Get number of D3D9 adapters

d3d9Test.cpp

// compile with: x86_64-w64-mingw32-g++ d3d9Test.cpp

#include <d3d9.h>
#include <stdio.h>

static BOOL Monitorenumproc(
  HMONITOR hMonitor,
  HDC unnamedParam2,
  LPRECT bounds,
  LPARAM unnamedParam4
) {
    MONITORINFOEX mi;
    mi.cbSize = sizeof(mi);
    if(GetMonitorInfo(hMonitor, &mi)) {
        printf("%p: %s\n", hMonitor, mi.szDevice);
        printf("%d, %d, %d, %d\n", bounds->left, bounds->top, bounds->right, bounds->bottom);
    } else {
        printf("GetMonitorInfo failed for %p\n", hMonitor);
    }
    return TRUE;
}

int main(int argc, char **argv) {
    HRESULT hr = E_FAIL;
    HMODULE libHandle = NULL;
    UINT m_uD3DAdapterCount = 0;
    HMONITOR *hMonitor = NULL;

    // Manually load the d3d9.dll library.
    libHandle = LoadLibrary("d3d9.dll");

    if (libHandle != NULL) {
        // Define a function pointer to the Direct3DCreate9Ex function.
        typedef HRESULT
        (WINAPI *LPDIRECT3DCREATE9EX)(UINT, IDirect3D9Ex**);

        // Obtain the address of the Direct3DCreate9Ex function.
        LPDIRECT3DCREATE9EX Direct3DCreate9ExPtr = NULL;

        Direct3DCreate9ExPtr = (LPDIRECT3DCREATE9EX) GetProcAddress(libHandle,
                "Direct3DCreate9Ex");

        if (Direct3DCreate9ExPtr != NULL) {
            // Direct3DCreate9Ex is supported.
            hr = S_OK;
            IDirect3D9Ex *pD3D = NULL;
            if (FAILED(hr = Direct3DCreate9ExPtr(D3D_SDK_VERSION, &pD3D))) {
                printf("Failed\n");
            } else {
                m_uD3DAdapterCount = pD3D->GetAdapterCount();
                hMonitor = (HMONITOR*) calloc(m_uD3DAdapterCount, sizeof(*hMonitor));
                printf("\nD3D9 says you have %d adapter(s):\n", m_uD3DAdapterCount);
                for (UINT i = 0; i < m_uD3DAdapterCount; i++) {
                    D3DADAPTER_IDENTIFIER9 id;
                    pD3D->GetAdapterIdentifier(i, 0, &id);
                    HMONITOR mon = pD3D->GetAdapterMonitor(i);
                    printf(" - %s (%s) %p\n", id.DeviceName, id.Description, mon);
                }
                pD3D->Release();
            }
        } else {
            // Direct3DCreate9Ex is not supported on this
            // operating system.
            hr = ERROR_NOT_SUPPORTED;
            printf("Not supported\n");
        }

        // Free the library.
        FreeLibrary(libHandle);
    }

    printf("\nEnumDisplayDevices:\n");
    UINT m_rgpDisplaysCount = 0;
    for (UINT uDevice = 0; true; uDevice++) {
        DISPLAY_DEVICE dd;
        ZeroMemory(&dd, sizeof(dd));
        dd.cb = sizeof(dd);

        if (!EnumDisplayDevices(NULL, uDevice, &dd, 0))
            break; // no more devices

        printf("- %d: %s", uDevice, dd.DeviceName);

        if (!(dd.StateFlags & DISPLAY_DEVICE_ATTACHED_TO_DESKTOP)) {
            printf(" (not attached to desktop)\n");
            continue;
        }

        if (dd.StateFlags
                & (DISPLAY_DEVICE_REMOTE | DISPLAY_DEVICE_MIRRORING_DRIVER)) {
            if (dd.StateFlags & DISPLAY_DEVICE_MIRRORING_DRIVER) {
                printf(" (mirroring driver)\n");
                continue;  // mirror devices are considered hidden and should
                // be excluded as display.  Remembering that a
                // non-local device is present is sufficient for
                // now.
            }
        }

        m_rgpDisplaysCount++;
        printf(" (OK)\n");
    }

    printf("\nEnumDisplayDevices says %d device(s) are OK\n\n", m_rgpDisplaysCount);

    // If DX reported adapters that m_rgpDisplays doesn't have, dotnet assumes it's due to mode change.
    if (m_uD3DAdapterCount > m_rgpDisplaysCount) {
        printf("DotNet assumes a mode change, which causes issues in rendering, when m_uD3DAdapterCount > m_rgpDisplaysCount (%d > %d)\n",
                m_uD3DAdapterCount, m_rgpDisplaysCount);
        printf("See https://github.com/dotnet/wpf/blob/c4e74175da6108104491e1ae64982444d7c8713d/src/Microsoft.DotNet.Wpf/src/WpfGfx/core/common/display.cpp#L1629\n");
    } else {
        printf("DotNet should be happy\n");
    }

    printf("\nEnumDisplayMonitors:\n");
    BOOL ret = EnumDisplayMonitors(NULL, NULL, Monitorenumproc, NULL);
    if (!ret) printf("EnumDisplayMonitors ret: %d\n", ret);

    return hr;
}

compile with: x86_64-w64-mingw32-g++ d3d9Test.cpp