コード例 #1
0
static void
AdjustDisplayPortForScrollDelta(mozilla::layers::FrameMetrics& aFrameMetrics,
                                const CSSPoint& aActualScrollOffset)
{
    // Correct the display-port by the difference between the requested scroll
    // offset and the resulting scroll offset after setting the requested value.
    LayerPoint shift =
        (aFrameMetrics.GetScrollOffset() - aActualScrollOffset) *
        aFrameMetrics.LayersPixelsPerCSSPixel();
    LayerMargin margins = aFrameMetrics.GetDisplayPortMargins();
    margins.left -= shift.x;
    margins.right += shift.x;
    margins.top -= shift.y;
    margins.bottom += shift.y;
    aFrameMetrics.SetDisplayPortMargins(margins);
}
コード例 #2
0
static void
MaybeAlignAndClampDisplayPort(mozilla::layers::FrameMetrics& aFrameMetrics,
                              const CSSPoint& aActualScrollOffset)
{
  // Correct the display-port by the difference between the requested scroll
  // offset and the resulting scroll offset after setting the requested value.
  CSSRect& displayPort = aFrameMetrics.mDisplayPort;
  displayPort += aFrameMetrics.mScrollOffset - aActualScrollOffset;

  // Expand the display port to the next tile boundaries, if tiled thebes layers
  // are enabled.
  if (gfxPlatform::GetPrefLayersEnableTiles()) {
    displayPort =
      ExpandDisplayPortToTileBoundaries(displayPort + aActualScrollOffset,
                                        aFrameMetrics.LayersPixelsPerCSSPixel())
      - aActualScrollOffset;
  }

  // Finally, clamp the display port to the expanded scrollable rect.
  CSSRect scrollableRect = aFrameMetrics.GetExpandedScrollableRect();
  displayPort = scrollableRect.Intersect(displayPort + aActualScrollOffset)
    - aActualScrollOffset;
}