How do I clear a Direct2D render target to fully transparent

Question

I\'m trying to draw semi-transparent rectangles on an invisible HWND. However, clearing the window with ID2D1HwndRenderTarget::Clear just makes the entire w

Answer 1

Use ID2D1DCRendTarget instead of ID2D1HwndRendTarget, then bind the device context (DC) of your window before drawing begins.

Of course, you need to set the WS_EX_LAYERED for your window and then call SetLayeredWindowAttributes to set the transparent color:

SetLayeredWindowAttributes(hWnd, RGB(0, 0, 0), 0, LWA_COLORKEY);

Screenshot: