Why is my call to SetDisplayMode not supported?

Question

I have some legacy DirectX code that always returns DDERR_UNSUPPORTED.

I originally developed the code using DirectX3, and I am porting it to DirectX7 after spending years away from programming.

The following line is returning DDERR_UNSUPPORTED rather than DD_OK:

hrRetVal = pDDraw->SetDisplayMode(dwWidth, dwHeight, dwBPP, 0, 0);

Could someone please take a quick peek and respond if you see why this might be the case? This is not a commercial application... just something to do for fun.

Based on the Microsoft on-line documents, the SetDisplayMode method is not deprecated, and should work. A compiled version of my legacy program written with DirectX3 renders graphics on newer OS's such as Windows 10, without issue. I am interested in making some changes.

This Video compilation unit:

• Sets the video mode to 1024 X 768
• Create a DirectX instance, set the cooperative level.
• Which when destroyed will Restore video to original mode, and flip to GDI

void Video::Initialize(void)
{

  TRACE("Video::Initialize invoked\n");

  hrRetVal = {0};
  DWORD dwDefaultRefreshRate = 0x0;
  DWORD  dwWidth = 1024, dwHeight = 768, dwBPP = 8, dwRefreshRate = dwDefaultRefreshRate, dwFlags = 0x0;

  try
  {
    Check(hrRetVal); // check for DD_OK     

    TRACE("Video: using emulation mode, no hardware\n"); // debugging
    TRACE("Video: DirectDrawCreateEx invoked\n");
    hrRetVal = DirectDrawCreateEx((GUID*)DDCREATE_EMULATIONONLY, (LPVOID*)&pDDraw, IID_IDirectDraw7, NULL);

    Check(hrRetVal); // TRACE value of hrRetVal
    if (DD_OK == hrRetVal)
    {
      TRACE("Video SetCooperativeLevel invoked\n");
      hrRetVal = pDDraw->SetCooperativeLevel(hwnd, DDSCL_EXCLUSIVE | DDSCL_FULLSCREEN);
      Check(hrRetVal);
      if (DD_OK == hrRetVal)
      {

        // Lets see if the video is supported 
        hrRetVal = QueryVideoCapability();
        Check(hrRetVal);

        if (DD_OK == hrRetVal)
        {

          TRACE("Attempting to set video resolution to: %d %d \n", dwWidth, dwHeight);

          hrRetVal = pDDraw->SetDisplayMode(dwWidth, dwHeight, dwBPP, 0, 0); // this line always returns DDERR_UNSUPPORTED

          // hrRetVal == DDERR_UNSUPPORTED after call to SetDisplayMode

          Check(hrRetVal);
          if (DD_OK != hrRetVal)
            throw (VIDEO_EXCEPTION); // with throw an exception since hrRetVal == DDERR_UNSUPPORTED
        }
      }
      else
      {
        Check(hrRetVal);
        throw (VIDEO_EXCEPTION); 
      }
    }
    else
    {
      Check(hrRetVal);
      throw (VIDEO_EXCEPTION);
    }
  }

  catch(int exception)
  {
    TRACE("%Xh exception caught by Video::Initialize\n", exception);
    Video::Check(hrRetVal);

    if (exception == VIDEO_EXCEPTION)
    {
      char message[80];
      strcpy_s ( message, "Unable to initialize video. ");
      strcat_s ( message, "\nApplication will now terminate.");
      FatalMessageBox( message );

      TRACE("APP_EXCEPTION thrown by Video::Initialize\n");
      throw (APP_EXCEPTION);
    }
  }
}

I'm using Visual Studio 2017 Pro v15.7.2, on Windows 10 Build 1803.

Answer 1

Another possible cause is that the old sample apps and the SDK's themselves used ANSI 8 bits 'char' as their character sets and x32 as the apps bitness.

Come to this era and the default is always Unicode and invariably x64.

It pays to 'OutputDebugString' and see the text that is used to set the DX structures, the character set settings could be the problem.

Answer 2

The below method works fine to initialize the Video 1024x768x32.

I did not find the code to be deprecated. If you install the "DirectX Control Panel" you can see what video modes are supported.

void Video::Initialize(void)
{
    TRACE("Video::Initialize invoked\n");
    
    try
    {
        hrRetVal = DirectDrawCreateEx(NULL, (LPVOID*) &pDDraw, IID_IDirectDraw7, NULL);
        
        if (DD_OK == hrRetVal)
        {
                        
            hrRetVal = pDDraw->SetCooperativeLevel(hwnd, DDSCL_EXCLUSIVE | DDSCL_FULLSCREEN);

            if (DD_OK == hrRetVal)
            {
                // Lets see if the video is supported 
                hrRetVal = QueryVideoCapability();
                if (DD_OK != hrRetVal)
                {
                    Check(hrRetVal);
                }
                
                hrRetVal = pDDraw->SetDisplayMode(1024, 768, 32, 0, DDSDM_STANDARDVGAMODE);
                if (DD_OK != hrRetVal)
                   throw (VIDEO_EXCEPTION);
            }
            else
               throw (VIDEO_EXCEPTION);
        }
        else
            throw (VIDEO_EXCEPTION);
    }

    catch(int exception)
    {

        TRACE("%Xh exception caught by Video::Initialize\n", exception);
        Video::Check(hrRetVal);

        if (exception == VIDEO_EXCEPTION)
        {
            char message[80];
            strcpy_s ( message, "Unable to initialize video. ");
            strcat_s ( message, "\nApplication will now terminate.");
            FatalMessageBox( message );

            TRACE("APP_EXCEPTION thrown by Video::Initialize\n");
            throw (APP_EXCEPTION);
        }   
    }
}