Drawing a jpg in MFC - c++

Question

I've been trying to show a jpg image in MFC, but I can't get it drawn. I'm a complete MFC newbie an everything I got up until now is mostly adapted from things I found on the net. Currently I have this:
Picture.h:
#pragma once
#include <afxwin.h>
class Picture
{
public:
Picture();
bool load(LPCTSTR filePath);
bool draw( CDC* deviceContext
, CRect clientRect
, LPCRECT prcMFBounds);
CSize getSize(CDC* pDC);
private:
LPPICTURE m_picture;
};
Picture.cpp:
#include "Picture.h"
Picture::Picture()
: m_picture(0)
{
}
bool Picture::load(LPCTSTR szFile)
{
HANDLE hFile = CreateFile(szFile, GENERIC_READ, 0, NULL, OPEN_EXISTING, 0, NULL);
if (hFile == INVALID_HANDLE_VALUE)
return false;
DWORD dwFileSize = GetFileSize(hFile, NULL);
if (dwFileSize == (DWORD)-1)
{
CloseHandle(hFile);
return false;
}
LPVOID pvData = NULL;
// alloc memory based on file size
HGLOBAL hGlobal = GlobalAlloc(GMEM_MOVEABLE, dwFileSize);
if (hGlobal == NULL)
{
CloseHandle(hFile);
return false;
}
pvData = GlobalLock(hGlobal);
if (pvData == NULL)
{
GlobalUnlock(hGlobal);
CloseHandle(hFile);
return false;
}
DWORD dwBytesRead = 0;
// read file and store in global memory
bool bRead = ReadFile(hFile, pvData, dwFileSize, &dwBytesRead, NULL) != 0;
GlobalUnlock(hGlobal);
CloseHandle(hFile);
if (!bRead)
return false;
LPSTREAM pstm = NULL;
// create IStream* from global memory
HRESULT hr = CreateStreamOnHGlobal(hGlobal, TRUE, &pstm);
if (!(SUCCEEDED(hr)))
{
if (pstm != NULL)
pstm->Release();
return false;
}
else if (pstm == NULL)
return false;
// Create IPicture from image file
if (m_picture)
m_picture->Release();
hr = ::OleLoadPicture(pstm, dwFileSize, FALSE, IID_IPicture, (LPVOID *)&(m_picture));
if (!(SUCCEEDED(hr)))
{
pstm->Release();
return false;
}
else if (m_picture == NULL)
{
pstm->Release();
return false;
}
pstm->Release();
return true;
}
bool Picture::draw(CDC* deviceContext, CRect clientRect, LPCRECT prcMFBounds)
{
if (clientRect.IsRectNull())
{
CSize imageSize = getSize(deviceContext);
clientRect.right = imageSize.cx;
clientRect.bottom = imageSize.cy;
}
long pictureWidth = 0;
long pictureHeigth = 0;
m_picture->get_Width(&pictureWidth);
m_picture->get_Height(&pictureHeigth);
m_picture->Render( *deviceContext
, clientRect.left
, clientRect.top
, clientRect.Width()
, clientRect.Height()
, 0
, pictureHeigth
, pictureWidth
, -pictureHeigth
, prcMFBounds);
return true;
}
CSize Picture::getSize(CDC* deviceContext)
{
if (!m_picture)
return CSize(0,0);
LONG width, height; // HIMETRIC units
m_picture->get_Width(&width);
m_picture->get_Height(&height);
CSize size(width, height);
if (deviceContext==NULL)
{
CWindowDC dc(NULL);
dc.HIMETRICtoDP(&size); // convert to pixels
}
else
{
deviceContext->HIMETRICtoDP(&size);
}
return size;
}
PictureView.h:
#pragma once
#include <afxwin.h>
#include <string>
class Picture;
class PictureView : public CStatic
{
public:
PictureView(std::string path);
protected:
virtual void DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct);
private:
Picture* m_picture;
};
PictureView.cpp:
#include "PictureView.h"
#include "Picture.h"
PictureView::PictureView(std::string path)
{
m_picture = new Picture();
m_picture->load(path.c_str());
}
void PictureView::DrawItem(LPDRAWITEMSTRUCT /*lpDrawItemStruct*/)
{
CRect rect;
GetClientRect(&rect);
m_picture->draw(GetDC(), rect, rect);
}
Constructor call:
CWnd* GenericChildWidget::addImage(std::string path, int horizontalPos, int width, int verticalPos, int height, int childId)
{
PictureView* image = new PictureView(path);
image->Create("", SS_OWNERDRAW, CRect(horizontalPos, verticalPos, width + horizontalPos, height + verticalPos), this, childId);
return image;
}
The problem is that I can't get the DrawItem function to be called. What am I doing wrong?
Any help will be appreciated.

Answer 1

Here's an easy way to draw an image in an MFC dialog box:
link with gdiplus.dll
#include "atlimage.h>
#include "gdiplus.h>
using namespace Gdiplus
.
.
.
CImage ci;
ci.Load((CString)"D:\\Pictures\\mycat.jpg");
CDC *dc = AfxGetMainWnd()->GetDC();
HDC hdc = *dc;
ci.Draw(hdc,10,10);
Hope it works!

Answer 2

with the help of a colleague of mine I've found the answer. He told me it's not possible to have an ownerdrawn CStatic. So when I now inherit PictureView from CButton and make it BS_OWNERDRAW my image is rendered.
Personally I think this is an ugly solution but I'm so tired of this problem now that I don't really care that much. These are the changes I've made to make it work:
Constructor call:
CWnd* GenericChildWidget::addImage(std::string path, int horizontalPos, int width, int verticalPos, int height, int childId)
{
PictureView* image = new PictureView(path);
image->Create("", BS_OWNERDRAW | WS_CHILD | WS_VISIBLE, CRect(horizontalPos, verticalPos, width + horizontalPos, height + verticalPos), this, childId);
return image;
}
PictureView.h:
#pragma once
#include <afxwin.h>
#include <string>
class Picture;
class PictureView : public CButton
{
public:
PictureView(std::string path);
protected:
virtual void DrawItem(LPDRAWITEMSTRUCT lpDrawItemStruct);
private:
Picture* m_picture;
};
Thank's everybody for all the help.

Answer 3

I'm not sure that the GetDC in the call to m_picture->draw will necessarily refer to the same DC that's given in the CREATESTRUCT. What I've done is:
CDC* pDC = CDC::FromHandle(lpDrawItemStruct->hDC);
EDIT: Since I can't comment, hopefully an edit will suffice. I think your colleague is mistaken, as I just recently implemented a CStatic control using SS_OWNERDRAW. I'm guessing that the addition of WS_CHILD | WS_VISIBLE on the Create call is key.

Answer 4

I've never used MFC but a quick perusal of the CStatic::DrawItem documentation says that it must be created with the SS_OWNERDRAW style for DrawItem to get called. You haven't shown the Create line for your PictureView so perhaps it's that?