private void SetBitmap(Bitmap bitmap, byte opacity)
{
if (bitmap.PixelFormat != PixelFormat.Format32bppArgb)
{
throw new ApplicationException("The bitmap must be 32ppp with alpha-channel.");
}
var screenDc = WinApi.GetDC(IntPtr.Zero);
var memDc = WinApi.CreateCompatibleDC(screenDc);
var hBitmap = IntPtr.Zero;
var oldBitmap = IntPtr.Zero;
try
{
hBitmap = bitmap.GetHbitmap(Color.FromArgb(0));
oldBitmap = WinApi.SelectObject(memDc, hBitmap);
var size = new WinApi.SIZE(bitmap.Width, bitmap.Height);
var pointSource = new WinApi.POINT(0, 0);
var topPos = new WinApi.POINT(Left, Top);
var blend = new WinApi.BLENDFUNCTION
{
BlendOp = WinApi.AC_SRC_OVER,
BlendFlags = 0,
SourceConstantAlpha = opacity,
AlphaFormat = WinApi.AC_SRC_ALPHA
};
WinApi.UpdateLayeredWindow(Handle, screenDc, ref topPos, ref size, memDc, ref pointSource, 0,
ref blend, WinApi.ULW_ALPHA);
}
finally
{
WinApi.ReleaseDC(IntPtr.Zero, screenDc);
if (hBitmap != IntPtr.Zero)
{
WinApi.SelectObject(memDc, oldBitmap);
WinApi.DeleteObject(hBitmap);
}
WinApi.DeleteDC(memDc);
}
}
private void Render()
{
var screenDc = WinApi.GetDC(WinApi.NullHandleRef);
if (screenDc == IntPtr.Zero)
{
return;
}
try {
var memDc = WinApi.CreateCompatibleDC(new HandleRef(null, screenDc));
if (memDc == IntPtr.Zero)
{
return;
}
try {
using (Bitmap bmp = GetWindowBitmap(Size.Width, Size.Height)) {
IntPtr hBitmap = bmp.GetHbitmap(_transparent);
IntPtr hOldBitmap = WinApi.SelectObject(memDc, hBitmap);
WinApi.POINT newLocation = new WinApi.POINT(Location);
WinApi.SIZE newSize = new WinApi.SIZE(Size);
WinApi.UpdateLayeredWindow(Handle, screenDc, ref newLocation, ref newSize, memDc, ref _ptZero, 0, ref _blend, WinApi.BlendingFlags.ULW_ALPHA);
if (hBitmap != IntPtr.Zero)
{
WinApi.SelectObject(memDc, hOldBitmap);
WinApi.DeleteObject(hBitmap);
}
}
} finally {
WinApi.DeleteDC(new HandleRef(null, memDc));
}
} finally {
WinApi.ReleaseDC(WinApi.NullHandleRef, new HandleRef(null, screenDc));
}
}
