary scale we should compensate translation
    // using temporary scale value
    aTempScaleDiffX *= GetXScale(shadowTransform) * config.mXScale;
    aTempScaleDiffY *= GetYScale(shadowTransform) * config.mYScale;
    ViewTransform viewTransform = ComputeShadowTreeTransform(
      aFrame, aFrameLoader, metrics, view->GetViewConfig(),
      aTempScaleDiffX, aTempScaleDiffY
    );

    // Apply the layer's own transform *before* the view transform
    shadowTransform = gfx3DMatrix(viewTransform) * currentTransform;

    layerTransform = viewTransform;
    if (metrics->IsRootScrollable()) {
      // Apply the translation *before* we do the rest of the transforms.
      nsIntPoint offset = GetContentRectLayerOffset(aFrame, aBuilder);
      shadowTransform = shadowTransform *
          gfx3DMatrix::Translation(float(offset.x), float(offset.y), 0.0);
    }
  }

  if (aLayer->GetIsFixedPosition() &&
      !aLayer->GetParent()->GetIsFixedPosition()) {
    // Alter the shadow transform of fixed position layers in the situation
    // that the view transform's scroll position doesn't match the actual
    // scroll position, due to asynchronous layer scrolling.
    float offsetX = layerTransform.mTranslation.x;
    float offsetY = layerTransform.mTranslation.y;
    ReverseTranslate(shadowTransform, gfxPoint(offsetX, offsetY));
    const nsIntRect* clipRect = shadow->GetShadowClipRect();
    if (clipRect) {
      nsIntRect transformedClipRect(*clipRect);
      transformedClipRect.MoveBy(-offsetX, -offsetY);
      shadow->SetShadowClipRect(&transformedClipRect);
    }
  }

  // The transform already takes the resolution scale into account.  Since we
  // will apply the resolution scale again when computing the effective
  // transform, we must apply the inverse resolution scale here.
  if (ContainerLayer* c = aLayer->AsContainerLayer()) {
    shadowTransform.Scale(1.0f/c->GetPreXScale(),
                          1.0f/c->GetPreYScale(),
                          1);
  }
  shadowTransform.ScalePost(1.0f/aLayer->GetPostXScale(),
                            1.0f/aLayer->GetPostYScale(),
                            1);

  shadow->SetShadowTransform(shadowTransform);
  for (Layer* child = aLayer->GetFirstChild();
       child; child = child->GetNextSibling()) {
    TransformShadowTree(aBuilder, aFrameLoader, aFrame, child, layerTransform,
                        aTempScaleDiffX, aTempScaleDiffY);
  }
}

void
LayerManagerComposite::PostProcessLayers(Layer* aLayer,
                                         nsIntRegion& aOpaqueRegion,
                                         LayerIntRegion& aVisibleRegion)
{
  nsIntRegion localOpaque;
  Matrix transform2d;
  Maybe<nsIntPoint> integerTranslation;
  // If aLayer has a simple transform (only an integer translation) then we
  // can easily convert aOpaqueRegion into pre-transform coordinates and include
  // that region.
  if (aLayer->GetLocalTransform().Is2D(&transform2d)) {
    if (transform2d.IsIntegerTranslation()) {
      integerTranslation = Some(TruncatedToInt(transform2d.GetTranslation()));
      localOpaque = aOpaqueRegion;
      localOpaque.MoveBy(-*integerTranslation);
    }
  }

  // Save the value of localOpaque, which currently stores the region obscured
  // by siblings (and uncles and such), before our descendants contribute to it.
  nsIntRegion obscured = localOpaque;

  // Recurse on our descendants, in front-to-back order. In this process:
  //  - Occlusions are computed for them, and they contribute to localOpaque.
  //  - They recalculate their visible regions, and accumulate them into
  //    descendantsVisibleRegion.
  LayerIntRegion descendantsVisibleRegion;
  for (Layer* child = aLayer->GetLastChild(); child; child = child->GetPrevSibling()) {
    PostProcessLayers(child, localOpaque, descendantsVisibleRegion);
  }

  // Recalculate our visible region.
  LayerComposite* composite = aLayer->AsLayerComposite();
  LayerIntRegion visible = composite->GetShadowVisibleRegion();

  // If we have descendants, throw away the visible region stored on this
  // layer, and use the region accumulated by our descendants instead.
  if (aLayer->GetFirstChild()) {
    visible = descendantsVisibleRegion;
  }

  // Subtract any areas that we know to be opaque.
  if (!obscured.IsEmpty()) {
    visible.SubOut(LayerIntRegion::FromUnknownRegion(obscured));
  }

  composite->SetShadowVisibleRegion(visible);

  // Transform the newly calculated visible region into our parent's space,
  // apply our clip to it (if any), and accumulate it into |aVisibleRegion|
  // for the caller to use.
  ParentLayerIntRegion visibleParentSpace = TransformTo<ParentLayerPixel>(
      aLayer->GetLocalTransform(), visible);
  if (const Maybe<ParentLayerIntRect>& clipRect = composite->GetShadowClipRect()) {
    visibleParentSpace.AndWith(*clipRect);
  }
  aVisibleRegion.OrWith(ViewAs<LayerPixel>(visibleParentSpace,
      PixelCastJustification::MovingDownToChildren));

  // If we have a simple transform, then we can add our opaque area into
  // aOpaqueRegion.
  if (integerTranslation &&
      !aLayer->HasMaskLayers() &&
      aLayer->IsOpaqueForVisibility()) {
    if (aLayer->GetContentFlags() & Layer::CONTENT_OPAQUE) {
      localOpaque.OrWith(composite->GetFullyRenderedRegion());
    }
    localOpaque.MoveBy(*integerTranslation);
    const Maybe<ParentLayerIntRect>& clip = aLayer->GetEffectiveClipRect();
    if (clip) {
      localOpaque.AndWith(clip->ToUnknownRect());
    }
    aOpaqueRegion.OrWith(localOpaque);
  }
}