EndPaint hooking to draw text to a DirectX window

Question

I want to draw text to a DirectX game, so I've injected a DLL which hooks EndPaint. My logic was that since EndPaint is supposed to be the last step in the WM_PAINT operation, I could, in my hook, draw the text, and then call EndPaint myself. By doing this, I avoid the DX interface altogether.

The problem is that it is doing absolutely nothing. Here is my code.

#include <windows.h>
#include "Hooks.h"

static const TCHAR g_cszMessage[] = TEXT("utterly fantastic");

BOOL (WINAPI * _EndPaint)(__in HWND hWnd, __in const LPPAINTSTRUCT lpPaint) = EndPaint;

BOOL WINAPI EndPaintHook(__in HWND hWnd, __in const LPPAINTSTRUCT lpPaint)
{
  // write message
  TextOut(lpPaint->hdc, 0, 0, g_cszMessage, lstrlen(g_cszMessage));
  GdiFlush();

  // return original
  return _EndPaint(hWnd, lpPaint);
}

BOOL APIENTRY DllMain(__in HINSTANCE hModule, __in DWORD fdwReason, __in __reserved LPVOID lpvReserved)
{
  UNREFERENCED_PARAMETER(lpvReserved);

  switch (fdwReason)
  {
  case DLL_PROCESS_ATTACH:
    if (AttachHook(reinterpret_cast<PVOID*>(&_EndPaint), EndPaintHook))
    {
      DisableThreadLibraryCalls(hModule);
      break;
    }
    return FALSE;

  case DLL_PROCESS_DETACH:
    DetachHook(reinterpret_cast<PVOID*>(&_EndPaint), EndPaintHook);
    break;
  }
  return TRUE;
}

I know the issue isn't with my AttachHook/DetachHook functions because I've tested via message boxes and confirmed that the hooks are installed. The text simply isn't showing up.

Anyone have any idea? I don't really want to hook the DX interface. Shouldn't it work either way, since WM_PAINT is still used at the base level?

Thanks in advance.

Answer 1

You are better off hooking the present of DirectX and then using ID3DXFont to do some font rendering. AFAIK WM_PAINT is not used for DirectX rendering.