[Qgis-developer] Re: New Symbology : merge borders on nodes for lines

[Martin Dobias]

On Thu, Feb 17, 2011 at 1:33 PM, kimaidou <kimaidou at gmail.com> wrote:
>
> 2011/2/17 Carson Farmer <carson.farmer at gmail.com>
>>
>> Perhaps 'Symbol layer ordering' or simply 'layer order'?
>
> I dislike "layer order" as it is confusing : do we speak of layers from the
> canvas ? Or "style" layers ?
> For me we should use the term "layer" in Qgis only for vector and raster
> layers

Frankly, with the introduction of symbology-ng I have created some
mess in the terminology and I am not sure how to get out of this.
Where are the problems:
- "style" - before the style referred to Layer style (i.e. renderer,
labeling). symbology-ng uses this term for a collection of symbols
(and other visual items)
- "color ramp" - a convenient source of colors for symbology-ng.
Shouldn't that be called a "colormap" since it could be either a color
gradient, colors from a palette or just a bunch of random colors?
- "layer" - there are map layers and there are symbol layers. I think
that generally speaking, a layer always means a map layer.
- "categorized" / "graduated" renderer - I remember Carson raising the
discussion that these terms are not very clear

An insight from a english native speaker and preferably a user of
several GIS would be valuable. It would be good to disambiguate the
terms.


> Shouldnt we use a different terme for styles within one vector layer ?
> We could name them "substyles"
> This way  "Symbol Levels" would become "substyle order"

Personally I do not like the term substyle order.


> So correct me if I am wrong, but you can define the order with 2 different
> manners :
> * A/ use the arrows in [1] (left side of the ui) to change the order of the
> different styles
> * B/ click on "symbol levels" and change the integers in the table : this
> 2nd manner overwrite the first, no ?

No, it is more complex. Normally when a renderer renders a map layer,
for each feature it renders symbol layers one by one and proceeds to
another feature. By enabling symbol levels you tell the renderer that
it should first render first symbol layer of each feature and then
render second symbol layer of each feature. The numbers in the symbol
level table tell in what pass a symbol layer will be drawn (smaller
number = drawing earlier).

This probably needs a better introduction in a blog post or
documentation with examples.

Martin