1 ;;; animate.el --- make text dance
3 ;; Copyright (C) 2001-2017 Free Software Foundation, Inc.
5 ;; Maintainer: Richard Stallman <rms@gnu.org>
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software: you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation, either version 3 of the License, or
13 ;; (at your option) any later version.
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
25 ;; (animate-string STRING VPOS &optional HPOS)
26 ;; makes the string STRING appear starting at VPOS, HPOS
27 ;; by having each letter swoop into place from random starting position.
29 ;; animate-birthday-present was the first application of this program.
33 ;;; STRING is the string to be displayed,
34 ;;; and DEST-X, DEST-Y say where on the screen
37 ;;; This function returns a list describing
38 ;;; all the characters and the paths they should take.
39 ;;; Each element has the form
40 ;;; (CHAR START-Y START-X DEST-Y DEST-X).
42 ;;; The start position of each character is chosen randomly.
43 ;;; The destination is chosen to put it in the right place
44 ;;; in the string when the whole string finally reaches its
45 ;;; specified position.
52 (defun animate-initialize (string vpos hpos
)
53 (let ((characters nil
))
54 (dotimes (i (length string
))
56 (cons (list (aref string i
)
57 ;; Random starting positions.
58 (random (window-height))
59 (random (1- (window-width)))
60 ;; All the chars should end up
61 ;; on the specified line.
63 ;; The Ith character in the string
64 ;; needs to end up I positions later.
69 ;;; Display the characters in CHARACTERS,
70 ;;; each one FRACTION of the way from its start to its destination.
71 ;;; If FRACTION is 0, the characters appear in their starting positions.
72 ;;; If FRACTION is 1, the characters appear in their destinations.
74 (defun animate-step (characters fraction
)
75 (let ((remains (- 1 fraction
)))
76 (dolist (item characters
)
77 (let ((vpos (+ (* remains
(nth 1 item
))
78 (* fraction
(nth 3 item
))))
79 (hpos (+ (* remains
(nth 2 item
))
80 (* fraction
(nth 4 item
)))))
81 (animate-place-char (car item
) vpos hpos
)))))
83 ;;; Place the character CHAR at position VPOS, HPOS in the current buffer.
84 (defun animate-place-char (char vpos hpos
)
85 (goto-char (window-start))
89 (if (= (forward-line 1) 1)
92 (move-to-column (floor hpos
) t
)
93 (unless (eolp) (delete-char 1))
96 (defcustom animate-n-steps
10
97 "Number of steps `animate-string' will place a char before its last position."
100 (defvar animation-buffer-name nil
101 "String naming the default buffer for animations.
102 When nil animations displayed in the buffer named *Animation*.")
105 (defun animate-string (string vpos
&optional hpos
)
106 "Display STRING animations starting at position VPOS, HPOS.
107 The characters start at randomly chosen places,
108 and all slide in parallel to their final positions,
109 passing through `animate-n-steps' positions before the final ones.
110 If HPOS is nil (or omitted), center the string horizontally
111 in the current window."
113 (animate-initialize string vpos
115 ;; HPOS unspecified, so compute
116 ;; it so as to center the string.
117 (max 0 (/ (- (window-width) (length string
)) 2)))))
118 (show-trailing-whitespace nil
)
119 ;; Make sure indentation does not use tabs.
120 ;; They would confuse things.
121 (indent-tabs-mode nil
))
122 (dotimes (i animate-n-steps
)
123 ;; Bind buffer-undo-list so it will be unchanged when we are done.
124 ;; (We're going to undo all our changes anyway.)
125 (let (buffer-undo-list
127 ;; Display the characters at the Ith position.
128 ;; This inserts them in the buffer.
129 (animate-step characters
(/ i
1.0 animate-n-steps
))
130 ;; Make sure buffer is displayed starting at the beginning.
131 (set-window-start nil
1)
132 ;; Display it, and wait just a little while.
134 ;; Now undo the changes we made in the buffer.
135 (setq list-to-undo buffer-undo-list
)
137 (let ((undo-in-progress t
))
138 (setq list-to-undo
(primitive-undo 1 list-to-undo
))))))
139 ;; Insert the characters in their final positions.
140 (animate-step characters
1)
141 ;; Put the cursor at the end of the text on the line.
143 ;; Redisplay so they appear on the screen there.
145 ;; This is so that the undo command, used afterwards,
146 ;; will undo the "animate" calls one by one.
150 (defun animate-sequence (list-of-strings space
)
151 "Display animation strings from LIST-OF-STRING with buffer *Animation*.
152 Strings will be separated from each other by SPACE lines.
153 When the variable `animation-buffer-name' is non-nil display
154 animation in the buffer named by variable's value, creating the
155 buffer if one does not exist."
156 (let ((vpos (/ (- (window-height)
157 1 ;; For the mode-line
158 (* (1- (length list-of-strings
)) space
)
159 (length list-of-strings
))
161 (switch-to-buffer (get-buffer-create
162 (or animation-buffer-name
166 (while list-of-strings
167 (animate-string (car list-of-strings
) vpos
)
168 (setq vpos
(+ vpos space
1))
169 (setq list-of-strings
(cdr list-of-strings
)))))
172 (defun animate-birthday-present (&optional name
)
173 "Return a birthday present in the buffer *Birthday-Present*.
174 When optional arg NAME is non-nil or called-interactively, prompt for
175 NAME of birthday present receiver and return a birthday present in
176 the buffer *Birthday-Present-for-Name*."
177 (interactive (list (read-string "Birthday present for: "
179 ;; Make a suitable buffer to display the birthday present in.
180 (switch-to-buffer (get-buffer-create
182 (concat "*A-Present-for-" (capitalize name
) "*")
183 "*Birthday-Present*")))
185 ;; Display the empty buffer.
189 (animate-string "Happy Birthday," 6)
190 (animate-string "Happy Birthday" 6))
191 (when name
(animate-string (format "%s" (capitalize name
)) 7))
194 (animate-string "You are my sunshine," 10 30)
196 (animate-string "My only sunshine." 11 30)
198 (animate-string "I'm awful sad that" 12 30)
200 (animate-string "You've moved away." 13 30)
202 (animate-string "Let's talk together" 15 30)
204 (animate-string "And love more deeply." 16 30)
206 (animate-string "Please bring back" 17 30)
207 (animate-string "my sunshine" 18 34)
208 (animate-string "to stay!" 19 34))
212 ;;; animate.el ends here