private void InnerMeasureCore(Size availableSize)
{
var(minSize, maxSize) = this.GetMinMax();
var marginSize = this.GetMarginSize();
// NaN values are accepted as input here, particularly when coming from
// SizeThatFits in Image or Scrollviewer. Clamp the value here as it is reused
// below for the clipping value.
availableSize = availableSize
.NumberOrDefault(MaxSize);
var frameworkAvailableSize = availableSize
.Subtract(marginSize)
.AtLeastZero()
.AtMost(maxSize);
var desiredSize = MeasureOverride(frameworkAvailableSize);
_logDebug?.Trace($"{DepthIndentation}{FormatDebugName()}.MeasureOverride(availableSize={frameworkAvailableSize}): desiredSize={desiredSize} minSize={minSize} maxSize={maxSize} marginSize={marginSize}");
if (
double.IsNaN(desiredSize.Width) ||
double.IsNaN(desiredSize.Height) ||
double.IsInfinity(desiredSize.Width) ||
double.IsInfinity(desiredSize.Height)
)
{
throw new InvalidOperationException($"{FormatDebugName()}: Invalid measured size {desiredSize}. NaN or Infinity are invalid desired size.");
}
desiredSize = desiredSize
.AtLeast(minSize)
.AtLeastZero();
_unclippedDesiredSize = desiredSize;
var clippedDesiredSize = desiredSize
.Add(marginSize)
// Making sure after adding margins that clipped DesiredSize is not bigger than the AvailableSize
.AtMost(availableSize)
// Margin may be negative
.AtLeastZero();
// DesiredSize must include margins
LayoutInformation.SetDesiredSize(this, clippedDesiredSize);
_logDebug?.Debug($"{DepthIndentation}[{FormatDebugName()}] Measure({Name}/{availableSize}/{Margin}) = {clippedDesiredSize} _unclippedDesiredSize={_unclippedDesiredSize}");
}
partial void OnMeasurePartial(Size slotSize)
{
MeasureCallCount++;
AvailableMeasureSize = slotSize;
if (DesiredSizeSelector != null)
{
var desiredSize = DesiredSizeSelector(slotSize);
LayoutInformation.SetDesiredSize(this, desiredSize);
RequestedDesiredSize = desiredSize;
}
else if (RequestedDesiredSize != null)
{
var desiredSize = RequestedDesiredSize.Value;
LayoutInformation.SetDesiredSize(this, desiredSize);
}
}
public void When_UpdateLayout_Then_TreeNotMeasuredUsingCachedValue()
{
if (Window.Current.RootElement is Panel root)
{
var sut = new Grid
{
HorizontalAlignment = HorizontalAlignment.Stretch,
VerticalAlignment = VerticalAlignment.Stretch
};
var originalRootAvailableSize = LayoutInformation.GetAvailableSize(root);
var originalRootDesiredSize = LayoutInformation.GetDesiredSize(root);
var originalRootLayoutSlot = LayoutInformation.GetLayoutSlot(root);
Size availableSize;
Rect layoutSlot;
try
{
LayoutInformation.SetAvailableSize(root, default);
LayoutInformation.SetDesiredSize(root, default);
LayoutInformation.SetLayoutSlot(root, default);
root.Children.Add(sut);
sut.UpdateLayout();
availableSize = LayoutInformation.GetAvailableSize(sut);
layoutSlot = LayoutInformation.GetLayoutSlot(sut);
}
finally
{
LayoutInformation.SetAvailableSize(root, originalRootAvailableSize);
LayoutInformation.SetDesiredSize(root, originalRootDesiredSize);
LayoutInformation.SetLayoutSlot(root, originalRootLayoutSlot);
root.Children.Remove(sut);
try { root.UpdateLayout(); }
catch { } // Make sure to restore visual tree if test has failed!
}
Assert.AreNotEqual(default, availableSize);