///<devdoc>
/// Creates a new clipping region from the intersection of the current clipping region and
/// the specified rectangle.
///</devdoc>
public void IntersectClip(WindowsRegion wr)
{
//if the incoming windowsregion is infinite, there is no need to do any intersecting.
if (wr.HRegion == IntPtr.Zero)
{
return;
}
WindowsRegion clip = new WindowsRegion(0, 0, 0, 0);
try {
int result = IntUnsafeNativeMethods.GetClipRgn(new HandleRef(this, this.Hdc), new HandleRef(clip, clip.HRegion));
// If the function succeeds and there is a clipping region for the given device context, the return value is 1.
if (result == 1)
{
Debug.Assert(clip.HRegion != IntPtr.Zero);
wr.CombineRegion(clip, wr, RegionCombineMode.AND); //1 = AND (or Intersect)
}
SetClip(wr);
}
finally {
clip.Dispose();
}
}