MemDC.h
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上传日期:2010-02-01
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文件大小:3k
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开发平台:
Visual C++
- #if !defined(AFX_MEMDC_H__CA1D3541_7235_11D1_ABBA_00A0243D1382__INCLUDED_)
- #define AFX_MEMDC_H__CA1D3541_7235_11D1_ABBA_00A0243D1382__INCLUDED_
- #if _MSC_VER >= 1000
- #pragma once
- #endif // _MSC_VER >= 1000
- // MemDC.h : header file
- //
- //////////////////////////////////////////////////
- // CMemDC - memory DC
- //
- // Author: Keith Rule
- // Email: keithr@europa.com
- // Copyright 1996-1997, Keith Rule
- //
- // You may freely use or modify this code provided this
- // Copyright is included in all derived versions.
- //
- // History - 10/3/97 Fixed scrolling bug.
- // Added print support.
- // 25 feb 98 - fixed minor assertion bug
- //
- // This class implements a memory Device Context
- class CMemDC : public CDC
- {
- public:
- // constructor sets up the memory DC
- CMemDC(CDC* pDC) : CDC()
- {
- ASSERT(pDC != NULL);
- m_pDC = pDC;
- m_pOldBitmap = NULL;
- m_bMemDC = !pDC->IsPrinting();
- if (m_bMemDC) // Create a Memory DC
- {
- pDC->GetClipBox(&m_rect);
- CreateCompatibleDC(pDC);
- m_bitmap.CreateCompatibleBitmap(pDC, m_rect.Width(), m_rect.Height());
- m_pOldBitmap = SelectObject(&m_bitmap);
- SetWindowOrg(m_rect.left, m_rect.top);
- }
- else // Make a copy of the relevent parts of the current DC for printing
- {
- m_bPrinting = pDC->m_bPrinting;
- m_hDC = pDC->m_hDC;
- m_hAttribDC = pDC->m_hAttribDC;
- }
- }
- // Destructor copies the contents of the mem DC to the original DC
- ~CMemDC()
- {
- if (m_bMemDC)
- {
- // Copy the offscreen bitmap onto the screen.
- m_pDC->BitBlt(m_rect.left, m_rect.top, m_rect.Width(), m_rect.Height(),
- this, m_rect.left, m_rect.top, SRCCOPY);
- //Swap back the original bitmap.
- SelectObject(m_pOldBitmap);
- } else {
- // All we need to do is replace the DC with an illegal value,
- // this keeps us from accidently deleting the handles associated with
- // the CDC that was passed to the constructor.
- m_hDC = m_hAttribDC = NULL;
- }
- }
- // Allow usage as a pointer
- CMemDC* operator->() {return this;}
- // Allow usage as a pointer
- operator CMemDC*() {return this;}
- private:
- CBitmap m_bitmap; // Offscreen bitmap
- CBitmap* m_pOldBitmap; // bitmap originally found in CMemDC
- CDC* m_pDC; // Saves CDC passed in constructor
- CRect m_rect; // Rectangle of drawing area.
- BOOL m_bMemDC; // TRUE if CDC really is a Memory DC.
- };
- /////////////////////////////////////////////////////////////////////////////
- //{{AFX_INSERT_LOCATION}}
- // Microsoft Developer Studio will insert additional declarations immediately before the previous line.
- #endif // !defined(AFX_MEMDC_H__CA1D3541_7235_11D1_ABBA_00A0243D1382__INCLUDED_)