Submitted by Anonymous on Mon, 02/11/2002 - 23:36. Developers
Hi,

I`m using a Container to display a large number of objects (a few 1000s)
arranged in hierarchy. I needed to be able to expand/collapse all the
nodes in the hierarchy up to a certain level, e.g. display all nodes up
to second level in the hierarchy. I used a push button and in its
callback, I used XtVaSetValues() to change the XmNoutlineState for
all the nodes (in reverse depth-first order, ie expand children before
their parents).

The above works okay, the problem is the speed.

I was first using XmDETAIL, the expand & collpase up to the first 2
or 3 levels were ok (a few seconds) but if I go more than this it takes
a really long time (a few minutes). I switched to XmOUTLINE and found
that it is much (orders of magnitude) faster, but still relatively slow
to an average user. (FYI, I`m using a Sun Ultra10 and this is the
only user application running on it, so the delay would be even worse
when the load on the workstation is more realistic).

It seems to me that every time XtVaSetValues() is called, the whole
container is redrawn. Is it possible to freeze requests for redrawing
until I`m done using the container and then issue a single expose request?

I tried to use my own event loop

XEvent event;

for(;;) {
XtAppNextEvent(&event);

printf("Event %d
", event.type);

XtDispatchEvent(&event);
}

however, I found that during the time when the tree is being expanded, no
new events are generated! Isn`t the drawing code executed in the
event loop?

I have another program written in Java that uses the JTree component
with a similarly large number of tree nodes, and it works a lot
faster than XmOUTLINE. So I believe it should be doable in motif,
I don`t know how exactly though.

I apologize for the lengthy message.

Regards,
inas