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300 lines
11 KiB
EmacsLisp
300 lines
11 KiB
EmacsLisp
;;; image.el --- image API
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;; Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
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;; Maintainer: FSF
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;; Keywords: multimedia
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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 2, or (at your option)
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;; 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; see the file COPYING. If not, write to the
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;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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;; Boston, MA 02111-1307, USA.
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;;; Commentary:
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;;; Code:
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(defgroup image ()
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"Image support."
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:group 'multimedia)
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(defconst image-type-regexps
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'(("\\`/[\t\n\r ]*\\*.*XPM.\\*/" . xpm)
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("\\`P[1-6]" . pbm)
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("\\`GIF8" . gif)
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("\\`\211PNG\r\n" . png)
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("\\`[\t\n\r ]*#define" . xbm)
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("\\`\\(MM\0\\*\\|II\\*\0\\)" . tiff)
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("\\`[\t\n\r ]*%!PS" . postscript)
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("\\`\xff\xd8" . (image-jpeg-p . jpeg)))
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"Alist of (REGEXP . IMAGE-TYPE) pairs used to auto-detect image types.
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When the first bytes of an image file match REGEXP, it is assumed to
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be of image type IMAGE-TYPE if IMAGE-TYPE is a symbol. If not a symbol,
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IMAGE-TYPE must be a pair (PREDICATE . TYPE). PREDICATE is called
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with one argument, a string containing the image data. If PREDICATE returns
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a non-nil value, TYPE is the image's type ")
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(defun image-jpeg-p (data)
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"Value is non-nil if DATA, a string, consists of JFIF image data.
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We accept the tag Exif because that is the same format."
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(when (string-match "\\`\xff\xd8" data)
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(catch 'jfif
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(let ((len (length data)) (i 2))
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(while (< i len)
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(when (/= (aref data i) #xff)
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(throw 'jfif nil))
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(setq i (1+ i))
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(when (>= (+ i 2) len)
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(throw 'jfif nil))
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(let ((nbytes (+ (lsh (aref data (+ i 1)) 8)
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(aref data (+ i 2))))
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(code (aref data i)))
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(when (and (>= code #xe0) (<= code #xef))
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;; APP0 LEN1 LEN2 "JFIF\0"
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(throw 'jfif
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(string-match "JFIF\\|Exif" (substring data i (+ i nbytes)))))
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(setq i (+ i 1 nbytes))))))))
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;;;###autoload
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(defun image-type-from-data (data)
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"Determine the image type from image data DATA.
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Value is a symbol specifying the image type or nil if type cannot
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be determined."
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(let ((types image-type-regexps)
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type)
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(while (and types (null type))
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(let ((regexp (car (car types)))
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(image-type (cdr (car types))))
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(when (or (and (symbolp image-type)
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(string-match regexp data))
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(and (consp image-type)
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(funcall (car image-type) data)
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(setq image-type (cdr image-type))))
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(setq type image-type))
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(setq types (cdr types))))
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type))
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;;;###autoload
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(defun image-type-from-file-header (file)
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"Determine the type of image file FILE from its first few bytes.
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Value is a symbol specifying the image type, or nil if type cannot
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be determined."
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(unless (file-name-directory file)
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(setq file (expand-file-name file data-directory)))
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(setq file (expand-file-name file))
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(let ((header (with-temp-buffer
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(set-buffer-multibyte nil)
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(insert-file-contents-literally file nil 0 256)
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(buffer-string))))
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(image-type-from-data header)))
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;;;###autoload
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(defun image-type-available-p (type)
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"Value is non-nil if image type TYPE is available.
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Image types are symbols like `xbm' or `jpeg'."
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(and (boundp 'image-types) (not (null (memq type image-types)))))
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;;;###autoload
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(defun create-image (file-or-data &optional type data-p &rest props)
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"Create an image.
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FILE-OR-DATA is an image file name or image data.
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Optional TYPE is a symbol describing the image type. If TYPE is omitted
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or nil, try to determine the image type from its first few bytes
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of image data. If that doesn't work, and FILE-OR-DATA is a file name,
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use its file extension as image type.
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Optional DATA-P non-nil means FILE-OR-DATA is a string containing image data.
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Optional PROPS are additional image attributes to assign to the image,
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like, e.g. `:mask MASK'.
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Value is the image created, or nil if images of type TYPE are not supported."
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(when (and (not data-p) (not (stringp file-or-data)))
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(error "Invalid image file name `%s'" file-or-data))
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(cond ((null data-p)
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;; FILE-OR-DATA is a file name.
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(unless (or type
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(setq type (image-type-from-file-header file-or-data)))
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(let ((extension (file-name-extension file-or-data)))
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(unless extension
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(error "Cannot determine image type"))
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(setq type (intern extension)))))
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(t
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;; FILE-OR-DATA contains image data.
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(unless type
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(setq type (image-type-from-data file-or-data)))))
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(unless type
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(error "Cannot determine image type"))
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(unless (symbolp type)
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(error "Invalid image type `%s'" type))
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(when (image-type-available-p type)
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(append (list 'image :type type (if data-p :data :file) file-or-data)
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props)))
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;;;###autoload
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(defun put-image (image pos &optional string area)
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"Put image IMAGE in front of POS in the current buffer.
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IMAGE must be an image created with `create-image' or `defimage'.
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IMAGE is displayed by putting an overlay into the current buffer with a
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`before-string' STRING that has a `display' property whose value is the
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image. STRING is defaulted if you omit it.
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POS may be an integer or marker.
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AREA is where to display the image. AREA nil or omitted means
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display it in the text area, a value of `left-margin' means
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display it in the left marginal area, a value of `right-margin'
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means display it in the right marginal area."
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(unless string (setq string "x"))
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(let ((buffer (current-buffer)))
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(unless (eq (car-safe image) 'image)
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(error "Not an image: %s" image))
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(unless (or (null area) (memq area '(left-margin right-margin)))
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(error "Invalid area %s" area))
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(setq string (copy-sequence string))
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(let ((overlay (make-overlay pos pos buffer))
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(prop (if (null area) image (list (list 'margin area) image))))
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(put-text-property 0 (length string) 'display prop string)
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(overlay-put overlay 'put-image t)
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(overlay-put overlay 'before-string string))))
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;;;###autoload
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(defun insert-image (image &optional string area)
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"Insert IMAGE into current buffer at point.
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IMAGE is displayed by inserting STRING into the current buffer
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with a `display' property whose value is the image. STRING is
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defaulted if you omit it.
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AREA is where to display the image. AREA nil or omitted means
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display it in the text area, a value of `left-margin' means
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display it in the left marginal area, a value of `right-margin'
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means display it in the right marginal area."
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;; Use a space as least likely to cause trouble when it's a hidden
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;; character in the buffer.
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(unless string (setq string " "))
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(unless (eq (car-safe image) 'image)
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(error "Not an image: %s" image))
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(unless (or (null area) (memq area '(left-margin right-margin)))
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(error "Invalid area %s" area))
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(if area
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(setq image (list (list 'margin area) image))
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;; Cons up a new spec equal but not eq to `image' so that
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;; inserting it twice in a row (adjacently) displays two copies of
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;; the image. Don't try to avoid this by looking at the display
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;; properties on either side so that we DTRT more often with
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;; cut-and-paste. (Yanking killed image text next to another copy
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;; of it loses anyway.)
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(setq image (cons 'image (cdr image))))
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(let ((start (point)))
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(insert string)
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(add-text-properties start (point)
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(list 'display image
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;; `image' has the right properties to
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;; mark an intangible field.
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'intangible image
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'rear-nonsticky (list 'display)))))
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;;;###autoload
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(defun remove-images (start end &optional buffer)
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"Remove images between START and END in BUFFER.
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Remove only images that were put in BUFFER with calls to `put-image'.
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BUFFER nil or omitted means use the current buffer."
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(unless buffer
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(setq buffer (current-buffer)))
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(let ((overlays (overlays-in start end)))
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(while overlays
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(let ((overlay (car overlays)))
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(when (overlay-get overlay 'put-image)
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(delete-overlay overlay)))
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(setq overlays (cdr overlays)))))
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;;;###autoload
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(defun find-image (specs)
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"Find an image, choosing one of a list of image specifications.
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SPECS is a list of image specifications.
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Each image specification in SPECS is a property list. The contents of
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a specification are image type dependent. All specifications must at
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least contain the properties `:type TYPE' and either `:file FILE' or
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`:data DATA', where TYPE is a symbol specifying the image type,
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e.g. `xbm', FILE is the file to load the image from, and DATA is a
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string containing the actual image data. The specification whose TYPE
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is supported, and FILE exists, is used to construct the image
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specification to be returned. Return nil if no specification is
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satisfied.
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The image is looked for first on `load-path' and then in `data-directory'."
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(let (image)
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(while (and specs (null image))
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(let* ((spec (car specs))
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(type (plist-get spec :type))
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(data (plist-get spec :data))
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(file (plist-get spec :file))
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found)
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(when (image-type-available-p type)
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(cond ((stringp file)
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(let ((path load-path))
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(while (and (not found) path)
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(let ((try-file (expand-file-name file (car path))))
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(when (file-readable-p try-file)
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(setq found try-file)))
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(setq path (cdr path)))
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(unless found
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(let ((try-file (expand-file-name file data-directory)))
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(if (file-readable-p try-file)
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(setq found try-file))))
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(if found
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(setq image
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(cons 'image (plist-put (copy-sequence spec)
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:file found))))))
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((not (null data))
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(setq image (cons 'image spec)))))
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(setq specs (cdr specs))))
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image))
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;;;###autoload
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(defmacro defimage (symbol specs &optional doc)
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"Define SYMBOL as an image.
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SPECS is a list of image specifications. DOC is an optional
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documentation string.
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Each image specification in SPECS is a property list. The contents of
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a specification are image type dependent. All specifications must at
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least contain the properties `:type TYPE' and either `:file FILE' or
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`:data DATA', where TYPE is a symbol specifying the image type,
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e.g. `xbm', FILE is the file to load the image from, and DATA is a
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string containing the actual image data. The first image
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specification whose TYPE is supported, and FILE exists, is used to
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define SYMBOL.
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Example:
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(defimage test-image ((:type xpm :file \"~/test1.xpm\")
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(:type xbm :file \"~/test1.xbm\")))"
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`(defvar ,symbol (find-image ',specs) ,doc))
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(provide 'image)
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;;; image.el ends here
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