Re: maximing/resizing multiple x11: change of palette

[Daniel J S. <dan...@ie...>]

Petr Mikulik wrote:

>>The complete color map needs to be stored as part of the structure.
>> That is, plot->cmap needs to point at something that is dynamically
>>allocated independent of the current color map.  I'll work on that fix,
>>but if this doesn't sound correct, let me know.  Also, maybe think if
>>what I've added in this patch is adequate to fix the problem when I have
>>the plot->cmap problem fixed.  That is, are there any other details
>>about the GC that also must be updated?
>>    
>>
>
>I have just tried the patch, but it was rejected. Don't you have an
>up-to-date version?
>

Why would that patch be rejected? I don't think anyone has altered that 
bit of code in CVS... Anyway, that patch was just a lame alteration to 
illustrate where the problem lies. Basically, search for this line of 
code in gplt_x11.c

    if (plot->cmap->allocated < min_colors && !recursion) {


and replace it with the following

    if (!recursion) {


That fixes the problem of keeping track of the color map, but it also 
results in an incorrect color map. It looks like a tricky bit of code 
because it is recursive. I'm not exactly sure why it is recursive, as 
opposed to calling a subroutine twice. In fact, I'm looking at some code 
there and wondering what in fact it does. Here is the code in question:

if (plot->cmap->allocated < min_colors && !recursion) {
ReleaseColormap(plot);
/* create a private colormap. */
fprintf(stderr, "switching to private colormap\n");
plot->cmap = (cmap_t *) malloc(sizeof(cmap_t));
assert(plot->cmap);
CmapClear(plot->cmap);
plot->cmap->colormap = XCreateColormap(dpy, root, vis, AllocNone);
assert(plot->cmap->colormap);
pr_color(plot->cmap); /* set default colors for lines */
RecolorWindow(plot);
recursion = 1;
PaletteMake(plot, (t_sm_palette *) 0);
} else {
/* this is just for calculating the number of unique colors */
int i;
unsigned long previous = plot->cmap->allocated ? plot->cmap->pixels[0] : 0;
int unique_colors = 1;
for (i = 0; i < plot->cmap->allocated; i++) {
if (plot->cmap->pixels[i] != previous) {
previous = plot->cmap->pixels[i];
unique_colors++;
}
}
}

Notice that the second portion of the if/else statement alters two local 
variables, previous and unique_colors, and that is all. That's a useless 
bit of code, as I see it. I wish there were a short note explaining why 
this is recursive, i.e., on the second time through, what portion of the 
code is important?

Dan