如何在DXGI中获得显示器/输出的当前显示模式(分辨率，刷新率)

Question

我正在创建一个多显示器全屏DXGI/D3D应用程序。我正在列举可用的输出和适配器，为创建它们的交换链做准备。

当使用DXGI的IDXGIFactory::CreateSwapChain方法创建我的交换链时，我需要提供一个交换链描述，其中包括DXGI_MODE_DESC类型的缓冲区描述，详细说明宽度，高度，刷新率等。我怎样才能知道输出当前设置为什么(或者我怎样才能知道输出当前的显示模式是什么)?当我使用这个交换链切换到全屏时，我不想改变用户的分辨率或刷新率

Answer 1

在浏览了一些之后，我偶然发现了EnumDisplaySettings遗留的GDI功能，它允许我访问当前分辨率和刷新率。结合IDXGIOutput::FindClosestMatchingMode功能，我可以得到非常接近当前显示模式:

void getClosestDisplayModeToCurrent(IDXGIOutput* output, DXGI_MODE_DESC* outCurrentDisplayMode)
{
  DXGI_OUTPUT_DESC outputDesc;
  output->GetDesc(&outputDesc);
  HMONITOR hMonitor = outputDesc.Monitor;
  MONITORINFOEX monitorInfo;
  monitorInfo.cbSize = sizeof(MONITORINFOEX);
  GetMonitorInfo(hMonitor, &monitorInfo);
  DEVMODE devMode;
  devMode.dmSize = sizeof(DEVMODE);
  devMode.dmDriverExtra = 0;
  EnumDisplaySettings(monitorInfo.szDevice, ENUM_CURRENT_SETTINGS, &devMode);
  DXGI_MODE_DESC current;
  current.Width = devMode.dmPelsWidth;
  current.Height = devMode.dmPelsHeight;
  bool useDefaultRefreshRate = 1 == devMode.dmDisplayFrequency || 0 == devMode.dmDisplayFrequency;
  current.RefreshRate.Numerator = useDefaultRefreshRate ? 0 : devMode.dmDisplayFrequency;
  current.RefreshRate.Denominator = useDefaultRefreshRate ? 0 : 1;
  current.Format = DXGI_FORMAT_R8G8B8A8_UNORM;
  current.ScanlineOrdering = DXGI_MODE_SCANLINE_ORDER_UNSPECIFIED;
  current.Scaling = DXGI_MODE_SCALING_UNSPECIFIED;
  output->FindClosestMatchingMode(&current, outCurrentDisplayMode, NULL);
}

…但我不认为这是正确的答案因为我需要使用遗留函数。是否有任何方法可以使用DXGI来获得确切的当前显示模式，而不是使用此方法?

Answer 2

我看到了解决方案:http://www.rastertek.com/dx11tut03.html

在以下部分:

   // Now go through all the display modes and find the one that matches the screen width and height.
    // When a match is found store the numerator and denominator of the refresh rate for that monitor.
    for(i=0; i<numModes; i++)
    {
        if(displayModeList[i].Width == (unsigned int)screenWidth)
        {
            if(displayModeList[i].Height == (unsigned int)screenHeight)
            {
                numerator = displayModeList[i].RefreshRate.Numerator;
                denominator = displayModeList[i].RefreshRate.Denominator;
            }
        }
    }

我的理解是正确的，可用的分辨率是在displayModeList。

Answer 3

This might be what you are looking for:

            // Get display mode list
            std::vector<DXGI_MODE_DESC*> modeList = GetDisplayModeList(*outputItor);
            for(std::vector<DXGI_MODE_DESC*>::iterator modeItor = modeList.begin(); modeItor != modeList.end(); ++modeItor)
            {
            //  PrintDisplayModeInfo(*modeItor);
            }
        }


std::vector<DXGI_MODE_DESC*> GetDisplayModeList(IDXGIOutput* output)
{
    UINT num = 0;
    DXGI_FORMAT format = DXGI_FORMAT_R32G32B32A32_TYPELESS;
    UINT flags = DXGI_ENUM_MODES_INTERLACED | DXGI_ENUM_MODES_SCALING;
    // Get number of display modes
    output->GetDisplayModeList(format, flags, &num, 0);
    // Get display mode list
    DXGI_MODE_DESC * pDescs = new DXGI_MODE_DESC[num];
    output->GetDisplayModeList(format, flags, &num, pDescs);
    std::vector<DXGI_MODE_DESC*> displayList;
    for(int i = 0; i < num; ++i)
    {
        displayList.push_back(&pDescs[i]);
    }
    return displayList;
}