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>.