[Qgis-developer] color ramps improvements

[Paolo Cavallini]

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.
> 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?
> 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.

NB: palettes with transparency are not previewed in a meaningful way.
>
> 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.
> 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.
> 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).
>
> 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.
>> 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?)
All the best.

-- 
Paolo Cavallini - Faunalia
www.faunalia.eu
Full contact details at www.faunalia.eu/pc
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