public static Bitmap GetWindowImage(IntPtr hDC)
{
//In size variable we shall keep the size of the screen.
SIZE size;
//Variable to keep the handle to bitmap.
IntPtr hBitmap;
//Here we get the handle to the desktop device context.
//Here we make a compatible device context in memory for screen
//device context.
IntPtr hMemDC = PlatformInvokeGDI32.CreateCompatibleDC(hDC);
//We pass SM_CXSCREEN constant to GetSystemMetrics to get the
//X coordinates of the screen.
size.cx = PlatformInvokeUSER32.GetSystemMetrics
(PlatformInvokeUSER32.SM_CXSCREEN);
//We pass SM_CYSCREEN constant to GetSystemMetrics to get the
//Y coordinates of the screen.
size.cy = PlatformInvokeUSER32.GetSystemMetrics
(PlatformInvokeUSER32.SM_CYSCREEN);
//We create a compatible bitmap of the screen size and using
//the screen device context.
hBitmap = PlatformInvokeGDI32.CreateCompatibleBitmap
(hDC, size.cx, size.cy);
//As hBitmap is IntPtr, we cannot check it against null.
//For this purpose, IntPtr.Zero is used.
if (hBitmap != IntPtr.Zero)
{
//Here we select the compatible bitmap in the memeory device
//context and keep the refrence to the old bitmap.
IntPtr hOld = (IntPtr)PlatformInvokeGDI32.SelectObject
(hMemDC, hBitmap);
//We copy the Bitmap to the memory device context.
PlatformInvokeGDI32.BitBlt(hMemDC, 0, 0, size.cx, size.cy, hDC,
0, 0, PlatformInvokeGDI32.SRCCOPY);
//We select the old bitmap back to the memory device context.
PlatformInvokeGDI32.SelectObject(hMemDC, hOld);
//We delete the memory device context.
PlatformInvokeGDI32.DeleteDC(hMemDC);
//We release the screen device context.
PlatformInvokeUSER32.ReleaseDC(PlatformInvokeUSER32.
GetDesktopWindow(), hDC);
//Image is created by Image bitmap handle and stored in
//local variable.
Bitmap bmp = System.Drawing.Image.FromHbitmap(hBitmap);
//Release the memory to avoid memory leaks.
PlatformInvokeGDI32.DeleteObject(hBitmap);
//This statement runs the garbage collector manually.
GC.Collect();
//Return the bitmap
return(bmp);
}
//If hBitmap is null, retun null.
return(null);
}
public static Bitmap GetDesktopImage( )
{
return(GetWindowImage(PlatformInvokeUSER32.GetDC
(PlatformInvokeUSER32.GetDesktopWindow())));
}