C++ ContainerLayer::GetPostYScale方法代码示例

void
AsyncCompositionManager::TransformScrollableLayer(Layer* aLayer, const LayoutDeviceToLayerScale& aResolution)
{
  LayerComposite* layerComposite = aLayer->AsLayerComposite();
  ContainerLayer* container = aLayer->AsContainerLayer();

  const FrameMetrics& metrics = container->GetFrameMetrics();
  // We must apply the resolution scale before a pan/zoom transform, so we call
  // GetTransform here.
  const gfx3DMatrix& currentTransform = aLayer->GetTransform();
  gfx3DMatrix oldTransform = currentTransform;

  gfx3DMatrix treeTransform;

  CSSToLayerScale geckoZoom = metrics.mDevPixelsPerCSSPixel * aResolution;

  LayerIntPoint scrollOffsetLayerPixels = RoundedToInt(metrics.mScrollOffset * geckoZoom);

  if (mIsFirstPaint) {
    mContentRect = metrics.mScrollableRect;
    SetFirstPaintViewport(scrollOffsetLayerPixels,
                          geckoZoom,
                          mContentRect);
    mIsFirstPaint = false;
  } else if (!metrics.mScrollableRect.IsEqualEdges(mContentRect)) {
    mContentRect = metrics.mScrollableRect;
    SetPageRect(mContentRect);
  }

  // We synchronise the viewport information with Java after sending the above
  // notifications, so that Java can take these into account in its response.
  // Calculate the absolute display port to send to Java
  LayerIntRect displayPort = RoundedToInt(
    (metrics.mCriticalDisplayPort.IsEmpty()
      ? metrics.mDisplayPort
      : metrics.mCriticalDisplayPort
    ) * geckoZoom);
  displayPort += scrollOffsetLayerPixels;

  LayerMargin fixedLayerMargins(0, 0, 0, 0);
  ScreenPoint offset(0, 0);

  // Ideally we would initialize userZoom to AsyncPanZoomController::CalculateResolution(metrics)
  // but this causes a reftest-ipc test to fail (see bug 883646 comment 27). The reason for this
  // appears to be that metrics.mZoom is poorly initialized in some scenarios. In these scenarios,
  // however, we can assume there is no async zooming in progress and so the following statement
  // works fine.
  CSSToScreenScale userZoom(metrics.mDevPixelsPerCSSPixel.scale * metrics.mResolution.scale);
  ScreenPoint userScroll = metrics.mScrollOffset * userZoom;
  SyncViewportInfo(displayPort, geckoZoom, mLayersUpdated,
                   userScroll, userZoom, fixedLayerMargins,
                   offset);
  mLayersUpdated = false;

  // Apply the render offset
  mLayerManager->GetCompositor()->SetScreenRenderOffset(offset);

  // Handle transformations for asynchronous panning and zooming. We determine the
  // zoom used by Gecko from the transformation set on the root layer, and we
  // determine the scroll offset used by Gecko from the frame metrics of the
  // primary scrollable layer. We compare this to the user zoom and scroll
  // offset in the view transform we obtained from Java in order to compute the
  // transformation we need to apply.
  LayerToScreenScale zoomAdjust = userZoom / geckoZoom;

  LayerIntPoint geckoScroll(0, 0);
  if (metrics.IsScrollable()) {
    geckoScroll = scrollOffsetLayerPixels;
  }

  LayerPoint translation = (userScroll / zoomAdjust) - geckoScroll;
  treeTransform = gfx3DMatrix(ViewTransform(-translation, userZoom / metrics.mDevPixelsPerCSSPixel));

  // 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.
  gfx3DMatrix computedTransform = treeTransform * currentTransform;
  computedTransform.Scale(1.0f/container->GetPreXScale(),
                          1.0f/container->GetPreYScale(),
                          1);
  computedTransform.ScalePost(1.0f/container->GetPostXScale(),
                              1.0f/container->GetPostYScale(),
                              1);
  layerComposite->SetShadowTransform(computedTransform);
  NS_ASSERTION(!layerComposite->GetShadowTransformSetByAnimation(),
               "overwriting animated transform!");

  // Apply resolution scaling to the old transform - the layer tree as it is
  // doesn't have the necessary transform to display correctly.
  oldTransform.Scale(aResolution.scale, aResolution.scale, 1);

  // Make sure that overscroll and under-zoom are represented in the old
  // transform so that fixed position content moves and scales accordingly.
  // These calculations will effectively scale and offset fixed position layers
  // in screen space when the compensatory transform is performed in
  // AlignFixedLayersForAnchorPoint.
  ScreenRect contentScreenRect = mContentRect * userZoom;
  gfxPoint3D overscrollTranslation;
  if (userScroll.x < contentScreenRect.x) {
    overscrollTranslation.x = contentScreenRect.x - userScroll.x;
//.........这里部分代码省略.........