Re: [matplotlib-devel] MEP26: Artist-level stylesheets

[jamesramm <jam...@gm...>]

R Hattersley wrote
> I'm not sure what it is about CSS syntax that isn't up to the job.
> Forexample, SVG works with standard CSS syntax
> (seehttp://www.w3.org/TR/SVG/styling.html#StylingWithCSS). Perhaps we just
> havea different view of what constitutes CSS vs. HTML/SVG/whatever.The
> example in the SVG spec is:

> rect {  fill: red;  stroke: blue;  stroke-width: 3}

> But if we define the element name for a Line2D instance as "line2d"
> thenCSS snippet could just become:

> line2d {  stroke: blue;  stroke-width: 3}

You've just noted it: Line2D isn't a CSS selector..likewise, the properties
we want to call upon (like linewidth) are not CSS attributes. There are many
matplotlib properties that don't have an analogous CSS property/attribute
(that I know of); we might aswell define the mpl properties in our 'CSS'
subset.So we could base our language on CSS rules, but we need to define new
tokens. This means writing, or more likely, extending a parser. Not huge,
but not trivial. 
R Hattersley wrote
> The DOM facade could help bridge the gap. For example, a "DOM"
> instancereturned by an Axes object could pretend to have "text" element
> children.Styling those would route the style information back to the
> underlying Axesobject. For example:

> text {  font-size: 12pt;}axes text.ylabel {  font-size: 10pt;}

This could be one way. Another way that would fit and I quite like is
similar to what is employed by mapnik/the tilemill, in that we simply have
nested declaration blocks, e.g:
    Axes {        gid: 'axes1';        autoscalex_on: True;        ::ylabel
{                text: 'Y-Axis';                font-size: 10;                 
}        }
I think this would be easier to parse and slightly clearer to read as it can
be 'attached' to the artist container it refers to (imagine if there were 2
axes in a figure...). It is also easy to write in BNF, by just adding
another option to the Declaration block:
Rule := Selector '{' [Declaration] '}'Declaration := Attribute':' Value';' |
Rule...
But...small steps. I would start by introducing something for artist
primitives and for selectively applying to primitives using the  gid 



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