how to use wxMetaFile(wxMetaFileDC) to convert WMF image to jpg file

[jank...@sina.com]

                      In my program, I need convert some WMF format images which are dynamically generated to save jpg format files,  how can I use wxMetaFile(wxMetaFileDC) to convert? could anybody give me a piece of code?

[Gadget/Steve]

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As the help file says that wxMetaFile can only be used to copy data to
the clipboard for the moment the simple answer is that you can't. If
you were working in wxPython the simple answer would be to use PIL, the
python image library, if you are in C++ you will have to find another
library that supports this.

Gadget/Steve

[Julian Smart]

On Windows, you could do something like the following.

Regards,

Julian

static void wxHIMETRICToPixel(LONG *x, LONG *y)
{
*x = (*x) * 96 / 2540;
*y = (*y) * 96 / 2540;
}

// This function is more accurate and consistent than the wxWidgets one
static wxSize wxEnhMetaFileGetSize(wxEnhMetaFile& mf)
{
wxSize size = wxDefaultSize;

if ( mf.Ok() )
{
ENHMETAHEADER hdr;
if (
!::GetEnhMetaFileHeader(((HENHMETAFILE)mf.GetHENHMETAFILE()),
sizeof(hdr), &hdr) )
{
wxLogLastError(_T("GetEnhMetaFileHeader"));
}
else
{
// the width and height are in HIMETRIC (0.01mm) units,
transform
// them to pixels
LONG w = hdr.rclFrame.right,
h = hdr.rclFrame.bottom;

wxHIMETRICToPixel(&w, &h);

size.x = w;
size.y = h;
}
}
return size;
}
#endif

// Image is simply read in into hash map keyed by its name
if (FileUtilities::GetExtension(name).Lower() == wxT("wmf") ||
FileUtilities::GetExtension(name).Lower() == wxT("emf"))
{
#ifdef __WXMSW__
if (wxFileExists(filename))
{
wxLogNull log;
wxEnhMetaFile* enhMetafile = new wxEnhMetaFile(filename);
if (enhMetafile->IsOk())
{
//wxSize sz = enhMetafile->GetSize();
wxSize sz = wxEnhMetaFileGetSize(*enhMetafile);

if (sz.x != 0 && sz.y != 0)
{
wxRect rect(0, 0, sz.x, sz.y);

wxBitmap bitmap(sz.x, sz.y);
wxMemoryDC dc;
dc.SelectObject(bitmap);
dc.SetBackground(*wxWHITE_BRUSH);
dc.Clear();

if (enhMetafile->Play(& dc, & rect))
{
dc.SelectObject(wxNullBitmap);

if (bitmap.IsOk())
{
wxImage image = bitmap.ConvertToImage();

...
delete enhMetafile;
}
}
}
}
delete enhMetafile;
}

[jank...@sina.com]

Thank you very much, I'll test it later

[jank...@sina.com]

On Wednesday, September 19, 2012 5:29:12 AM UTC+8, Julian wrote:

Hi, Julia,
 I have tested it with a image which saved from my program and have been opened properly by ms paint, the code does not work, and then I debuged my program and found it at the position if (enhMetafile->IsOk()), it always fail. what does I do not check ?

[Julian Smart]

On 20/09/2012 12:58, jank...@sina.com wrote:
>
> Hi, Julia,
> I have tested it with a image which saved from my program and have
> been opened properly by ms paint, the code does not work, and then I
> debuged my program and found it at the position if
> (enhMetafile->IsOk()), it always fail. what does I do not check ?

I guess it's not a supported type of enhanced metafile but alas I don't
know any more.. .sorry!

Regards,

Julian

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> Please read http://www.wxwidgets.org/support/mlhowto.htm before posting.
>
> To unsubscribe, send email to wx-users+u...@googlegroups.com
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