C # WinForm ComboBox control sub-item plus Delete button (original)

Effects such as, I search the information on the Internet and their own research finally realized in the ComboBox subkey plus Delete button.

First, the code in the form:

usingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Text;usingSystem.Windows.Forms;usingSystem.Runtime.InteropServices;usingSystem.Drawing.Drawing2D;namespacecomboboxex{ Public Partial classForm1:form {[DllImport ("User32")]        Private Static extern intGetcomboboxinfo (INTPTR hwnd, outcomboboxinfo comboinfo); structRECT { Public intLeft , top, right, bottom; }        structComboboxinfo { Public intcbsize;  PublicRECT RcItem;  PublicRECT Rcbutton;  Public intStatebutton;  PublicIntPtr Hwndcombo;  PublicIntPtr Hwnditem;  PublicIntPtr hwndlist; }        Private voidForm1_Load (Objectsender, EventArgs e) {Combobox1.drawmode=drawmode.ownerdrawfixed; COMBOBOX1.ITEMS.ADD (NewComboItem ("Sgset", pictureBox1.Image)); COMBOBOX1.ITEMS.ADD (NewComboItem ("SDGSDG", pictureBox1.Image)); COMBOBOX1.ITEMS.ADD (NewComboItem ("SDGSDG", pictureBox1.Image)); }         PublicForm1 () {InitializeComponent (); Combobox1.handlecreated+ = (s, e) = ={Comboboxinfo Combo=NewComboboxinfo (); Combo.cbsize=marshal.sizeof (combo); Getcomboboxinfo (Combobox1.handle, outcombo); HWND=combo.hwndlist; Init=false;        }; }        BOOLInit;        INTPTR hwnd; Nativecombo Nativecombo=NewNativecombo (); //This was to store the Rectangle info of your Icons//key:the Item Index//value:the Rectangle of the Icon of the item (not the Rectangle of the item)dictionary<int, rectangle> dict =Newdictionary<int, rectangle>();  Public classNativecombo:nativewindow {//This is a custom MouseDown event to hooks into later             Public EventMouseEventHandler MouseDown; protected Override voidWndProc (refMessage m) {                if(M.msg = =0x201)//wm_lbuttondown = 0x201                {                    intx = M.lparam.toint32 () &0x00ff; inty = M.lparam.toint32 () >> -; if(MouseDown! =NULL) MouseDown (NULL,NewMouseEventArgs (MouseButtons.Left,1, X, Y,0)); }                Base. WndProc (refm); }        }        Private voidCombobox1_drawitem (Objectsender, DrawItemEventArgs e) {                        if((E.state & drawitemstate.selected)! =0)//The mouse is selected on this item            {                //Gradient Paint BrushLinearGradientBrush brush =NewLinearGradientBrush (E.bounds, Color.FromArgb (255,251,237), Color.FromArgb (255,236,181), lineargradientmode.vertical); //Fill AreaRectangle Borderrect =NewRectangle (0, E.bounds.y, E.bounds.width, E.bounds.height-2);                E.graphics.fillrectangle (brush, borderrect); //Draw BorderPen pen =NewPen (Color.FromArgb (229,195,101));            E.graphics.drawrectangle (pen, borderrect); }            Else{SolidBrush Brush=NewSolidBrush (Color.FromArgb (217,223, the));            E.graphics.fillrectangle (brush, e.bounds); }            //get an item picture, draw a pictureComboItem item =(ComboItem) Combobox1.items[e.index]; Image img=item.            IMG; //the area where the picture is drawnRectangle Imgrect =NewRectangle (E.bounds.width- -, E.bounds.y, the, the); Dict[e.index]=Imgrect; if(img! =NULL&& (E.state & drawitemstate.selected)! =0) {e.graphics.drawimage (img, imgrect); } Rectangle Textrect=NewRectangle (Ten, Imgrect.y, E.bounds.width-imgrect.width, E.bounds.height +2); stringItemtext =Combobox1.items[e.index].            ToString (); StringFormat Strformat=NewStringFormat (); Strformat.linealignment=Stringalignment.center; E.graphics.drawstring (Itemtext,NewFont ("Song Body", -), Brushes.black, Textrect, Strformat); }        Private voidCombobox1_dropdown (Objectsender, EventArgs e) {            if(!init) {                //Register The MouseDown event handler <--- This was what you want.Nativecombo.mousedown + =Combolistmousedown;                Nativecombo.assignhandle (HWND); Init=true; }        }        //The MouseDown event handler to handle the clicked icon        Private voidCombolistmousedown (Objectsender, MouseEventArgs e) {            foreach(varKvinchdict) {                if(KV. Value.contains (e.location)) {//Show the item index whose the corresponding icon was held downMessageBox.Show (KV.                    Key.tostring ()); return; }            }        }    }}

Second, the Child auxiliary class

usingSystem;usingSystem.Collections.Generic;usingSystem.Text;usingSystem.Drawing;namespacecomboboxex{ Public classComboItem:Object    {        PrivateImage img =NULL; Private stringText =NULL;  PublicComboItem () {} PublicComboItem (stringtext) {Text=text; }         PublicComboItem (stringtext,image img) {Text=text; IMG=img; }        //Item IMG         PublicImage Img {Get            {                returnimg; }            Set{img=value; }        }        //Item Text         Public stringText {Get            {                returntext; }            Set{text=value; }        }        //ToString () should return item text         Public Override stringToString () {returntext; }    }}

C # WinForm ComboBox control sub-item plus Delete button (original)