的System.Window.Forms.ComboBox（C＃）防止自選行爲

Question

背景：

我有一個DropDownStyle = DropDown一個Forms.ComboBox。

我不使用AutoComplete，但我實現了類似的東西，它不僅過濾文本的開頭，而且使用正則表達式並顯示與輸入的文本相匹配的所有項目。這工作正常。

然而，當我鍵入一個匹配項的第一個字母，將ComboBox回落到原來的行爲，並設置DroppedDown = true和經銷商的選擇第一項，並完成對所選擇的項目（類似於AutoCompleteMode追加）匹配的文本。我想要的是沒有自動選擇和自動完成。

我發現到目前爲止，我總得要防止SendMessage()與被稱爲CB_FINDSTRING與CB_FINDSTRINGEXACT（MSDN Link）取代CB_FINDSTRING。

我想我必須擴展ComboBox類，但我不知道我必須重寫哪些方法。我正在使用C＃.NET Framework v3.5。

問題：

• 如何延長Windows.Forms.ComboBox防止自動選擇的行爲嗎？

鏈接：

How can I prevent auto-select in ComboBox on drop-down except for exact matches?（沒有幫助我）

Answer 1

試試這個：

using System; 
using System.Collections.Generic; 
using System.Runtime.InteropServices; 
using System.Windows.Forms; 

using Opulos.Core.Win32; 

namespace Opulos.Core.UI { 

// Extension class to disable the auto-select behavior when a combobox is in DropDown mode. 
public static class ComboBoxAutoSelectEx { 

    public static void AutoSelectOff(this ComboBox combo) { 
     Data.Register(combo); 
    } 

    public static void AutoSelectOn(this ComboBox combo) { 
     Data data = null; 
     if (Data.dict.TryGetValue(combo, out data)) { 
      data.Dispose(); 
      Data.dict.Remove(combo); 
     } 
    } 

    private class Data { 
     // keep a reference to the native windows so they don't get disposed 
     internal static Dictionary<ComboBox, Data> dict = new Dictionary<ComboBox, Data>(); 

     // a ComboBox consists of 3 windows (combobox handle, text edit handle and dropdown list handle) 
     ComboBox combo; 
     NW nwList = null; // handle to the combobox's dropdown list 
     NW2 nwEdit = null; // handle to the edit window 

     internal void Dispose() { 
      dict.Remove(this.combo); 
      this.nwList.ReleaseHandle(); 
      this.nwEdit.ReleaseHandle(); 
     } 

     public static void Register(ComboBox combo) { 
      if (dict.ContainsKey(combo)) 
       return; // already registered 

      Data data = new Data() { combo = combo }; 
      Action assign =() => { 
       if (dict.ContainsKey(combo)) 
        return; // already assigned 

       COMBOBOXINFO info = COMBOBOXINFO.GetInfo(combo); // new COMBOBOXINFO(); 
       //info.cbSize = Marshal.SizeOf(info); 
       //COMBOBOXINFO2.SendMessageCb(combo.Handle, 0x164, IntPtr.Zero, out info); 

       dict[combo] = data; 
       data.nwList = new NW(combo, info.hwndList); 
       data.nwEdit = new NW2(info.hwndEdit); 
      }; 

      if (!combo.IsHandleCreated) 
       combo.HandleCreated += delegate { assign(); }; 
      else 
       assign(); 

      combo.HandleDestroyed += delegate { 
       data.Dispose(); 
      }; 
     } 
    } 

    private class NW : NativeWindow { 
     ComboBox combo; 
     public NW(ComboBox combo, IntPtr handle) { 
      this.combo = combo; 
      AssignHandle(handle); 
     } 

     private const int LB_FINDSTRING = 0x018F; 
     private const int LB_FINDSTRINGEXACT = 0x01A2; 

     protected override void WndProc(ref Message m) { 
      if (m.Msg == LB_FINDSTRING) { 
       m.Msg = LB_FINDSTRINGEXACT; 
      } 

      base.WndProc(ref m); 

      if (m.Msg == LB_FINDSTRINGEXACT) { 
       String find = Marshal.PtrToStringAuto(m.LParam); 
       for (int i = 0; i < combo.Items.Count; i++) { 
        Object item = combo.Items[i]; 
        if (item.Equals(find)) { 
         m.Result = new IntPtr(i); 
         break; 
        } 
       } 
      } 
     } 
    } 

    private class NW2 : NativeWindow { 
     public NW2(IntPtr handle) { 
      AssignHandle(handle); 
     } 

     private const int EM_SETSEL = 0x00B1; 
     private const int EM_GETSEL = 0x00B0; 

     protected override void WndProc(ref Message m) { 
      if (m.Msg == EM_SETSEL) { 
       // if this code is not here, then the entire combobox text is selected 
       // which looks ugly, especially when there are multiple combo boxes. 
       // 
       // if this method returns immediately, then the caret position is set 
       // to (0, 0). However, it seems that calling EM_GETSEL has a side effect 
       // that the caret position is mostly maintained. Sometimes it slips back 
       // to (0, 0). 
       SendMessage(Handle, EM_GETSEL, IntPtr.Zero, IntPtr.Zero); 
       //int selStart = (sel & 0x00ff); 
       //int selEnd = (sel >> 16) & 0x00ff; 
       //Debug.WriteLine("EM_GETSEL: " + selStart + " nEnd: " + selEnd); 
       return; 
      } 
      base.WndProc(ref m); 
     } 

     [DllImportAttribute("user32.dll", SetLastError=true)] 
     private static extern int SendMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam); 
    } 

} 

[StructLayout(LayoutKind.Sequential)] 
public struct COMBOBOXINFO { 
    public Int32 cbSize; 
    public RECT rcItem; 
    public RECT rcButton; 
    public int buttonState; 
    public IntPtr hwndCombo; 
    public IntPtr hwndEdit; 
    public IntPtr hwndList; 

    public static COMBOBOXINFO GetInfo(ComboBox combo) { 
     COMBOBOXINFO info = new COMBOBOXINFO(); 
     info.cbSize = Marshal.SizeOf(info); 
     SendMessageCb(combo.Handle, 0x164, IntPtr.Zero, out info); 
     return info; 
    } 

    [DllImport("user32.dll", EntryPoint = "SendMessageW", CharSet = CharSet.Unicode)] 
    private static extern IntPtr SendMessageCb(IntPtr hWnd, int msg, IntPtr wp, out COMBOBOXINFO lp); 
} 

//[StructLayout(LayoutKind.Sequential)] 
//public struct RECT { 
// public int Left; 
// public int Top; 
// public int Right; 
// public int Bottom; 
//} 

}