MFC Support for Direct2D – Part 5: Interoperability with GDI

There are two ways to combine Direct2D with Windows GDI API in the same application:

  1. Drawing Direct2D content to a GDI device context
  2. Drawing GDI content to a Direct2D GDI-compatible render target

Let’s see each one!

Drawing Direct2D content to a GDI device context

For this purpose, use ID2D1DCRenderTarget instead of ID2D1HwndRenderTarget interface. If using MFC shipped with Visual Studio 2015 or newer, then CDCRenderTarget wrapper class makes the programmer life easier. Here are the steps:

  1. In the WM_CREATE message handler call CWnd::EnableD2DSupport passing TRUE as second parameter. This way, the MFC framework creates a CD2DRenderTarget instead of a CHwndRenderTarget object.
  2. Map AFX_WM_DRAW2D registered messge.

  3. Finally, get the CDCRenderTarget* passed by MFC framework in LPARAM and enjoy.

Drawing GDI content to a Direct2D GDI-compatible render target

So far, MFC has not a wrapper class for ID2D1GdiInteropRenderTarget interface. Also, CWnd::EnableD2DSupport creates a CHwndRenderTarget which is not GDI-compatible. So, we must do it ourselves. Here is the sample code:

Demo projects

Download: Direct2D and GDI Interop Demo.zip (95)

The Visual C++ solution attached here has two simple projects showing the both Direct2D and GDI interoperatibily methods listed above.

Direct2D and GDI Interop - Demo Application

Direct2D and GDI Interop – Demo Application

 

Notes

  • can be observed that Direct2D drawing quality is higher than GDI drawing, because Direct2D is capable of rendering with antialiasing;
  • given the first note, my opinion is that GDI drawing has no much sense once using Direct2D but never know…

Resources and related articles

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