WIN CE 实现透明控件

1、导入一张背景图：IDB_BKGND

2、资源里添加一按钮和一静态文本框

3、声明如下：

HBRUSH GetBkBrush( HWND hWnd, UINT nID, HBITMAP hBmBk );

HBITMAP m_hBmBkgnd; // 对话框背景图片
HBRUSH m_hBrCtl[2]; // 控件背景画刷

4、添加WM_CTCOLOR WM_PAINT WM_DESTROY 消息；

5、OnInitDialog中加入如下代码：

m_hBmBkgnd = ::LoadBitmap( AfxGetInstanceHandle(), MAKEINTRESOURCE(IDB_BKGND) );

if( m_hBmBkgnd )
{
m_hBrCtl[0] = GetBkBrush( GetSafeHwnd(), IDC_BUTTON1, m_hBmBkgnd );
m_hBrCtl[1] = GetBkBrush( GetSafeHwnd(), IDC_STATIC1, m_hBmBkgnd );
}

6、

HBRUSH CTransButtonDlg::GetBkBrush( HWND hWnd, UINT nID, HBITMAP hBmBk )
{
#define _X(x) (x.left)
#define _Y(x) (x.top)
#define _W(x) (x.right - x.left)
#define _H(x) (x.bottom - x.top)
HWND hWndCtrl;
hWndCtrl = ::GetDlgItem( hWnd, nID );
HBRUSH hBrushCtrl = NULL;
if( NULL != hWndCtrl )
{
RECT rcCtrl;
::GetWindowRect( hWndCtrl, &rcCtrl );
::ScreenToClient(hWnd, (LPPOINT)&rcCtrl);
::ScreenToClient(hWnd, ((LPPOINT)&rcCtrl)+1);

HDC hDC = ::GetDC(hWnd);
HDC hMemDCBk = CreateCompatibleDC( hDC );
HDC hMemDCCtrl = CreateCompatibleDC( hDC );

HBITMAP hBmCtrl = CreateCompatibleBitmap( hDC, _W(rcCtrl), _H(rcCtrl) );
HBITMAP hBmOldBk;
HBITMAP hBmOldCtrl;

hBmOldBk = (HBITMAP) ::SelectObject( hMemDCBk, hBmBk );
hBmOldCtrl = (HBITMAP) ::SelectObject( hMemDCCtrl, hBmCtrl );

::BitBlt( hMemDCCtrl, 0, 0, _W(rcCtrl), _H(rcCtrl), hMemDCBk, _X(rcCtrl), _Y(rcCtrl), SRCCOPY );

::SelectObject(hMemDCCtrl, hBmOldCtrl );
::SelectObject(hMemDCBk, hBmOldBk );

hBrushCtrl = ::CreatePatternBrush( hBmCtrl );

DeleteObject( hBmCtrl );

::DeleteDC( hMemDCBk );
::DeleteDC( hMemDCCtrl );
::ReleaseDC( hWnd, hDC );
}

return hBrushCtrl;
}
void CTransButtonDlg::OnPaint()
{
CPaintDC dc(this); // device context for painting

CDC memDC;
CBitmap bmBkgnd;
bmBkgnd.Attach( m_hBmBkgnd );

memDC.CreateCompatibleDC(&dc);
CBitmap *pOldBm = memDC.SelectObject( &bmBkgnd );

BITMAP bm;
bmBkgnd.GetObject(sizeof(bm), &bm);

dc.BitBlt(0, 0, bm.bmWidth, bm.bmHeight, &memDC, 0, 0, SRCCOPY );
memDC.SelectObject( pOldBm );
bmBkgnd.Detach();

}

HBRUSH CTransButtonDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);
if(pWnd->GetDlgCtrlID() == IDC_BUTTON1 )
{
pDC->SetTextColor(RGB(0, 0, 0));
pDC->SetBkMode( TRANSPARENT ) ;
return m_hBrCtl[0];
}
else if(pWnd->GetDlgCtrlID() == IDC_STATIC1)
{
pDC->SetTextColor(RGB(0, 0, 0));
pDC->SetBkMode( TRANSPARENT ) ;
return m_hBrCtl[1];
}

return hbr;
}

void CTransButtonDlg::OnDestroy()
{
CDialog::OnDestroy();

::DeleteObject( m_hBmBkgnd );
::DeleteObject( m_hBrCtl[0] );
::DeleteObject( m_hBrCtl[1] );
}