Re: drawHistogramWithDouble ()

[Paul E Johnson]

This thread has me interested.

Maybe this is something we can talk over at Swarmfest. I'm often wishing 
Swarm had better graph things and don't know if the current design can 
accomplish them.  I want scatterplots and bar charts and currently have 
to use addon things to get them.

I'm willing to try to fix up the Histogram class to work in a java 
compatible way. Is there a recommended JNI/Obj-C manual to explain about 
rewriting Obj-C code so that it can be accessed from Java?

Or, in the alternative, can I please ask.

1. Is this the problem: any Obj-C method that requires a pointer as 
input is not Java compatible?

Examples in Histogram.m:
- (void)drawHistogramWithDouble: (double *)points
- (void)drawHistogramWithInt: (int *)points



2. Is fixing the problem as easy as writing new methods that accept 
arrays rather than pointers??????

I mean does this fix it, even though the contents of the method do not 
change at all?

- drawHistogramWithDouble: (double[]) points
{
  unsigned i;

  for (i = 0; i < binCount; i++)
    [globalTkInterp eval: "%s element configure %s -data { %g %g }",
                    widgetName, elements[i], locations[i], points[i]];
}

Or I can leave the old method and name this:

- drawHistogramWithDoubleArray: (double[]) points

So I'd just systematically have to go through Histogram and make sure 
all methods we want exposed to the Java layer do not use pointers?

Then, after we make some change in the files that control the way Swarm 
compiles, then these methods would work in Java?


3. What the heck does this declaration mean and what is to be done about it?

- (void)setLabels: (const char * const *)l count: (unsigned)labelCount

I think this wants to receive from Java an array of Strings, which C 
sees as a two dimensional array of char. Is there any existing Obj-C 
example of how to pass through an array of Strings that I could learn from.


Marcus G. Daniels wrote:

> > > > > > "JM" == Marshall, James A R <address@hidden> writes:
>
> JM> I'll be looking at this with interest as I'm moving over to
> JM> Java from Objective-C...  I hope there's not too much missing!
>
> Hmm, the wrong reason to switch to some other plotting toolkit is just
> because of things that are "missing".  By adding a few methods to
> Swarm it is usually possible to add pointer-free alternatives for the
> sake of Java.  (And no, I'm not volunteering to do this for people
> that just `identify the problem'.)
>
>                   ==================================

--
Paul E. Johnson                       email: address@hidden
Dept. of Political Science            http://lark.cc.ukans.edu/~pauljohn
University of Kansas                  Office: (785) 864-9086
Lawrence, Kansas 66045                FAX: (785) 864-5700


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