在MFC应用程序中显示JPG/GIF图像文件

　2010-06-15 20:40:11　来源：WEB开发网　　　

核心提示：三、程序代码/// Picture object--encapsulates IPicture#pragma once#include <atlbase.h>class CPicture {public:CPicture();~CPicture();// Load frm various sosurcesB

三、程序代码

/////////////////// Picture object--encapsulates IPicture #pragma once #include <atlbase.h> class CPicture { public: CPicture(); ~CPicture(); // Load frm various sosurces BOOL Load(UINT nIDRes); BOOL Load(LPCTSTR pszPathName); BOOL Load(CFile& file); BOOL Load(CArchive& ar); BOOL Load(IStream* pstm); // render to device context BOOL Render(CDC* pDC, CRect rc=CRect(0,0,0,0), LPCRECT prcMFBounds=NULL) const; CSize GetImageSize(CDC* pDC=NULL) const; operator IPicture*() { 　return m_spIPicture; } void GetHIMETRICSize(OLE_XSIZE_HIMETRIC& cx, OLE_YSIZE_HIMETRIC& cy) const { 　cx = cy = 0; 　const_cast<CPicture*>(this)->m_hr = m_spIPicture->get_Width(&cx); 　ASSERT(SUCCEEDED(m_hr)); 　const_cast<CPicture*>(this)->m_hr = m_spIPicture->get_Height(&cy); 　ASSERT(SUCCEEDED(m_hr)); } void Free() { 　if (m_spIPicture) { 　　m_spIPicture.Release(); 　} } protected: CComQIPtr<IPicture>m_spIPicture; // ATL smart pointer to IPicture HRESULT m_hr; // last error code }; /////////////////////////////////////////////////////////////// CPicture implementation #include "StdAfx.h" #include "Picture.h" #ifdef _DEBUG #define new DEBUG_NEW #undef THIS_FILE static char THIS_FILE[] = __FILE__; #endif CPicture::CPicture() {} CPicture::~CPicture() {} BOOL CPicture::Load(UINT nIDRes) // Load from resource. Looks for "IMAGE" type. { 　// find resource in resource file 　HINSTANCE hInst = AfxGetResourceHandle(); 　HRSRC hRsrc = ::FindResource(hInst,MAKEINTRESOURCE(nIDRes),"IMAGE"); // type 　if (!hRsrc) 　　return FALSE; 　// load resource into memory 　DWORD len = SizeofResource(hInst, hRsrc); 　BYTE* lpRsrc = (BYTE*)LoadResource(hInst, hRsrc); 　if (!lpRsrc) 　　return FALSE; 　// create memory file and load it 　CMemFile file(lpRsrc, len); 　BOOL bRet = Load(file); 　FreeResource(hRsrc); 　GlobalFree(lpRsrc); 　return bRet; } BOOL CPicture::Load(LPCTSTR pszPathName) // Load from path name. { 　CFile file; 　if (!file.Open(pszPathName, CFile::modeRead|CFile::shareDenyWrite)) 　　return FALSE; 　BOOL bRet = Load(file); 　file.Close(); 　return bRet; } BOOL CPicture::Load(CFile& file) // Load from CFile { 　CArchive ar(&file, CArchive::load | CArchive::bNoFlushOnDelete); 　return Load(ar); } ////// Load from archive--create stream and load from stream. BOOL CPicture::Load(CArchive& ar) { 　CArchiveStream arcstream(&ar); 　return Load((IStream*)&arcstream); } ////////////////// // Load from stream (IStream). This is the one that really does it: call // OleLoadPicture to do the work. BOOL CPicture::Load(IStream* pstm) { 　Free(); 　HRESULT hr = OleLoadPicture(pstm, 0, FALSE,IID_IPicture, (void**)&m_spIPicture); 　ASSERT(SUCCEEDED(hr) && m_spIPicture); 　return TRUE; } ////////////////// // Render to device context. Covert to HIMETRIC for IPicture. BOOL CPicture::Render(CDC* pDC, CRect rc, LPCRECT prcMFBounds) const { 　ASSERT(pDC); 　if (rc.IsRectNull()) { 　　CSize sz = GetImageSize(pDC); 　　rc.right = sz.cx; 　　rc.bottom = sz.cy; 　} 　long hmWidth,hmHeight; // HIMETRIC units 　GetHIMETRICSize(hmWidth, hmHeight); 　m_spIPicture->Render(*pDC, rc.left, rc.top, rc.Width(), rc.Height(),0, hmHeight, hmWidth, -hmHeight, prcMFBounds); 　return TRUE; } ////////////////// // Get image size in pixels. Converts from HIMETRIC to device coords. CSize CPicture::GetImageSize(CDC* pDC) const { 　if (!m_spIPicture) 　　return CSize(0,0); 　LONG hmWidth, hmHeight; // HIMETRIC units 　m_spIPicture->get_Width(&hmWidth); 　m_spIPicture->get_Height(&hmHeight); 　CSize sz(hmWidth,hmHeight); 　if (pDC==NULL) { 　　CWindowDC dc(NULL); 　　dc.HIMETRICtoDP(&sz); // convert to pixels 　} else { 　　pDC->HIMETRICtoDP(&sz); 　} 　return sz; } ///////////////////////////////////// Picture view is a typical scroll view. #include "Doc.h" class CPictureView : public CScrollView { 　public: 　　virtual ~CPictureView(); 　　CPictureDoc* GetDocument() { return (CPictureDoc*)m_pDocument; } 　protected: 　　BOOL m_rcImage; // rect to display image in 　　UINT m_iHowScale; // how to scale image 　　CPictureView(); 　　void GetImageRect(CRect& rc); 　　void SetScrollSizes(); 　　virtual void OnDraw(CDC* pDC); // overridden to draw this view 　　virtual void OnInitialUpdate(); // called first time after construct 　　// command/message handlers 　　afx_msg void OnViewScale(UINT nID); 　　afx_msg void OnUpdateViewScale(CCmdUI* pCmdUI); 　　afx_msg BOOL OnEraseBkgnd(CDC* pDC); 　　afx_msg void OnSize(UINT nType, int cx, int cy); 　　DECLARE_DYNCREATE(CPictureView) 　　DECLARE_MESSAGE_MAP() }; ////////////////////////////////////////////////////////////// CPictureView #include "StdAfx.h" #include "View.h" #include "resource.h" #ifdef _DEBUG #define new DEBUG_NEW #undef THIS_FILE static char THIS_FILE[] = __FILE__; #endif IMPLEMENT_DYNCREATE(CPictureView, CScrollView) BEGIN_MESSAGE_MAP(CPictureView, CScrollView) 　ON_WM_ERASEBKGND() 　ON_WM_SIZE() 　ON_COMMAND_RANGE(ID_VIEW_TOFIT, ID_VIEW100, OnViewScale) 　ON_UPDATE_COMMAND_UI_RANGE(ID_VIEW_TOFIT, ID_VIEW100, OnUpdateViewScale) END_MESSAGE_MAP() CPictureView::CPictureView() { 　m_iHowScale = ID_VIEW_TOFIT; } CPictureView::~CPictureView() {} void CPictureView::OnInitialUpdate() { 　SetScrollSizes(); } //////////////////// Set scroll sizes based on picture. Page size = client hieight/width; // line size = 1/10 of this. void CPictureView::SetScrollSizes() { 　CRect rcClient; 　GetClientRect(&rcClient); 　CRect rcImage; 　GetImageRect(rcImage); 　CSize szTotal = rcImage.Size(); 　CSize szPage = rcClient.Size(); 　CSize szLine = szPage; 　szLine.cx /= 10; 　szLine.cy /= 10; 　CScrollView::SetScrollSizes(MM_TEXT, szTotal, szPage, szLine); 　Invalidate(); } //////////////////// View was sized: readjust scroll sizes if I'm in "zoom to fit" mode void CPictureView::OnSize(UINT nType, int cx, int cy) { 　CScrollView::OnSize(nType, cx, cy); 　if (m_iHowScale==ID_VIEW_TOFIT) { 　　SetScrollSizes(); 　} } ////////////////// // Erase the background. This is required in case the image is smaller than // the client area, to paint the extra background. Use clipping to avoid flicker. BOOL CPictureView::OnEraseBkgnd(CDC* pDC) { 　CPictureDoc* pDoc = GetDocument(); 　ASSERT_VALID(pDoc); 　// get client rectangle 　CRect rcClient; 　GetClientRect(&rcClient); 　CRect rc = rcClient; 　// get image rectangle 　CRect rcImage; 　GetImageRect(rcImage); 　rc = rcImage; 　CPoint pt = pDC->GetViewportOrg(); 　CSize sz = GetTotalSize(); 　// create clipping region 　CRgn clipRgn; 　clipRgn.CreateRectRgnIndirect(&rcClient); 　pDC->SelectClipRgn(&clipRgn); 　pDC->ExcludeClipRect(&rcImage); 　CBrush brush(RGB(0,0,0)); // black 　pDC->FillRect(&rcClient, &brush); 　pDC->SelectClipRgn(NULL); 　return TRUE; } ////////////////// // Draw the picture -- call CPicture to do it. void CPictureView::OnDraw(CDC* pDC) { 　CPictureDoc* pDoc = GetDocument(); 　ASSERT_VALID(pDoc); 　CPicture* ppic = pDoc->GetPicture(); 　ASSERT(ppic); 　if (*ppic) { 　　CRect rc; 　　GetImageRect(rc); 　　ppic->Render(pDC,rc); 　} } ////////////////// // Get image rectangle, scaled for current zoom factor. void CPictureView::GetImageRect(CRect& rc) { 　CPictureDoc* pDoc = GetDocument(); 　ASSERT_VALID(pDoc); 　CPicture* ppic = pDoc->GetPicture(); 　ASSERT(ppic); 　if (!ppic || !*ppic) { 　　rc.SetRect(0,0,0,0); 　} else if (m_iHowScale==ID_VIEW_TOFIT) { 　　GetClientRect(&rc); 　} else { 　　CSize sz = ppic->GetImageSize(); 　　switch (m_iHowScale) { 　　　case ID_VIEW25: 　　　　sz.cx >>= 2; 　　　　sz.cy >>= 2; 　　　　break; 　　　case ID_VIEW33: 　　　　sz.cx /= 3; 　　　　sz.cy /= 3; 　　　　break; 　　　case ID_VIEW50: 　　　　sz.cx >>= 1; 　　　　sz.cy >>= 1; 　　　　break; 　　　case ID_VIEW75: 　　　　sz.cx = (sz.cx * 3)/4; 　　　　sz.cy = (sz.cy * 3)/4; 　　　　break; 　　} 　　rc.SetRect(0,0,sz.cx,sz.cy); 　} } ////////////////// // Handle zoom command. void CPictureView::OnViewScale(UINT nID) { 　if (m_iHowScale != nID) { 　　m_iHowScale = nID; 　　ScrollToPosition(CPoint(0,0)); 　　OnInitialUpdate(); 　} } //////////// Update zoom menu -- check the whichever zoom factor I'm at now. void CPictureView::OnUpdateViewScale(CCmdUI* pCmdUI) { 　pCmdUI->SetCheck(pCmdUI->m_nID == m_iHowScale); }