// This is needed in Silverlight because of a Silverlight bug
// that causes a Path with a PathGeometry that was created using
// <Path ... Data="M0 0 L10 20 ..." />
// to have ZERO Bounds after trying to access the PathGeometry.Figures property.
//
// In both WPF and Silverlight Paths constructed using the Path markup syntax
// using the StreamGeometry mini-language are supposed to be "black boxes".
// There is no way to walk the PathGeometry.Figures to determine its actual geometry.
// One can only get the PathGeometry.Bounds.
// We have to treat it as a rectangular shape.
// Note: Silverlight does not support the PathFigureCollection mini-language.
// (Example: <PathGeometry Figures="M0 0 L10 20 ..." />.)
// WPF supports both the StreamGeometry mini-language and the PathFigureCollection mini-language.
//
// So if the programmer wants to use a Node containing Paths for which Links want to
// connect at the edge of the Paths (when Spot.None, of course),
// they have to construct a PathFigureCollection containing PathFigures.
//
// But in Silverlight there is a bug causing the PathGeometry to have zero Bounds
// once our code tries to get the value of PathGeometry.Figures,
// if the Path was defined in XAML.
// This causes that Path to disappear, to the consternation of our customers.
// Typically that happenened (before version 1.2.6f) when routing a link to a node
// containing a Path defined in XAML, when the Spot was None and no surrounding
// Panel with a Background hid the actual shape of the Path.
//
// Our work-around requires our code to construct each PathGeometry with an
// explicitly created PathFigureCollection containing PathFigures.
// Explicitly setting PathGeometry.Figures gives it a local value which
// tells this predicate that it's OK to try to get the PathGeometry.Figures property.
// If it hasn't been set, it won't have a local value, which means
// (most likely) that it was created in XAML using Data="...".
public static bool PathGeometryHasFigures(PathGeometry path) {
object val = path.ReadLocalValue(PathGeometry.FiguresProperty);
var pfc = val as PathFigureCollection;
return pfc != null && pfc.Count > 0;
}
