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add file previewing to the documentation

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Mentioned in #5.
This commit is contained in:
Gokcehan 2016-09-15 21:44:06 +03:00
parent 0395f75ea9
commit 878d28237a
2 changed files with 95 additions and 2 deletions
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47
doc.go
View File

@ -47,6 +47,7 @@ The following options can be used to customize the behavior of lf.
scrolloff int (default 0) scrolloff int (default 0)
tabstop int (default 8) tabstop int (default 8)
ifs string (default "") (not exported if empty) ifs string (default "") (not exported if empty)
previewer string (default "") (not filtered if empty)
shell string (default "$SHELL") shell string (default "$SHELL")
showinfo string (default "none") showinfo string (default "none")
sortby string (default "name") sortby string (default "name")
@ -171,7 +172,7 @@ It is possible to use different command types.
cmd open-file &xdg-open "$f" cmd open-file &xdg-open "$f"
You may want to use either file extensions or mime types with "file". You may want to use either file extensions or mime types from "file" command.
cmd open-file ${{ cmd open-file ${{
case $(file --mime-type "$f" -b) in case $(file --mime-type "$f" -b) in
@ -185,5 +186,49 @@ file openers as you like. Possible options are "open" (for Mac OS X only),
"xdg-utils" (executable name is "xdg-open"), "libfile-mimeinfo-perl" "xdg-utils" (executable name is "xdg-open"), "libfile-mimeinfo-perl"
(executable name is "mimeopen"), "rifle" (ranger's default file opener), or (executable name is "mimeopen"), "rifle" (ranger's default file opener), or
"mimeo" to name a few. "mimeo" to name a few.
Previewing Files
lf previews files on the preview pane by printing the file until the end or the
preview pane is filled. This output can be enhanced by providing a custom
preview script for filtering. This can be used to highlight source codes, list
contents of archive files or view pdf or image files as text to name few. For
coloring lf recognizes ansi escape codes.
In order to use this feature you need to set the value of "previewer" option to
the path of an executable file. lf passes the current file name as the first
argument and the height of the preview pane as the second argument when running
this file. Output of the execution is printed in the preview pane. You may want
to use the same script in your pager mapping as well if any.
set previewer ~/.config/lf/pv.sh
map i $~/.config/lf/pv.sh "$f" | less -R
Since this script is called for each file selection change it needs to be as
efficient as possible and this responsibility is left to the user. You may use
file extensions to determine the type of file more efficiently compared to
obtaining mime types from "file" command. Extensions can then be used to match
cleanly within a conditional.
#!/bin/sh
case "$1" in
*.tar*) tar tf "$1";;
*.zip) unzip -l "$1";;
*.rar) unrar l "$1";;
*.7z) 7z l "$1";;
*.pdf) pdftotext "$1" -;;
*) highlight -O ansi "$1" || cat "$1";;
esac
Another important consideration for efficiency is the use of programs with
short startup times for preview. For this reason, "highlight" is recommended
over "pygmentize" for syntax highlighting. Besides, it is also important that
the application is processing the file on the fly rather than first reading it
to the memory and then do the processing afterwards. This is especially
relevant for big files. lf automatically closes the previewer script output
pipe with a SIGPIPE when enough lines are read. When everything else fails, you
can make use of the height argument to only feed the first portion of the file
to a program for preview.
*/ */
package main package main

50
docstring.go
View File

@ -51,6 +51,7 @@ The following options can be used to customize the behavior of lf.
scrolloff int (default 0) scrolloff int (default 0)
tabstop int (default 8) tabstop int (default 8)
ifs string (default "") (not exported if empty) ifs string (default "") (not exported if empty)
previewer string (default "") (not filtered if empty)
shell string (default "$SHELL") shell string (default "$SHELL")
showinfo string (default "none") showinfo string (default "none")
sortby string (default "name") sortby string (default "name")
@ -184,7 +185,8 @@ It is possible to use different command types.
cmd open-file &xdg-open "$f" cmd open-file &xdg-open "$f"
You may want to use either file extensions or mime types with "file". You may want to use either file extensions or mime types from "file"
command.
cmd open-file ${{ cmd open-file ${{
case $(file --mime-type "$f" -b) in case $(file --mime-type "$f" -b) in
@ -198,4 +200,50 @@ file openers as you like. Possible options are "open" (for Mac OS X only),
"xdg-utils" (executable name is "xdg-open"), "libfile-mimeinfo-perl" "xdg-utils" (executable name is "xdg-open"), "libfile-mimeinfo-perl"
(executable name is "mimeopen"), "rifle" (ranger's default file opener), or (executable name is "mimeopen"), "rifle" (ranger's default file opener), or
"mimeo" to name a few. "mimeo" to name a few.
Previewing Files
lf previews files on the preview pane by printing the file until the end or
the preview pane is filled. This output can be enhanced by providing a
custom preview script for filtering. This can be used to highlight source
codes, list contents of archive files or view pdf or image files as text to
name few. For coloring lf recognizes ansi escape codes.
In order to use this feature you need to set the value of "previewer" option
to the path of an executable file. lf passes the current file name as the
first argument and the height of the preview pane as the second argument
when running this file. Output of the execution is printed in the preview
pane. You may want to use the same script in your pager mapping as well if
any.
set previewer ~/.config/lf/pv.sh
map i $~/.config/lf/pv.sh "$f" | less -R
Since this script is called for each file selection change it needs to be as
efficient as possible and this responsibility is left to the user. You may
use file extensions to determine the type of file more efficiently compared
to obtaining mime types from "file" command. Extensions can then be used to
match cleanly within a conditional.
#!/bin/sh
case "$1" in
*.tar*) tar tf "$1";;
*.zip) unzip -l "$1";;
*.rar) unrar l "$1";;
*.7z) 7z l "$1";;
*.pdf) pdftotext "$1" -;;
*) highlight -O ansi "$1" || cat "$1";;
esac
Another important consideration for efficiency is the use of programs with
short startup times for preview. For this reason, "highlight" is recommended
over "pygmentize" for syntax highlighting. Besides, it is also important
that the application is processing the file on the fly rather than first
reading it to the memory and then do the processing afterwards. This is
especially relevant for big files. lf automatically closes the previewer
script output pipe with a SIGPIPE when enough lines are read. When
everything else fails, you can make use of the height argument to only feed
the first portion of the file to a program for preview.
` `