protected override void OnResize(EventArgs e)
{
base.OnResize(e);
// NOTE: This Bitmap and Region work is done to workaround
// the performance issues causes by using BackColor = Color.Transparent,
// which would allow the exact functionality we want, but which is very
// slow when the window is big or maximized.
int width = Width, height = Height;
if (width > 0 && height > 0)
{
// Update the boundaries of the control so we only draw within our own area
int arcSize = (int)(width / 14.5);
if (Region != null)
{
Region.Dispose();
Region = null;
}
using (GraphicsPath path = GraphicsHelpers.CreateRoundedRectangle(width, height, arcSize))
{
Region = new Region(path);
}
// Update the background underlying image to be rendered under
// the sprites
if (_underImage != null)
{
_underImage.Dispose();
}
_underImage = new Bitmap(width, height, PixelFormat.Format32bppPArgb);
using (Graphics g = Graphics.FromImage(_underImage))
{
_grid.DrawToGraphics(g, _grid.ClientRectangle);
using (SolidBrush b = new SolidBrush(Color.FromArgb(128, Color.SlateGray)))
{
g.FillRectangle(b, ClientRectangle);
}
}
}
}