有什么办法不调用Control Event吗？

发布于 2025-01-04 00:56:18 字数 372 浏览 2 评论 0原文

假设有类似这样的事件 ComboBox_SelectedIndexChange

private void MyComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
  //do something//
}

我有一个更改 ComboBox 值的函数。

Private void MyFunction()
{
   MyComboBox.Text = "New Value";
}

我可以让 MyFunction 在更改 MyComboBox 的值时阻止调用事件 MyComboBox_SelectedIndexChanged 吗？

原文

Let's say there is event ComboBox_SelectedIndexChange something like this

private void MyComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
  //do something//
}

And i have a function which changes value of ComboBox.

Private void MyFunction()
{
   MyComboBox.Text = "New Value";
}

Can i make MyFunction prevent from calling the event MyComboBox_SelectedIndexChanged while changing the value of MyComboBox?

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迷路的信 2025-01-11 00:56:18

我可以让 MyFunction 在更改 MyComboBox 的值时阻止调用事件 MyComboBox_SelectedIndexChanged 吗？

不，你不能。您有两个基本选项，它们都完成相同的任务：

您可以从控件中取消事件处理程序方法，设置值，然后将事件处理程序方法重新附加到控件。例如：

private void MyFunction()
{
    MyComboBox.SelectedIndexChanged -= MyComboBox_SelectedIndexChanged;
    MyComboBox.Text = "新值";
    MyComboBox.SelectedIndexChanged += MyComboBox_SelectedIndexChanged;
}

您可以声明一个类级字段，该字段将跟踪该值是通过编程方式更新还是由用户更新。当您想要以编程方式更新组合框时设置该字段，并在 SelectedIndexChanged 事件处理程序方法中验证其值。
例如：

private bool allowedComboBoxChange = true;

私人无效MyComboBox_SelectedIndexChanged（对象发送者，EventArgs e）
{
    如果（允许组合框更改）
    {
        //做某事
    }
}

私有无效 MyFunction()
{
    允许ComboBoxChange = false;
    MyComboBox.Text = "新值";
    允许ComboBoxChange = true;
}

Can i make MyFunction prevent from calling the event MyComboBox_SelectedIndexChanged while changing the value of MyComboBox?

No, you cannot. You have two fundamental options, both of which accomplish the same thing:

You can unhook the event handler method from the control, set the value, and then reattach the event handler method to the control. For example:

private void MyFunction()
{
    MyComboBox.SelectedIndexChanged -= MyComboBox_SelectedIndexChanged;
    MyComboBox.Text = "New Value";
    MyComboBox.SelectedIndexChanged += MyComboBox_SelectedIndexChanged;
}

You can declare a class-level field that will keep track of whether the value was updated programmatically or by the user. Set the field when you want to update the combo box programmatically, and verify its value in the SelectedIndexChanged event handler method.
For example:

private bool allowComboBoxChange = true;

private void MyComboBox_SelectedIndexChanged(object sender, EventArgs e)
{
    if (allowComboBoxChange)
    {
        //do something
    }
}

private void MyFunction()
{
    allowComboBoxChange = false;
    MyComboBox.Text = "New Value";
    allowComboBoxChange = true;
}

回复收藏 0 原文

对你的占有欲 2025-01-11 00:56:18

您可以附加或分离事件处理程序。

//attach the handler
MyComboBox.SelectedIndexChanged+=(sender,eventArgs)=>
{
  //code
};
//detach the handler
MyComboBox.SelectedIndexChanged-=(sender,eventArgs)=>
{
  //code
};

或者

Private void MyFunction()
{
   comboBox1.SelectedIndexChanged -= new EventHandler(TestIt);
   MyComboBox.Text = "New Value";
   comboBox1.SelectedIndexChanged += new EventHandler(TestIt);
}

private void TestIt(object sender, EventArgs e)
{
  //do something//
}

You may attach or detach an event handler.

//attach the handler
MyComboBox.SelectedIndexChanged+=(sender,eventArgs)=>
{
  //code
};
//detach the handler
MyComboBox.SelectedIndexChanged-=(sender,eventArgs)=>
{
  //code
};

Private void MyFunction()
{
   comboBox1.SelectedIndexChanged -= new EventHandler(TestIt);
   MyComboBox.Text = "New Value";
   comboBox1.SelectedIndexChanged += new EventHandler(TestIt);
}

private void TestIt(object sender, EventArgs e)
{
  //do something//
}

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