f5667953f7
* lisp/image/image-converter.el (image-convert): Make image-convert bug out earlier on a wrong IMAGE-FORMAT value (bug#38310).
247 lines
10 KiB
EmacsLisp
247 lines
10 KiB
EmacsLisp
;;; image-converter.el --- Converting images from exotic formats -*- lexical-binding: t -*-
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;; Copyright (C) 2019 Free Software Foundation, Inc.
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;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
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;; Keywords: images
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software: you can redistribute it and/or modify
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;; it 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
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;; (at your option) any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but 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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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; The main interface function here is `image-convert'.
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;;; Code:
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(require 'cl-generic)
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(eval-when-compile (require 'cl-lib))
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(defcustom image-converter nil
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"Type of the external image converter to use.
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The value should a symbol, either `imagemagick', `graphicsmagick',
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or `ffmpeg'.
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If nil, Emacs will try to find one of the supported converters
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installed on the system."
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:group 'image
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:type 'symbol
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:version "27.1")
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(defvar image-converter-regexp nil
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"A regexp that matches the file name suffixes that can be converted.")
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(defvar image-converter--converters
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'((graphicsmagick :command ("gm" "convert") :probe ("-list" "format"))
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(ffmpeg :command "ffmpeg" :probe "-decoders")
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(imagemagick :command "convert" :probe ("-list" "format")))
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"List of supported image converters to try.")
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(defun image-convert-p (source &optional data-p)
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"Return `image-convert' if SOURCE is an image that can be converted.
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SOURCE can either be a file name or a string containing image
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data. In the latter case, DATA-P should be non-nil. If DATA-P
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is a string, it should be a MIME format string like
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\"image/gif\"."
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;; Find an installed image converter.
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(unless image-converter
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(image-converter--find-converter))
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(and image-converter
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(or (and (not data-p)
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(string-match image-converter-regexp source))
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(and data-p
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(symbolp data-p)
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(string-match "/" (symbol-name data-p))
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(string-match
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image-converter-regexp
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(concat "foo." (image-converter--mime-type data-p)))))
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'image-convert))
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(defun image-convert (image &optional image-format)
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"Convert IMAGE file to the PNG format.
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IMAGE can either be a file name or image data.
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To pass in image data, IMAGE should a string containing the image
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data, and IMAGE-FORMAT should be a symbol with a MIME format name
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like \"image/webp\". For instance:
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(image-convert data-string 'image/bmp)
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IMAGE can also be an image object as returned by `create-image'.
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This function converts the image to PNG, and the converted image
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data is returned as a string."
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;; Find an installed image converter.
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(unless image-converter
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(image-converter--find-converter))
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(unless image-converter
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(error "No external image converters available"))
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(when (and image-format
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(not (= (length (split-string (symbol-name image-format) "/")) 2)))
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(error "IMAGE-FORMAT should be a symbol like `image/png'"))
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(with-temp-buffer
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(set-buffer-multibyte nil)
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(when-let ((err (image-converter--convert
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image-converter
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(if (listp image)
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(plist-get (cdr image) :file)
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image)
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(if (listp image)
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(plist-get (cdr image) :data-p)
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image-format))))
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(error "%s" err))
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(if (listp image)
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;; Return an image object that's the same as we were passed,
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;; but ignore the :type value.
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(apply #'create-image (buffer-string) 'png t
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(cl-loop for (key val) on (cdr image) by #'cddr
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unless (eq key :type)
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append (list key val)))
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(buffer-string))))
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(defun image-converter--value (type elem)
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"Return the value of ELEM of image converter TYPE."
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(let ((value (plist-get (cdr (assq type image-converter--converters)) elem)))
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(if (stringp value)
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(list value)
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value)))
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(cl-defmethod image-converter--probe ((type (eql graphicsmagick)))
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"Check whether the system has GraphicsMagick installed."
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(with-temp-buffer
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(let ((command (image-converter--value type :command))
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formats)
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(when (and (executable-find (car command))
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(zerop (apply #'call-process (car command) nil '(t nil) nil
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(append (cdr command)
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(image-converter--value type :probe)))))
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(goto-char (point-min))
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(when (re-search-forward "^-" nil t)
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(forward-line 1)
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;; Lines look like
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;; " 8BIM P rw- Photoshop resource format".
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(while (re-search-forward "^ *\\([A-Z0-9]+\\) +. +r" nil t)
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(push (downcase (match-string 1)) formats)))
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(nreverse formats)))))
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(cl-defmethod image-converter--probe ((type (eql imagemagick)))
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"Check whether the system has ImageMagick installed."
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(with-temp-buffer
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(let ((command (image-converter--value type :command))
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formats)
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;; Can't check return value; ImageMagick convert usually returns
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;; a non-zero result on "-list format".
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(when (executable-find (car command))
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(apply #'call-process (car command) nil '(t nil) nil
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(append (cdr command) (image-converter--value type :probe))))
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(goto-char (point-min))
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(when (re-search-forward "^-" nil t)
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(forward-line 1)
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;; Lines look like
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;; " WPG* r-- Word Perfect Graphics".
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(while (re-search-forward "^ *\\([A-Z0-9]+\\)\\*? +r" nil t)
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(push (downcase (match-string 1)) formats)))
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(nreverse formats))))
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(cl-defmethod image-converter--probe ((type (eql ffmpeg)))
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"Check whether the system has ffmpeg installed."
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(with-temp-buffer
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(let ((command (image-converter--value type :command))
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formats)
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(when (and (executable-find (car command))
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(zerop (apply #'call-process (car command) nil '(t nil) nil
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(append (cdr command)
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(image-converter--value type :probe)))))
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(goto-char (point-min))
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(when (re-search-forward "^ *-" nil t)
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(forward-line 1)
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;; Lines look like
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;; " V....D alias_pix Alias/Wavefront PIX image"
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(while (re-search-forward "^ *V[^ ]+ +\\([a-z0-9_]+\\)" nil t)
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(push (match-string 1) formats)))
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(nreverse formats)))))
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(defun image-converter--find-converter ()
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"Find an installed image converter."
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(catch 'done
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(dolist (elem image-converter--converters)
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(when-let ((formats (image-converter--probe (car elem))))
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(setq image-converter (car elem)
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image-converter-regexp (concat "\\." (regexp-opt formats) "\\'"))
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(throw 'done image-converter)))))
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(cl-defmethod image-converter--convert ((type (eql graphicsmagick)) source
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image-format)
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"Convert using GraphicsMagick."
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(image-converter--convert-magick type source image-format))
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(cl-defmethod image-converter--convert ((type (eql imagemagick)) source
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image-format)
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"Convert using ImageMagick."
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(image-converter--convert-magick type source image-format))
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(defun image-converter--mime-type (image-format)
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(and (symbolp image-format)
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(cadr (split-string (symbol-name image-format) "/"))))
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(defun image-converter--convert-magick (type source image-format)
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(let ((command (image-converter--value type :command)))
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(unless (zerop (if image-format
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;; We have the image data in SOURCE.
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(progn
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(insert source)
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(apply #'call-process-region (point-min) (point-max)
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(car command) t t nil
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(append
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(cdr command)
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(list (format "%s:-"
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(image-converter--mime-type
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image-format))
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"png:-"))))
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;; SOURCE is a file name.
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(apply #'call-process (car command)
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nil t nil
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(append (cdr command)
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(list (expand-file-name source) "png:-")))))
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;; If the command failed, hopefully the buffer contains the
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;; error message.
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(buffer-string))))
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(cl-defmethod image-converter--convert ((type (eql ffmpeg)) source
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image-format)
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"Convert using ffmpeg."
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(let ((command (image-converter--value type :command)))
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(unless (zerop (if image-format
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(progn
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(insert source)
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(apply #'call-process-region
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(point-min) (point-max) (car command)
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t '(t nil) nil
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(append
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(cdr command)
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(list "-i" "-"
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"-c:v" "png"
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"-f" "image2pipe" "-"))))
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(apply #'call-process
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(car command)
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nil '(t nil) nil
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(append (cdr command)
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(list "-i" (expand-file-name source)
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"-c:v" "png" "-f" "image2pipe"
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"-")))))
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"ffmpeg error when converting")))
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(provide 'image-converter)
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;;; image-converter.el ends here
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