Question

如何以编程方式检查控件时阻止触发CheckedChanged事件？

我通常按照以下方式执行此操作。

private bool isFrozen = false;

private void btn1_CheckedChanged(object sender, EventArgs e)
{
    if (isFrozen) 
        return;

    isFrozen = true;
    btn2.Checked = false;
    isFrozen = false;

    // Do some stuff
}

private void btn2_CheckedChanged(object sender, EventArgs e)
{
    if (isFrozen) 
        return;

    isFrozen = true;
    btn1.Checked = false;
    isFrozen = false;

    // Do another stuff
}

是否有更好或更常见的解决方案？

Answer 1

我认为你的方式很好。

另一种方法是在检查之前删除EventHandler，然后在检查后再将其添加回来。这种方式消除了对isFrozen变量的需求。

private void btn1_CheckedChanged(object sender, EventArgs e)
{
  btn2.CheckedChanged -= btn2_CheckedChanged;
  btn2.Checked = false;
  btn2.CheckedChanged += btn2_CheckedChanged;

    // Do some staff
}

private void btn2_CheckedChanged(object sender, EventArgs e)
{
  btn1.CheckedChanged -= btn1_CheckedChanged;
  btn1.Checked = false;
  btn1.CheckedChanged += btn1_CheckedChanged;

    // Do another staff
}

Answer 2

在VB中：

RemoveHandler btn2.CheckedChanged, AddressOf btn2_CheckedChanged
btn2.Checked = false
AddHandler btn2.CheckedChanged, AddressOf btn2_CheckedChanged

Answer 3

在想要实现这样的事情一段时间后，我遇到了这篇文章。我经常使用National Instruments的Measurement Studio，以及具有事件StateChanging或StateChanged的WinForms控件传递ActionEventArgs类型的参数，该参数具有可以采用三个值的属性Action：ByKeyboard，ByMouse和Programatic。这在确定导致控件状态发生变化的原因时非常有用。我想在标准的WinForms复选框中复制它。

这是我的代码：

public enum ControlSource
{
    Programatic,
    ByKeyboard,
    ByMouse
}

public class AwareCheckBox : Checkbox
{
    public AwareCheckBox()
            : base()
    {
        this.MouseDown += AwareCheckbox_MouseDown;
        this.KeyDown += AwareCheckbox_KeyDown;
    }

    private ControlSource controlSource = ControlSource.Programatic;

    void AwareCheckbox_KeyDown(object sender, KeyEventArgs e)
    {
        controlSource = ControlSource.ByKeyboard;
    }

    void AwareCheckbox_MouseDown(object sender, MouseEventArgs e)
    {
        controlSource = ControlSource.ByMouse;
    }

    public new event AwareControlEventHandler CheckedChanged;
    protected override void OnCheckedChanged(EventArgs e)
    {
        var handler = CheckedChanged;
        if (handler != null)
            handler(this, new AwareControlEventArgs(controlSource));

        controlSource = ControlSource.Programatic;
    }
}

public delegate void AwareControlEventHandler(object source, AwareControlEventArgs e);

public class AwareControlEventArgs : EventArgs
{
    public ControlSource Source { get; private set; }

    public AwareControlEventArgs(ControlSource s)
    {
        Source = s;
    }
}

我确信有一些改进，但我的初步测试证明它有效。我已经发布在这里，以防其他人偶然发现这个问题，并希望更清楚地区分变更的起源。欢迎任何评论。

Answer 4

只需设置一个计数器值，然后在事件开始时检查该值即可。它在10分钟内解决了我的问题。我正在Xamarin中使用5个滑动按钮使其成为单选按钮。

 private void testtoggle1(object sender, ToggledEventArgs e)
        {
            if (chk_ctr == 1) { return; }
            chk_ctr = 1;
            sw2.IsToggled= false;
            sw3.IsToggled = false;
            sw4.IsToggled = false;
            sw5.IsToggled = false;
            chk_ctr = 0;
        }
        private void testtoggle2(object sender, ToggledEventArgs e)
        {
            if (chk_ctr == 1) { return; }
            chk_ctr = 1;
            sw1.IsToggled = false;
            sw3.IsToggled = false;
            sw4.IsToggled = false;
            sw5.IsToggled = false;
            chk_ctr = 0;

        }
        private void testtoggle3(object sender, ToggledEventArgs e)
        {
            if (chk_ctr == 1) { return; }
            chk_ctr = 1;
            sw1.IsToggled = false;
            sw2.IsToggled = false;
            sw4.IsToggled = false;
            sw5.IsToggled = false;
            chk_ctr = 0;
        }
        private void testtoggle4(object sender, ToggledEventArgs e)
        {
            if (chk_ctr == 1) { return; }
            chk_ctr = 1;
            sw1.IsToggled = false;
            sw2.IsToggled = false;
            sw3.IsToggled = false;
            sw5.IsToggled = false;
            chk_ctr = 0;
        }
        private void testtoggle5(object sender, ToggledEventArgs e)
        {
            if (chk_ctr == 1) { return; }
            chk_ctr = 1;
            sw1.IsToggled = false;
            sw2.IsToggled = false;
            sw3.IsToggled = false;
            sw4.IsToggled = false;
            chk_ctr = 0;
        }

如何以编程方式检查控件时阻止触发CheckedChanged事件？

4 个答案: