列表框切换项目向上 [英] listbox switch item in up down

问题描述

我按下按钮点击向下按下swtich项目的列表框控件...

i have listbox control to swtich item up down in button click ...

推荐答案

这不是太难 - 我用一个选定的曲目列表我的音乐播放器：

It's not too difficult - I do with with a list of selected tracks in my music player:

/// <summary>
/// Move all tracks at indexes up one row
/// </summary>
/// <param name="indexes"></param>
public void MoveUp(IEnumerable<int> indexes)
    {
    List<Track> tracks = new List<Track>();
    List<Track> insertThese = new List<Track>();
    int[] indexesSorted = indexes.ToArray();
    Array.Sort(indexesSorted);
    ExtractTracksByIndex(_Playlist, tracks, insertThese, indexes);
    int newIndex = indexesSorted.FirstOrDefault() - 1;
    newIndex = Math.Min(newIndex, tracks.Count);
    newIndex = Math.Max(newIndex, 0);
    tracks.InsertRange(newIndex, insertThese);
    _Playlist.Tracks = tracks;
    Selected = insertThese;
    }
/// <summary>
/// Move all tracks at indexes down one row
/// </summary>
/// <param name="indexes"></param>
public void MoveDown(IEnumerable<int> indexes)
    {
    List<Track> tracks = new List<Track>();
    List<Track> insertThese = new List<Track>();
    int[] indexesSorted = indexes.ToArray();
    Array.Sort(indexesSorted);
    ExtractTracksByIndex(_Playlist, tracks, insertThese, indexesSorted);
    int newIndex = indexesSorted.FirstOrDefault() + 1;
    newIndex = Math.Min(newIndex, tracks.Count);
    newIndex = Math.Max(newIndex, 0);
    tracks.InsertRange(newIndex, insertThese);
    _Playlist.Tracks = tracks;
    Selected = insertThese;
    }

我向他们传递要移动的项目索引的列表，并从列表中删除它们（按相反顺序，最高索引优先）然后重新插入新位置。最后一位确保之后重新选择所选曲目。

I pass them a list of the item indexes to move, and they are removed from the list (in reverse order, highest index first) then re-inserted at the new location. This final bit just makes sure the selected tracks are re-selected afterwards.

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