Selecting all items in a ListBox Winform Control

问题

I'm trying to select all items in ListBox and made this extension method for this purpose:

    public static void SetSelectedAllItems(this ListBox ctl)
    {
        for (int i = 0; i < ctl.Items.Count; i++)
        {
            ctl.SetSelected(i, true);
        }
    }

Problem is that if I have lots of items in the ListBox, it takes a long time to accomplish this task and I can watch how the ListBox is automatically scrolling down and selecting items.

Is there a way to temporary pause the update of a control, so that the task would finish faster? I tried using:

ctl.SuspendLayout();
  for (int i = 0; i < ctl.Items.Count; i++)
  ...
ctl.ResumeLayout();

But that doesn't seem to do anything.

回答1:

Call the BeginUpdate and EndUpdate methods to prevent the drawing/rendering of the control while properties on that control are being set.

Here is the revised code:

public static void SetSelectedAllItems(this ListBox ctl)
{
    ctl.BeginUpdate();

    for (int i = 0; i < ctl.Items.Count; i++)
    {
        ctl.SetSelected(i, true);
    }

    ctl.EndUpdate();
}

You said that you've tried calling SuspendLayout and ResumeLayout, but that only affects the control's layout events. This pair of methods is used when you want to change a control's position relative to other controls, like when you set the Size, Location, Anchor, or Dock properties.

来源：https://stackoverflow.com/questions/15398091/selecting-all-items-in-a-listbox-winform-control