protected override Size MeasureOverride(Size availableSize)
{
if (TemplateChild == null)
{
return(Size.Zero);
}
TemplateChild.Measure(availableSize);
return(TemplateChild.DesiredSize);
}
protected override Size MeasureOverride(Size availableSize)
{
if (TemplateChild == null)
{
return(Size.Zero);
}
ComputedHorizontalScrollBarVisibility = GetScrollBarVisibility(HorizontalScrollBarVisibility, false);
ComputedVerticalScrollBarVisibility = GetScrollBarVisibility(VerticalScrollBarVisibility, false);
ComputedScrollBarsVisibility = ComputedHorizontalScrollBarVisibility == Visibility.Visible && ComputedVerticalScrollBarVisibility == Visibility.Visible ? Visibility.Visible : Visibility.Collapsed;
// 3 passes, each pass can cause an overflow (and add a scrollbar which invalidates the measure), starting with no overlaps
for (int measurePass = 0; measurePass < 3; measurePass++)
{
// computed visibilities can invalidate the ScrollBars measure, invalidate their path so they will be re-measured through TemplateChild
InvalidateElementMeasurePath(this, HorizontalScrollBar);
InvalidateElementMeasurePath(this, VerticalScrollBar);
TemplateChild.Measure(availableSize);
Visibility measuredHorizontalScrollBarVisibility = GetScrollBarVisibility(HorizontalScrollBarVisibility, scrollContentPresenter != null && scrollContentPresenter.ViewportSize.Width < scrollContentPresenter.ExtentSize.Width);
Visibility measuredVerticalScrollBarVisibility = GetScrollBarVisibility(VerticalScrollBarVisibility, scrollContentPresenter != null && scrollContentPresenter.ViewportSize.Height < scrollContentPresenter.ExtentSize.Height);
if (ComputedHorizontalScrollBarVisibility == measuredHorizontalScrollBarVisibility &&
ComputedVerticalScrollBarVisibility == measuredVerticalScrollBarVisibility)
{
break;
}
ComputedHorizontalScrollBarVisibility = measuredHorizontalScrollBarVisibility;
ComputedVerticalScrollBarVisibility = measuredVerticalScrollBarVisibility;
ComputedScrollBarsVisibility = ComputedHorizontalScrollBarVisibility == Visibility.Visible && ComputedVerticalScrollBarVisibility == Visibility.Visible ? Visibility.Visible : Visibility.Collapsed;
}
SetScrollInfoSizes();
return(TemplateChild.DesiredSize);
}