How to read an old Windows Meta File?

David Webber 136

I am reading Enhanced Meta Files with ::GetEnhMetaFile( pszFilename ) which returns a HENHMETAFILE handle.

But I want to read the old fashioned Windows Meta Files too. Can anyone tell me how to do this???

I am going round in circles with the docuemtation.

GetMetaFile

The docs tell me that ::GetMetaFile( pszFilename ) does the job, but also that "GetMetaFile is no longer available for use as of Windows 2000. Instead, use GetEnhMetaFile".

GetEnhMetaFile

The documentation for GetEnhMetaFile says:

"A Windows-format metafile must be converted to the enhanced format before it can be processed by the GetEnhMetaFile function. To convert the file, use the SetWinMetaFileBits function."

SetWinMetaFileBits

So I look at SetWinMetaFileBits(). IT has a number of arguments, none of which is a file name but including "A pointer to a buffer that contains the Windows-format metafile data. (It is assumed that the data was obtained by using the GetMetaFileBitsEx or GetWinMetaFileBits function.)"

Now SetWinMetaFileBits() returns an HENMETAFILE handle which is great, but if I have that, then I don't need GetEnhMetaFile() so what was that about? Furthermore

GetWinMetaFileBits

takes an HENHMETAFILE as an argument, and fills in a buffer with Win Meta File format data; But haven't got an HENHMETAFILE.

GetMetaFileBitsEx

fills in a data buffer in WMF format, if you have an HMETAFILE. But to get an HMETAFILE from my file on disk, the obvious way is to use GetMetaFile() but...

There's a hole in my bucket?

Dave

Yasar Mughal Yasar Mughal 0 Reputation points

2023-06-13T12:27:30.5133333+00:00

Mughal bodyssho

Accepted answer

RLWA32 40,021 Reputation points

2020-11-17T17:37:01.803+00:00

Check out this thread (I haven't tested the solution) - convert-wmf-file-to-emf-file-with-setwinmetafilebits-api-in-c
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1 person found this answer helpful.
David Webber 136 Reputation points

2020-11-18T18:19:08.623+00:00

Thanks! I copied the code given there, and it seems to work. I have no idea how, as it relies on knowledge of the innards of WMF files. But I note that something similar is suggested on Joseph M Newcomer's http://www.flounder.com/ site - which takes me back a few years!

Dave
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2 additional answers

David Lowndes 4,711 Reputation points

2020-11-17T17:53:51.677+00:00

Gdiplus seems to be able to load a WMF file.

>

GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
GdiplusStartup( &gdiplusToken, &gdiplusStartupInput, NULL );

Metafile gdimf( Path to a WMF file );
GdiplusShutdown( gdiplusToken );
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David Webber 136 Reputation points

2020-11-18T16:15:45.123+00:00

Thanks for the idea David.
The

Metafile::Metafile( LPCWSTR szPath )

constructor documentation isn't too precise about which kind of metafile it reads, and I assumed it was only Enhanced Metafiles. This would have been really nice if it were also to work on .WMF as (a) I am already using the metafile class for other purposes, and (b) it would have meant opening .EMF and .WMF with no case handling at all.

But I've put in

Metafile mf( szPath ); HENHMETAFILE hEmf = mf.GetHENHMETAFILE();

Paths to both EMF and WMF get me a non-null handle, but ::GetEnhMetaFileBits() fails (returns zero size) when I pass a HENHMETAFILE handle obtained in this way from a WMF. So it looks like either the Metafile is duff when it appears to read a WMF, or the HENHMETAFILE is. :-(

Unless there's something else I have to do to get a valid HENHMETAFILE ?

Dave

David Lowndes 4,711 Reputation points

2020-11-18T16:45:23.783+00:00

I don't know what gdi+ does under the covers, but it will display either a WMF or EMF file using its facilities:

In a WM_PAINT handler:

Metafile gdimf( Path to WMF or EMF file );
Graphics gr( hdc );
gr.DrawImage( &gdimf, 10, 10 );

David Webber 136 Reputation points

2020-11-19T14:08:55.847+00:00

Interesting!

In my case I am embedding one or more enhanced metafiles as illustrations in my MFC CDocument derived class. The embedded 'illustration' is embodied as an object with a byte count and an array of bytes.

Adding an EMF illustration to the document reads an EMF file with

HENHMETAFILE hEmf = ::GetEnhMetaFile( pszwFilename );

and then converts it to an array of bytes for storage within the document with

::GetEnhMetaFileBits( hEmf, ... );

Reading the EMF file with the metafile constructor, then using Metafile::GetHENHMETAFILE() to get my HENHMETAFILE and thence to an array of BYTES works equally well. But if I try to use this method on a WMF, whilst I get a non-NULL hEmf (promising!), the ::GetEnhMetaFileBits( hEmf, ... ) does not work - it returns zero when I ask for the size of the array.

Dave

RLWA32 40,021 Reputation points

2020-11-19T15:15:31.21+00:00

That's because the gdiplus MetaFile object doesn't really contain an enhanced meta file.
For example -

Metafile mf(L"F:\\RLWA32\\Win32WMF\\Win32WMF\\BD18187_.WMF"); MetafileHeader mfh{}; Gdiplus::Status stat = mf.GetMetafileHeader(&mfh); _ASSERTE(mfh.GetType() == Gdiplus::MetafileTypeWmf);

David Webber 136 Reputation points

2020-11-24T12:35:19.237+00:00

Thanks again for this. It would be nice if the Metafile had a simple method to convert it to a contiguous collection of data of known size, which could be saved as part of my CDocument derived class. So far I've failed to find anything. But the other method (despite my nervousness at not knowing enough to understand how it works) which effectively converts a WMF to an EMF, seems to work for now. (I still use the Metafile class to convert it to EMF+ and draw it with antialiasing.)

The more pressing task is now to find a method of reading SVG files !

RLWA32 40,021 Reputation points

2020-11-24T12:48:50.23+00:00

When loading a WMF into a gdiplus MetaFile object you can cast the value returned by MetaFile::GetENHMETAFILE() to an HMETAFILE handle. Then you can use the usual functions with the WMF handle to convert to an EMF.
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Castorix31 81,461 Reputation points

2020-11-17T18:44:03.907+00:00

There are several ways to load/display WMF
A simple one is with OleLoadPicture
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