怎样用GDI中的函数来设置窗体中的某一控件背景颜色？

Question

怎样用GDI中的函数来设置窗体中的某一控件背景颜色？

Answer 1

HBRUSH CAboutDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor) 
{
HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);
// TODO: Change any attributes of the DC here
if(m_hbBkgnd)
DeleteObject(m_hbBkgnd);
srand( (unsigned)time( NULL ) );
int color1 = rand()%256;
int colorg = rand()%256;
int colorb = rand()%256;
//The WM_CTLCOLORBTN message will affect radio buttons and check boxes, but not pushbuttons. 
//To change the color of a pushbutton you must make it an owner-drawn pushbutton and take 
//over responsibility for drawing every aspect of the button. 
pDC -> SetTextColor (RGB(255,255,colorb) ) ; 
pDC->SetBkColor(m_clrBkgnd);
m_hbBkgnd=::CreateSolidBrush(m_clrBkgnd);
return m_hbBkgnd;
return hbr;
}

Answer 2

有两种方法。其一，可以在父类中指定控件的颜色，或者利用MFC新的消息反       
射在控件类中指定颜色。                                                           
    当控件需要重新着色时，工作框调用父窗口（通常是对话框）的                     
CWnd: : OnCrtlColor,可以在父窗口类中重置该函数并指定控件的新的绘画属             
性。例如，下述代码将对话中的所有编辑控件文本颜色改为红色：                       
HBRUSH CAboutDig : : OnCtlColor (CDC * pDCM , CWnd * pWnd , UINT nCtlColor)      
                                                                                 
{                                                                                
    HBRUSH hbr = CDialog : : OnCtlColor (pDC, pWnd , nCtlColor );                
                                                                                 
    //Draw red text for all edit controls .                                      
    if (nCtlColor= = CTLCOLOR_EDIT )                                             
       pDC —> SetTextColor (RGB (255 , 0 , 0 , ) ) ;                            
                                                                                 
    return hbr ;                                                                 
}                                                                                
    然而，由于每个父窗口必须处理通知消息并指定每个控件的绘画属性，所以，         
这种方法不是完全的面向对象的方法。控件处理该消息并指定绘画属性更合情合理。       
    消息反射允许用户这样做。通知消息首先发送给父窗口，如果父窗口没有处理         
则发送给控件。创建一个定制彩色列表框控件必须遵循下述步骤。                       
    首先，使用ClassWizard 创建一个CListBox 的派生类并为该类添加下述数据          
成员。                                                                           
class CMyListBox ; publilc CListBox                                              
{                                                                                
…                                                                               
                                                                                 
private;                                                                         
    COLORREF m_clrFor ;     // foreground color                                  
    COLORREF m_clrBack ;   //background color                                    
    Cbrush m_brush ;         //background brush                                  
                                                                                 
…                                                                               
} ;                                                                              
    其次，在类的构造函数中，初始化数据中。                                       
CMyListBox : : CMyListBox ()                                                     
{                                                                                
    //Initialize data members .                                                  
    m_clrFore =RGB (255 , 255 , 0) ;   // yellow text                            
    m_clrBack=RGB (0 , 0 , 255) ;    // blue background                          
    m_brush . CreateSolidBrush  (m _clrBack );                                   
}                                                                                
    最后，使用ClassWizard处理反射的WM_CTLCOLOR(=WM_CTLCOLOR)消息并指定新         
的绘画属性。                                                                     
HBRUSH CMyListBox : : CtlColor (CDC* pDC, UINT nCtlColor )                       
{                                                                                
    pDC—>SetTextColor (m_clrFore);                                              
    pDC—>SetBkColor  (m_clrBack);                                               
                                                                                 
    return (HBRUSH) m_brush.GetSafeHandle ()                                     
}                                                                                
    现在，控件可以自己决定如何绘画，与父窗口无关。