67 lines
2.8 KiB
Scheme
67 lines
2.8 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2015 Andy Wingo <wingo@igalia.com>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu build svg)
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#:use-module (rsvg)
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#:use-module (cairo)
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#:use-module (srfi srfi-11)
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#:export (svg->png))
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(define* (downscaled-surface surface
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#:key
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source-width source-height
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width height)
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"Return a new rendering context where SURFACE is scaled to WIDTH x HEIGHT."
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(let ((cr (cairo-create (cairo-image-surface-create 'argb32
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width height))))
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(cairo-scale cr (/ width source-width) (/ height source-height))
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(cairo-set-source-surface cr surface 0 0)
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(cairo-pattern-set-filter (cairo-get-source cr) 'best)
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(cairo-rectangle cr 0 0 source-width source-height)
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(cairo-fill cr)
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cr))
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(define* (svg->png in-svg out-png
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#:key width height)
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"Render the file at IN-SVG as a PNG file in OUT-PNG. When WIDTH and HEIGHT
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are provided, use them as the dimensions of OUT-PNG; otherwise preserve the
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dimensions of IN-SVG."
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(define svg
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(rsvg-handle-new-from-file in-svg))
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(let-values (((origin-width origin-height em ex)
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(rsvg-handle-get-dimensions svg)))
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(let* ((surf (cairo-image-surface-create 'argb32
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origin-width origin-height))
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(cr (cairo-create surf)))
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(rsvg-handle-render-cairo svg cr)
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(cairo-surface-flush surf)
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(let ((cr (if (and width height
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(not (= width origin-width))
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(not (= height origin-height)))
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(downscaled-surface surf
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#:source-width origin-width
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#:source-height origin-height
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#:width width
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#:height height)
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cr)))
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(cairo-surface-write-to-png (cairo-get-target cr) out-png)))))
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;;; svg.scm ends here
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