onkeypress函数是在键盘上输入或操作时，引入InvokeOnClick，就可以触发下面的ButtonOnClick方法；

 点击InvokeOnClick就可以看到它的内部构造如下：

 从上面可以看出，实际上，触发的是OnClick事件。

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Where is InvokeOnClick() method called when I click a button in C# WinForms?

InvokeOnClick is currently not used.

The Click event is raised by the Control.OnClick method:

EventHandler handler = (EventHandler)Events[EventClick];
if (handler != null) handler(this, e);

For a Button, this occurs e.g. on mouse up and on calling PerformClick: see here.