Re: Using fixed-size data buffer with GtkPlot

Dear Al,

Thank you very much for responding.  Being a GtkExtra newbie makes
it hard to ask meaningful questions, but it's newbies who need most
help.

On 2/25/06, Al Hooton <[email protected]> wrote:
>
> > I would like to be able to append points and plot them one at a time,
> > which is pretty much what the 'testrealtime' example does.  The
> additional constraint I
> > have is that, unlike 'testrealtime', I > cannot store data points in a
> dynamically allocated buffer and let
> > this buffer grow indefinitely.
>
>         So, if I understand you correctly, you want to have an
> ever-growing
> number of points plotted, but every so often you want to throw away the
> points you've already plotted and start over with a clean plot?


Precisely.   I need a way of telling the library: "forget everything and
start
over fresh BUT USE THE SAME FIXED SIZE BUFFER TO STORE DATA POINTS".

        Or, do you want to have an unknown number of points plotted as they
> come in, but you do not want to manage the memory for them dynamically?


Yes, the number of points *will* be unknown, and they *will* be plotted as
they come in.  All I am trying to avoid is allowing the data buffer to grow
indefinitely in size.  Hence the need to throw old points away and force the
library to start from scratch and NOT to allocate any new memory.  I just
can't afford keeping the entire history around.  Isn't that the most natural
way to go about this?  I would expect everyone who wants to plot things on
the fly to want to do something similar to this.   Why, indeed, would you
want
your plotter to keep allocating memory to store data points (to pass them to
the library) and eventually make the system run out of memory?

I don't seem to be able to modify the 'testrealtime' example to use a fixed,
rather than dynamic, buffer to store data points and pass this buffer to the
library.  This is where my confusion comes from.

Are my questions making more sense now?


Best,

Nickolai