[ViewVC] Contents of: cvs/CV/README

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

SYNOPSIS
       cv [file...]

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

    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:	1.10
Committed:	Tue Jan 26 02:20:32 2010 UTC (14 years, 3 months ago) by root
Branch:	MAIN
CVS Tags:	rel-1_61, rel-1_55, rel-1_56
Changes since 1.9:	+2 -2 lines
Log Message:	1.55
#	Content
1	NAME
2	cv - a fast gtk+ image viewer loosely modeled after XV
3
4	SYNOPSIS
5	cv [file...]
6
7	FEATURES
8	CV is supposed to work similar to the venerable XV image viewer, just
9	faster. Why faster?
10
11	* optimized directory scanning algorithm
12
13	The directory scanning in CV uses some tricks that - on most modern
14	filesystems - makes it possible to detect filetypes faster than
15	stat()'ing every file. This makes CV suitable for directories with
16	lots of files (10000+).
17
18	This algorithm is quite unprecise - it doesn't make a difference
19	between files, device nodes, symlinks and the like, and filetype
20	detection is done using the file extension only.
21
22	On the positive side, it is usually many orders of magnitude faster
23	than traditional scanning techniques (good for directories with
24	10000 or 100000+ files).
25
26	* queuing for all time-consuming background tasks
27
28	All tasks, such as unlinking files or generating thumbnails, that
29	can be done in the background will be done so - no waiting required,
30	even when changing directories.
31
32	* use of asynchronous I/O
33
34	CV tries to use asynchronous I/O whereever it makes sense, for
35	example while scanning directories, waiting for stat data, unlinking
36	files or generating thumbnails. This usually decreases scanning
37	times for large directories a bit (especially on RAID devices and
38	over NFS) and makes CV much more interactive.
39
40	* fast image loading
41
42	The time span between the user issuing a command and displaying the
43	new image should be as small as possible. CV uses optimized
44	(especially for JPEG) loading functions and sacrifices some quality
45	(e.g no gamma correction, although this might change) to achieve
46	this speed.
47
48	* fast thumbnail creation
49
50	Thumbnail creation uses both CPU and Disk-I/O. CV interleaves both,
51	so on modern CPUs, thumbnailing is usually limited by I/O speed.
52	Thumbnail creation for JPEGs has been specially optimized and can
53	even take advantage of multiple CPUs.
54
55	* minimum optical clutter
56
57	CV has no menus or other user interface elements that take up a lot
58	of screen space (or are useful for beginning users). The schnauzer
59	windows can also be somewhat crowded.
60
61	The point of an image viewer is viewing images, not a nice GUI. This
62	is similar to XV's behaviour.
63
64	* efficient (and hard to learn) user interface
65
66	CV uses key combinations. A lot. If you are an experienced XV user,
67	you will find most of these keys familiar. If not, CV might be hard
68	to use at first, but will be an efficient tool later.
69
70	* multi-window GUI
71
72	CV doesn't force you to use a specific layout, instead it relies on
73	your window manager, thus enabling you to chose whatever layout that
74	suits you most.
75
76	* i18n'ed filename handling throughout
77
78	As long as glib can recognize your filename encoding (either UTF-8
79	or locale-specific, depending on the setting of G_BROKEN_FILENAMES)
80	and you have the relevant fonts, CV will display your filenames
81	correctly.
82
83	* extensible through plug-ins
84
85	I have weird plug-ins that access remote databases to find a
86	directory. This is not likely to be of any use to other people.
87	Likewise, others might have weird requirements I cannot dream of.
88
89	* filename clustering
90
91	Among the standard plug-ins is a filename clustering plug-in, that
92	(in case of tens of thousands images in one directory) might be able
93	to cluster similar names together.
94
95	DESCRIPTION
96	THE IMAGE WINDOW
97	You can use the following keys in the image window:
98
99	q quit the program
100	< half the image size
101	> double the image size
102	, shrink the image by 10%
103	. enlarge the image by 10%
104	n reset to normal size
105	m maximize to screensize
106	M maximize to screensize, respecting image aspect
107	ctrl-m toggle maxpect-always mode
108	ctrl-sift-m toggle using current image size as max image size
109	u uncrop
110	r set scaling mode to 'nearest' (fastest)
111	s set scaling mode to 'bilinear' (default)
112	shift-s set scaling mode to 'hyper' (slowest)
113	t rotate clockwise 90°
114	T rotate counterclockwise°
115	a apply all rotations loslessly to a jpeg file (using exiftran)
116	ctrl-v open a new visual schnauzer window for the current dir
117	ctrl-c clone the current image window
118	ctrl-e run an editor ($CV_EDITOR or "gimp") on the current image
119	ctrl-p fire up the print dialog
120	escape cancel a crop action
121
122	And when playing movies, these additional keys are active:
123
124	left rewind by 10 seconds
125	right forward by 10 seconds
126	down rewind by 60 seconds
127	up forward by 60 seconds
128	pg_up rewind by 600 seconds
129	pg_down forward by 600 seconds
130	o toggle on-screen display
131	p pause/unpause
132	escape stop playing
133	9 turn volume down
134	0 turn volume up
135
136	Any other keys will be sent to the default schnauzer window, which can
137	be toggled on and off by right-clicking into the image window.
138
139	Left-clicking into the image window will let you crop the image (usually
140	to zoom into large images that CV scales down).
141
142	THE VISUAL SCHNAUZER
143	Any image-loading action in a schnauzer window acts on the
144	"last-recently-activated" imagewindow, which currently is simply the
145	last image window that received a keypress.
146
147	You can use the following keys in the schnauzer window:
148
149	ctrl-space,
150	space move to and display next image
151	ctrl-backspace,
152	backspace move to and display previous image
153	ctrl-return,
154	return display selected picture, or enter directory
155
156	cursor keys move selection
157	page-up move one page up
158	page-down move one page down
159	home move to first file
160	end move to last file
161
162	ctrl-a select all files
163	ctrl-shift-a select all files currently displayed in the schnauzer window
164	ctrl-d delete selected files WITHOUT ASKING AGAIN
165	ctrl-g force generation of thumbnais for the selected files
166	ctrl-s rescan current direcory or files updates/deletes etc.
167	ctrl-u update selected (or all) icons if neccessary
168	ctrl-- unselected thumbnailed images
169	ctrl-+ keep only thumbnailed images, deselect others
170
171	^ go to parent directory (caret).
172
173	0-9,
174	a-z find the first filename beginning with this letter
175
176	Right-clicking into the schnauzer window displays a pop-up menu with
177	additional actions.
178
179	SELECTION
180	You can select entries in the Schnauzer in a variety of ways:
181
182	Keyboard
183	Moving the cursor with the keyboard will first deselect all files
184	and then select the file you moved to.
185
186	Clicking
187	Clicking on an entry will select the one you clicked and deselect
188	all others.
189
190	Shift-Clicking
191	Shift-clicking will toggle the selection on the entry under the
192	mouse.
193
194	Dragging
195	Dragging will select all entries between the one selected when
196	pushing the button and the one selected when releasing the button.
197	If you move above or below the schnauzer area while drag-selecting,
198	the schnauzer will move up/down one row twice per second. In
199	addition, horizontal mouse movement acts as a kind of invisible
200	horizontal scrollbar.
201
202	Hint: double-click works while click-selecting
203	You can double-click any image while click-selecting to display it
204	without stopping the selection process. This will act as if you
205	normally double-clicked the image to display it, and will toggle the
206	selection twice, resulting in no change.
207
208	FILES
209	When starting, CV runs the .cvrc file in your $HOME directory as if it
210	were a perl script. in that, you will mostly load plug-ins.
211
212	Example:
213
214	system "fping -q -t 10 ether"
215	or require "/fs/cv/cvplugin.pl";
216
217	This will load a plug-in, but only if the machine ether is reachable
218	(supposedly the plug-in is networked in some way :).
219
220	ENVIRONMENT VARIABLES
221	CV_EDITOR
222	The program that gets executed when the user presses "CTRL-e" in the
223	Schnauzer or image window. The default is "gimp".
224
225	CV_AUDIO_PLAYER
226	Program used to play all sorts of audio (wav, aif, mp3, ogg...),
227	default "play". Will be called like "$CV_AUDIO_PLAYER -- <path>".
228
229	CV_PRINT_DESTINATION
230	The default (perl-style) destination to use in the print dialog.
231
232	CV_TRASHCAN
233	When set, must point to a directory where all files that are deleted
234	by the "Delete Physically" (ctrl-d) action are moved to (other
235	deletion actions still delete!). If unset, files that are deleted
236	are really being deleted.
237
238	SIGNALS
239	Sending CV a SIGUSR1 signal will cause all image viewers to reload the
240	currently loaded image. This is useful if you use CV as a viewer for
241	changing data - just run it in the background with some path and each
242	time the image changes, send it a SIGUSR1.
243
244	SECURITY CONSIDERATIONS
245	CV uses Pixbuf to load non-JPEG images. Pixbuf is not considered safe
246	for this purpose, though (from the gtk-2.2 release notes):
247
248	"While efforts have been made to make gdk-pixbuf robust against invalid
249	images, using gdk-pixbuf to load untrusted data is not recommended, due
250	to the likelyhood that there are additional problems where an invalid
251	image could cause gdk-pixbuf to crash or worse."
252
253	BUGS/TODO
254	Lots of functionality is missing.
255
256	Pixbuf doesn't always honor G_BROKEN_FILENAMES, so accessing files with
257	names incompatible with utf-8 might fail.
258
259	rotate on disk
260	lots of ui issues
261	save(?)
262	preferences
263
264	AUTHOR
265	Marc Lehmann <cv@plan9.de>.
266