删除动态创建的控件 [英] Delete dynamically created controls

问题描述

我一直卡在我程序的这一部分.每当我调用 listbox.selectitemchange 事件时，我都希望显示适当数量的轨迹栏和标签.

I keep getting stuck on this part of my program. whenver i call an listbox.selectitemchange event, i want the proper amount of trackbar and labels to be displayed.

现在，它不能正常工作.调用事件时，其中一些会被删除，而另一些则不会.

now, it does not work properly. Some of them get removed when the event is called, some of them don't.

foreach (Label label in Controls.OfType<Label>())
{
    if (label.Tag != null && label.Tag.ToString() == "dispose")
    {
        label.Dispose();
    }
}

foreach (TrackBar trackBar in Controls.OfType<TrackBar>())
{
    if (trackBar.Tag != null && trackBar.Tag.ToString() == "dispose")
    {
        trackBar.Dispose();
    }
}


    for (int i = 0; i < calc; i++)
    {
        //string[] LineWidthSplitted = lines[lineWidth].Split(' ');
        //Int32.TryParse(LineWidthSplitted[2], out WidthValue);


        Label Label = new Label();
        Label.Name = "TrackbarWidth" + LabelName++;
        Label.Tag = "dispose";
        Label.Text = "Board -" + LabelName + "- Height:";
        Label.Location = new Point(10, 450 + (50 * LabelName));
        Label.Size = new System.Drawing.Size(100, 25);
        this.Controls.Add(Label);



        TrackBar trackBar = new TrackBar();
        trackBar.Name = "TrackbarWidth" + trackbarName++;
        trackBar.Tag = "dispose";
        trackBar.Maximum = 85;
        trackBar.Minimum = 65;
        trackBar.SmallChange = 5;
        trackBar.TickFrequency = 5;
        trackBar.Value = 65;
        trackBar.Location = new Point(150, 450 + (50 * trackbarName));
        trackBar.Size = new System.Drawing.Size(100, 25);
        this.Controls.Add(trackBar);


        lineWidth += 4;

    }

同时，当我删除跟踪栏的 foreach 时，所有标签都会正确显示.它们都被删除，然后根据需要创建的价格重新创建，没有例外.

while, when i remove the foreach for the trackbar, all labels get properly displayed. they all get deleted, en recreated for the pricese amount needed to be created, no exceptions.

有什么理由吗?

谢谢.

推荐答案

不要立即在标签上使用Dispose".首先删除它们.请注意，您无法修改 foreach 中的 Controls 集合，因此您必须执行以下操作:

Don't use "Dispose" on the labels right away. First remove them. Note that you can't modify the Controls collection inside the foreach so you have to do something like this:

List<Label> itemsToRemove = new List<Label>();
foreach (Label label in Controls.OfType<Label>())
{
    if (label.Tag != null && label.Tag.ToString() == "dispose")
    {
        itemsToRemove.Add(label);
    }
}

foreach (Label label in itemsToRemove)
{
    Controls.Remove(label);
    label.Dispose();
}

如果您想一次性删除所有不同类型的控件:

If you want to remove all different kinds of controls in one swoop:

List<Control> itemsToRemove = new List<Control>();
foreach (Control ctrl in Controls)
{
    if (ctrl.Tag != null && ctrl.Tag.ToString() == "dispose")
    {
        itemsToRemove.Add(ctrl);
    }
}

foreach (Control ctrl in itemsToRemove)
{
    Controls.Remove(ctrl);
    ctrl.Dispose();
}

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