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** Foundation and appearing in the file LICENSE.GPL included in the
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#include "qwindowsopengltester.h"
#include "qt_windows.h"
#include "qwindowscontext.h"

QT_BEGIN_NAMESPACE

bool QWindowsOpenGLTester::testDesktopGL()
{
    HMODULE lib = 0;
    HWND wnd = 0;
    HDC dc = 0;
    HGLRC context = 0;
    LPCTSTR className = L"qtopengltest";

    HGLRC (WINAPI * CreateContext)(HDC dc) = 0;
    BOOL (WINAPI * DeleteContext)(HGLRC context) = 0;
    BOOL (WINAPI * MakeCurrent)(HDC dc, HGLRC context) = 0;
    PROC (WINAPI * WGL_GetProcAddress)(LPCSTR name) = 0;

    bool result = false;

    // Test #1: Load opengl32.dll and try to resolve an OpenGL 2 function.
    // This will typically fail on systems that do not have a real OpenGL driver.
    lib = LoadLibraryA("opengl32.dll");
    if (lib) {
        CreateContext = reinterpret_cast<HGLRC (WINAPI *)(HDC)>(::GetProcAddress(lib, "wglCreateContext"));
        if (!CreateContext)
            goto cleanup;
        DeleteContext = reinterpret_cast<BOOL (WINAPI *)(HGLRC)>(::GetProcAddress(lib, "wglDeleteContext"));
        if (!DeleteContext)
            goto cleanup;
        MakeCurrent = reinterpret_cast<BOOL (WINAPI *)(HDC, HGLRC)>(::GetProcAddress(lib, "wglMakeCurrent"));
        if (!MakeCurrent)
            goto cleanup;
        WGL_GetProcAddress = reinterpret_cast<PROC (WINAPI *)(LPCSTR)>(::GetProcAddress(lib, "wglGetProcAddress"));
        if (!WGL_GetProcAddress)
            goto cleanup;

        WNDCLASS wclass;
        wclass.cbClsExtra = 0;
        wclass.cbWndExtra = 0;
        wclass.hInstance = (HINSTANCE) GetModuleHandle(0);
        wclass.hIcon = 0;
        wclass.hCursor = 0;
        wclass.hbrBackground = (HBRUSH) (COLOR_BACKGROUND);
        wclass.lpszMenuName = 0;
        wclass.lpfnWndProc = DefWindowProc;
        wclass.lpszClassName = className;
        wclass.style = CS_OWNDC;
        if (!RegisterClass(&wclass))
            goto cleanup;
        wnd = CreateWindow(className, L"qtopenglproxytest", WS_OVERLAPPED,
                           0, 0, 640, 480, 0, 0, wclass.hInstance, 0);
        if (!wnd)
            goto cleanup;
        dc = GetDC(wnd);
        if (!dc)
            goto cleanup;

        PIXELFORMATDESCRIPTOR pfd;
        memset(&pfd, 0, sizeof(PIXELFORMATDESCRIPTOR));
        pfd.nSize = sizeof(PIXELFORMATDESCRIPTOR);
        pfd.nVersion = 1;
        pfd.dwFlags = PFD_SUPPORT_OPENGL | PFD_DRAW_TO_WINDOW | PFD_GENERIC_FORMAT;
        pfd.iPixelType = PFD_TYPE_RGBA;
        // Use the GDI functions. Under the hood this will call the wgl variants in opengl32.dll.
        int pixelFormat = ChoosePixelFormat(dc, &pfd);
        if (!pixelFormat)
            goto cleanup;
        if (!SetPixelFormat(dc, pixelFormat, &pfd))
            goto cleanup;
        context = CreateContext(dc);
        if (!context)
            goto cleanup;
        if (!MakeCurrent(dc, context))
            goto cleanup;

        // Now that there is finally a context current, try doing something useful.
        if (WGL_GetProcAddress("glCreateShader")) {
            result = true;
            qCDebug(lcQpaGl, "OpenGL 2.0 entry points available");
        } else {
            qCDebug(lcQpaGl, "OpenGL 2.0 entry points not found");
        }
    } else {
        qCDebug(lcQpaGl, "Failed to load opengl32.dll");
    }

cleanup:
    if (MakeCurrent)
        MakeCurrent(0, 0);
    if (context)
        DeleteContext(context);
    if (dc && wnd)
        ReleaseDC(wnd, dc);
    if (wnd) {
        DestroyWindow(wnd);
        UnregisterClass(className, GetModuleHandle(0));
    }
    // No FreeLibrary. Some implementations, Mesa in particular, deadlock when trying to unload.

    return result;
}

QT_END_NAMESPACE