MFC 中ListBox 与 ComboBox 中的文本如何实现水平居中与垂直居中

    具体应用的时候我们往往不能满足于MFC提供的标准功能，这种情况下我们一般会对控件进行重载定制，对于ComboBox自然也不例外。不过ComboBox略显复杂，它本身还包括子控件，要想完全重载就要对这些子控件同样进行定制。有经验的朋友一定知道这个时候我们需要对这些子控件进行子类化，用我们自己的类去代替。微软同样为我们想到了这一点，在上文提到的链接中介绍说如果要重载ComboBox可以通过一篇文章《How to subclass CListBox and CEdit inside of CComboBox》介绍的方法来实现。这篇文章用的方法是通过OnCtlColor来实现对子控件的子类化的，应该说这个方法很巧妙但并不优雅，而且文章中也提到这个方法必须在ComboBox至少绘制一次的基础上才能起作用，对于一些要求在这之前就要实现替换的需求并不适用，文章相关原文如下：

Note that for subclassing to occur, the dialog box must be painted at least once. There are cases when the dialog box doesn't paint at all (for example, closing the dialog box before it is displayed, hidden dialog boxes). This method may not be suitable when access to the subclassed windows are needed in these cases.

    那么有什么更好的方法实现ComboBox对其子控件的子类化么，本文就是要解决这个问题。要实现子类化其实只要解决一个问题，那就是过去要子类化的控件的句柄。我们知道ComboBox的信息都封装到了COMBOBOXINFO这个结构中，通过ComboBox的成员函数GetComboBoxInfo即可获取这些信息。看一下这个结构的定义，

[cpp] view plaincopy
/*
 * Combobox information
 */ 
typedef struct tagCOMBOBOXINFO 
{ 
    DWORD cbSize; 
    RECT rcItem; 
    RECT rcButton; 
    DWORD stateButton; 
    HWND hwndCombo; 
    HWND hwndItem; 
    HWND hwndList; 
} COMBOBOXINFO, *PCOMBOBOXINFO, *LPCOMBOBOXINFO; 
 

我们发现hwndItem和hwndList应该就是我们想要的。然后我们要为子类化选择一个合适的时间，对于控件来说在PreSubclassWindow函数中处理再合适不过了。这样我们就很好的解决了子类化的途径和时机的问题，动手试一下吧，我重载重载了CComboBox做了测试，为了验证子类化是否成功我没有对ComboBox进行初始化，而是通过子类化的新控件完成的，核心代码如下：

[cpp] view plaincopy
void CExComboBox::PreSubclassWindow() 
{ 
    CComboBox::PreSubclassWindow();  
    COMBOBOXINFO    comboInfo;  
    //获取控件信息 
    comboInfo.cbSize = sizeof(COMBOBOXINFO); 
    GetComboBoxInfo(&comboInfo);  
    //子类化编辑框 
    if(comboInfo.hwndItem != NULL) 
    { 
        m_editReplace.SubclassWindow(comboInfo.hwndItem); 
        m_editReplace.SetWindowText(_T("编辑框已被子类化")); 
    }  
    //子类化列表框 
    if(comboInfo.hwndList != NULL) 
    { 
        m_listboxReplace.SubclassWindow(comboInfo.hwndList); 
        m_listboxReplace.AddString(_T("列表框已被子类化")); 
    } 
} 
 

    运行程序成功实现目的。我整理了一个小例子，有兴趣的朋友可以下载研究一下，不过大家也能看得出来，功能和实现都比较简单，所以其实这个实例的价值也不是很大。

    个人认为这个方案相对来说比较合理，对于动态创建的控件可通过OnCreate函数来完成子类化。找到了合理的子类化途径我们也就可以更好的对ComboBox做自绘和扩展，以实现更加丰富的功能。Following is a owner drawn Combo Box which will be filled with the names of the fonts.. And each entry is in same font as selected. This is something similar to the one in Netscape 4.x font selector.

This is pretty simple. All it does is to enumerate the fonts and store the LOGFONTs in the Item data. and when the painting is to be done, takes the value from the Item data and paints the item..

It has a very nice effect.. Since this does only the font names, you might need another combobox for the sizes..

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You can also set the colors for the highlight and normal..
To use this, Create a ComboBox in your Resource Editor, Set the Owner draw to "Variable" and check the "Has strings".

Then, In the OnInitDialog () or OnInitialUpdate() call the function FillFonts (). Thats it.. You have got your fonts in the Combo box. To get the selected font, Use GetSelFont () with LOGFONT& as the argument. this argument will be filled in upon return.

P.S:If you make the ComboBox to be a "Drop down List" then the edit window (actually the static control window) will hav the name in the same font as selected.. Otherwise, it will be in the dialog box's font..

//*************************************************************************
//CCustComboBox.h
 
#if !defined(AFX_CUSTCOMBOBOX_H__F8528B4F_396E_11D1_9384_00A0248F6145__INCLUDED_)
#define AFX_CUSTCOMBOBOX_H__F8528B4F_396E_11D1_9384_00A0248F6145__INCLUDED_
 
#if _MSC_VER >= 1000
#pragma once
#endif // _MSC_VER >= 1000
// CustComboBox.h : header file
//
 
///////////////////////////////////////////////////////////////////////////
//
// CCustComboBox window
 
typedef enum {FONTS} STYLE;      //Why have I enumerated, Cos, Maybe I might want something other than Fonts here
 
 
class CCustComboBox : public CComboBox
{
// Construction
public:
     CCustComboBox();
     CCustComboBox (STYLE);
 
// Attributes
public:
     void SetHilightColors (COLORREF hilight,COLORREF hilightText)
     {
          m_clrHilight = hilight;
          m_clrHilightText = hilightText;
     };
     void SetNormalColors (COLORREF clrBkgnd,COLORREF clrText)
     {
          m_clrNormalText = clrText;
          m_clrBkgnd = clrBkgnd;
     };
     static BOOL CALLBACK EnumFontProc (LPLOGFONT lplf, LPTEXTMETRIC lptm, DWORD dwType, LPARAM lpData);
     void FillFonts ();
     int  GetSelFont (LOGFONT&);
 
 
// Operations
public:
 
// Overrides
     // ClassWizard generated virtual function overrides
     //{{AFX_VIRTUAL(CCustComboBox)
     public:
     virtual void DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct);
     virtual void MeasureItem(LPMEASUREITEMSTRUCT lpMeasureItemStruct);
     protected:
     virtual void PreSubclassWindow();
     //}}AFX_VIRTUAL
 
// Implementation
public:
     virtual ~CCustComboBox();
 
     // Generated message map functions
protected:
     STYLE m_enStyle;
     COLORREF m_clrHilight;
     COLORREF m_clrNormalText;
     COLORREF m_clrHilightText;
     COLORREF m_clrBkgnd;
     BOOL m_bInitOver;
 
 
     void DrawDefault (LPDRAWITEMSTRUCT);
     void DrawFont(LPDRAWITEMSTRUCT);
 
     void InitFonts ();
     //{{AFX_MSG(CCustComboBox)
     afx_msg int OnCreate(LPCREATESTRUCT lpCreateStruct);
     afx_msg void OnDestroy();
     //}}AFX_MSG
     afx_msg   long OnInitFonts (WPARAM, LPARAM);
     DECLARE_MESSAGE_MAP()
};
 
///////////////////////////////////////////////////////////////////////////
//
 
//{{AFX_INSERT_LOCATION}}
// Microsoft Developer Studio will insert additional declarations immediately before the previous line.
 
#endif //!defined(AFX_CUSTCOMBOBOX_H__F8528B4F_396E_11D1_9384_00A0248F6145__INCLUDED_)
 
 
 
 
 
//**************************************************************************
// CustComboBox.cpp : implementation file
//
 
#include "stdafx.h"
#include "CustComboBox.h"
 
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
 
#define WM_INITFONTS          (WM_USER + 123)
//I chose 123 cos nobody might use the same exact number.. I can improve this by use RegisterWindowMessage..
 
///////////////////////////////////////////////////////////////////////////
//
// CCustComboBox
 
//Initial values of the text and highlight stuff
 
CCustComboBox::CCustComboBox()
{
     m_enStyle = FONTS;
     m_clrHilight = GetSysColor (COLOR_HIGHLIGHT);
     m_clrNormalText = GetSysColor (COLOR_WINDOWTEXT);
     m_clrHilightText = GetSysColor (COLOR_HIGHLIGHTTEXT);
     m_clrBkgnd = GetSysColor (COLOR_WINDOW);
     m_bInitOver = FALSE;
 
}
 
 
CCustComboBox::CCustComboBox (STYLE enStyle)
{
     m_enStyle = enStyle;
     m_clrHilight = GetSysColor (COLOR_HIGHLIGHT);
     m_clrNormalText = GetSysColor (COLOR_WINDOWTEXT);
     m_clrHilightText = GetSysColor (COLOR_HIGHLIGHTTEXT);
     m_clrBkgnd = GetSysColor (COLOR_WINDOW);
     m_bInitOver =FALSE;
}
 
CCustComboBox::~CCustComboBox()
{
}
 
 
BEGIN_MESSAGE_MAP(CCustComboBox, CComboBox)
     //{{AFX_MSG_MAP(CCustComboBox)
     ON_WM_CREATE()
     ON_WM_DESTROY()
     //}}AFX_MSG_MAP
     ON_MESSAGE (WM_INITFONTS,OnInitFonts)
END_MESSAGE_MAP()
 
///////////////////////////////////////////////////////////////////////////
//
// CCustComboBox message handlers
 
 
void CCustComboBox::DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct)
{
     //I might want to add something else someday
     switch (m_enStyle)
     {
     case FONTS:
          DrawFont(lpDrawItemStruct);
          break;
     }
}
 
 
//I dont need the MeasureItem to do anything. Whatever the system says, it stays
 
void CCustComboBox::MeasureItem(LPMEASUREITEMSTRUCT lpMeasureItemStruct)
{
}
 
void CCustComboBox::DrawFont(LPDRAWITEMSTRUCT lpDIS)
{
     CDC* pDC = CDC::FromHandle(lpDIS->hDC);
     CRect rect;
 
     TRACE0 ("In Draw Font\n");
 
    // draw the colored rectangle portion
     rect.CopyRect(&lpDIS->rcItem);
 
     pDC->SetBkMode( TRANSPARENT );
 
     if (lpDIS->itemState & ODS_SELECTED)
     {
          pDC->FillSolidRect (rect,m_clrHilight);
          pDC->SetTextColor (m_clrHilightText);
     }
     else
     {
          pDC->FillSolidRect (rect,m_clrBkgnd);
          pDC->SetTextColor (m_clrNormalText);
     }
 
     if ((int)(lpDIS->itemID) < 0) // Well its negetive so no need to draw text
     {
     }
     else
     {
          CString strText;
          GetLBText (lpDIS->itemID,strText);
          CFont newFont;
          CFont *pOldFont;
 
          ((LOGFONT*)lpDIS->itemData)->lfHeight = 90; //9 point size
          ((LOGFONT*)lpDIS->itemData)->lfWidth = 0;
          newFont.CreatePointFontIndirect ((LOGFONT*)lpDIS->itemData);
          pOldFont = pDC->SelectObject (&newFont);
          pDC->DrawText(strText, rect, DT_LEFT | DT_VCENTER | DT_SINGLELINE);
          pDC->SelectObject (pOldFont);
          newFont.DeleteObject ();
     }
}
 
void CCustComboBox::InitFonts ()
{
     CDC *pDC = GetDC ();
     ResetContent (); //Delete whatever is there
     EnumFonts (pDC->GetSafeHdc(),NULL,(FONTENUMPROC) EnumFontProc,(LPARAM)this);//Enumerate
     m_bInitOver = TRUE;
}
 
BOOL CALLBACK CCustComboBox::EnumFontProc (LPLOGFONT lplf, LPTEXTMETRIC lptm, DWORD dwType, LPARAM lpData)
{
     if (dwType == TRUETYPE_FONTTYPE) //Add only TTF fellows, If you want you can change it to check for others
     {
          int index = ((CCustComboBox *) lpData)->AddString(lplf->lfFaceName);
          LPLOGFONT lpLF;
          lpLF = new LOGFONT;
          CopyMemory ((PVOID) lpLF,(CONST VOID *) lplf,sizeof (LOGFONT));
          ((CCustComboBox *) lpData)->SetItemData (index,(DWORD) lpLF);
     }
     return TRUE;
}
 
int CCustComboBox::OnCreate(LPCREATESTRUCT lpCreateStruct)
{
     if (CComboBox::OnCreate(lpCreateStruct) == -1)
          return -1;
 
     // TODO: Add your specialized creation code here
     if (m_enStyle == FONTS)
     {
          PostMessage (WM_INITFONTS,0,0);
     }
     return 0;
}
 
long CCustComboBox::OnInitFonts (WPARAM, LPARAM)
{
     InitFonts ();
     return 0L;
}
 
 
void CCustComboBox::OnDestroy()
{
 
     if (m_enStyle == FONTS)
     {
          int nCount;
          nCount = GetCount ();
          for (int i = 0; i <  nCount; i++)
          {
               delete ((LOGFONT*)GetItemData (i)); //delete the LOGFONTS actually created..
          }
     }
     // TODO: Add your message handler code here
     CComboBox::OnDestroy();
}
 
void CCustComboBox::FillFonts ()
{
     m_enStyle = FONTS;
     PostMessage (WM_INITFONTS,0,0); //Process in one place
}
 
int  CCustComboBox::GetSelFont (LOGFONT& lf)
{
     int index = GetCurSel ();
     if (index == LB_ERR)
          return LB_ERR;
     LPLOGFONT lpLF = (LPLOGFONT) GetItemData (index);
     CopyMemory ((PVOID)&lf, (CONST VOID *) lpLF, sizeof (LOGFONT));
     return index; //return the index here.. Maybe the user needs it:-)
}
 
void CCustComboBox::PreSubclassWindow()
{
     // TODO: Add your specialized code here and/or call the base class
     //Tried to do what Roger Onslow did for the button.. Did not work..?? Any R&D guys around :-)
}

Comments

good`
Posted by xixihaha on 12/02/2010 05:50am
so nice ,hahah

Reply
How Can I do Dynamic Creation of a ComboBox
Posted by subbaraovnrt on 12/15/2004 07:59am
In a Dialog box I used one Push Button When I press that button New Combobox Dynamically created but the all font in that ComboBox all are same bold Arial.
How my Dialog box behaves as static your implementation.
Reply
How to initalize the Font combobox after FillFonts()
Posted by Legacy on 11/14/2001 12:00am
Originally posted by: Chris Hambleton

To initalize the Font combobox after FillFonts(), simply change the PostMessage() calls to SendMessage().

PostMessage() returns as soon as the message is posted (while the combobox is still empty), but SendMessage() returns only after the message has been handled (after the combobox has been filled).

The reason you're currently unable to initialize the Font combobox is because you're calling SetCurSel() / SetString() on a combobox that's currently empty.

Hope this helps!!

Reply
How do you intialize the editor box?
Posted by Legacy on 11/05/2001 12:00am
Originally posted by: Butch

Great.

But how do you initialize the editor box portion of the combo to say a default font selection?

Thanks.
Reply
!!!
Posted by Legacy on 07/11/2001 12:00am
Originally posted by: Chethana Sastry

This is great. I could finish a week's work in just 15 mins!
Thanks!

I have a problem though...
If i say SetCurSel(0) it fails and returns -1
Have you encountered the same problem? If so, what is the solution?
Reply
super
Posted by Legacy on 02/08/2001 12:00am
Originally posted by: pierre

super!!

its works

Reply
Great !
Posted by Legacy on 05/01/2000 12:00am
Originally posted by: Ergin Salih

This is wonderful, it is easily modified to work off a list

of font objects. 

Exactly what I wanted.

Thanks