;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2015 Andy Wingo <wingo@igalia.com>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu build svg)
  #:use-module (rsvg)
  #:use-module (cairo)
  #:use-module (srfi srfi-11)
  #:export (svg->png))

(define* (downscaled-surface surface
                             #:key
                             source-width source-height
                             width height)
  "Return a new rendering context where SURFACE is scaled to WIDTH x HEIGHT."
  (let ((cr (cairo-create (cairo-image-surface-create 'argb32
                                                      width height))))
    (cairo-scale cr (/ width source-width) (/ height source-height))
    (cairo-set-source-surface cr surface 0 0)
    (cairo-pattern-set-filter (cairo-get-source cr) 'best)
    (cairo-rectangle cr 0 0 source-width source-height)
    (cairo-fill cr)
    cr))

(define* (svg->png in-svg out-png
                   #:key width height)
  "Render the file at IN-SVG as a PNG file in OUT-PNG.  When WIDTH and HEIGHT
are provided, use them as the dimensions of OUT-PNG; otherwise preserve the
dimensions of IN-SVG."
  (define svg
    (rsvg-handle-new-from-file in-svg))

  (let-values (((origin-width origin-height em ex)
                (rsvg-handle-get-dimensions svg)))
    (let* ((surf (cairo-image-surface-create 'argb32
                                             origin-width origin-height))
           (cr   (cairo-create surf)))
      (rsvg-handle-render-cairo svg cr)
      (cairo-surface-flush surf)
      (let ((cr (if (and width height
                         (not (= width origin-width))
                         (not (= height origin-height)))
                    (downscaled-surface surf
                                        #:source-width origin-width
                                        #:source-height origin-height
                                        #:width width
                                        #:height height)
                    cr)))
        (cairo-surface-write-to-png (cairo-get-target cr) out-png)))))

;;; svg.scm ends here
</tr>
<tr><td><span title='2020-12-08 16:40:30 +0100'>2020-12-08</span></td><td><a href='/guix/commit/tests/opam.scm?id=15ee1b8317adeb74938f3bb7f0c7cb635a818292'>guix: opam: Pass default repository to recursive importer.</a><span class='msg-avail'>...</span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2020-10-02 00:44:14 +0200'>2020-10-02</span></td><td><a href='/guix/commit/tests/opam.scm?id=23dc21f05b54ef63daaea9eb301cfddbc4c82ddb'>tests: opam: Test additional syntax.</a><span class='msg-avail'>...</span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2020-10-02 00:30:23 +0200'>2020-10-02</span></td><td><a href='/guix/commit/tests/opam.scm?id=ad05537e32173403d034a0d552092f566abd05a5'>tests: opam: Factorize tests.</a><span class='msg-avail'>...</span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2020-01-17 14:22:07 +0100'>2020-01-17</span></td><td><a href='/guix/commit/tests/opam.scm?id=282f91790a5bbd0d9b3223c4bfd45b66e418c200'>import: opam: Avoid uses of '@@' in tests.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-09-07 22:25:14 +0200'>2019-09-07</span></td><td><a href='/guix/commit/tests/opam.scm?id=1d03a9198db6f3656a34d62eb89e5f7d5a99e76a'>tests: opam: Fix input type in import test.</a><span class='msg-avail'>...</span></td><td>Julien Lepiller</td></tr>