检测使用 C# 更改的活动窗口而无需轮询 [英] Detect active window changed using C# without polling

问题描述

当当前活动窗口发生变化时，如何调用回调.我已经看到如何使用 CBTProc 来完成它.但是，全局事件不容易与托管代码挂钩.我有兴趣找到一种不需要轮询的方法.我更喜欢事件驱动的方法.

How might one invoke a callback whenever the current active window changes. I've seen how it might be done using CBTProc. However, global events aren't easy to hook into with managed code. I'm interested in finding a way that doesn't require polling. I'd prefer an event driven approach.

问候

推荐答案

新建一个windows窗体项目，添加一个文本框，使其成为多行，并设置文本框的Dock属性为fill，命名为Log，粘贴如下代码(您需要将 System.Runtime.InteropServices 添加到您的使用中)...

Create a new windows forms project, add a textbox, make it multiline, and set the textbox Dock property to fill, name it Log and paste in the following code (you'll need to add System.Runtime.InteropServices to your usings)...

    WinEventDelegate dele = null;

    public Form1()
    {
        InitializeComponent();
        dele = new WinEventDelegate(WinEventProc);
        IntPtr m_hhook = SetWinEventHook(EVENT_SYSTEM_FOREGROUND, EVENT_SYSTEM_FOREGROUND, IntPtr.Zero, dele, 0, 0, WINEVENT_OUTOFCONTEXT);
    }

    delegate void WinEventDelegate(IntPtr hWinEventHook, uint eventType, IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime);

    [DllImport("user32.dll")]
    static extern IntPtr SetWinEventHook(uint eventMin, uint eventMax, IntPtr hmodWinEventProc, WinEventDelegate lpfnWinEventProc, uint idProcess, uint idThread, uint dwFlags);

    private const uint WINEVENT_OUTOFCONTEXT = 0;
    private const uint EVENT_SYSTEM_FOREGROUND = 3;

    [DllImport("user32.dll")]
    static extern IntPtr GetForegroundWindow();

    [DllImport("user32.dll")]
    static extern int GetWindowText(IntPtr hWnd, StringBuilder text, int count);

    private string GetActiveWindowTitle()
    {
        const int nChars = 256;
        IntPtr handle = IntPtr.Zero;
        StringBuilder Buff = new StringBuilder(nChars);
        handle = GetForegroundWindow();

        if (GetWindowText(handle, Buff, nChars) > 0)
        {
            return Buff.ToString();
        }
        return null;
    }

    public void WinEventProc(IntPtr hWinEventHook, uint eventType, IntPtr hwnd, int idObject, int idChild, uint dwEventThread, uint dwmsEventTime)
    {
        Log.Text += GetActiveWindowTitle() + "
";
    } 

这篇关于检测使用 C# 更改的活动窗口而无需轮询的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！