m_memDC.SetWindowOrg( m_ptOrg ) 画出来黑色的。

[ruoge2007]

一：只用一次memdc，能画出来，用两次就画不出来了。

                PAINTSTRUCT ps;
		CDC * pDC = NULL;
		pDC = BeginPaint( &ps);
		CRect rectWin;
		GetWindowRect( rectWin);
		rectWin.SetRect( 0, 0, rectWin.Width(), rectWin.Height());
		if ( m_pXStaticMulti >0)
		{
			//((CXUIBase*)m_pXStaticMulti)->Draw( pDC);
			CDC * pMemDC1, *pMemDC2;
			CXMemDC memDC1;
			pMemDC1 = memDC1.CreateMemDC( pDC);
			pMemDC1->DrawText( _T("abcdefg"), CRect( 0, 0, 100, 100), DT_CENTER);
			/*
			CXMemDC memDC2;
			pMemDC2 = memDC2.CreateMemDC( pMemDC1);
			pMemDC1->DrawText( _T("123456789"), CRect( 0, 0, 100, 100), DT_CENTER);
			memDC2.ReleaseMemDC();*/
			memDC1.ReleaseMemDC();
		}	EndPaint( &ps);

如果用CXMemDC memDC2;再画一次，上一次的也看不到了。
二：代码memdc

CXMemDC::CXMemDC()
{	
	m_bMemDC = FALSE;
	m_ptOrg.x = 0;
	m_ptOrg.y = 0;
}

CXMemDC::~CXMemDC()
{
	
}
CDC * CXMemDC::CreateMemDC( CDC * pDC)
{
	m_bMemDC = !pDC->IsPrinting();	
	m_pDC = pDC;
	if ( m_bMemDC)
	{	
		CRect rectClip;
		pDC->GetClipBox( rectClip);
		m_rectClip = rectClip;
		m_memDC.CreateCompatibleDC( pDC);
		m_pDC->LPtoDP( m_rectClip);
		m_bitmap.CreateCompatibleBitmap(pDC, m_rectClip.Width(), m_rectClip.Height());
		m_pOldBitmap = m_memDC.SelectObject(&m_bitmap);
		m_memDC.SetMapMode( m_pDC->GetMapMode());
		m_pDC->DPtoLP( m_rectClip);
		CPoint ptOrg;
		ptOrg = m_memDC.GetWindowOrg();
		ptOrg = pDC->GetWindowOrg();
		m_ptOrg.x = m_rectClip.left + ptOrg.x;
		m_ptOrg.y = m_rectClip.top + ptOrg.x;
		m_memDC.SetWindowOrg( m_ptOrg );
	}
	else
	{
		m_memDC.m_bPrinting = pDC->m_bPrinting; 
		m_memDC.m_hDC = pDC->m_hDC; 
		m_memDC.m_hAttribDC = pDC->m_hAttribDC; 
	}	
	return &m_memDC;
}
void CXMemDC::ReleaseMemDC()
{
	if ( m_bMemDC)
	{
		m_pDC->BitBlt( m_ptOrg.x, m_ptOrg.y, m_rectClip.Width(), m_rectClip.Height(), &m_memDC, m_ptOrg.x, m_ptOrg.y, SRCCOPY);
		m_memDC.SelectObject(m_pOldBitmap); 
		m_bitmap.DeleteObject();
		m_memDC.DeleteDC();
	}
	else
	{
		m_memDC.m_hDC = m_memDC.m_hAttribDC = NULL; 
	}
}

[ruoge2007]

不好意思，更正一下。

CXMemDC memDC2;
pMemDC2 = memDC2.CreateMemDC( pMemDC1);
pMemDC2->DrawText( _T("123456789"), CRect( 0, 50, 100, 150), DT_CENTER);
memDC2.ReleaseMemDC();

只显示第二次画的。第一次画的不见了。

[gameslq]

应该是这句计算的区域不对:

 m_pDC->BitBlt( m_ptOrg.x, m_ptOrg.y, m_rectClip.Width(), m_rectClip.Height(), &m_memDC, m_ptOrg.x, m_ptOrg.y, SRCCOPY);

调试下,看看BitBlt值是否正确.

[ruoge2007]

[Quote=引用 2 楼 gameslq 的回复:]

应该是这句计算的区域不对:
C/C++ code

m_pDC->BitBlt( m_ptOrg.x, m_ptOrg.y, m_rectClip.Width(), m_rectClip.Height(), &m_memDC, m_ptOrg.x, m_ptOrg.y, SRCCOPY);


调试下,看看BitBlt值是否正确.
[/Quote]

那咋调试呢？？？谢谢

是这样计算的：

        CPoint ptOrg;
        ptOrg = m_memDC.GetWindowOrg();
        ptOrg = pDC->GetWindowOrg();
        m_ptOrg.x = m_rectClip.left + ptOrg.x;
        m_ptOrg.y = m_rectClip.top + ptOrg.x;
        m_memDC.SetWindowOrg( m_ptOrg );

[向立天]

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