Re: Coloring broken in Lily 2.19.51? (PNG alpha-transparency coloring is broken)

[Hans Aikema]

> On 3 Dec 2016, at 13:52, Hans Aikema <address@hidden> wrote:
> 
> 
>> On 3 Dec 2016, at 13:18, Hans Aikema <address@hidden> wrote:
>> 
>> Ponders,
>> 
>> Anyone else using coloring in scores, using lilypond unstable and spotting 
>> coloring-issues when generating scores?
>> 
>> I spotted a horrible output for a score I created for beamer in our church 
>> service and upon futher inspection it appears caused by only partial 
>> coloring of the score from black to white: some barlines / stems were still 
>> in black and from the looks of it the ouline of the Lyric font is 
>> consistently black (filling is white; in 2.19.49 both appear to be white at 
>> first glance)
>> 
>> For recoloring the score I use the following LSR snippet:
>> http://lsr.di.unimi.it/LSR/Item?id=443
>> 
>> I’ll try to compose a minimal example showing the erratice behavior, but am 
>> curious if others are seeing the same.
> 
> Tracked down the issue to be related to PNG alpha-transparency… The PNG alpha 
> transparency no longer uses the actual color of the grobs, but black for 
> generating the partially transparent pixels
> 
> Modify the LSR snippet by adding
> 
> #(ly:set-option 'pixmap-format "pngalpha") % set PNG background to use Alpha 
> transparency
> 
> and the partial transparent blue pixels will become partial transparent black 
> pixels
> 
> 
> The modified LSR snippet showing the issue, using white, which makes the 
> sympoms even clearer (as there should be no hint of darkness in a partially 
> transparent white line):
> 
> 
> % PNG partially transparent pixels should be in grob-color (white)
> % but in 2.19.51 they are in black
> #(define (override-color-for-all-grobs color)
>  (lambda (context)
>   (let loop ((x all-grob-descriptions))
>    (if (not (null? x))
>     (let ((grob-name (caar x)))
>      (ly:context-pushpop-property context grob-name 'color color)
>      (loop (cdr x)))))))
> 
> #(ly:set-option 'pixmap-format "pngalpha") % set PNG background to use Alpha 
> transparency
> 
> \relative c' {
>  \applyContext #(override-color-for-all-grobs (x11-color ‘white))
>  c4\pp\< d e f
>  \grace { g16[( a g fis]) } g1\ff\!
> }
> 

Did a validation on 2.19.50…. there it was still fine, so the issue surfaced in 
between 2.19.50 and 2.19.51 releases. My gut-feel is that this is an undetected 
side-effect of David Kastrups changes to properly initialize with a pre-init as 
the other commits from there message seem to me to be unrelated to the issue at 
hand.