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date Mon, 13 Aug 2007 09:02:59 +0200
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1 @c $Id: tm-view-m=en.texi,v 1.1.1.1 1996/12/18 22:43:52 steve Exp $
2
3 @node method, Mechanism of tm-view, mime/viewer-mode, tm-view
4 @comment node-name, next, previous, up
5 @section method
6 @cindex method
7
8 In @code{mime/viewer-mode}, you can do play (@key{v}), extract
9 (@key{e}), or print (@key{C-c C-p}) for each content. These operations
10 are called ``decoding operation(s) (for a content)''. And kind of
11 decoding operations are called @strong{decoding-mode}.
12
13 When decoding operation is driven, tm-view calls a procedure matched
14 for the condition, such as content-type. This procedure is called
15 @strong{method}.
16
17 There are two kinds of method. One is Emacs Lisp function, called
18 @strong{internal method}. Another one is external program, called
19 @strong{external method}.
20
21 Internal method operates in Emacs, so it can do carefully.
22
23 External method is called as asynchronous process, so Emacs does not
24 wait while method is running. So it is good for big data, such as
25 audio, image or video.
26
27 @menu
28 * decoding-condition:: Setting of content decoding condition
29 * Format of method value::
30 * Example of decoding-condition::
31 * environment variables::
32 @end menu
33
34
35 @node decoding-condition, Format of method value, method, method
36 @comment node-name, next, previous, up
37 @subsection Setting of content decoding condition
38 @cindex content decoding condition
39
40 When decoding operation is driven, tm-view calls a method matched for
41 the condition searched from the variable
42 @code{mime/content-decoding-condition}.
43
44 Variable @code{mime/content-decoding-condition} is defined as a list
45 with the following syntax:
46
47 @lisp
48 (condition1 condition2 ...)
49 @end lisp
50
51 Each condition are association-list with the following syntax:
52
53 @lisp
54 ((field-type_1 . value_1)
55 (field-type_2 . value_2)
56 ...)
57 @end lisp
58
59 For example, if you want to call the external method named tm-plain to
60 decode every text/plain type content, you can define the condition
61 like
62
63 @lisp
64 ((type . "text/plain")
65 (method "tm-plain" nil 'file 'type 'encoding 'mode 'name))
66 @end lisp
67
68 As you notice, now you can define the arguments to pass to a external
69 method. Refer to @xref{Format of method value} section for more
70 explanation.
71
72 This condition definition will match all contents whose types are
73 text/plain. Here is an another example:
74
75 @lisp
76 ((type . "text/plain")
77 (method "tm-plain" nil 'file 'type 'encoding 'mode 'name)
78 (mode . "play"))
79 @end lisp
80
81 This will match the content whose type is text/plain and the mode is
82 play.
83
84 @lisp
85 ((method "metamail" t "-m" "tm" "-x" "-d" "-z" "-e" 'file)
86 (mode . "play"))
87 @end lisp
88
89 This will match all contents which have a mode of play.
90
91 The conditions defined in a mime/content-decoding-condition variable
92 are examined from top to bottom. The first matching condition becomes
93 valid and the method specified in that condition definition will be
94 executed.
95
96
97 @node Format of method value, Example of decoding-condition, decoding-condition, method
98 @comment node-name, next, previous, up
99 @subsection Format of method value part
100 @cindex Format of method value part
101
102 You can specify the method field of the decoding-condition definition
103 in two different ways,
104
105 @lisp
106 (method . SYMBOL)
107 @end lisp
108
109 or
110
111 @lisp
112 (method STRING FLAG ARGUMENT1 ARGUMENT2 ...)
113 @end lisp
114
115 can be accepted.
116
117 When a symbol is specified in the method field, a function whose name
118 is SYMBOL will be called as an internal method.
119
120 When a list is specified in the method field, it will be called as an
121 external method.
122
123 The list below shows the meaning of the parameters when the external
124 method is specified in the method field.
125
126 @table @samp
127 @item STRING
128 name of an external method
129 @item FLAG
130 If @code{t}, both the content header and the content body are
131 passed to an external method. if nil, only the content body is
132 passed to an external method.
133 @item ARGUMENTs
134 list of arguments passed to an external method
135 @end table
136
137 An argument passed to an external method can be in one of the
138 following formats:
139
140 @table @samp
141 @item STRING
142 string itself
143 @item 'SYMBOL
144 value gotten using SYMBOL as a key (see below)
145 @item 'STRING
146 value gotten using STRING as a key (see below)
147 @end table
148
149 'SYMBOL can be one of the following:
150
151 @table @samp
152 @item 'file
153 name of a file holding the original content
154 @item 'type
155 content-type/sub-type of Content-Type field
156 @item 'encoding
157 field body of Content-Transfer-Encoding field
158 @item 'mode
159 decoding-mode
160 @item 'name
161 name of a file created by decode operation
162 @end table
163
164 'STRING is used to search a parameter of the Content-Type field whose
165 name matches with it, and pass the value of that parameter to the
166 external method.
167
168
169 @node Example of decoding-condition, environment variables, Format of method value, method
170 @comment node-name, next, previous, up
171 @subsection Examples of decoding-condition
172 @cindex Examples of decoding-condition
173
174 The default definition of a mime/content-decoding-condition variable
175 is shown below.
176
177 @lisp
178 (defvar mime/content-decoding-condition
179 '(((type . "text/plain")
180 (method "tm-plain" nil 'file 'type 'encoding 'mode 'name))
181 ((type . "text/x-latex")
182 (method "tm-latex" nil 'file 'type 'encoding 'mode 'name))
183 ((type . "audio/basic")
184 (method "tm-au" nil 'file 'type 'encoding 'mode 'name))
185 ((type . "image/gif")
186 (method "tm-image" nil 'file 'type 'encoding 'mode 'name))
187 ((type . "image/jpeg")
188 (method "tm-image" nil 'file 'type 'encoding 'mode 'name))
189 ((type . "image/tiff")
190 (method "tm-image" nil 'file 'type 'encoding 'mode 'name))
191 ((type . "image/x-tiff")
192 (method "tm-image" nil 'file 'type 'encoding 'mode 'name))
193 ((type . "image/x-xbm")
194 (method "tm-image" nil 'file 'type 'encoding 'mode 'name))
195 ((type . "image/x-pic")
196 (method "tm-image" nil 'file 'type 'encoding 'mode 'name))
197 ((type . "video/mpeg")`
198 (method "tm-mpeg" nil 'file 'type 'encoding 'mode 'name))
199 ((type . "application/octet-stream")
200 (method "tm-file" nil 'file 'type 'encoding 'mode 'name))
201 ((type . "message/partial")
202 (method . mime/decode-message/partial-region))
203 ((method "metamail" t
204 "-m" "tm" "-x" "-d" "-z" "-e" 'file)(mode . "play"))
205 ))
206 @end lisp
207
208 For example, if you want to use metamail to decode any contents,
209
210 @lisp
211 (setq mime/content-decoding-condition
212 '(
213 ((method "metamail" t "-m" "tm" "-x" "-d" "-z" "-e" 'file))
214 ))
215 @end lisp
216
217 will work.
218
219 A mime/content-decoding-condition variable provides you of very flexible
220 way to define the conditions of decoding. It can be simple if you only
221 need the a few decoding methods, while it can be very complicated if you
222 want to use the separate decoding method for each type/mode combination.
223
224 Following function may be useful to set decoding-condition. It is a
225 function of tl-atype.el.
226
227
228 @deffn{Function} set-atype symbol alist
229
230 Add condition @var{alist} to symbol @var{symbol}.
231
232 Example:
233
234 @lisp
235 (set-atype 'mime/content-decoding-condition
236 '((type . "message/external-body")
237 ("access-type" . "anon-ftp")
238 (method . mime/decode-message/external-ftp)
239 ))
240 @end lisp
241 @end deffn
242
243
244 @node environment variables, , Example of decoding-condition, method
245 @comment node-name, next, previous, up
246 @subsection environment variables
247 @cindex environment variables
248
249 Standard methods of tm-view reference some environment variables. You
250 can specify them to customize.
251
252 @table @var
253 @item TM_TMP_DIR
254 Directory for temporary files or extracted files. Default value is
255 `/tmp/'.
256
257 @item VIDEO_DITHER
258 Dither for mpeg_play. Default value is `gray'.
259
260 @item TM_WWW_BROWSER
261 WWW browser name. Default value is `netscape'.
262 @end table