yang686526

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in old code written around opendwg i used the following two functions to find and display a preview of the dwg file:
// determin if there is a bmp for preview.
numbytes = adbmpsizefromfile(((void*)((const char*)csfilename)));
adextractbmpfromfiletofile( ((void*)((const char*)csfilename)), ((void*)((const char*)m_sbmpfilename)) );
would someone be able to post some sample code which shows doing this task in dwgdirect?
thanks.
al
here is a function which we use to extract the bitmap data - im afraid not directly in a file, but you can construct a bitmap in this way.
code:
//extern "c"
bool __declspec(dllexport) getthumbnailbitmapdwg(const char* pszfilename, void*& pbmpinfo, void*& poutdata, uint& noutdatasize)
{
_trace("getthumbnailbitmapdwg - %s\n", pszfilename);

_assert(pbmpinfo == 0);
_assert(poutdata == 0);

odthumbnailimage odimage;
try {
:ddbgetpreviewbitmap(theapp.services()->createfile(pszfilename), &odimage);

if (!odimage.hasbmp()) return false;

bitmapinfoheader* pbmpheader = (bitmapinfoheader*) (odimage.bmp.begin());
_assertptr(pbmpheader,sizeof(bitmapinfo));

_assertstatic(sizeof(byte)==1,bytemustbe1insize);

// now get the bitmap data

byte* p = (byte*)pbmpheader;

// go after the header data
p += pbmpheader->bisize;

// we must skip the rgbquad arrays that follows the info header
switch(pbmpheader->bibitcount) {
case 1: p += sizeof(rgbquad)*2; break;
case 4: p += sizeof(rgbquad)*16; break;
case 8: p += sizeof(rgbquad)*256; break;
} //switch

// get the remaining size
noutdatasize = odimage.bmp.size() - (p-(byte*)pbmpheader);
//_assert(noutdatasize == pbmpheader->bisizeimage);
_assert(odimage.bmp.size()>0);
poutdata = new byte[noutdatasize];
_assertptr(p,noutdatasize);
::memcpy(poutdata,p,noutdatasize);

// copy the bitmap info - header + color table
const uint nbmpinfosize = odimage.bmp.size()-noutdatasize;
pbmpinfo = new byte[nbmpinfosize];
::memcpy(pbmpinfo,pbmpheader,nbmpinfosize);

} catch(oderror& e) {
//_ifdebug(caddie::drw::reportoderror(e));
_trace("getthumbnailbitmapdwg: file=%s : error=%s\n", pszfilename,
caddie::drwimpl::caodutils::getoderrorstring(e).c_str());

unused_always(e);
return false;
} catch(...) {
_trace("unknown error in reading preview image\n");
return false;
} //catch

return true;
}
the caller of the function is responsible to delete the memory returned.
hope this helps...
regards
chudomir
thanks for the response. i did find this thread from 2002 which asnwered all my questions.