[ViewVC] Contents of: cvs/CV/README

NAME
    cv - a fast gtk+ image viewer loosely modeled after XV

SYNOPSIS
       cv

       cv directory

       cv path...

       cv -g <glob expression...>

       find .. -print0 | cv -0r

FEATURES
    CV is supposed to work similar to the venerable XV image viewer, just
    faster. Why faster?

    *   optimized directory scanning algorithm

        The directory scanning in CV uses some tricks that - on most modern
        filesystems - makes it possible to detect filetypes faster than
        stat()'ing every file. This makes CV suitable for directories with
        lots of files (10000+).

        This algorithm is quite unprecise - it doesn't make a difference
        between files, device nodes, symlinks and the like, and filetype
        detection is done using the file extension only.

        On the positive side, it is usually many orders of magnitude faster
        than traditional scanning techniques (good for directories with
        10000 or 100000+ files).

    *   queuing for all time-consuming background tasks

        All tasks, such as unlinking files or generating thumbnails, that
        can be done in the background will be done so - no waiting required,
        even when changing directories.

    *   use of asynchronous I/O

        CV tries to use asynchronous I/O whereever it makes sense, for
        example while scanning directories, waiting for stat data, unlinking
        files or generating thumbnails. This usually decreases scanning
        times for large directories a bit (especially on RAID devices and
        over NFS) and makes CV much more interactive.

    *   fast image loading

        The time span between the user issuing a command and displaying the
        new image should be as small as possible. CV uses optimized
        (especially for JPEG) loading functions and sacrifices some quality
        (e.g no gamma correction, although this might change) to achieve
        this speed.

    *   fast thumbnail creation

        Thumbnail creation uses both CPU and Disk-I/O. CV interleaves both,
        so on modern CPUs, thumbnailing is usually limited by I/O speed.
        Thumbnail creation for JPEGs has been specially optimized and can
        even take advantage of multiple CPUs.

    *   minimum optical clutter

        CV has no menus or other user interface elements that take up a lot
        of screen space (or are useful for beginning users). The schnauzer
        windows can also be somewhat crowded.

        The point of an image viewer is viewing images, not a nice GUI. This
        is similar to XV's behaviour.

    *   efficient (and hard to learn) user interface

        CV uses key combinations. A lot. If you are an experienced XV user,
        you will find most of these keys familiar. If not, CV might be hard
        to use at first, but will be an efficient tool later.

    *   multi-window GUI

        CV doesn't force you to use a specific layout, instead it relies on
        your window manager, thus enabling you to chose whatever layout that
        suits you most.

    *   i18n'ed filename handling throughout

        As long as glib can recognize your filename encoding (either UTF-8
        or locale-specific, depending on the setting of G_BROKEN_FILENAMES)
        and you have the relevant fonts, CV will display your filenames
        correctly.

    *   extensible through plug-ins

        I have weird plug-ins that access remote databases to find a
        directory. This is not likely to be of any use to other people.
        Likewise, others might have weird requirements I cannot dream of.

    *   filename clustering

        Among the standard plug-ins is a filename clustering plug-in, that
        (in case of tens of thousands images in one directory) might be able
        to cluster similar names together.

DESCRIPTION
  THE IMAGE WINDOW
    You can use the following keys in the image window:

     q            quit the program
     <            half the image size
     >            double the image size
     ,            shrink the image by 10%
     .            enlarge the image by 10%
     n            reset to normal size
     m            maximize to screensize
     M            maximize to screensize, respecting image aspect
     ctrl-m       toggle maxpect-always mode
     ctrl-sift-m  toggle using current image size as max image size
     u            uncrop
     r            set scaling mode to 'nearest' (fastest)
     s            set scaling mode to 'bilinear' (default)
     shift-s      set scaling mode to 'hyper' (slowest)
     t            rotate clockwise 90°
     T            rotate counterclockwise°
     a            apply all rotations loslessly to a jpeg file (using exiftran)
     ctrl-shift-t apply current rotation for future image loads
     ctrl-v       open a new visual schnauzer window for the current dir
     ctrl-c       clone the current image window
     ctrl-e       run an editor ($CV_EDITOR or "gimp") on the current image
     ctrl-p       fire up the print dialog
     ctrl-shift-p same as ctrl-p, but automatically selects "ok"
     escape       cancel a crop action

    And when playing movies, these additional keys are active:

     left         rewind by 10 seconds
     right        forward by 10 seconds
     down         rewind by 60 seconds
     up           forward by 60 seconds
     pg_up        rewind by 600 seconds
     pg_down      forward by 600 seconds
     o            toggle on-screen display
     p            pause/unpause
     escape       stop playing
     9            turn volume down
     0            turn volume up

    Any other keys will be sent to the default schnauzer window, which can
    be toggled on and off by right-clicking into the image window.

    Left-clicking into the image window will let you crop the image (usually
    to zoom into large images that CV scales down).

  THE VISUAL SCHNAUZER
    Any image-loading action in a schnauzer window acts on the
    "last-recently-activated" imagewindow, which currently is simply the
    last image window that received a keypress.

    You can use the following keys in the schnauzer window:

     ctrl-space,
     space        move to and display next image
     ctrl-backspace,
     backspace    move to and display previous image
     ctrl-return,
     return       display selected picture, or enter directory

     cursor keys  move selection
     page-up      move one page up
     page-down    move one page down
     home         move to first file
     end          move to last file

     ctrl-a       select all files
     ctrl-shift-a select all files currently displayed in the schnauzer window
     ctrl-d       delete selected files WITHOUT ASKING AGAIN
     ctrl-g       force generation of thumbnails for the selected files
     ctrl-shift-g remove thumbnails for the selected files
     ctrl-s       rescan current direcory or files updates/deletes etc.
     ctrl-u       update selected (or all) icons if neccessary
     ctrl--       unselected thumbnailed images
     ctrl-+       keep only thumbnailed images, deselect others

     ^            go to parent directory (caret).

     0-9,
     a-z          find the first filename beginning with this letter

    Right-clicking into the schnauzer window displays a pop-up menu with
    additional actions.

   SELECTION
    You can select entries in the Schnauzer in a variety of ways:

    Keyboard
        Moving the cursor with the keyboard will first deselect all files
        and then select the file you moved to.

    Clicking
        Clicking on an entry will select the one you clicked and deselect
        all others.

    Shift-Clicking
        Shift-clicking will toggle the selection on the entry under the
        mouse.

    Dragging
        Dragging will select all entries between the one selected when
        pushing the button and the one selected when releasing the button.
        If you move above or below the schnauzer area while drag-selecting,
        the schnauzer will move up/down one row twice per second. In
        addition, horizontal mouse movement acts as a kind of invisible
        horizontal scrollbar.

    Hint: double-click works while click-selecting
        You can double-click any image while click-selecting to display it
        without stopping the selection process. This will act as if you
        normally double-clicked the image to display it, and will toggle the
        selection twice, resulting in no change.

FILES
    When starting, CV runs the .cvrc file in your $HOME directory as if it
    were a perl script. in that, you will mostly load plug-ins.

    Example:

       system "fping -q -t 10 ether"
         or require "/fs/cv/cvplugin.pl";

    This will load a plug-in, but only if the machine *ether* is reachable
    (supposedly the plug-in is networked in some way :).

ENVIRONMENT VARIABLES
    CV_EDITOR
        The program that gets executed when the user presses "CTRL-e" in the
        Schnauzer or image window. The default is "gimp".

    CV_AUDIO_PLAYER
        EXPERIMENTAL: audio playback is now via mpv, this variable is
        currently ignored.

        Program used to play all sorts of audio (wav, aif, mp3, ogg...),
        default "play". Will be called like "$CV_AUDIO_PLAYER -- <path>".

    CV_MPLAYER
        Program used to play all sorts of video files. Unlike
        "CV_AUDIO_PLAYER", this really must be one of the "mplayer",
        "mplayer2" or "mpv" programs, or something that is very command-line
        compatible to them.

        Currently, if this string contains the substring "mpv", then it is
        assumed to be mpv-compatible, otherwise it is assumed to be
        mplayer-compatible.

        Note: for video-thumbnailing, mplayer is still used (and hardcoded).

    CV_PRINT_DESTINATION
        The default (perl-style) destination to use in the print dialog.

    CV_TRASHCAN
        When set, must point to a directory where all files that are deleted
        by the "Delete Physically" (ctrl-d) action are moved to (other
        deletion actions still delete!). If unset, files that are deleted
        are really being deleted.

SIGNALS
    Sending CV a SIGUSR1 signal will cause all image viewers to reload the
    currently loaded image. This is useful if you use CV as a viewer for
    changing data - just run it in the background with some path and each
    time the image changes, send it a SIGUSR1.

SECURITY CONSIDERATIONS
    CV uses Pixbuf to load non-JPEG images. Pixbuf is not considered safe
    for this purpose, though (from the gtk-2.2 release notes):

    "While efforts have been made to make gdk-pixbuf robust against invalid
    images, using gdk-pixbuf to load untrusted data is not recommended, due
    to the likelyhood that there are additional problems where an invalid
    image could cause gdk-pixbuf to crash or worse."

BUGS/TODO
     Lots of functionality is missing.

     Pixbuf doesn't always honor G_BROKEN_FILENAMES, so accessing files with
     names incompatible with utf-8 might fail.

     rotate on disk
     lots of ui issues
     save(?)
     preferences

AUTHOR
    Marc Lehmann <cv@plan9.de>.

Revision:	1.12
Committed:	Wed Dec 27 17:48:16 2017 UTC (8 years, 4 months ago) by root
Branch:	MAIN
CVS Tags:	rel-1_9, rel-1_8, rel-1_71, rel-1_7
Changes since 1.11:	+15 -0 lines
Log Message:	1.7
#	Content
1	NAME
2	cv - a fast gtk+ image viewer loosely modeled after XV
3
4	SYNOPSIS
5	cv
6
7	cv directory
8
9	cv path...
10
11	cv -g <glob expression...>
12
13	find .. -print0 \| cv -0r
14
15	FEATURES
16	CV is supposed to work similar to the venerable XV image viewer, just
17	faster. Why faster?
18
19	* optimized directory scanning algorithm
20
21	The directory scanning in CV uses some tricks that - on most modern
22	filesystems - makes it possible to detect filetypes faster than
23	stat()'ing every file. This makes CV suitable for directories with
24	lots of files (10000+).
25
26	This algorithm is quite unprecise - it doesn't make a difference
27	between files, device nodes, symlinks and the like, and filetype
28	detection is done using the file extension only.
29
30	On the positive side, it is usually many orders of magnitude faster
31	than traditional scanning techniques (good for directories with
32	10000 or 100000+ files).
33
34	* queuing for all time-consuming background tasks
35
36	All tasks, such as unlinking files or generating thumbnails, that
37	can be done in the background will be done so - no waiting required,
38	even when changing directories.
39
40	* use of asynchronous I/O
41
42	CV tries to use asynchronous I/O whereever it makes sense, for
43	example while scanning directories, waiting for stat data, unlinking
44	files or generating thumbnails. This usually decreases scanning
45	times for large directories a bit (especially on RAID devices and
46	over NFS) and makes CV much more interactive.
47
48	* fast image loading
49
50	The time span between the user issuing a command and displaying the
51	new image should be as small as possible. CV uses optimized
52	(especially for JPEG) loading functions and sacrifices some quality
53	(e.g no gamma correction, although this might change) to achieve
54	this speed.
55
56	* fast thumbnail creation
57
58	Thumbnail creation uses both CPU and Disk-I/O. CV interleaves both,
59	so on modern CPUs, thumbnailing is usually limited by I/O speed.
60	Thumbnail creation for JPEGs has been specially optimized and can
61	even take advantage of multiple CPUs.
62
63	* minimum optical clutter
64
65	CV has no menus or other user interface elements that take up a lot
66	of screen space (or are useful for beginning users). The schnauzer
67	windows can also be somewhat crowded.
68
69	The point of an image viewer is viewing images, not a nice GUI. This
70	is similar to XV's behaviour.
71
72	* efficient (and hard to learn) user interface
73
74	CV uses key combinations. A lot. If you are an experienced XV user,
75	you will find most of these keys familiar. If not, CV might be hard
76	to use at first, but will be an efficient tool later.
77
78	* multi-window GUI
79
80	CV doesn't force you to use a specific layout, instead it relies on
81	your window manager, thus enabling you to chose whatever layout that
82	suits you most.
83
84	* i18n'ed filename handling throughout
85
86	As long as glib can recognize your filename encoding (either UTF-8
87	or locale-specific, depending on the setting of G_BROKEN_FILENAMES)
88	and you have the relevant fonts, CV will display your filenames
89	correctly.
90
91	* extensible through plug-ins
92
93	I have weird plug-ins that access remote databases to find a
94	directory. This is not likely to be of any use to other people.
95	Likewise, others might have weird requirements I cannot dream of.
96
97	* filename clustering
98
99	Among the standard plug-ins is a filename clustering plug-in, that
100	(in case of tens of thousands images in one directory) might be able
101	to cluster similar names together.
102
103	DESCRIPTION
104	THE IMAGE WINDOW
105	You can use the following keys in the image window:
106
107	q quit the program
108	< half the image size
109	> double the image size
110	, shrink the image by 10%
111	. enlarge the image by 10%
112	n reset to normal size
113	m maximize to screensize
114	M maximize to screensize, respecting image aspect
115	ctrl-m toggle maxpect-always mode
116	ctrl-sift-m toggle using current image size as max image size
117	u uncrop
118	r set scaling mode to 'nearest' (fastest)
119	s set scaling mode to 'bilinear' (default)
120	shift-s set scaling mode to 'hyper' (slowest)
121	t rotate clockwise 90°
122	T rotate counterclockwise°
123	a apply all rotations loslessly to a jpeg file (using exiftran)
124	ctrl-shift-t apply current rotation for future image loads
125	ctrl-v open a new visual schnauzer window for the current dir
126	ctrl-c clone the current image window
127	ctrl-e run an editor ($CV_EDITOR or "gimp") on the current image
128	ctrl-p fire up the print dialog
129	ctrl-shift-p same as ctrl-p, but automatically selects "ok"
130	escape cancel a crop action
131
132	And when playing movies, these additional keys are active:
133
134	left rewind by 10 seconds
135	right forward by 10 seconds
136	down rewind by 60 seconds
137	up forward by 60 seconds
138	pg_up rewind by 600 seconds
139	pg_down forward by 600 seconds
140	o toggle on-screen display
141	p pause/unpause
142	escape stop playing
143	9 turn volume down
144	0 turn volume up
145
146	Any other keys will be sent to the default schnauzer window, which can
147	be toggled on and off by right-clicking into the image window.
148
149	Left-clicking into the image window will let you crop the image (usually
150	to zoom into large images that CV scales down).
151
152	THE VISUAL SCHNAUZER
153	Any image-loading action in a schnauzer window acts on the
154	"last-recently-activated" imagewindow, which currently is simply the
155	last image window that received a keypress.
156
157	You can use the following keys in the schnauzer window:
158
159	ctrl-space,
160	space move to and display next image
161	ctrl-backspace,
162	backspace move to and display previous image
163	ctrl-return,
164	return display selected picture, or enter directory
165
166	cursor keys move selection
167	page-up move one page up
168	page-down move one page down
169	home move to first file
170	end move to last file
171
172	ctrl-a select all files
173	ctrl-shift-a select all files currently displayed in the schnauzer window
174	ctrl-d delete selected files WITHOUT ASKING AGAIN
175	ctrl-g force generation of thumbnails for the selected files
176	ctrl-shift-g remove thumbnails for the selected files
177	ctrl-s rescan current direcory or files updates/deletes etc.
178	ctrl-u update selected (or all) icons if neccessary
179	ctrl-- unselected thumbnailed images
180	ctrl-+ keep only thumbnailed images, deselect others
181
182	^ go to parent directory (caret).
183
184	0-9,
185	a-z find the first filename beginning with this letter
186
187	Right-clicking into the schnauzer window displays a pop-up menu with
188	additional actions.
189
190	SELECTION
191	You can select entries in the Schnauzer in a variety of ways:
192
193	Keyboard
194	Moving the cursor with the keyboard will first deselect all files
195	and then select the file you moved to.
196
197	Clicking
198	Clicking on an entry will select the one you clicked and deselect
199	all others.
200
201	Shift-Clicking
202	Shift-clicking will toggle the selection on the entry under the
203	mouse.
204
205	Dragging
206	Dragging will select all entries between the one selected when
207	pushing the button and the one selected when releasing the button.
208	If you move above or below the schnauzer area while drag-selecting,
209	the schnauzer will move up/down one row twice per second. In
210	addition, horizontal mouse movement acts as a kind of invisible
211	horizontal scrollbar.
212
213	Hint: double-click works while click-selecting
214	You can double-click any image while click-selecting to display it
215	without stopping the selection process. This will act as if you
216	normally double-clicked the image to display it, and will toggle the
217	selection twice, resulting in no change.
218
219	FILES
220	When starting, CV runs the .cvrc file in your $HOME directory as if it
221	were a perl script. in that, you will mostly load plug-ins.
222
223	Example:
224
225	system "fping -q -t 10 ether"
226	or require "/fs/cv/cvplugin.pl";
227
228	This will load a plug-in, but only if the machine ether is reachable
229	(supposedly the plug-in is networked in some way :).
230
231	ENVIRONMENT VARIABLES
232	CV_EDITOR
233	The program that gets executed when the user presses "CTRL-e" in the
234	Schnauzer or image window. The default is "gimp".
235
236	CV_AUDIO_PLAYER
237	EXPERIMENTAL: audio playback is now via mpv, this variable is
238	currently ignored.
239
240	Program used to play all sorts of audio (wav, aif, mp3, ogg...),
241	default "play". Will be called like "$CV_AUDIO_PLAYER -- <path>".
242
243	CV_MPLAYER
244	Program used to play all sorts of video files. Unlike
245	"CV_AUDIO_PLAYER", this really must be one of the "mplayer",
246	"mplayer2" or "mpv" programs, or something that is very command-line
247	compatible to them.
248
249	Currently, if this string contains the substring "mpv", then it is
250	assumed to be mpv-compatible, otherwise it is assumed to be
251	mplayer-compatible.
252
253	Note: for video-thumbnailing, mplayer is still used (and hardcoded).
254
255	CV_PRINT_DESTINATION
256	The default (perl-style) destination to use in the print dialog.
257
258	CV_TRASHCAN
259	When set, must point to a directory where all files that are deleted
260	by the "Delete Physically" (ctrl-d) action are moved to (other
261	deletion actions still delete!). If unset, files that are deleted
262	are really being deleted.
263
264	SIGNALS
265	Sending CV a SIGUSR1 signal will cause all image viewers to reload the
266	currently loaded image. This is useful if you use CV as a viewer for
267	changing data - just run it in the background with some path and each
268	time the image changes, send it a SIGUSR1.
269
270	SECURITY CONSIDERATIONS
271	CV uses Pixbuf to load non-JPEG images. Pixbuf is not considered safe
272	for this purpose, though (from the gtk-2.2 release notes):
273
274	"While efforts have been made to make gdk-pixbuf robust against invalid
275	images, using gdk-pixbuf to load untrusted data is not recommended, due
276	to the likelyhood that there are additional problems where an invalid
277	image could cause gdk-pixbuf to crash or worse."
278
279	BUGS/TODO
280	Lots of functionality is missing.
281
282	Pixbuf doesn't always honor G_BROKEN_FILENAMES, so accessing files with
283	names incompatible with utf-8 might fail.
284
285	rotate on disk
286	lots of ui issues
287	save(?)
288	preferences
289
290	AUTHOR
291	Marc Lehmann <cv@plan9.de>.
292