protected override void OnRenderSizeChanged(SizeChangedInfo sizeInfo)
{
base.OnRenderSizeChanged(sizeInfo);
//
// In WPF, using layered windows to make non-rectangular windows incurs a huge performance hit
// in rendering because the rendering system has to get a device context from GDI, which is
// currently only supported in software.
//
// To avoid this, we use interop to get access to old Win32 functions to programmatically describe
// what the shape of our window will be. We do this whenever the size changes to make sure the window's
// shape remains the same.
//
// Note: ScaleUI is a class Mike Malinak wrote to account for different DPI settings. I will elaborate
// more on WPF and DPI in a future blog post
// First, we create the rounded portion of the title bar area with a call to CreateRoundRectRgn
IntPtr titleArea = GDI32.CreateRoundRectRgn(
0,
0,
(int)ScaleUI.UpScaleX(sizeInfo.NewSize.Width),
(int)ScaleUI.UpScaleY(MainContentBorder.ActualHeight),
12,
12);
//IntPtr clientArea = GDI32.CreateRoundRectRgn(
// 0,
// 0,
// (int)ScaleUI.UpScaleX(sizeInfo.NewSize.Width),
// (int)ScaleUI.UpScaleY(MainContentBorder.ActualHeight) + 10,
// 10,
// 10);
//// Next, we create a rectangle for the client area
//IntPtr clientArea = GDI32.CreateRectRgn(
// 0,
// (int)ScaleUI.UpScaleY(MainContentBorder.ActualHeight),
// (int)ScaleUI.UpScaleX(sizeInfo.NewSize.Width),
// (int)ScaleUI.UpScaleY(sizeInfo.NewSize.Height));
//// After the regions have been created, you have to combine them
//IntPtr windowArea = GDI32.CreateRectRgn(0, 0, 0, 0);
//GDI32.CombineRgn(windowArea, titleArea, clientArea, GDI32.CombineRgnStyles.RGN_OR);
// Last, SetWindowRgn tells GDI what the windows final shape will look like
var win = new System.Windows.Interop.WindowInteropHelper(this);
User32.SetWindowRgn(win.Handle, titleArea, true);
}