为何setFocus对其他进程窗口无效

最新推荐文章于 2023-03-23 17:29:29 发布

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最新推荐文章于 2023-03-23 17:29:29 发布

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文章标签： thread function input processing keyboard windows

本文链接：https://blog.youkuaiyun.com/zfqcn/article/details/6254788

在Windows中，不同线程创建的窗口通常独立处理输入。使用AttachThreadInput函数可以将一个线程的输入处理附加到另一个线程，实现线程间输入状态的共享，如键盘焦点设置等。此功能需注意的是，若任一线程没有消息队列或安装了日志记录钩子，则该函数会失败。

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Windows created in different threads typically process input independently of each other. That is, they have their own input states (focus, active, capture windows, key state, queue status, and so on), and they are not synchronized with the input processing of other threads. By using the AttachThreadInput function, a thread can attach its input processing to another thread. This also allows threads to share their input states, so they can call the SetFocus function to set the keyboard focus to a window of a different thread. This also allows threads to get key-state information. These capabilities are not generally possible.

The AttachThreadInput function fails if either of the specified threads does not have a message queue. The system creates a thread's message queue when the thread makes its first call to one of the USER or GDI functions. The AttachThreadInput function also fails if a journal record hook is installed. Journal record hooks attach all input queues together.

Note that key state, which can be ascertained by calls to the GetKeyState or GetKeyboardState function, is reset after a call to AttachThreadInput. You cannot attach a thread to a thread in another desktop.