被迫写一个类似qq登陆框上面的那个下拉框控件

蓝色边框,选择时是深蓝色边框,下拉按钮可以自定义图片,不过只能是 15*16的BMP

class CMyComboBox : public CComboBox
...{
// Construction
public:
    CMyComboBox();
    // normal_id 普通状态图片的ID
    // hover_id  hover状态图片的ID
    // push_id   push状态图片的ID
    CMyComboBox(unsigned int normal_id,unsigned int hover_id,unsigned int push_id);

// Attributes
public:

// Operations
public:

// OverridesClassWizard
    //  generated virtual function overrides
    //{{AFX_VIRTUAL(CMyComboBox)
    protected:
    virtual void PreSubclassWindow();
    //}}AFX_VIRTUAL

// Implementation
public:
    virtual ~CMyComboBox();

    // Generated message map functions
protected:
    //{{AFX_MSG(CMyComboBox)
    afx_msg void OnPaint();
    afx_msg void OnMouseMove(UINT nFlags, CPoint point);
    afx_msg void OnTimer(UINT nIDEvent);
    afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
    afx_msg void OnLButtonUp(UINT nFlags, CPoint point);
    //}}AFX_MSG

    DECLARE_MESSAGE_MAP()
private:
    void DrawButton(CDC* pDC);
private:

    unsigned int m_normal_id;
    unsigned int m_hover_id;
    unsigned int m_push_id;

    //0-normal 1-hover 2-push
    int  m_button_state;

    bool m_active;
    bool m_draw;
};




#define BUTTON_STATE_NORMAL 0
#define BUTTON_STATE_HOVER    (1<<1)
#define BUTTON_STATE_PUSH    (1<<2)

/**//////////////////////////////////////////////////////////////////////////////
// CMyComboBox

CMyComboBox::CMyComboBox():m_active(false),
                           m_normal_id(0),
                           m_hover_id(0),
                           m_push_id(0),
                           m_button_state(BUTTON_STATE_NORMAL)
...{

}

CMyComboBox::CMyComboBox(unsigned int normal_id,
                         unsigned int hover_id,
                         unsigned int push_id):
                            m_active(false),
                            m_normal_id(normal_id),
                            m_hover_id(hover_id),
                            m_push_id(push_id),
                            m_button_state(BUTTON_STATE_NORMAL)
...{

}

CMyComboBox::~CMyComboBox()
...{
}


BEGIN_MESSAGE_MAP(CMyComboBox, CComboBox)
    //{{AFX_MSG_MAP(CMyComboBox)
    ON_WM_PAINT()
    ON_WM_MOUSEMOVE()
    ON_WM_TIMER()
    ON_WM_LBUTTONDOWN()
    ON_WM_LBUTTONUP()
    //}}AFX_MSG_MAP
END_MESSAGE_MAP()

/**//////////////////////////////////////////////////////////////////////////////
// CMyComboBox message handlers




void CMyComboBox::PreSubclassWindow() 
...{
    CRect rc;
    GetWindowRect(&rc);

    rc.left -= 2;
    rc.top -= 15;
    rc.bottom -= 23;
    rc.right -= 8;

    MoveWindow(&rc);

    ModifyStyle(0,BS_OWNERDRAW);
    CComboBox::PreSubclassWindow();
}



void
CMyComboBox::OnPaint()
...{
    CRect    rc;
    CDC*    pDC;

    Default();

    
    pDC = GetDC();

    GetClientRect(rc);

    if(m_active)
        pDC->Draw3dRect(rc, RGB(78,108,133), RGB(78,108,133));
    else
        pDC->Draw3dRect(rc, RGB(126,157,185), RGB(126,157,185));

    //填充掉阴影
    rc.DeflateRect(1,1);
    pDC->Draw3dRect(rc, RGB(255,255,255), RGB(255,255,255));
    //填充掉原来的按钮
    rc.left += (rc.Width() - 18);
    rc.DeflateRect(1,1);
    pDC->Draw3dRect(rc, RGB(255,255,255), RGB(255,255,255));

    DrawButton(pDC);
    ReleaseDC(pDC);
}

void CMyComboBox::OnMouseMove(UINT nFlags, CPoint point) 
...{
    m_draw = true;
    SetTimer(1,10,NULL);
    OnTimer(1);

    CComboBox::OnMouseMove(nFlags, point);
}

void 
CMyComboBox::OnTimer(UINT nIDEvent) 
...{
    POINT pt;
    CRect rc,rc_button;

    GetCursorPos(&pt);

    GetWindowRect(&rc);
    
    rc_button = rc;
    rc_button.left += rc_button.Width() - 17;
    
    if(rc_button.PtInRect(pt))
    ...{
        if(m_button_state != BUTTON_STATE_PUSH)
            m_button_state = BUTTON_STATE_HOVER;
    }
    else
        m_button_state = BUTTON_STATE_NORMAL;

    if(rc.PtInRect(pt))
    ...{
        m_active = true;
        if(m_draw)
        ...{
            m_draw = false;
            Invalidate();
        }
    }
    else
    ...{
        KillTimer (1);
        m_active       = false;
        m_button_state = 0;

        Invalidate();
    }

    CComboBox::OnTimer(nIDEvent);
}

void 
CMyComboBox::DrawButton(CDC* pDC)
...{
    if(m_normal_id == 0 || m_hover_id ==0 || m_push_id == 0)
        return;
    CDC            MemDC;
    CBitmap        bitmap;
    CRect        rc;

    GetWindowRect(&rc);
    
    MemDC.CreateCompatibleDC(pDC);

    if( m_button_state == BUTTON_STATE_NORMAL )
    ...{
        bitmap.LoadBitmap(m_normal_id);
    }
    else if( m_button_state == BUTTON_STATE_HOVER )
    ...{
        bitmap.LoadBitmap(m_hover_id);
    }
    else
    ...{
        bitmap.LoadBitmap(m_push_id);
    }

    MemDC.SelectObject(&bitmap);
    pDC->BitBlt(rc.Width()-17,3,15,16,&MemDC,0,0,SRCCOPY);
}



void CMyComboBox::OnLButtonDown(UINT nFlags, CPoint point) 
...{
    m_button_state = BUTTON_STATE_PUSH;
    Invalidate();
    CComboBox::OnLButtonDown(nFlags, point);
}

void CMyComboBox::OnLButtonUp(UINT nFlags, CPoint point) 
...{
    m_button_state = BUTTON_STATE_HOVER;
    Invalidate();
    CComboBox::OnLButtonUp(nFlags, point);
}