在 vb.net 中检测鼠标按钮是否按下 [英] Detecting whether a mouse button is down in vb.net

问题描述

我不想使用 mouseup 事件，因为我想允许用户拖动到控件之外.我需要通过计时器检查状态.我依稀记得以前使用

I don't want to use the mouseup event because I want to allow the user to drag outside the control. I need to check the state via a timer. I vaguely remember doing this before at some point by using

If MouseButtons = MouseButtons.Left Then...

但现在它说 MouseButtons 是一种类型，不能用作表达式(这是真的，它是一个枚举类型).

But now it says that MouseButtons is a type and cannot be used as an expression (which is true, its an enum type).

也许他们改变了一些东西，或者也许我只是记错了......不管怎样，我如何检查按钮是否仍然按下?

Maybe they changed things or maybe I just remember wrong.. either way, how would I check if the button is still down?

推荐答案

这是经过试验和测试的.我创建了一个新类:testmouseclass 并创建了一个共享函数，您可以随时使用它来确定 LeftMouseButton 是否已关闭.这在 GetAsyncKeyState 调用的帮助下是可能的.

This is tried and tested. I created a new class: testmouseclass and created a shared function you can use anytime to determine if the LeftMouseButton is down. This is possible with the help of GetAsyncKeyState call.

 Imports System.Runtime.InteropServices 'Need to import...

 Public Class testmouseclass

 <DllImport("user32.dll", CharSet:=CharSet.Auto, ExactSpelling:=True)> Public Shared Function GetAsyncKeyState(ByVal vkey As Long) As Long
End Function

Public Shared Function LeftMouseIsDown() As Boolean
    Return GetAsyncKeyState(Keys.LButton) > 0 And &H8000
End Function

 End Class

示例用法

   Private Sub Timer1_Tick(sender As Object, e As System.EventArgs) Handles Timer1.Tick
    If testmouseclass.LeftMouseIsDown() Then MsgBox("It IS!")
   End Sub 

根据计时器滴答，这也可能令人头疼.不知道你是如何使用它的，但在我的例子中，我有 3 秒的计时器，当我按下 LeftMouseButton 时，会弹出一条消息，当我再次单击它时，由于计时器和鼠标左键按下.此外，这项工作甚至在您的应用程序之外...

Depending on the timer tick's this can be a headache as well. Not sure how you are using this, but in my example I had the timer at 3 seconds and when I held the LeftMouseButton down a message popped up and when I clicked it again it popped up again because of the timer and the left mouse was down. Also this work's even outside of your application...

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