Win32 消息泵和 std::thread 用于创建 OpenGL 上下文和渲染

Question

如果我有一个函数执行以下操作：

bool foo::init()
{
    [Code that creates window]
    std::thread run(std::bind(&foo::run, this));

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

其中运行定义为：

void foo::run()
{
    [Code that creates initial opengl context]
    [Code that recreates window based on new PixelFormat using wglChoosePixelFormatARB]
    [Code that creates new opengl context using wglCreateContextAttribsARB]

    do {
        [Code that handles rendering]
    } while (!terminate);   
}

由于 window 是在渲染线程上重新创建的，消息泵将在主线程上执行，这是否安全？ WndProc 将调用什么函数？上面的代码可以被认为是糟糕的设计，但这不是我感兴趣的。我只对定义的行为感兴趣。

Answer 1

Win32 window 绑定到创建它的线程。只有那个线程可以为window接收和发送消息，只有那个线程可以销毁window。

因此，如果您在工作线程中重新创建 window，则该线程必须接管管理 window 并发送其消息的责任。

否则，您需要将 window 的重新创建委托回您的主线程，以便它保持在最初创建它的同一线程中。

bool foo::init()
{
    [Code that creates window]

    std::thread run(std::bind(&foo::run, this));

    while (GetMessage(&msg, NULL, 0, 0)) {
        if (recreate needed) {
            [Code that recreates window and signals worker thread]
            continue;
        }
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
}

void foo::run()
{
    [Code that creates initial opengl context]

    [Code that asks main thread to recreate window based on new PixelFormat using wglChoosePixelFormatARB, and waits for signal that the recreate is finished]

    [Code that creates new opengl context using wglCreateContextAttribsARB]

    do {
        [Code that handles rendering]
    } while (!terminate);   
}

否则，在启动工作线程之前在主线程中调用 wglChoosePixelFormatARB()，并将选择的 PixelFormat 存储在线程可以访问的地方。

bool foo::init()
{
    [Code that creates window]
    [Code that gets PixelFormat using wglChoosePixelFormatARB]

    std::thread run(std::bind(&foo::run, this));

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

void foo::run()
{
    [Code that creates opengl context using wglCreateContextAttribsARB]

    do {
        [Code that handles rendering]
    } while (!terminate);   
}

Win32 消息泵和 std::thread 用于创建 OpenGL 上下文和渲染

Win32 Message Pump and std::thread Used to Create OpenGL Context and Render

opengl

winapi

multithreading

c++11