comboboxex.cpp

Combox控件编程技巧2

// ComboBoxEx.cpp : implementation file
//
// Autocompleting combo-box (like the URL edit box in netscape)
//
// Written by Chris Maunder ([e-mail])
// Copyright (c) 1998.
//
// This code may be used in compiled form in any way you desire. This
// file may be redistributed unmodified by any means PROVIDING it is 
// not sold for profit without the authors written consent, and 
// providing that this notice and the authors name is included. If 
// the source code in  this file is used in any commercial application 
// then acknowledgement must be made to the author of this file 
// (in whatever form you wish).
//
// This file is provided "as is" with no expressed or implied warranty.
// The author accepts no liability if it causes any damage to your
// computer, causes your pet cat to fall ill, increases baldness or
// makes you car start emitting strange noises when you start it up.
//
// Expect bugs.
// 
// Please use and enjoy. Please let me know of any bugs/mods/improvements 
// that you have found/implemented and I will fix/incorporate them into this
// file. 
//
// Modified: 12 Sep 1998 Setting correct cursor position after 
//                       auto-complete: Petr Stejskal and Ryan Schneider
//
// 本代码供免费使用，使用时请遵守如上协定
/////////////////////////////////////////////////////////////////////////////

#include "stdafx.h"
#include "ComboBoxEx.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

/////////////////////////////////////////////////////////////////////////////
// CComboBoxExt

CComboBoxExt::CComboBoxExt()
{
	m_bAutoComplete = TRUE;
}

CComboBoxExt::~CComboBoxExt()
{
}


BEGIN_MESSAGE_MAP(CComboBoxExt, CComboBox)
//{{AFX_MSG_MAP(CComboBoxExt)
ON_CONTROL_REFLECT(CBN_EDITUPDATE, OnEditUpdate)
//}}AFX_MSG_MAP
END_MESSAGE_MAP()

/////////////////////////////////////////////////////////////////////////////
// CComboBoxExt message handlers

BOOL CComboBoxExt::PreTranslateMessage(MSG* pMsg)
{
	// Need to check for backspace/delete. These will modify the text in
	// the edit box, causing the auto complete to just add back the text
	// the user has just tried to delete. 
	
	if (pMsg->message == WM_KEYDOWN)
	{
		m_bAutoComplete = TRUE;
		
		int nVirtKey = (int) pMsg->wParam;
		if (nVirtKey == VK_DELETE || nVirtKey == VK_BACK)
			m_bAutoComplete = FALSE;
	}
	
	return CComboBox::PreTranslateMessage(pMsg);
}

void CComboBoxExt::OnEditUpdate() 
{
	// if we are not to auto update the text, get outta here
	if (!m_bAutoComplete) 
		return;
	
	// Get the text in the edit box
	CString str;
	GetWindowText(str);
	int nLength = str.GetLength();
	
	// Currently selected range
	DWORD dwCurSel = GetEditSel();
	WORD dStart = LOWORD(dwCurSel);
	WORD dEnd   = HIWORD(dwCurSel);
	
	// Search for, and select in, and string in the combo box that is prefixed
	// by the text in the edit box
	if (SelectString(-1, str) == CB_ERR)
	{
		SetWindowText(str);		// No text selected, so restore what was there before
		if (dwCurSel != CB_ERR)
			SetEditSel(dStart, dEnd);	//restore cursor postion
	}
	
	// Set the text selection as the additional text that we have added
	if (dEnd < nLength && dwCurSel != CB_ERR)
		SetEditSel(dStart, dEnd);
	else
		SetEditSel(nLength, -1);
}