删除动态创建的控件

Question

我一直困在我的程序的这一部分.当我调用一个listbox.selectitemchange事件时,我希望显示适当数量的轨迹栏和标签.

现在,它无法正常工作.其中一些在调用事件时被删除,其中一些没有.

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;

    }

而当我删除轨迹栏的foreach时,所有标签都会正确显示.它们都被删除,为需要创建的价格重新创建,没有例外.

有什么理由吗？

谢谢.

Answer 1

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:

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();
}

如果你想一举删除所有不同类型的控件:

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();
}