[Qgis-developer] color ramps improvements

[Etienne Tourigny]

On Fri, Aug 3, 2012 at 12:16 PM, Paolo Cavallini <cavallini at faunalia.it> wrote:
> Il 03/08/2012 16:52, Etienne Tourigny ha scritto:
>> is there an existing infrastructure for this in qgis/qt to do the following?
>>
>> 1) download the file
>> 2) unzip - I have added the GDAL funcitons to read zips, but not sure
>> if it's easy to unzip a file.
> quite the same as for plugins: I guess having the same widgets for
> installing plugins, styles, and ramps would be a great plus, both for
> users and for developers.

this is done in python - which has builtin functionality for unzipping files.

It might be better to invest in a plugin which can download the file
as well as look for updates periodically. Jim is working on some
python code to do that.

Perhaps the people working on the GSoC symbology project (Arun's work)
can give us any insight as to how the sharing of symbols works?

>> where would you get the metadata from? There is metadata for author,
>> group, but not for each gradient. Do you mean the gradient name?
> yes, name is often descriptive enough - when not, we can probably add tags?

again - this depends on Arun's work in progress. I'll have a look at his code.

>> Someone would have to step in, select a few and propose them. These
>> would be part of the symbols available by default.
> ok, let's start:
> - at least one DEM
> - one batymetry
> - a red, a green,and a blue scale
> - one "semaphore" (green to red through yellow)
> - two other diverging
> - more?
> Maybe we could make a poll? I'm sure specific sectors have their
> requirements.

would be nice. can you lead this effort starting from next week?

>
> NB: palettes with transparency are not previewed in a meaningful way.

you mean the transparency is not applied?

>>
>> I think that this will be easier once Arun's work on symbology
>> grouping and "social styles" is merged.
> agreed - see my other thread on GSoC, who was triggered by this issue.
>> Are you talking about clutter in the style manager or the cpt-city
>> dialog?
> in the style manager: we have now a long list of gradients, and the New
> ramp entry could be easily overlooked.

yes - it might be nice to have items for creating new elements inside
each box? I mean one for each type: *new gradient* *new random* *new
CollorBrewer* *new cpt-city*

>> If the latter - In this case you have about 3-4 groups which are
>> duplicated, out of more than 100, so I don't see how it adds to
>> clutter. I thought about removing the ColorBrewer option(as they are
>> available in cpt-city), but it is still relevant because there are
>> fewer options to choose from and it is simpler (and nicer) to work with.
> I think adding only the default ones (see above), and letting the users
> build the others, should be ok.

yes

>> This topic is more related to how the gradient is applied to the
>> raster/vector, so this sort of lies outside of the cpt-city dialog (I
>> think) - unless those classification methods are tied to specific
>> gradients?
> some of them yes. some gradients should be applied on absolute numbers,
> not relatively (e.g. slopes, DEM).

I guess I should add a property to each gradient relative vs. absolute

>>
>> Another functionality from 1-band plugin that is missing is the
>> possibility to invert colors and palette. This would be very useful,
>> but should it be inside the style manager or in the vector/raster
>> layer dialogs?
> IMHO, in the layer dialog.
>>> - the raster layer property dialog should be made more clear, and more
>>> homogeneous with that of vectors.
>> I agree - perhaps you can submit a mock-up?
> perhaps someone with better designing skills is more suitable.
> IMHO the default interpolation should be linear, not discrete.

should that be a user-selectable default by project or global?

>>> One more: I think the default listing should be by theme, not by author.
>> hmm do you mean the selection view? Because aside from that there is
>> no "theme" grouping yet.
> I mean in the cpt-city color ramp dialog (View is by default switched to
> All by author, should be Selections by theme?)

ok - but that is only a small selection from the cpt-city site

> All the best.
>
> --
> Paolo Cavallini - Faunalia
> www.faunalia.eu
> Full contact details at www.faunalia.eu/pc
> Nuovi corsi QGIS e PostGIS: http://www.faunalia.it/calendario
>