C++学习（一六五）qt是如何决定使用何种操作系统窗口

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我是靠谱客的博主怡然白猫，最近开发中收集的这篇文章主要介绍C++学习（一六五）qt是如何决定使用何种操作系统窗口，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

通过QPlatformIntegration *platformIntegration来创建。

创建windows窗口过程：

qtbasesrcpluginsplatformswindowsqwindowsglcontext.cpp
HWND QWindowsContext::createDummyWindow(const QString &classNameIn,
                                        const wchar_t *windowName,
                                        WNDPROC wndProc, DWORD style)
{
    if (!wndProc)
        wndProc = DefWindowProc;
    QString className = registerWindowClass(classNameIn, wndProc);
    return CreateWindowEx(0, reinterpret_cast<LPCWSTR>(className.utf16()),
                          windowName, style,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          HWND_MESSAGE, NULL, static_cast<HINSTANCE>(GetModuleHandle(0)), NULL);
}

创建窗口opengl上下文过程：


static HGLRC createContext(const QOpenGLStaticContext &staticContext,
                           HDC hdc,
                           const QSurfaceFormat &format,
                           const QWindowsOpenGLAdditionalFormat &,
                           HGLRC shared = 0)
{
    const HGLRC result =
        staticContext.wglCreateContextAttribsARB(hdc, shared, attributes);
}

platformIntegration的创建过程如下：


static void init_platform(const QString &pluginNamesWithArguments, const QString &platformPluginPath, const QString &platformThemeName, int &argc, char **argv)
{
     QGuiApplicationPrivate::platform_integration = QPlatformIntegrationFactory::create(name, arguments, argc, argv, platformPluginPath);
}

通过下面的factory创建，key为“windows”代表windows系统。

corelibpluginqfactoryloader_p.h
template <class PluginInterface, class FactoryInterface, typename ...Args>
PluginInterface *qLoadPlugin(const QFactoryLoader *loader, const QString &key, Args &&...args)
{
    const int index = loader->indexOf(key);
    if (index != -1) {
        QObject *factoryObject = loader->instance(index);
        if (FactoryInterface *factory = qobject_cast<FactoryInterface *>(factoryObject))
            if (PluginInterface *result = factory->create(key, std::forward<Args>(args)...))
                return result;
    }
    return nullptr;
}

windows版qt支持direct2d、minimal、offscreen、webgl、windows几类窗口

windows窗口是由msvc2017/plugins/platforms/qwindowsd.dll创建的