c# combobox实现复选框以及自定义样式 示例源码

【实例截图】

【核心代码】

using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Drawing;
using System.Diagnostics;
using System.Windows.Forms;

namespace xComboBox
{
	public class PowerComboBox : ComboBox
	{

//APIs
//TODO: INSTANT C# TODO TASK: Insert the following converted event handlers at the end of the 'InitializeComponent' method for forms, 'Page_Init' for web pages, or into a constructor for other classes:


	[System.Runtime.InteropServices.DllImport("user32.dll")]
	private extern static int SendMessage(System.IntPtr hWnd, int Msg, System.Int32 wParam, System.IntPtr lParam);


//properties
	private string mDividerFormat = "";
	private Color mGroupColor = System.Drawing.SystemColors.WindowText; //ForeColor 'mediumblue
	private bool[] mItemsChecks;
	private bool mCheckBoxes;
	private Color mGridColor = Color.FromArgb(240, 248, 255);

//vars - last selected item
	private bool mRedrawingUnselected;
	private Graphics mGraphics;
	private Rectangle mBounds;
	private Int32 mIndex;
	private char mItemSeparator1 = ',';
	private char mItemSeparator2 = '&';
	private Graphics mGraphics_t;
	private Rectangle mBounds_t;
	private Int32 mIndex_t;

	private long mHoverIndex;

	private Timer mTimer1;


//events
	public delegate void ItemHoverEventHandler(Int32 eIndex);
	public event ItemHoverEventHandler ItemHover;

//vars
	private Int32 mLastSelectedIndex = -1;


//constructor
	public PowerComboBox()
	{

		// set draw mode to owner draw
		this.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawFixed; //DrawMode.OwnerDrawFixed

	}


//properties
	[System.ComponentModel.Description("Use this property to set divider flag.  Recommend you use three hyphens ---."), System.ComponentModel.Category("Power Properties")]
	public string DividerFormat
	{
	get
	{

		return mDividerFormat;

	}
	set
	{

		mDividerFormat = value;

	}

	}
	[System.ComponentModel.Description("Use this property to set the ForeColor of the grouping text."), System.ComponentModel.Category("Power Properties")]
	public Color GroupColor
	{

	get
	{

		return mGroupColor;

	}
	set
	{

		mGroupColor = value;

	}

	}
	[System.ComponentModel.Description("Use this property to set the BackColor of the grid."), System.ComponentModel.Category("Power Properties")]
	public Color GridColor
	{

	get
	{

		return mGridColor;

	}
	set
	{

		mGridColor = value;

	}

	}
//ORIGINAL LINE: Public Property ItemsChecks(ByVal xIndex As Int32) As Boolean
//INSTANT C# NOTE: C# does not support parameterized properties - the following property has been divided into two methods:
	[System.ComponentModel.Description("Use this property to get/set corresponding checkboc values."), System.ComponentModel.Category("Power Properties")]
	public bool GetItemsChecks(Int32 xIndex)
	{

		return mItemsChecks[xIndex];


	}
		public void SetItemsChecks(Int32 xIndex, bool value)
		{
			mItemsChecks[xIndex] = value;
		}
	[System.ComponentModel.Description("Use this property to enable checkboxes."), System.ComponentModel.Category("Power Properties")]
	public bool CheckBoxes
	{
		get
		{
		return mCheckBoxes;
		}
		set
		{
		mCheckBoxes = value;
		}
	}
	[System.ComponentModel.Description("Use this property to set item separator1 character."), System.ComponentModel.Category("Power Properties")]
	public char ItemSeparator1
	{
		get
		{
		return mItemSeparator1;
		}
		set
		{
		mItemSeparator1 = value;
		}
	}
	[System.ComponentModel.Description("Use this property to set item separator2 character."), System.ComponentModel.Category("Power Properties")]
	public char ItemSeparator2
	{
		get
		{
		return mItemSeparator2;
		}
		set
		{
		mItemSeparator2 = value;
		}
	}


//overrides
	protected override void OnTextChanged(System.EventArgs e)
	{


		base.OnTextChanged(e);

	}
	protected override void OnSelectedIndexChanged(System.EventArgs e)
	{

			//cancels SIC when user try to select a group
			if (this.DividerFormat.Length > 0 && this.Text.Contains(this.mDividerFormat))
			{
			this.SelectedIndex = mLastSelectedIndex; //NOTE restorre last valid selection
			return;
			}

		mLastSelectedIndex = this.SelectedIndex;
		base.OnSelectedIndexChanged(e);

	}
	protected override void OnDrawItem(DrawItemEventArgs e)
	{

	Int32 zX1 = 0;
	Pen zPen = null;
	float zWidth = 0F;
	string zText = null;
	Font zFont = null;
	Color zFore = new Color();
	System.Windows.Forms.VisualStyles.CheckBoxState zState = 0;

			if (e.Index < 0)
			{
			base.OnDrawItem(e);
			return; //fix for designer error - hope doesnt effect runtime drawing
			}

			//NOTE 1st part of if statement draw group item, 2nd draws actual item
			if (this.Items[e.Index].ToString().Contains(this.mDividerFormat) & mDividerFormat.Length > 0)
			{
			//background
			   if (e.Index == SelectedIndex)
			   {
				e.DrawBackground();
				}
			zText = this.Items[e.Index].ToString();
			zText = " "   zText.Replace(this.mDividerFormat, "")   " ";
			zFont = new Font(Font, FontStyle.Bold); //group item
				if (e.BackColor == System.Drawing.SystemColors.Highlight)
				{
				zFore = Color.Gainsboro; //Color.LightGray 'Color.Silver 'gray colr lets user know that shouldn't be selecting a group item
				}
				else
				{
				zFore = this.GroupColor; //e.ForeColor
				}
			zPen = new Pen(zFore);
			//draw group
			zWidth = e.Graphics.MeasureString(zText, zFont).Width;
            zX1 = Convert.ToInt32(e.Bounds.Width - zWidth) / 2;
			e.Graphics.DrawRectangle(zPen, new Rectangle(e.Bounds.X, e.Bounds.Y   e.Bounds.Height / 2, zX1, 1));
			e.Graphics.DrawRectangle(zPen, new Rectangle(e.Bounds.Width - zX1, e.Bounds.Y   e.Bounds.Height / 2, e.Bounds.Width, 1));
			e.Graphics.DrawString(zText, zFont, new SolidBrush(zFore), zX1, e.Bounds.Top);
			}
			else
			{

				if (mRedrawingUnselected)
				{
					if (mIndex % 2 == 0)
					{
					e.Graphics.FillRectangle(new SolidBrush(Color.White), mBounds); //e.Bounds)'FIX for wrong bound being passed
					}
					else
					{
					e.Graphics.FillRectangle(new SolidBrush(mGridColor), mBounds); //e.Bounds) 'FIX for wrong bound being passed
					}
				}
				else
				{
					if (e.Index == SelectedIndex)
					{
					e.DrawBackground();
					}
					else
					{
						if (e.Index % 2 == 0)
						{
						e.Graphics.FillRectangle(new SolidBrush(Color.White), e.Bounds);
						}
						else
						{
						e.Graphics.FillRectangle(new SolidBrush(mGridColor), e.Bounds);
						}
					}
				}


				//checkbox work
				if (mCheckBoxes)
				{
					if (e.BackColor == System.Drawing.SystemColors.Highlight)
					{
						if (this.GetItemsChecks(e.Index))
						{
						zState = System.Windows.Forms.VisualStyles.CheckBoxState.CheckedHot;
						}
						else
						{
						zState = System.Windows.Forms.VisualStyles.CheckBoxState.UncheckedHot;
						}
					}
					else
					{
						if (this.GetItemsChecks(e.Index))
						{
						zState = System.Windows.Forms.VisualStyles.CheckBoxState.CheckedNormal;
						}
						else
						{
						zState = System.Windows.Forms.VisualStyles.CheckBoxState.UncheckedNormal;
						}
					}
				zX1 = this.FontHeight; /// 2 'variable re-use
				zPen = new Pen(Color.Black, 1F);
				zPen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dot;
				//e.Graphics.DrawLine(zPen, e.Bounds.Left, e.Bounds.Top   zX1, e.Bounds.Left   e.Bounds.Width, e.Bounds.Top   zX1)
				System.Windows.Forms.CheckBoxRenderer.DrawCheckBox(e.Graphics, new System.Drawing.Point(e.Bounds.X   e.Bounds.Width - 15, e.Bounds.Y   1), e.Bounds, "", this.Font, false, zState);
				}

			//text work
			e.Graphics.DrawString(this.Items[e.Index].ToString(), Font, new SolidBrush(e.ForeColor), e.Bounds.Left, e.Bounds.Top);
			}

			//exits here when redrawing unselected
			if (mRedrawingUnselected)
			{
			mRedrawingUnselected = false;
			}
			else
			{

				//NOTE just seems to work 100% when timer is used in conjunction with .Bound override of old graphics property
				if (SelectedIndex == e.Index)
				{
				mGraphics_t = e.Graphics;
				mBounds_t = e.Bounds;
				mIndex_t = e.Index;
				mTimer1 = new Timer();
				mTimer1.Interval = 5;
				mTimer1.Enabled = true;
                mTimer1.Tick  = new EventHandler(mTimer1_Tick);
				}

			}

		base.OnDrawItem(e);

	}
	protected override void WndProc(ref System.Windows.Forms.Message m)
	{

	const Int32 WM_SETCURSOR = 32;
	const Int32 WM_WINDOWPOSCHANGING = 70;
	const Int32 WM_COMMAND = 273;
	const int WM_CTLCOLORLISTBOX = 308;
	const Int32 CB_ADDSTRING = 323;
	const Int32 CB_GETCURSEL = 327;
	const Int32 WM_LBUTTONUP = 514;
	const Int32 OCM_COMMAND = 8465;

	Int32 yPos = 0;

//INSTANT C# NOTE: The following VB 'Select Case' included range-type or non-constant 'Case' expressions and was converted to C# 'if-else' logic:
//			Select Case true
//ORIGINAL LINE: Case m.Msg = WM_WINDOWPOSCHANGING //.DropDownClose (more effective catching of )
			if (true == (m.Msg == WM_WINDOWPOSCHANGING)) //.DropDownClose (more effective catching of )
			{



			}
//ORIGINAL LINE: Case m.Msg = WM_CTLCOLORLISTBOX Or m.Msg = WM_SETCURSOR //.ItemHover (more effective catching of )
			else if (true == (m.Msg == WM_CTLCOLORLISTBOX | m.Msg == WM_SETCURSOR)) //.ItemHover (more effective catching of )
			{
			yPos = this.PointToClient(System.Windows.Forms.Cursor.Position).Y;
				if (this.DropDownStyle == ComboBoxStyle.Simple)
				{
				yPos -= (this.ItemHeight   10);
				}
				else
				{
				yPos -= (this.Size.Height   1);
				}
			mHoverIndex = yPos / this.ItemHeight;

				if (mHoverIndex >= 0) //FIX for not raising event on mouse over text
				{
				mHoverIndex = Convert.ToInt32(mHoverIndex);
					if (mHoverIndex > -1 & mHoverIndex < this.Items.Count & this.DroppedDown)
					{
					if (ItemHover != null)
						ItemHover(Convert.ToInt32(mHoverIndex));
					}
				}
				else
				{
				//NOTE should really raisevent with -1
				}

			}
//ORIGINAL LINE: Case m.Msg = CB_ADDSTRING And m.WParam = new IntPtr(0) //.AddItem(s) for stretching ItemChecks array
			else if (true == (m.Msg == CB_ADDSTRING & m.WParam == new IntPtr(0))) //.AddItem(s) for stretching ItemChecks array
			{
			StretchCheckList();



			}
//ORIGINAL LINE: Case m.Msg = WM_COMMAND And m.WParam = new System.IntPtr(66536) //intercepts WM_COMMAND (which prevent DropDownBox from closing after WM_LBUTTONDOWN)
			else if (true == (m.Msg == WM_COMMAND & m.WParam == new System.IntPtr(66536))) //intercepts WM_COMMAND (which prevent DropDownBox from closing after WM_LBUTTONDOWN)
			{
//.(.ToString)

				//0. normal behaviour when no checkboxes
				if (! this.mCheckBoxes)
				{
				base.WndProc(ref m);
				return;
				}

				//cancels SIC when user try to select a group
				if (this.DividerFormat.Length > 0 && Convert.ToString(this.Items[Convert.ToInt32(mHoverIndex)]).Contains(this.mDividerFormat))
				{
				//Me.SelectedIndex = mLastSelectedIndex 'NOTE restorre last valid selection
				//Exit Sub
				base.WndProc(ref m);
				return;
				}

			//1. reconstructs (cancelled) child events from WM_COMMAND MSG
			PowerComboBox.SendMessage(this.Handle, OCM_COMMAND, 591814, new IntPtr(1705748)); //1 event reconstruuction
			PowerComboBox.SendMessage(this.Handle, OCM_COMMAND, 67526, new IntPtr(1705748)); //2 flagging redraw
			PowerComboBox.SendMessage(this.Handle, CB_GETCURSEL, 0, new IntPtr(0)); //3 event reconstruuction
			PowerComboBox.SendMessage(this.Handle, WM_LBUTTONUP, 0, new IntPtr(721012)); //4 flagging redraw

				//2. toggle checkbox
				if (SelectedIndex > -1)
				{
				this.SetItemsChecks(SelectedIndex, ! (this.GetItemsChecks(SelectedIndex)));
				}

			// Me.ItemsChecks(mHoverIndex) = Not Me.ItemsChecks(mHoverIndex)

				//3. throw 'hover' \ Msg308 Or Msg32  so item is repainted
				if (this.SelectedIndex == 0)
				{
				yPos = this.Font.Height;
				}
				else
				{
				yPos = this.Font.Height * -1;
				}
			System.Windows.Forms.Cursor.Position = new Point(System.Windows.Forms.Cursor.Position.X, System.Windows.Forms.Cursor.Position.Y   yPos);
			Application.DoEvents();
			System.Windows.Forms.Cursor.Position = new Point(System.Windows.Forms.Cursor.Position.X, System.Windows.Forms.Cursor.Position.Y - yPos);

			this.Text = GetCommaText(); //NEW CSV test for checkboxes

			//4. cancels event
			return;
			}

		base.WndProc(ref m);

	}


//private
	private void StretchCheckList()
	{

		Array.Resize(ref mItemsChecks, this.Items.Count);

	}
	private void mTimer1_Tick(object sender, System.EventArgs e)
	{

		mTimer1.Enabled = false;
		mRedrawingUnselected = true;
		base.OnDrawItem(new System.Windows.Forms.DrawItemEventArgs(mGraphics, this.Font, mBounds, mIndex, DrawItemState.Default));
		mGraphics = mGraphics_t;
		mBounds = mBounds_t;
		mIndex = mIndex_t;

	}
	private string GetCommaText()
	{

	Int32 i = 0;
	System.Text.StringBuilder sb = new System.Text.StringBuilder("");
	string s = null;
	string zFirst = null;
	string zLast = null;
	Int32 zLastComa = 0;
    string zconverterror=null;

			if (! this.CheckBoxes)
			{
				return this.Text;
			}

			for (i = 0; i < this.Items.Count; i  )
			{
				if (this.GetItemsChecks(i) == true)
				{
				sb.Append(this.Items[i]);
				sb.Append(mItemSeparator1);
				}
			}

		s = sb.ToString();
			if (s.Length == 0)
			{
				return this.Text;
			}
		s = s.Substring(0, s.Length - 1);
		zLastComa = s.LastIndexOf(mItemSeparator1);
			if (zLastComa == -1)
			{
				return this.Text;
			}
		zLast = s.Substring(zLastComa);
		zFirst = s.Substring(0, zLastComa);
        zconverterror = Convert.ToString(mItemSeparator2);
        zconverterror  = Convert.ToString(" ");
        s = zFirst   Convert.ToString(" ");
        s  = zLast.Replace(Convert.ToString(mItemSeparator1), zconverterror);
		return s;

	}
	}

}