[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 ~9% (opposite of .)
     .            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)
     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 some version of the "mpv"
        programs, or something that is very command-line compatible to them.

        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:	1.13
Committed:	Thu Jul 15 00:41:44 2021 UTC (2 years, 10 months ago) by root
Branch:	MAIN
Changes since 1.12:	+3 -9 lines
Log Message:	* empty log message *
#	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 ~9% (opposite of .)
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	t rotate clockwise 90°
121	T rotate counterclockwise°
122	a apply all rotations loslessly to a jpeg file (using exiftran)
123	ctrl-shift-t apply current rotation for future image loads
124	ctrl-v open a new visual schnauzer window for the current dir
125	ctrl-c clone the current image window
126	ctrl-e run an editor ($CV_EDITOR or "gimp") on the current image
127	ctrl-p fire up the print dialog
128	ctrl-shift-p same as ctrl-p, but automatically selects "ok"
129	escape cancel a crop action
130
131	And when playing movies, these additional keys are active:
132
133	left rewind by 10 seconds
134	right forward by 10 seconds
135	down rewind by 60 seconds
136	up forward by 60 seconds
137	pg_up rewind by 600 seconds
138	pg_down forward by 600 seconds
139	o toggle on-screen display
140	p pause/unpause
141	escape stop playing
142	9 turn volume down
143	0 turn volume up
144
145	Any other keys will be sent to the default schnauzer window, which can
146	be toggled on and off by right-clicking into the image window.
147
148	Left-clicking into the image window will let you crop the image (usually
149	to zoom into large images that CV scales down).
150
151	THE VISUAL SCHNAUZER
152	Any image-loading action in a schnauzer window acts on the
153	"last-recently-activated" imagewindow, which currently is simply the
154	last image window that received a keypress.
155
156	You can use the following keys in the schnauzer window:
157
158	ctrl-space,
159	space move to and display next image
160	ctrl-backspace,
161	backspace move to and display previous image
162	ctrl-return,
163	return display selected picture, or enter directory
164
165	cursor keys move selection
166	page-up move one page up
167	page-down move one page down
168	home move to first file
169	end move to last file
170
171	ctrl-a select all files
172	ctrl-shift-a select all files currently displayed in the schnauzer window
173	ctrl-d delete selected files WITHOUT ASKING AGAIN
174	ctrl-g force generation of thumbnails for the selected files
175	ctrl-shift-g remove thumbnails for the selected files
176	ctrl-s rescan current direcory or files updates/deletes etc.
177	ctrl-u update selected (or all) icons if neccessary
178	ctrl-- unselected thumbnailed images
179	ctrl-+ keep only thumbnailed images, deselect others
180
181	^ go to parent directory (caret).
182
183	0-9,
184	a-z find the first filename beginning with this letter
185
186	Right-clicking into the schnauzer window displays a pop-up menu with
187	additional actions.
188
189	SELECTION
190	You can select entries in the Schnauzer in a variety of ways:
191
192	Keyboard
193	Moving the cursor with the keyboard will first deselect all files
194	and then select the file you moved to.
195
196	Clicking
197	Clicking on an entry will select the one you clicked and deselect
198	all others.
199
200	Shift-Clicking
201	Shift-clicking will toggle the selection on the entry under the
202	mouse.
203
204	Dragging
205	Dragging will select all entries between the one selected when
206	pushing the button and the one selected when releasing the button.
207	If you move above or below the schnauzer area while drag-selecting,
208	the schnauzer will move up/down one row twice per second. In
209	addition, horizontal mouse movement acts as a kind of invisible
210	horizontal scrollbar.
211
212	Hint: double-click works while click-selecting
213	You can double-click any image while click-selecting to display it
214	without stopping the selection process. This will act as if you
215	normally double-clicked the image to display it, and will toggle the
216	selection twice, resulting in no change.
217
218	FILES
219	When starting, CV runs the .cvrc file in your $HOME directory as if it
220	were a perl script. in that, you will mostly load plug-ins.
221
222	Example:
223
224	system "fping -q -t 10 ether"
225	or require "/fs/cv/cvplugin.pl";
226
227	This will load a plug-in, but only if the machine ether is reachable
228	(supposedly the plug-in is networked in some way :).
229
230	ENVIRONMENT VARIABLES
231	CV_EDITOR
232	The program that gets executed when the user presses "CTRL-e" in the
233	Schnauzer or image window. The default is "gimp".
234
235	CV_AUDIO_PLAYER
236	EXPERIMENTAL: audio playback is now via mpv, this variable is
237	currently ignored.
238
239	Program used to play all sorts of audio (wav, aif, mp3, ogg...),
240	default "play". Will be called like "$CV_AUDIO_PLAYER -- <path>".
241
242	CV_MPLAYER
243	Program used to play all sorts of video files. Unlike
244	"CV_AUDIO_PLAYER", this really must be some version of the "mpv"
245	programs, or something that is very command-line compatible to them.
246
247	Note: for video-thumbnailing, mplayer is still used (and hardcoded).
248
249	CV_PRINT_DESTINATION
250	The default (perl-style) destination to use in the print dialog.
251
252	CV_TRASHCAN
253	When set, must point to a directory where all files that are deleted
254	by the "Delete Physically" (ctrl-d) action are moved to (other
255	deletion actions still delete!). If unset, files that are deleted
256	are really being deleted.
257
258	SIGNALS
259	Sending CV a SIGUSR1 signal will cause all image viewers to reload the
260	currently loaded image. This is useful if you use CV as a viewer for
261	changing data - just run it in the background with some path and each
262	time the image changes, send it a SIGUSR1.
263
264	SECURITY CONSIDERATIONS
265	CV uses Pixbuf to load non-JPEG images. Pixbuf is not considered safe
266	for this purpose, though (from the gtk-2.2 release notes):
267
268	"While efforts have been made to make gdk-pixbuf robust against invalid
269	images, using gdk-pixbuf to load untrusted data is not recommended, due
270	to the likelyhood that there are additional problems where an invalid
271	image could cause gdk-pixbuf to crash or worse."
272
273	BUGS/TODO
274	Lots of functionality is missing.
275
276	Pixbuf doesn't always honor G_BROKEN_FILENAMES, so accessing files with
277	names incompatible with utf-8 might fail.
278
279	rotate on disk
280	lots of ui issues
281	save(?)
282	preferences
283
284	AUTHOR
285	Marc Lehmann <cv@plan9.de>.
286