protected virtual SizeF NativeMeasureOverride(SizeF availableSize)
{
var absoluteAvailableSize = new SizeF(
ScreenProperties.ConvertDPIToPixels(availableSize.Width),
ScreenProperties.ConvertDPIToPixels(availableSize.Height));
var margin = this.Margin;
var absoluteMargin = new Thickness(
(int)ScreenProperties.ConvertDPIToPixels(margin.LeftF()),
(int)ScreenProperties.ConvertDPIToPixels(margin.TopF()),
(int)ScreenProperties.ConvertDPIToPixels(margin.RightF()),
(int)ScreenProperties.ConvertDPIToPixels(margin.BottomF()));
int availableWidth;
int availableHeight;
// TODO: Unclear behavior. Incorrect on API 18
if (double.IsPositiveInfinity(absoluteAvailableSize.Width))
{
availableWidth = int.MaxValue;
}
else
{
availableWidth = (int)(absoluteAvailableSize.Width - absoluteMargin.HorizontalThicknessF());
}
if (availableWidth < 0)
{
availableWidth = 0;
}
if (double.IsPositiveInfinity(absoluteAvailableSize.Height))
{
availableHeight = int.MaxValue;
}
else
{
availableHeight = (int)(absoluteAvailableSize.Height - absoluteMargin.VerticalThicknessF());
}
if (availableHeight < 0)
{
availableHeight = 0;
}
int measuredWidth;
int measuredHeight;
switch (this.NativeUIElement.LayoutParameters.Width)
{
case ViewGroup.LayoutParams.WrapContent:
measuredWidth = View.MeasureSpec.MakeMeasureSpec(availableWidth, MeasureSpecMode.AtMost);
break;
case ViewGroup.LayoutParams.MatchParent:
measuredWidth = View.MeasureSpec.MakeMeasureSpec(availableWidth, MeasureSpecMode.Exactly);
break;
default:
measuredWidth = View.MeasureSpec.MakeMeasureSpec(availableWidth, MeasureSpecMode.Exactly);
break;
}
switch (this.NativeUIElement.LayoutParameters.Height)
{
case ViewGroup.LayoutParams.WrapContent:
measuredHeight = View.MeasureSpec.MakeMeasureSpec(availableHeight, MeasureSpecMode.AtMost);
break;
case ViewGroup.LayoutParams.MatchParent:
measuredHeight = View.MeasureSpec.MakeMeasureSpec(availableHeight, MeasureSpecMode.Exactly);
break;
default:
measuredHeight = View.MeasureSpec.MakeMeasureSpec(availableHeight, MeasureSpecMode.Exactly);
break;
}
this.NativeUIElement.Measure(measuredWidth, measuredHeight);
var absoluteMeasuredSize = new SizeF(
this.NativeUIElement.MeasuredWidth + absoluteMargin.HorizontalThicknessF(),
this.NativeUIElement.MeasuredHeight + absoluteMargin.VerticalThicknessF());
var dpiMeasuredSize = new SizeF(
Math.Min(ScreenProperties.ConvertPixelsToDPI(absoluteMeasuredSize.Width), availableSize.Width),
Math.Min(ScreenProperties.ConvertPixelsToDPI(absoluteMeasuredSize.Height), availableSize.Height));
return(dpiMeasuredSize);
}