MingW/Windows: Building g++ import lib for existing DLL

[Alf P. Steinbach]

Hi.

[I don't know whether this, MinGW g++ tool usage, is on-topic here. I've failed 
to find a more relevant group. *MULTI-POST*: posted yesterday to gnu.gcc.help.]


I'm trying to build an import library for the Windows GDI+ API (Windows' basic 
modern graphics API), because it isn't supported by MinGW 3.4.5.

I know that this "should" be possible since MinGW has bundled import libraries 
for other Windows APIs, e.g. import libraries for [user32.dll] etc.

I've generated a module definition file that goes like this:

<code filename="gdiplus.dll.def">
EXPORTS
    GdipAddPathArc@28 = GdipAddPathArc
    GdipAddPathArcI@28 = GdipAddPathArcI
    GdipAddPathBezier@36 = GdipAddPathBezier
    GdipAddPathBezierI@36 = GdipAddPathBezierI
    GdipAddPathBeziers@12 = GdipAddPathBeziers
...
</code>

The ornamented names on the left are the ones that g++ wants; the plain ones on 
the right are those exported by [gdiplus.dll]. Microsoft's documentation (always 
unreliable) states that they should be in opposite order and so I've tried also 
that. I don't use ordinal numbers because I have the impression that MinGW tools 
don't support identifying DLL routines via ordinal numbers, only via names, but 
just to have tried everything I tried also that.

I use the module definition file like this, via MinGW tools 'objdump' and 
'dlltool' (sorry about any added line-breaks in news article), where 
'gen_deffile' is a program that generates the file shown above:

<commands>
objdump -p "%windir%\SYSTEM32\gdiplus.dll" | find "Gdip" | gen_deffile > 
gdiplus.dll.def
dlltool --def gdiplus.dll.def --dllname gdiplus.dll --output-lib 
libgdiplus.dll.a
</commands>

This generates an import library that works on the g++ side of things, static 
linking OK, but when run the Windows loader looks for the ornamented names in 
the DLL, not the plain ones that the DLL exports, and coughs up an error message 
"not found" for one of these names.

What can I do instead?


TIA. for any help,

- Alf