transparent CStatic

// Method 1: class CTransparentStatic : public CStatic { DECLARE_DYNAMIC(CTransparentStatic) public: CTransparentStatic(); virtual ~CTransparentStatic(); protected: afx_msg LRESULT OnSetText(WPARAM,LPARAM); afx_msg HBRUSH CtlColor(CDC* /*pDC*/, UINT /*nCtlColor*/); DECLARE_MESSAGE_MAP() }; #include "TransparentStatic.h" // CTransparentStatic IMPLEMENT_DYNAMIC(CTransparentStatic, CStatic) CTransparentStatic::CTransparentStatic() { } CTransparentStatic::~CTransparentStatic() { } BEGIN_MESSAGE_MAP(CTransparentStatic, CStatic) ON_MESSAGE(WM_SETTEXT,OnSetText) ON_WM_CTLCOLOR_REFLECT() END_MESSAGE_MAP() // CTransparentStatic message handlers LRESULT CTransparentStatic::OnSetText(WPARAM wParam,LPARAM lParam) { LRESULT Result = Default(); CRect Rect; GetWindowRect(&Rect); GetParent()->ScreenToClient(&Rect); GetParent()->InvalidateRect(&Rect); //GetParent()->UpdateWindow(); return Result; } HBRUSH CTransparentStatic::CtlColor(CDC* pDC, UINT /*nCtlColor*/) { pDC->SetBkMode(TRANSPARENT); return (HBRUSH)GetStockObject(NULL_BRUSH); }

 

// Method 2: class CTransparentStatic2 : public CStatic { DECLARE_DYNAMIC(CTransparentStatic2) public: CTransparentStatic2(); virtual ~CTransparentStatic2(); protected: afx_msg LRESULT OnSetText(WPARAM,LPARAM); afx_msg HBRUSH CtlColor(CDC* /*pDC*/, UINT /*nCtlColor*/); afx_msg BOOL OnEraseBkgnd(CDC* pDC); DECLARE_MESSAGE_MAP() private: CBitmap m_Bmp; }; #include "TransparentStatic2.h" // CTransparentStatic2 IMPLEMENT_DYNAMIC(CTransparentStatic2, CStatic) CTransparentStatic2::CTransparentStatic2() { } CTransparentStatic2::~CTransparentStatic2() { } BEGIN_MESSAGE_MAP(CTransparentStatic2, CStatic) ON_MESSAGE(WM_SETTEXT,OnSetText) ON_WM_CTLCOLOR_REFLECT() ON_WM_ERASEBKGND() END_MESSAGE_MAP() // CTransparentStatic2 message handlers LRESULT CTransparentStatic2::OnSetText(WPARAM wParam,LPARAM lParam) { LRESULT Result = Default(); //call default base function. Invalidate(); //UpdateWindow(); return Result; } HBRUSH CTransparentStatic2::CtlColor(CDC* pDC, UINT /*nCtlColor*/) { pDC->SetBkMode(TRANSPARENT); return (HBRUSH)GetStockObject(NULL_BRUSH); } BOOL CTransparentStatic2::OnEraseBkgnd(CDC* pDC) { if (m_Bmp.GetSafeHandle() == NULL) { CRect Rect; GetWindowRect(&Rect); CWnd *pParent = GetParent(); ASSERT(pParent); pParent->ScreenToClient(&Rect); //convert our corrdinates to our parents // copy what's on the parents at this point // This DC is not the same with the pDC in the function parameter. CDC *pDC = pParent->GetDC(); CDC MemDC; MemDC.CreateCompatibleDC(pDC); m_Bmp.CreateCompatibleBitmap(pDC,Rect.Width(),Rect.Height()); CBitmap *pOldBmp = MemDC.SelectObject(&m_Bmp); // BitBlt the bitmap to the memdc, it means that copy the parent's background to the MemDc. // so the MemDC keep the background. MemDC.BitBlt(0,0,Rect.Width(),Rect.Height(),pDC,Rect.left,Rect.top,SRCCOPY); MemDC.SelectObject(pOldBmp); pParent->ReleaseDC(pDC); } else //copy what we copied off the parent the first time back onto the parent { CRect Rect; GetClientRect(Rect); CDC MemDC; MemDC.CreateCompatibleDC(pDC); CBitmap *pOldBmp = MemDC.SelectObject(&m_Bmp); // This pDC is the DC of the control itself(in the function's parameter), not its parent's DC. pDC->BitBlt(0,0,Rect.Width(),Rect.Height(),&MemDC,0,0,SRCCOPY); MemDC.SelectObject(pOldBmp); } return TRUE; }

 

These two methods can both implement a transparent CStatic.

But the second one can redunce flicker and flash.

 

I had added more comments to the secnod one to make it more easy the understand.