C#实现ListView组收缩与展开功能的完整方案

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Diagnostics;

namespace ListViewGroup
{
  public partial class MainForm : Form
  {
    public MainForm()
    {
      InitializeComponent();
    }

    // 声明外部API
    [DllImport("user32.dll")]
    static extern int SendMessage(IntPtr window, int message, int wParam, ref LVHITTESTINFO lParam);
    
    [DllImport("user32.dll")]
    static extern int SendMessage(IntPtr window, int message, int wParam, IntPtr lParam);

    // 批量折叠按钮点击事件
    private void btCollapse_Click(object sender, EventArgs e)
    {
      SetGroupCollapse(GroupState.COLLAPSED | GroupState.COLLAPSIBLE);
    }

    // 批量展开按钮点击事件
    private void btExpand_Click(object sender, EventArgs e)
    {
      SetGroupCollapse(GroupState.EXPANDED | GroupState.COLLAPSIBLE);
    }

    // 统一设置所有分组的状态
    private void SetGroupCollapse(GroupState state)
    {
      // 注意：Groups.Count 可能为0，建议增加判断逻辑避免索引异常
      for (int i = 0; i <= aoc.Groups.Count - 1; i++) // 修正原代码边界隐患
      {
        LVGROUP group = new LVGROUP();
        group.cbSize = Marshal.SizeOf(group);
        group.state = (int)state;
        group.mask = 4; // LVGF_STATE
        group.iGroupId = i;
        IntPtr ip = IntPtr.Zero;
        try
        {
          ip = Marshal.AllocHGlobal(group.cbSize);
          Marshal.StructureToPtr(group, ip, true);
          // LVM_FIRST is 0x1000, LVM_SETGROUPINFO is 147
          SendMessage(aoc.Handle, 0x1000 + 147, i, ip);
        }
        catch (Exception ex)
        {
          System.Diagnostics.Trace.WriteLine(ex.Message + Environment.NewLine + ex.StackTrace);
        }
        finally
        {
          if (null != ip) Marshal.FreeHGlobal(ip);
        }
      }
    }

    private void MainForm_Load(object sender, EventArgs e)
    {
      // 初始化：将所有分组标记为可折叠
      SetGroupCollapse(GroupState.COLLAPSIBLE);
      for (int i = 0; i < aoc.Groups.Count; i++)
      {
        aoc.Groups[i].Tag = "EXPANDED"; // 默认初始状态为展开
      }
    }

    // 鼠标按下事件：检测是否点击在分组标题上
    private void aoc_MouseDown(object sender, MouseEventArgs e)
    {
      LVHITTESTINFO lvHitInfo = new LVHITTESTINFO();
      Point p = new Point(e.X, e.Y); // 相对于客户区的坐标
      lvHitInfo.pt = p;
      
      try
      {
        // 查询命中测试：-1表示不针对特定的Item
        int id = SendMessage(aoc.Handle, 0x1000 + 18, -1, ref lvHitInfo);
        
        // 0x50000000 对应 HITTESTFLAGS.GROUPHEADER
        if (lvHitInfo.flags == 0x50000000)
        {
          string currentState = aoc.Groups[id].Tag.ToString();
          
          if (currentState == "EXPANDED")
          {
            // 切换到折叠状态
            SetGroupCollapseEx(id, GroupState.COLLAPSED | GroupState.COLLAPSIBLE);
            aoc.Groups[id].Tag = "COLLAPSED";
          }
          else if (currentState == "COLLAPSED")
          {
            // 切换到展开状态
            SetGroupCollapseEx(id, GroupState.EXPANDED | GroupState.COLLAPSIBLE);
            aoc.Groups[id].Tag = "EXPANDED";
          }
        }
      }
      catch (Exception ex)
      {
        Trace.WriteLine(ex.Message + Environment.NewLine + ex.StackTrace);
      }
    }

    // 针对单个ID的操作
    private void SetGroupCollapseEx(int id, GroupState groupState)
    {
      int i = id;
      LVGROUP group = new LVGROUP();
      group.cbSize = Marshal.SizeOf(group);
      group.state = (int)groupState;
      group.mask = 4; 
      group.iGroupId = i;
      IntPtr ip = IntPtr.Zero;
      try
      {
        ip = Marshal.AllocHGlobal(group.cbSize);
        Marshal.StructureToPtr(group, ip, true);
        SendMessage(aoc.Handle, 0x1000 + 147, i, ip); 
      }
      catch (Exception ex)
      {
        System.Diagnostics.Trace.WriteLine(ex.Message + Environment.NewLine + ex.StackTrace);
      }
      finally
      {
        if (null != ip) Marshal.FreeHGlobal(ip);
      }
    }
  }

  // Win32 结构体映射
  [StructLayout(LayoutKind.Sequential)]
  public struct LVGROUP
  {
    public int cbSize;
    public int mask;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string pszHeader;
    public int cchHeader;
    [MarshalAs(UnmanagedType.LPTStr)]
    public string pszFooter;
    public int cchFooter;
    public int iGroupId;
    public int stateMask;
    public int state;
    public int uAlign;
  }

  public enum GroupState
  {
    COLLAPSIBLE = 8,
    COLLAPSED = 1,
    EXPANDED = 0
  }

  [StructLayout(LayoutKind.Sequential)]
  public struct LVHITTESTINFO
  {
    public Point pt;
    public int flags;
    public int iItem;
    public int iSubItem;
    public int iGroup;
  }
}