Re: Add alpha transparency to SVG backend (issue 330300043 by address@hidden)

[beauleetienne0]

On 2017/09/21 10:04:53, Knut_Petersen_t-online.de wrote:
> > Message:
> > Adds more flexibility to the coloring of elements in SVG files. It
is
> > disappointing how there is no support in PS, and thus our generation
of
> > PNG. This is useful though in my view, and at least it's available
> > somewhere.

> Postscript/Ghostscript allows to define transparency for a pdf target.

> BUT: We build our scores from a lot of symbols and a few postscript
functions.
> Most of the time those symbols overlap. What would be the result if we
would use
> transparent colors for stems, noteheads, ledger lines, flags,
accidentals, etc?
> I think the result would be pretty useless unless your
> intention is to show how we  construct our scores. The attached
lilypond source
> demonstrates how to persuade lilypond to generate a pdf with
transparency, and
> it demonstrates the problem I mentioned.

> You invested a lot of work, so the probability is high that there is a
real use
> for the feature. Could you be so kind to give an example to a man with
a lack of
> imagination?

> Knut

Seems way less friendly than by integrating the feature with coloring
(rgb-color). This method is also more limited to PS, whereas my focus
was more on SVG. Thanks for the way though, as the integration with
other backends could be added too; I was mistaken.

As a use for this feature, it can be used to put focus on a specific
place, using a lower opacity elsewhere; more usefully, it would allow
objects with .transparent true to be added to the file, not completely
omitted (caused me some trouble). In your project for visual score
playback (video), it would allow for MuseScore-style bars (if wanted).
Basically, it is more for debugging, but cool stuff like color blending
with near objects and color interaction would also be possible through
this as a first step.

This was more a grep work; very little adds the alpha functionality,
most just updates existing colors. It's possible for me to waste time on
the useless anyways. :)

https://codereview.appspot.com/330300043/