WGL minamal example that enumates display devices

wgl_minimal_enum_display_devices.c

#include <windows.h>			/* must include this before GL/gl.h */
#include <GL/gl.h>			/* OpenGL header file */
#include <GL/glu.h>			/* OpenGL utilities header file */
#include <stdio.h>

#pragma comment (lib, "opengl32.lib")

void display()
{
    /* rotate a triangle around */
    glClear(GL_COLOR_BUFFER_BIT);
    glBegin(GL_TRIANGLES);
    glColor3f(1.0f, 0.0f, 0.0f);
    glVertex2i(0, 1);
    glColor3f(0.0f, 1.0f, 0.0f);
    glVertex2i(-1, -1);
    glColor3f(0.0f, 0.0f, 1.0f);
    glVertex2i(1, -1);
    glEnd();
    glFlush();
}

LONG WINAPI WindowProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    static PAINTSTRUCT ps;

    switch (uMsg) {
    case WM_PAINT:
        display();
        BeginPaint(hWnd, &ps);
        EndPaint(hWnd, &ps);
        return 0;

    case WM_SIZE:
        glViewport(0, 0, LOWORD(lParam), HIWORD(lParam));
        PostMessage(hWnd, WM_PAINT, 0, 0);
        return 0;

    case WM_CHAR:
        switch (wParam) {
        case 27:			/* ESC key */
            PostQuitMessage(0);
            break;
        }
        return 0;

    case WM_CLOSE:
        PostQuitMessage(0);
        return 0;
    }

    return DefWindowProc(hWnd, uMsg, wParam, lParam);
}

HWND CreateOpenGLWindow(const wchar_t* title, int x, int y, int width, int height, BYTE type, DWORD flags)
{
    int         pf;
    HDC         hDC;
    HWND        hWnd;
    WNDCLASS    wc;
    PIXELFORMATDESCRIPTOR pfd;
    static HINSTANCE hInstance = 0;

    /* only register the window class once - use hInstance as a flag. */
    if (!hInstance) {
        hInstance = GetModuleHandle(NULL);
        wc.style = CS_OWNDC;
        wc.lpfnWndProc = (WNDPROC)WindowProc;
        wc.cbClsExtra = 0;
        wc.cbWndExtra = 0;
        wc.hInstance = hInstance;
        wc.hIcon = LoadIcon(NULL, IDI_WINLOGO);
        wc.hCursor = LoadCursor(NULL, IDC_ARROW);
        wc.hbrBackground = NULL;
        wc.lpszMenuName = NULL;
        wc.lpszClassName = L"OpenGL";

        if (!RegisterClass(&wc)) {
            MessageBox(NULL, L"RegisterClass() failed:  "
                "Cannot register window class.", L"Error", MB_OK);
            return NULL;
        }
    }

    hWnd = CreateWindow(L"OpenGL", title, WS_OVERLAPPEDWINDOW |
        WS_CLIPSIBLINGS | WS_CLIPCHILDREN,
        x, y, width, height, NULL, NULL, hInstance, NULL);

    if (hWnd == NULL) {
        MessageBox(NULL, L"CreateWindow() failed:  Cannot create a window.",
            L"Error", MB_OK);
        return NULL;
    }

    hDC = GetDC(hWnd);

    /* there is no guarantee that the contents of the stack that become
       the pfd are zeroed, therefore _make sure_ to clear these bits. */
    memset(&pfd, 0, sizeof(pfd));
    pfd.nSize = sizeof(pfd);
    pfd.nVersion = 1;
    pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | flags;
    pfd.iPixelType = type;
    pfd.cColorBits = 32;

    pf = ChoosePixelFormat(hDC, &pfd);
    if (pf == 0) {
        MessageBox(NULL, L"ChoosePixelFormat() failed:  "
            "Cannot find a suitable pixel format.", L"Error", MB_OK);
        return 0;
    }

    if (SetPixelFormat(hDC, pf, &pfd) == FALSE) {
        MessageBox(NULL, L"SetPixelFormat() failed:  "
            "Cannot set format specified.", L"Error", MB_OK);
        return 0;
    }

    DescribePixelFormat(hDC, pf, sizeof(PIXELFORMATDESCRIPTOR), &pfd);

    ReleaseDC(hWnd, hDC);

    return hWnd;
}

extern "C" {
	_declspec(dllexport) DWORD NvOptimusEnablement = 0x00000001;
}

int main()
{
    HDC hDC;				/* device context */
    HGLRC hRC;				/* opengl context */
    HWND  hWnd;				/* window */
    MSG   msg;				/* message */

    hWnd = CreateOpenGLWindow(L"minimal", 0, 0, 256, 256, PFD_TYPE_RGBA, 0);
    if (hWnd == NULL)
        exit(1);

    hDC = GetDC(hWnd);
    hRC = wglCreateContext(hDC);
    wglMakeCurrent(hDC, hRC);

    ShowWindow(hWnd, SW_SHOW);

    DISPLAY_DEVICE lDevice;
    lDevice.cb = sizeof(DISPLAY_DEVICE);
    int i = 0;
    while (EnumDisplayDevices(NULL, i, &lDevice, EDD_GET_DEVICE_INTERFACE_NAME) != 0) {
        printf(
            "i: %d\n"
            "cb: %d\n"
            "DeviceName: %ws\n"
            "DeviceString: %ws\n"
            "StateFlags: %d\n"
            "DeviceID: %ws\n"
            "DeviceKey: %ws\n",
            i,
            lDevice.cb,
            lDevice.DeviceName,
            lDevice.DeviceString,
            lDevice.StateFlags,
            lDevice.DeviceID,
            lDevice.DeviceKey
        );
        i++;
    }

    while (GetMessage(&msg, hWnd, 0, 0)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    wglMakeCurrent(NULL, NULL);
    ReleaseDC(hWnd, hDC);
    wglDeleteContext(hRC);
    DestroyWindow(hWnd);

    return msg.wParam;
}