Re: rfc: basic color support

[Juergen Reuter]

On Thu, 17 Feb 2005, Erlend Aasland wrote:

> On Thu, 17 Feb 2005 02:13:54 +0100, Han-Wen Nienhuys <address@hidden> wrote:
> > * I'd almost be tempted to either make a smob, or use a vector.
> Hmmm, I'll have to look more into smobs...
> 
> > * don't forget about the svg and tex  backends.
> Ok
> 
> > * implementation seems fine.
> Great, but there is a irritating "bug": noteheads seems to be engraved
> pretty early in the process, so they are overwritten by other
> engravers (StaffSymbol). See attached pdf.
> 

We already had some discussion on color in the past, the last time maybe 
one year ago.  One of the issues that was discussed is layering of grobs 
in the output (i.e. like in xfig, assign a layer number as a property to 
each grob, and in the backend, output the grobs in ascending number of 
layers).

IIRC, Jan at that time mentioned that there is already support for layered 
output.  However, this was quite a long time ago, and I do not know what 
the situation with the new backends is.  Maybe this is the right time to 
think about layered output in the backend once again.

Another issue that I raised in the past is, that setting the color on the 
Grob level is a good starting point, but in many cases not sufficient 
(e.g. when having multi-colored lines as around 10th century, or in some 
contemporary educational works, where noteheads are colored depending on 
their pitch).  Instead of a single color property, some grobs may require 
a more detailed description (e.g. for the StaffSymbol grob, a 
per-staffline list of colors (or maybe even a scheme function that maps 
the staffline number to a color tuple?)).

In some cases, you also want to set a color for a bunch of grobs 
simultaneously (e.g. typically you won't change the color for solely the 
beams, but also for flags and stems).  But for common such cases, we could 
provide macros that set the color for all relevant grobs, I guess.

Greetings,
Jürgen

> 
> Erlend
> 
> > 
> > --
> > 
> >  Han-Wen Nienhuys   |   address@hidden   |   http://www.xs4all.nl/~hanwen
> > 
> >
>