Re: [PATCH] system: grub: Use librsvg to convert SVG to PNG

[Ludovic Courtès]

Hi Mark!

Mark H Weaver <address@hidden> skribis:

> The attached patch eliminates the use of 'inkscape' and 'imagemagick' to
> convert our grub background image from SVG to PNG.  The job is now done
> using 'librsvg' [1] via Guile's dynamic FFI.  I was unable to perform
> the needed scaling using the 'rsvg-convert' program, so I had to use
> librsvg directly.
>
> As a side benefit, the resulting image quality should be superior when
> scaling is performed, because scaling is now effectively done in the
> vector representation during rendering, whereas previously it was done
> in the raster representation as a separate step.
>
> What do you think?

I think it’s excellent.  :-)
> From a50f358b083cff4d156cd7116fee516952fc9bcf Mon Sep 17 00:00:00 2001
> From: Mark H Weaver <address@hidden>
> Date: Fri, 2 Sep 2016 02:26:43 -0400
> Subject: [PATCH] system: grub: Use librsvg to convert SVG to PNG.
>
> * guix/build/svg.scm: New file.
> * Makefile.am (MODULES): Add it.
> * gnu/system/grub.scm (svg->png): Add 'width' and 'height' arguments.
> Reimplement using (guix build svg).  Drop references to 'inkscape' and
> 'imagemagick'.
> (resize-image): Remove.
> (grub-background-image): Adapt to the incorporation of scaling into
> 'svg->png'.

[...]

> +(define-module (guix build svg)
> +  #:use-module (ice-9 match)
> +  #:use-module (system foreign)
> +  #:use-module (rnrs bytevectors)
> +  #:export (svg->png))

Is there are reason for not using guile-rsvg and guile-cairo?  Otherwise
I think it would be preferable (they’d need to be autoloaded so that
‘make’ doesn’t fail when they’re missing, but that’s OK.)

I found an example that Andy had posted:

  https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00753.html

Thank you!

Ludo’.