private void UpdateSubTree(VisualElement ve, int currentLayoutPass, bool isDisplayed = true)
{
Rect yogaLayoutRect = new Rect(ve.yogaNode.LayoutX, ve.yogaNode.LayoutY, ve.yogaNode.LayoutWidth, ve.yogaNode.LayoutHeight);
// This is not the "real" padding rect: it may differ in size and position because the borders are ignored.
// Alone, it cannot be used to identify padding size changes, because the bottom and right values depend on the
// layout rect width/height. A change in layout rect width/height with a corresponding variation in
// right/bottom values may yield the same pseudoPaddingRect. Fortunately, the layout rect size and padding rect
// size change trigger the same code path which explains why we haven't seen any issue with this so far.
Rect yogaPseudoPaddingRect = new Rect(
ve.yogaNode.LayoutPaddingLeft,
ve.yogaNode.LayoutPaddingTop,
ve.yogaNode.LayoutWidth - (ve.yogaNode.LayoutPaddingLeft + ve.yogaNode.LayoutPaddingRight),
ve.yogaNode.LayoutHeight - (ve.yogaNode.LayoutPaddingTop + ve.yogaNode.LayoutPaddingBottom));
Rect lastLayoutRect = ve.lastLayout;
Rect lastPseudoPaddingRect = ve.lastPseudoPadding;
bool wasHierarchyDisplayed = ve.isHierarchyDisplayed;
VersionChangeType changeType = 0;
// Changing the layout/padding size should trigger the following version changes:
// - Size: to update the clipping rect, when required
// - Repaint: to update the geometry inside the new rect
bool layoutSizeChanged = lastLayoutRect.size != yogaLayoutRect.size;
bool pseudoPaddingSizeChanged = lastPseudoPaddingRect.size != yogaPseudoPaddingRect.size;
if (layoutSizeChanged || pseudoPaddingSizeChanged)
{
changeType |= VersionChangeType.Size | VersionChangeType.Repaint;
}
// Changing the layout/padding position should trigger the following version change:
// - Transform: to draw the element and content at the right position
bool layoutPositionChanged = yogaLayoutRect.position != lastLayoutRect.position;
bool paddingPositionChanged = yogaPseudoPaddingRect.position != lastPseudoPaddingRect.position;
if (layoutPositionChanged || paddingPositionChanged)
{
changeType |= VersionChangeType.Transform;
}
isDisplayed &= ve.resolvedStyle.display != DisplayStyle.None;
ve.isHierarchyDisplayed = isDisplayed;
if (changeType != 0)
{
ve.IncrementVersion(changeType);
}
ve.lastLayout = yogaLayoutRect;
ve.lastPseudoPadding = yogaPseudoPaddingRect;
// ignore clean sub trees
bool hasNewLayout = ve.yogaNode.HasNewLayout;
if (hasNewLayout)
{
var childCount = ve.hierarchy.childCount;
for (int i = 0; i < childCount; ++i)
{
UpdateSubTree(ve.hierarchy[i], currentLayoutPass, isDisplayed);
}
}
// Only send GeometryChanged events when the layout changes
// (padding changes don't affect the element's geometry).
if ((layoutSizeChanged || layoutPositionChanged) && ve.HasEventCallbacksOrDefaultActions(GeometryChangedEvent.EventCategory))
{
using (var evt = GeometryChangedEvent.GetPooled(lastLayoutRect, yogaLayoutRect))
{
evt.layoutPass = currentLayoutPass;
evt.target = ve;
ve.HandleEventAtTargetAndDefaultPhase(evt);
}
}
if (hasNewLayout)
{
ve.yogaNode.MarkLayoutSeen();
}
}