Richard Penman wrote:
> hello,
>
> I am useing clipping with FLTK 1.1.7 on Debian but occassionally it stalls
> for a few seconds and I get these messages on the console:
>
> fl_push_clip: clip stack overflow!
> fl_pop_clip: clip stack underflow!
>
> What is going on? I only have one clipping region on the stack.
When I've seen that, I usually had a bug in my draw() code
where either:
1) I was either recursively calling draw() too many times
2) The logic of my draw() function was skipping an fl_pop_clip()
(causing the overflow).
The 'stall for a few seconds' sounds like something in your program
is going wrong, and I would try to identify that by running your app
in a debugger, and hitting 'break' when the stall is happening,
so you can inspect what's causing that.
The clip buffer is implemented as a stack which I think is
defined to a depth of 10 in fl_rect.cxx:
#define STACK_SIZE 10
#define STACK_MAX (STACK_SIZE - 1)
static Fl_Region rstack[STACK_SIZE];
[..]
void fl_push_clip(int x, int y, int w, int h) {
[..]
if (rstackptr < STACK_MAX) rstack[++rstackptr] = r;
else Fl::warning("fl_push_clip: clip stack overflow!\n");
10 is certainly a small value, but it shouldn't really
get all that large, and you definitely don't want it
too large, since all drawing operations have to be masked
through it.
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