EVC中透明控件的实现

本文从创建一个工程开始详细说明如何用EVC实现WINCE应用程序下的透明控件（这里实现按钮和STATIC）。

1.
新建一个MFC对话框工程取名TransButton

2.
在ResourceView处插入一背景图片IDB_BITMAP1

3.
在对话框中拉4个控件：两个按钮，两个STATIC

4.
增加TransButtonDlg.h文件中增加如下3个类成员

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

5.
在TransButtonDlg.cpp中增加GetBkBrush()的实现

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;

}

6.
在OnInitDialog()中增加下面一段截取控件所在部分的图片：

m_hBmBkgnd=::LoadBitmap(AfxGetInstanceHandle(),MAKEINTRESOURCE(IDB_BITMAP1) );

if( m_hBmBkgnd )

{

m_hBrCtl[0]=GetBkBrush(GetSafeHwnd(),IDC_BUTTON_TEST1, m_hBmBkgnd );

m_hBrCtl[1]=GetBkBrush(GetSafeHwnd(),IDC_STATIC_TEST1,m_hBmBkgnd );

}

7.
增加WM_PAINT的处理函数，并在函数中增加画背景的部分(OnPaint()函数)：

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();

8.
增加WM_CTLCOLOR的处理函数，并在其中增加画控件背景的部分：

if(pWnd->GetDlgCtrlID() == IDC_BUTTON_TEST1 )

{

pDC->SetTextColor(RGB(255, 0, 0));

pDC->SetBkMode( TRANSPARENT ) ;

return m_hBrCtl[0];

}

else if(pWnd->GetDlgCtrlID() == IDC_STATIC_TEST1)

{

pDC->SetTextColor(RGB(255, 0, 0));

pDC->SetBkMode( TRANSPARENT ) ;

return m_hBrCtl[1];

}

9.
编译链接

10.
运行后的图片如下：