c# listbox 获取显示的索引范围 [英] c# listbox get displayed range of indices

问题描述

我有一个列表框，我想显示一个标签:

i have a listbox and i would want to display a label displaying:

滚动查看 ZZZ 的 XXX 到 XYY 项.

scrolling through items XXX to XYY of ZZZ.

我该怎么做，因为使用 SelectedIndex 没有用，因为即使没有选择任何内容，我也希望标签更新.(也滚动，它不会选择一个项目).

how do I do this because using SelectedIndex will not be useful, as i would like the label to update even when nothing is selected. (scrolling too, it does not select an item).

更新:例如，我的列表框中有 200 个项目.由于列表框的高度，我在任何时候都只能显示 10 个项目.所以标签应该是:

update: for example I have 200 items in my listbox. at any one time i can only display only 10 items because of my listbox's height. so the label should read:

显示项目 1 到 10，共 200 个

displaying items 1 to 10 of 200

或

显示第 5 到 15 个项目，共 200 个

displaying items 5 to 15 of 200

但是我必须考虑到可能没有选择任何索引，因为我可以简单地滚动而不选择任何内容.

however i must take into account that there may not be any indices selected because i can simply scroll and not select anything.

推荐答案

您可以使用 listbox.TopIndex 获取顶部索引值，使用 listbox.Items.Count 获取计数> 但我看不出有什么方法可以从 listbox.GetItemHeight() 和 listbox.ClientSize.Height 的结果计算它的底部项目:

You can get the top index value using listbox.TopIndex and the count using listbox.Items.Count but I can't see any way to get the bottom item withotu calculating it from the result of listbox.GetItemHeight() and listbox.ClientSize.Height:

int visibleCount = listBox1.ClientSize.Height / listBox1.ItemHeight;
this.Text = string.Format("{0:d} to {1:d} of {2:d}", listBox1.TopIndex + 1, listBox1.TopIndex + visibleCount, listBox1.Items.Count);

这可以在计时器上完成，因为我看不到滚动事件.

This can be done on a timer as I see no scroll event.

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