【转帖】dwgdirect and q
 

dwgdirect and qt?
dwgdirect and qt?
i was wondering, is it possible to get dwgdirect vectorization module to work in trolltech's qt widget system? i can't seems to get it work.
alright, after a lot of testing and looking via examples, i've finally manage to get directdwg vectorization framework to work with qt. it's actually based on odgssimpledevice and winopengl example, and it's sortof work. however, there're some mysterious bugs that i can't seems to figure out.
1) after reading a dwg file, the device must be updated once before the real rendering happens? all the examples doesn't required it to be updated prior to rendering.
2) for some reason pdevice->update() generated some errors if i call it directly inside qt's slots functions. note that signals/slot is qt's version of windows message handling. it might be some incompatible issue between directdwg and qt. however, if i create another function with pdevice->update() and qt's slots function call that function, it'll work. odd.
code:
//qt slot function, direct update at here will not work
void pktdwg::resizegl(int width, int height) //qt slots
{
odgsdcrect screenrect(odgsdcpoint(0, height), odgsdcpoint(width, 0));

if(!pdevice.isnull())
pdevice->onsize(screenrect);
}
//odd, the following works
void pktdwg::resizegl(int width, int height) //qt slots
{
resize(width, height);
}
void pktdwg::resize(int width, int height)
{
odgsdcrect screenrect(odgsdcpoint(0, height), odgsdcpoint(width, 0));

if(!pdevice.isnull())
pdevice->onsize(screenrect);
}
there're other mysterious errors here and there, which i still cannot figure out where the real problems is. is there any problem with my implementation?
my sample project attached.
attached files (69.4 kb, 3 views)

what means 'emit' in qt? (i mean - what it is internally?)
the problem looks like a threading issue.
vladimir
emit is qt's version of postmessage. it is used to send custom window message to whichever receiver applied.
threading issue? does this means that both qt and dd should be on the same thread or different? sorry, i don't really know threading.
dd should live in one thread generally. that is: dd supports multithreading, but only for (simultaneous) reading.
you should probably communicate with dd via 'emit' messages, when calling from message handlers.
vladimir