CEdit & CStatic Transparency Control

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• Download demo project - 22.80 Kb

Introduction

To apply transparency on CEdit control, create a new class derived from CEdit control and simply add these members.

In the new class .h file add.

// Attributes
private:
    COLORREF    m_TextColor;
    COLORREF    m_BackColor;
    CBrush        m_Brush;
    // Operations
public:
    void SetTextColor(COLORREF col) 
    { 
        m_TextColor = col;
        UpdateCtrl();             
    }
    void SetBackColor(COLORREF col) 
    { 
        m_BackColor = col;                                                   
        UpdateCtrl();            
    }
private:
    void UpdateCtrl();
    // Generated message map functions
protected:
    //{{AFX_MSG(CEditTrans)
    afx_msg HBRUSH CtlColor(CDC* pDC, UINT nCtlColor);
    afx_msg void OnUpdate();
    afx_msg void OnLButtonDown(UINT nFlags, CPoint point);
    afx_msg void OnKillfocus();
    //}}AFX_MSG

    DECLARE_MESSAGE_MAP()

In the new class .cpp file add.

CEditTrans::CEditTrans()
{
    m_TextColor  = RGB(0, 0, 0);
    m_BackColor = TRANS_BACK;
}
BEGIN_MESSAGE_MAP(CEditTrans, CEdit)
    //{{AFX_MSG_MAP(CEditTrans)
    ON_WM_CTLCOLOR_REFLECT()
    ON_CONTROL_REFLECT(EN_UPDATE, OnUpdate)
    ON_WM_LBUTTONDOWN()
    ON_CONTROL_REFLECT(EN_KILLFOCUS, OnKillfocus)
    //}}AFX_MSG_MAP
END_MESSAGE_MAP()

HBRUSH CEditTrans::CtlColor(CDC* pDC, UINT nCtlColor) 
{
    m_Brush.DeleteObject();

    if (m_BackColor == TRANS_BACK) {
        m_Brush.CreateStockObject(HOLLOW_BRUSH);
        pDC->SetBkMode(TRANSPARENT);
    }
    else {
        m_Brush.CreateSolidBrush(m_BackColor);
        pDC->SetBkColor(m_BackColor);
    }

    pDC->SetTextColor(m_TextColor);

    return (HBRUSH)m_Brush;
}

void CEditTrans::OnUpdate() 
{
    UpdateCtrl();
}
void CEditTrans::UpdateCtrl()
{
    CWnd* pParent = GetParent();
    CRect   rect;

    GetWindowRect(rect);
    pParent->ScreenToClient(rect);
    rect.DeflateRect(2, 2);

    pParent->InvalidateRect(rect, FALSE); 
}

Implementation of the class

#include "EditTrans.h"

//Derived control from ClassWizard
CEditTrans m_edtTrans; 

//To make transparency
m_edtTrans.SetBackColor(TRANS_BACK); 

That all. Enjoy!