/// <summary>
/// A default implementation of MeasureOverride to be used by all WPF widgets
/// </summary>
/// <param name="constraint">Size constraints</param>
/// <param name="wpfMeasure">Size returned by the base MeasureOverride</param>
/// <returns></returns>
public System.Windows.Size MeasureOverride(System.Windows.Size constraint, System.Windows.Size wpfMeasure)
{
// Calculate the natural size, if that's what is being measured
if (gettingNaturalSize)
{
var defNaturalSize = eventSink.GetDefaultNaturalSize();
// -2 means use the WPF default, -1 use the XWT default, any other other value is used as custom natural size
var nw = DefaultNaturalWidth;
if (nw == -1)
{
nw = defNaturalSize.Width;
if (nw == 0)
{
nw = wpfMeasure.Width;
}
wpfMeasure.Width = nw;
}
else if (nw != -2)
{
wpfMeasure.Width = nw;
}
var nh = DefaultNaturalHeight;
if (nh == -1)
{
nh = defNaturalSize.Height;
if (nh == 0)
{
nh = wpfMeasure.Height;
}
wpfMeasure.Height = nh;
}
else if (nh != -2)
{
wpfMeasure.Height = nh;
}
}
// If we are calculating the default preferred size of the widget we end here.
// See note above about when GetPreferred* methods are called.
if (calculatingPreferredSize)
{
return(wpfMeasure);
}
Context.InvokeUserCode(delegate
{
if (eventSink.GetSizeRequestMode() == SizeRequestMode.HeightForWidth)
{
// Calculate the preferred width through the frontend if there is an overriden OnGetPreferredWidth, but only do it
// if we are not given a constraint. If there is a width constraint, we'll use that constraint value for calculating the height
if ((enabledEvents & WidgetEvent.PreferredWidthCheck) != 0 && constraint.Width == Double.PositiveInfinity)
{
var ws = eventSink.OnGetPreferredWidth();
wpfMeasure.Width = constraint.Width = gettingNaturalSize ? ws.NaturalSize : ws.MinSize;
}
// Now calculate the preferred height for that width, also using the override if available
if ((enabledEvents & WidgetEvent.PreferredHeightForWidthCheck) != 0)
{
var ws = eventSink.OnGetPreferredHeightForWidth(constraint.Width);
wpfMeasure.Height = gettingNaturalSize ? ws.NaturalSize : ws.MinSize;
}
}
else
{
// Calculate the preferred height through the frontend, if there is an overriden OnGetPreferredHeight
if ((enabledEvents & WidgetEvent.PreferredHeightCheck) != 0 && constraint.Height == Double.PositiveInfinity)
{
var ws = eventSink.OnGetPreferredHeight();
wpfMeasure.Height = constraint.Height = gettingNaturalSize ? ws.NaturalSize : ws.MinSize;
}
// Now calculate the preferred width for that height, also using the override if available
if ((enabledEvents & WidgetEvent.PreferredWidthForHeightCheck) != 0)
{
var ws = eventSink.OnGetPreferredWidthForHeight(constraint.Height);
wpfMeasure.Width = gettingNaturalSize ? ws.NaturalSize : ws.MinSize;
}
}
});
return(wpfMeasure);
}