当程序在后台时听按键 [英] Listen to key press when the program is in the background

问题描述

我目前正在使用一个应该在后台运行的程序，但还要检查是否按下了mod + o"，然后执行某些操作.但是我无法弄清楚当程序不是 Selected/Opened 时，vb.net 程序如何侦听按键.

I am currently working with a program which is supposed to run in the background but also check if "mod + o" is pressed then do something. But I cannot figure out how a vb.net program can listen to key presses when the program is not Selected / Opened.

推荐答案

您可以使用 P/Invocation 来使用 WinAPI 的 GetAsyncKeyState() 函数，然后在计时器中检查.

You can use P/Invocation to be able to use WinAPI's GetAsyncKeyState() function, then check that in a timer.

<DllImport("user32.dll")> _
Public Shared Function GetAsyncKeyState(ByVal vKey As System.Windows.Forms.Keys) As Short
End Function

Const KeyDownBit As Integer = &H8000

Private Sub Timer1_Tick(sender As Object, e As System.EventArgs) Handles Timer1.Tick
    If (GetAsyncKeyState(Keys.LWin) And KeyDownBit) = KeyDownBit AndAlso (GetAsyncKeyState(Keys.O) And KeyDownBit) = KeyDownBit Then
        'Do whatever you want when 'Mod + O' is held down.
    End If
End Sub

<小时>

要使代码每次按键仅执行一次，您可以添加一个小 While 循环以运行直到释放任一按钮(将其添加内部你的 If 语句):

To make the code only execute one time per key press, you can add a little While-loop to run until either of the buttons are released (add it inside your If-statement):

While GetAsyncKeyState(Keys.LWin) AndAlso GetAsyncKeyState(Keys.O)
End While

这将阻止您在按住按键时多次执行代码.

This will stop your code from executing more than once while you hold the keys down.

在控制台应用程序中使用它时，只需将每个 System.Windows.Forms.Keys 和 Keys 替换为 ConsoleKey，然后替换 LWin 和 LeftWindows.

When using this in a Console Application just replace every System.Windows.Forms.Keys and Keys with ConsoleKey, and replace LWin with LeftWindows.

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