我如何在ListView的起始索引和可见项目的数量？ [英] How do I get the start index and number of visible items in a ListView?

问题描述

我有一个ListView在虚拟模式下工作，在LargeIcons视图。检索是昂贵的，所以我想询问所有可见项目的数据。我如何获得可见项目的启动指数和总人数？

I have a listview working in virtual mode, in the LargeIcons view. Retrieves are expensive, so I want to ask for the data for all the visible items. How do I get the start index and total number of the visible items?

更新：我知道了CacheVirtualItems事件。我们使用第三方数据库需要3秒〜检索单个记录，但4S〜检索上千条记录，所以我必须做他们大块。我需要确保在可见的记录是那些我们检索中，所以我需要知道可见项目的启动指数和总数量。如果这不可行，我必须找到一个解决方法（这可能会涉及使用一个DataGridView与图像细胞负载模仿LargeIcons视图），但我想正确如果可能做到这一点。

Update: I am aware of the CacheVirtualItems event. The third-party database we're using takes ~3s to retrieve a single record, but ~4s to retrieve a thousand records, so I have to do them in large blocks. I need to make sure the visible records are among those we retrieve, so I need to know the start index and total number of the visible items. If that's not feasible, I'll have to find a workaround (which will probably involve using a DataGridView with a load of image cells to imitate the LargeIcons view) but I would like to do this properly if possible.

推荐答案

刚刚送走我的头顶，我没有测试过这一点，但你可以这样做：

Just off the top of my head, and I haven't tested this but could you do:

private void GetIndexes(ListView vv, out int startidx, out int count)
{
            ListViewItem lvi1 = vv.GetItemAt(vv.ClientRectangle.X+6, vv.ClientRectangle.Y + 6); 
            ListViewItem lvi2 = vv.GetItemAt(vv.ClientRectangle.X+6, vv.ClientRectangle.Bottom-10); 
            startidx = vv.Items.IndexOf(lvi1); 
            int endidx = vv.Items.IndexOf(lvi2);
            if (endidx == -1) endidx = vv.Items.Count;
            count = endidx - startidx;
}

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