C++ FrameMetrics::IsScrollable方法代码示例

// Recursively create a new array of scrollables, preserving any scrollables
// that are still in the layer tree.
//
// aXScale and aYScale are used to calculate any values that need to be in
// chrome-document CSS pixels and aren't part of the rendering loop, such as
// the initial scroll offset for a new view.
static void
BuildViewMap(ViewMap& oldContentViews, ViewMap& newContentViews,
             nsFrameLoader* aFrameLoader, Layer* aLayer,
             float aXScale = 1, float aYScale = 1,
             float aAccConfigXScale = 1, float aAccConfigYScale = 1)
{
  ContainerLayer* container = aLayer->AsContainerLayer();
  if (!container)
    return;
  const FrameMetrics metrics = container->GetFrameMetrics();
  const ViewID scrollId = metrics.mScrollId;
  const gfx3DMatrix transform = aLayer->GetTransform();
  aXScale *= GetXScale(transform);
  aYScale *= GetYScale(transform);

  if (metrics.IsScrollable()) {
    nscoord auPerDevPixel = aFrameLoader->GetPrimaryFrameOfOwningContent()
                                        ->PresContext()->AppUnitsPerDevPixel();
    nscoord auPerCSSPixel = auPerDevPixel * metrics.mDevPixelsPerCSSPixel;
    nsContentView* view = FindViewForId(oldContentViews, scrollId);
    if (view) {
      // View already exists. Be sure to propagate scales for any values
      // that need to be calculated something in chrome-doc CSS pixels.
      ViewConfig config = view->GetViewConfig();
      aXScale *= config.mXScale;
      aYScale *= config.mYScale;
      view->mFrameLoader = aFrameLoader;
      // If scale has changed, then we should update
      // current scroll offset to new scaled value
      if (aAccConfigXScale != view->mParentScaleX ||
          aAccConfigYScale != view->mParentScaleY) {
        float xscroll = 0, yscroll = 0;
        view->GetScrollX(&xscroll);
        view->GetScrollY(&yscroll);
        xscroll = xscroll * (aAccConfigXScale / view->mParentScaleX);
        yscroll = yscroll * (aAccConfigYScale / view->mParentScaleY);
        view->ScrollTo(xscroll, yscroll);
        view->mParentScaleX = aAccConfigXScale;
        view->mParentScaleY = aAccConfigYScale;
      }
      // Collect only config scale values for scroll compensation
      aAccConfigXScale *= config.mXScale;
      aAccConfigYScale *= config.mYScale;
    } else {
      // View doesn't exist, so generate one. We start the view scroll offset at
      // the same position as the framemetric's scroll offset from the layer.
      // The default scale is 1, so no need to propagate scale down.
      ViewConfig config;
      config.mScrollOffset = nsPoint(
        NSIntPixelsToAppUnits(metrics.mScrollOffset.x, auPerCSSPixel) * aXScale,
        NSIntPixelsToAppUnits(metrics.mScrollOffset.y, auPerCSSPixel) * aYScale);
      view = new nsContentView(aFrameLoader, scrollId, config);
      view->mParentScaleX = aAccConfigXScale;
      view->mParentScaleY = aAccConfigYScale;
    }

    view->mViewportSize = nsSize(
      NSIntPixelsToAppUnits(metrics.mViewport.width, auPerDevPixel) * aXScale,
      NSIntPixelsToAppUnits(metrics.mViewport.height, auPerDevPixel) * aYScale);
    view->mContentSize = nsSize(
      NSIntPixelsToAppUnits(metrics.mContentRect.width, auPerDevPixel) * aXScale,
      NSIntPixelsToAppUnits(metrics.mContentRect.height, auPerDevPixel) * aYScale);

    newContentViews[scrollId] = view;
  }

  for (Layer* child = aLayer->GetFirstChild();
       child; child = child->GetNextSibling()) {
    BuildViewMap(oldContentViews, newContentViews, aFrameLoader, child,
                 aXScale, aYScale, aAccConfigXScale, aAccConfigYScale);
  }
}

float
LayerManagerComposite::ComputeRenderIntegrity()
{
  // We only ever have incomplete rendering when progressive tiles are enabled.
  Layer* root = GetRoot();
  if (!gfxPlatform::GetPlatform()->UseProgressivePaint() || !root) {
    return 1.f;
  }

  FrameMetrics rootMetrics = LayerMetricsWrapper::TopmostScrollableMetrics(root);
  if (!rootMetrics.IsScrollable()) {
    // The root may not have any scrollable metrics, in which case rootMetrics
    // will just be an empty FrameMetrics. Instead use the actual metrics from
    // the root layer.
    rootMetrics = LayerMetricsWrapper(root).Metrics();
  }
  ParentLayerIntRect bounds = RoundedToInt(rootMetrics.GetCompositionBounds());
  IntRect screenRect(bounds.x,
                       bounds.y,
                       bounds.width,
                       bounds.height);

  float lowPrecisionMultiplier = 1.0f;
  float highPrecisionMultiplier = 1.0f;

#ifdef MOZ_WIDGET_ANDROID
  // Use the transform on the primary scrollable layer and its FrameMetrics
  // to find out how much of the viewport the current displayport covers
  nsTArray<Layer*> rootScrollableLayers;
  GetRootScrollableLayers(rootScrollableLayers);
  if (rootScrollableLayers.Length() > 0) {
    // This is derived from the code in
    // AsyncCompositionManager::TransformScrollableLayer
    Layer* rootScrollable = rootScrollableLayers[0];
    const FrameMetrics& metrics = LayerMetricsWrapper::TopmostScrollableMetrics(rootScrollable);
    Matrix4x4 transform = rootScrollable->GetEffectiveTransform();
    transform.PostScale(metrics.GetPresShellResolution(), metrics.GetPresShellResolution(), 1);

    // Clip the screen rect to the document bounds
    Rect documentBounds =
      transform.TransformBounds(Rect(metrics.GetScrollableRect().x - metrics.GetScrollOffset().x,
                                     metrics.GetScrollableRect().y - metrics.GetScrollOffset().y,
                                     metrics.GetScrollableRect().width,
                                     metrics.GetScrollableRect().height));
    documentBounds.RoundOut();
    screenRect = screenRect.Intersect(IntRect(documentBounds.x, documentBounds.y,
                                                documentBounds.width, documentBounds.height));

    // If the screen rect is empty, the user has scrolled entirely into
    // over-scroll and so we can be considered to have full integrity.
    if (screenRect.IsEmpty()) {
      return 1.0f;
    }

    // Work out how much of the critical display-port covers the screen
    bool hasLowPrecision = false;
    if (!metrics.GetCriticalDisplayPort().IsEmpty()) {
      hasLowPrecision = true;
      highPrecisionMultiplier =
        GetDisplayportCoverage(metrics.GetCriticalDisplayPort(), transform, screenRect);
    }

    // Work out how much of the display-port covers the screen
    if (!metrics.GetDisplayPort().IsEmpty()) {
      if (hasLowPrecision) {
        lowPrecisionMultiplier =
          GetDisplayportCoverage(metrics.GetDisplayPort(), transform, screenRect);
      } else {
        lowPrecisionMultiplier = highPrecisionMultiplier =
          GetDisplayportCoverage(metrics.GetDisplayPort(), transform, screenRect);
      }
    }
  }

  // If none of the screen is covered, we have zero integrity.
  if (highPrecisionMultiplier <= 0.0f && lowPrecisionMultiplier <= 0.0f) {
    return 0.0f;
  }
#endif // MOZ_WIDGET_ANDROID

  nsIntRegion screenRegion(screenRect);
  nsIntRegion lowPrecisionScreenRegion(screenRect);
  Matrix4x4 transform;
  ComputeRenderIntegrityInternal(root, screenRegion,
                                 lowPrecisionScreenRegion, transform);

  if (!screenRegion.IsEqual(screenRect)) {
    // Calculate the area of the region. All rects in an nsRegion are
    // non-overlapping.
    float screenArea = screenRect.width * screenRect.height;
    float highPrecisionIntegrity = screenRegion.Area() / screenArea;
    float lowPrecisionIntegrity = 1.f;
    if (!lowPrecisionScreenRegion.IsEqual(screenRect)) {
      lowPrecisionIntegrity = lowPrecisionScreenRegion.Area() / screenArea;
    }

    return ((highPrecisionIntegrity * highPrecisionMultiplier) +
            (lowPrecisionIntegrity * lowPrecisionMultiplier)) / 2;
  }

//.........这里部分代码省略.........