加载中…在MFC中如何读取并显示jpg文件
(2012-05-23 17:44:02)
标签：
杂谈 |
分类： MFC |
今天要在MFC中显示JPG文件。在网上找了很久。最后找到这段代码终于可以用：
//picture.h
{
CShowImageDoc* pDoc =
GetDocument();
ASSERT_VALID(pDoc);
CPicture* ppic = new
CPicture();
std::string
filename("图片文件路径");
int len;
ASSERT(ppic);
if (*ppic) {
CRect
rc(0,0,500,500);
//GetImageRect(rc);
ppic->Render(pDC,rc);
}
}
////////////////////////////////////////////////////////////////
// MSDN Magazine -- October 2001
// If this code works, it was written by Paul DiLascia.
// If not, I don't know who wrote it.
// Compiles with Visual C++ 6.0 for Windows 98 and probably
Windows 2000 too.
// Set tabsize = 3 in your editor.
//
#pragma once
#include <atlbase.h>
//////////////////
// Picture object--encapsulates IPicture
//
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();
}
}
//picture.cpp
#include "stdafx.h"
#include "Picture.h"
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
////////////////////////////////////////////////////////////////
// CPicture implementation
//
CPicture::CPicture()
{
}
CPicture::~CPicture()
{
}
//////////////////
// Load from resource. Looks for "IMAGE" type.
//
BOOL CPicture::Load(UINT nIDRes)
{
// find resource in resource file
HINSTANCE hInst = AfxGetResourceHandle();
HRSRC hRsrc = ::FindResource(hInst,
MAKEINTRESOURCE(nIDRes),
(LPCWSTR)"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);
return bRet;
}
//////////////////
// Load from path name.
//
BOOL CPicture::Load(LPCTSTR pszPathName)
{
CFile file;
if (!file.Open(pszPathName,
CFile::modeRead|CFile::shareDenyWrite))
return FALSE;
BOOL bRet = Load(file);
file.Close();
return bRet;
}
//////////////////
// Load from CFile
//
BOOL CPicture::Load(CFile& file)
{
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;
}
最后在CView类的OnDraw方法中加入调用：
void CShowImageView::OnDraw(CDC* pDC)
int slength = (int)filename.length() + 1;
len = MultiByteToWideChar(CP_ACP, 0, filename.c_str(),
slength, 0, 0);
wchar_t* buf = new wchar_t[len];
MultiByteToWideChar(CP_ACP, 0, filename.c_str(), slength, buf,
len);
std::wstring r(buf);
delete[] buf;
ppic->Load(r.c_str());
protected:
CComQIPtr<IPicture>m_spIPicture;
// ATL smart pointer to IPicture
HRESULT m_hr; // last error code
};
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