- ENVIRONMENT VARIABLES
- SECURITY CONSIDERATIONS
cv - a fast gtk+ image viewer loosely modeled after XV
cv cv directory cv path... cv -g <glob expression...> find .. -print0 | cv -0r
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.
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.
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.
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).
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.
You can select entries in the Schnauzer in a variety of ways:
Moving the cursor with the keyboard will first deselect all files and then select the file you moved to.
Clicking on an entry will select the one you clicked and deselect all others.
Shift-clicking will toggle the selection on the entry under the mouse.
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.
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.
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 :).
The program that gets executed when the user presses
CTRL-ein the Schnauzer or image window. The default is
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>.
Program used to play all sorts of video files. Unlike
CV_AUDIO_PLAYER, this really must be one of the
mpvprograms, 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).
The default (perl-style) destination to use in the print dialog.
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.
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.
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."
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
Marc Lehmann <email@example.com>.