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Re: [PATCH] system: grub: Convert grub background using rsvg-convert
From: |
Andy Wingo |
Subject: |
Re: [PATCH] system: grub: Convert grub background using rsvg-convert |
Date: |
Mon, 31 Aug 2015 10:57:17 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
On Fri 28 Aug 2015 19:15, Luis Felipe López Acevedo <address@hidden> writes:
> Modifying the document background does not affect the design at all,
> because we are using the dark rectangle on top of it as the background
> of the image, so it doesn't matter what the background of the document
> is.
>
> Could it be that rsvg-convert is complaining about transparency in the
> page/document background and not about the transparency of the
> checkerboard pattern in the "Background" layer? Because it is not
> complaining about the transparency in the layer that contains the logo
> (which has transparency as well), is it?
We could use guile-cairo / guile-rsvg to convert, fwiw. Better to do
that than to cause our graphics people to modify the image.
(use-modules (rsvg) (cairo))
(define (->int x) (inexact->exact (ceiling x)))
(define (render-to-png in-svg out-png)
(let ((svg (rsvg-handle-new-from-file in-svg)))
(call-with-values (lambda () (rsvg-handle-get-dimensions svg))
(lambda (width height em ex)
(let* ((surf (cairo-image-surface-create 'argb32
(->int width)
(->int height)))
(cr (cairo-create surf)))
(rsvg-handle-render-cairo svg cr)
(cairo-surface-flush surf)
(cairo-surface-write-to-png (cairo-get-target cr) out-png))))))
That will render a png with the svg's natural pixel dimensions. You can
use the png as is, or instead of rendering to a png you could use "surf"
as a source surface for other paint operations, for example if you want
to down-scale the image nicely. Here's an example, for a suitable
definition of create-image-surface and scale-dimensions:
(call-with-values (lambda () (create-image-surface filename width height))
(lambda (surface swidth sheight)
(if surface
(call-with-values (lambda () (scale-dimensions (/ swidth 1.0
sheight)))
(lambda (x0 y0 width height)
(cairo-save cr)
(cairo-translate cr x0 y0)
(cairo-scale cr (/ width swidth) (/ height sheight))
(cairo-set-source-surface cr surface 0 0)
(cairo-pattern-set-filter (cairo-get-source cr) 'best)
(cairo-rectangle cr 0 0 swidth sheight)
(cairo-fill cr)
(cairo-restore cr)
(values width height)))
(values 0 0))))
FWIW :)
Cheers,
Andy