如何取消选中复选框而不引发事件 [英] How to uncheck Checkbox without raising event

问题描述

我有一个C#项目，其中已经注册了checkox事件.当未选中该复选框时，我将显示一个消息框，提示用户进行确认，如果用户未确认，则该复选框应保留状态(已选中)因此，在代码中，我尝试检查它是否再次引发同一事件.
有没有一种方法可以在不引发事件的情况下更改值
我知道这可以通过取消注册事件，设置值然后重新注册来完成.但是我正在寻找一种更简洁的方法. :doh:

I have a C# project wherein i have registered checkox event.When the checkbox is Unchecked i am displaying a message box which will prompt the user to confirm,if the user does not confirm then the checkbox should retain the state(Checked) So in code i try to check it which again raises the same event.
Is there a way to change the value without raising the event
I know this can be done by un-registering the event,set the value then re-register.but i am looking for a cleaner way. :doh:

推荐答案

public class MyCheckEventArgs: EventArgs {
    public bool CurrentState { get; protected set; }
    public bool CancelEvent { get; set; }

    public MyCheckEventArgs(bool currentState) {
        CancelEvent = false;
        CurrentState = currentState;
    }
}

public class MyCheck : CheckBox {
    public EventHandler<MyCheckEventArgs> BeforeChecked;

    protected override void OnClick(EventArgs e) {
        bool handled = false;
        if (BeforeChecked != null) {
            MyCheckEventArgs myCheckEventArgs = new MyCheckEventArgs(this.Checked);
            BeforeChecked(this, myCheckEventArgs);
            handled = myCheckEventArgs.CancelEvent;
        }

        if (!handled)
            base.OnClick(e);
    }
}

我相信您可以自己做剩下的事情.

问候，
Alexey

I''m sure the rest you can do by yourself.

Regards,
Alexey

其他人发布的代码无法正常工作有多种原因.

There are multiple reasons why the code someone else posted will not work.

if (UserChangedMind)
        CheckBox1.Checked = true;
    UserChangedMind = false;

UserChangedMind只是其中之一，因为第二次分配始终在运行，所以它只适用于一微秒.

is just one of them UserChangedMind is only ever true for a microsecond, as the second assignment always runs.

在表单类中尝试这种方式:

Try it this way in your form class:

private bool initialized = false;

public MyForm()
{
    InitializeComponents();
    this.initialized = true;
}

void checkbox_clickevent(object sender, EventArgs e)
{
    // initialized prevents the message box from being displayed in the 
    // setting is loaded at startup that results in the checkbox being 
    // unchecked.
    if (initialized)
    {
        CheckBox checkBox = sender as CheckBox;
        // this will only ex3cute if the checkbox is unchecked by the user
        if (!checkBox.Checked)
        {
            if (!UserVerified())
            {
                checkBox.Checked = true;
            }
        }
    }
}

您可能需要稍微调整一下，但我想您明白了.

You may need to tweak this a bit, but I think you get the idea.

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