[GRASS-dev] Rast_add_d_colour

[Yann Chemin]

Thanks,
Will try again today.
 On Dec 7, 2014 3:36 AM, "Vaclav Petras" <wenzeslaus at gmail.com> wrote:

>
>
> On Sat, Dec 6, 2014 at 3:59 PM, Markus Metz <markus.metz.giswork at gmail.com
> > wrote:
>
>> Yann Chemin wrote:
>> > Hi,
>> >
>> > I am working on beautifying the output of i.theilsen, a new addon.
>> >
>> > For some reason, I cannot apply a grayscale palette.
>> > ---------------
>> > Rast_init_colors(&colors);
>> > DCELL val1 = ts_min;
>> > DCELL val2 = ceil(ts_max);
>> > Rast_add_d_color_rule(&val1, 0, 0, 0, &val2, 255, 255, 255, &colors);
>> > ---------------
>> >
>> > ts_min, ts_max are known from the data processed,
>> > val1 and val2 are declared as DCELL instead of const DCELL as required,
>> > but if I declare const DCELL val1, then I cannot write stats to it for
>> > palette definition...
>> >
>> > What I am doing wrong?
>>
>> If you declare const DCELL val1, you can not pass a pointer to val1 to
>> another function, because this other function could then easily modify
>> to contents of that pointer.
>
>
> This is of course true.
>
>
>> Rast_add_d_color_rule() requires const
>> DCELL *, not const DCELL.
>>
>
> Strange, (generated) documentation says const DCELL * [1] which fits with
> the source code [2, 3].
>
> I haven't tried compile anything now but isn't `const DCELL` constant
> (value) and `const DCELL *` pointer to constant value. While `const DCELL *
> const` would be constant pointer to constant value.
>
> Also
>
> const DCELL val;
> const DCELL * pval = &val;
>
> should work and carry on the constness which is exactly what should be
> happening when calling the Rast_add_d_color_rule() function.
>
> So, I don't understand.
>
> Vaclav
>
> [1]
> http://grass.osgeo.org/programming7/color__rule_8c.html#a160535a46694589674f68c60eac23a05
> [2] lib/raster/color_rule.c:35:void Rast_add_d_color_rule(const DCELL *
> val1, int r1, int g1, int b1, ...
> [3] include/defs/raster.h:198:void Rast_add_d_color_rule(const DCELL *,
> int, int, int, ...
>
>
>> Markus M
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>>
>
>
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