【转帖】create a bitmap from a macrodefinition
 

create a bitmap from a macrodefinition
create a bitmap from a macrodefinition
how can i create a previewbitmap from a blocktablerecord ?
here is a code which forms a bitmap from the current model or paper space.
code:
odgsdcrect gsrect(0, width , height, 0);
odgicontextfordbdatabaseptr pctx = odgicontextfordbdatabase::createobject();
pctx->setdatabase(m_pdb);
pdevice = oddbgsmanager::setupactivelayoutviews(pdevice, pctx);
odcolorref clrbackground(odrgb(255,255,255));
clrbackground = (odcolorref)drwservices()->vars()->get<int>("thumbnailimagebkcolor");
pdevice->setbackgroundcolor(clrbackground);
pdevice->setlogicalpalette(odcmacadpalette(clrbackground), 256);
pdevice->onsize(gsrect);
pdevice->properties()->putat("bitperpixel", odrxvariantvalue(oduint32(8)));

// zoom to the extents if the option needs it
if (nthumboption == thumbextents) {
this->odgsview_zoomextents(pdevice->viewat(0));
}

pdevice->update();
odgirasterimageptr praster = pdevice->properties()->getat("rasterimage");
bitmapinfoheader bmih = {0};
praster->getbitmapinfoheader(bmih);
thumbimg.header.clear();
thumbimg.header.resize(80, 0);
thumbimg.bmp.clear();
oduint32 nbytes = 0;
const oduint8* bytes = praster->getscanlines(nbytes);
oduint32 npalettebytes = 0;
const oduint8* palettebytes = praster->getpalettedata(npalettebytes);
thumbimg.bmp.resize(sizeof(bitmapinfoheader) + npalettebytes + nbytes);
::memcpy(thumbimg.bmp.asarrayptr(), (void **)&bmih, sizeof(bitmapinfoheader));
::memcpy(thumbimg.bmp.asarrayptr() + sizeof(bitmapinfoheader), palettebytes, npalettebytes);
::memcpy(thumbimg.bmp.asarrayptr() + sizeof(bitmapinfoheader) + npalettebytes, bytes, nbytes);
it won't work for you truly, because you cannot set an active layout block a block table record which is not a layout (i.e. model or paperspace). can't you do it in a temp database which has external reference of the block table record, or simply create a temp paperspace layout, then insert a block reference in it, give zoom all, and then call pdevice->update()? probably it is not the easiest way...
regards
chudomir
best regards
chudomir