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C#实现多选下拉框

news 来源：原创 2024/9/20 21:28:37

1、创建多选下拉框控件

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;namespace DFT_FFTApp.userCtrl
{/// <summary>/// 多选下拉控件/// </summary>public class MultiComboBox:UserControl{public ComboBox ComboBox { get; set; }public CheckedListBox CheckedListBox { get; set; }public ComboBox.ObjectCollection Items{get{return ComboBox?.Items;}}public MultiComboBox(){//面板this.VerticalScroll.Enabled = true;this.AutoSize = true;//多项列表CheckedListBox = new CheckedListBox();CheckedListBox.CheckOnClick = true;CheckedListBox.BorderStyle = BorderStyle.Fixed3D;CheckedListBox.Visible = false;CheckedListBox.Margin=new Padding(0);CheckedListBox.MouseUp += (ss, se) =>{//更新ComboBox显示文本var list = new List<string>();foreach(var item in CheckedListBox.CheckedItems){list.Add(item.ToString());}ComboBox.Text = string.Join(",", list);ComboBox.Tag = list;};CheckedListBox.MouseLeave += (ss, se) =>{//隐藏多选框CheckedListBox.Hide();};//下拉框ComboBox=new ComboBox();ComboBox.Width = 150;ComboBox.DrawMode = DrawMode.OwnerDrawFixed;ComboBox.IntegralHeight = false;ComboBox.DroppedDown = false;ComboBox.DropDownHeight = 1;ComboBox.Margin=new Padding(0);ComboBox.Location=new System.Drawing.Point(0,0);ComboBox.DropDownStyle = ComboBoxStyle.DropDown;ComboBox.AutoCompleteSource = AutoCompleteSource.ListItems;ComboBox.MouseDown += (ss, se) =>{ComboBox.DroppedDown = false;};ComboBox.MouseLeave += (ss, se) =>{//不在下拉区时隐藏多项列表var curMousePos = this.PointToClient(Control.MousePosition);var downArea = CheckedListBox.Location;if (curMousePos.X < downArea.X || curMousePos.X>(downArea.X+CheckedListBox.Width)|| curMousePos.Y<downArea.Y || curMousePos.Y>(downArea.Y+CheckedListBox.Height)){CheckedListBox.Hide();}};ComboBox.DropDown += (ss, se) =>{//显示下拉多选框CheckedListBox.Items.Clear();//添加并设置选中项var lastChecked = ComboBox.Tag as List<string>;ComboBox.BeginUpdate();foreach(var item in this.Items){var ck = false;if(lastChecked!=null && lastChecked.Contains(item.ToString())){ck = true;}CheckedListBox.Items.Add(item, ck);}//显示下拉框CheckedListBox.Width=ComboBox.Width;CheckedListBox.ItemHeight = ComboBox.ItemHeight;CheckedListBox.Size=new Size(ComboBox.DropDownWidth,this.Items.Count*18);CheckedListBox.Location = new Point(ComboBox.Left, ComboBox.Height);this.Controls.Add( CheckedListBox );CheckedListBox.Visible = true;ComboBox.EndUpdate();};//添加控件this.Controls.Add(ComboBox);}}
}

2、程序调用

using DFT_FFTApp.userCtrl;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;namespace DFT_FFTApp
{public partial class MainForm : Form{MultiComboBox multiComboBox;public MainForm(){InitializeComponent();multiComboBox = new MultiComboBox();multiComboBox.Items.AddRange(new string[] { "AIN1", "AIN2", "AIN3", "AIN4" });multiComboBox.Location = new Point(175, 15);this.Controls.Add(multiComboBox);}private void Btn_ComboBoxTest_Click(object sender, EventArgs e){//显示选择项CheckedListBox CheckedListBox =multiComboBox.CheckedListBox;foreach(var item in CheckedListBox.CheckedItems){Console.WriteLine(item);}//显示选项列表//foreach (string item in multiComboBox.Items)//{//    Console.WriteLine(item);//}}}
}