zgv.1

一个利用SDL语言来实现svgalib函数的示例程序

.\" *** Auto-generated by makeman, *edits will be lost*! ***
.\"
.\"
.TH ZGV 1 "28th January 2005" "Version 5.9" "Graphics Software"
.SH NAME
zgv \- picture viewer for VGA/SVGA displays
.\"
.SH SYNOPSIS
zgv [\fIoptions\fR] [\fIstart-dir\fR | \fIfile\fR [\fIfile2\fR ...]]
.SH "DESCRIPTION"
(NB: This man page is automagically generated from zgv's
texinfo file, and so may look a bit odd.
We apologise for the inconvenience. :-))
.PP
zgv lets you view pictures on Linux or FreeBSD boxes with VGA/SVGA
displays. The kinds of pictures it supports are raster-format pictures
(sometimes called `bitmaps' and/or `pixmaps'); things like GIF files,
JPEG files, PNG files, and so on. (The full list of file formats
supported is listed elsewhere. See \fBSupported File Formats\fR.)
.PP
Most of the time, you will probably want to use zgv's file selector
(see \fBThe File Selector\fR) to pick which file(s) to view. This is what
appears when you start zgv as just `\fBzgv\fR' (see \fBOptions\fR). It
displays a list of subdirectories and picture files in the current
directory, along with small `thumbnail' versions of the pictures if they
exist. (If no thumbnails appear for a given directory, or if they are
missing for some files, you can create/update them by pressing `\fBu\fR'.
See \fBUpdating Thumbnails\fR.)
.PP
When you've picked a file to view, you can view it by pressing
`\fBEnter\fR'. This puts you into the viewer, where the whole screen is
used to display the picture (see \fBThe Viewer\fR). You can then move
around the picture (if it is larger than the screen) using the cursor
keys. Pressing `\fBEsc\fR' returns you to the file selector, where you can
pick another file to view, or you can quit zgv by pressing `\fBEsc\fR'
again.
.PP
While zgv is by default controlled entirely from the keyboard, it does
have quite good mouse support you can enable if you like that sort of
thing. See \fBUsing a Mouse\fR.
.PP
This overview is, as you might expect, only the very simplest of
introductions to what zgv can do, and describes only a very basic use of
zgv. zgv can do a lot more; read on to find out what.
.PP
.SH "ACKNOWLEDGEMENTS"
zgv was primarily written by Russell Marks, who also wrote this manual.
.PP
Matan Ziv-Av added multiple-image animated GIF support, Photo-CD
support, brightness/contrast support in high-colour modes, the original
file-rename code, and some of the support for 32-bit modes, as well as
inspiring a few other changes like high-res file selector support.
.PP
Carsten Engelmann wrote the BMP support.
.PP
Edwin Fong added support for command-line slideshows, and a few other
features including the original mouse support.
.PP
Radim Kolar added support for FreeBSD.
.PP
Costa Sapuntzakis contributed code for much faster JPEG thumbnail
generation.
.PP
Dimitar Zhekov added SDL mouse support.
.PP
`\fBinstall-info\fR' is a (very) slightly modified version of the
original (which is part of the `\fBtexinfo\fR' package). This program is
used during installation. I think it was mostly written by Karl Berry,
but it's not terribly clear.
.PP
The authors of the special-purpose libraries zgv uses deserve credit ---
JPEG and PNG might not have been supported in zgv without the JPEG
library, libpng and zlib. Most of all though, zgv would certainly not
have been written without VGAlib and later svgalib, and thanks are due
to Tommy Frandsen, Harm Hanemaayer, Michael Weller, Matan Ziv-Av and
many others for that.
.PP
Thanks also to the zgv users who've contributed bug reports,
suggestions, ideas for features, and even... dare I say...
compliments. zgv would be even worse without their input, so count your
lucky stars. :-)
.PP
This program is based in part on the work of the Independent JPEG
Group.
.PP
``The Graphics Interchange Format(c) is the Copyright property of
CompuServe Incorporated. GIF(sm) is a Service Mark property of
CompuServe Incorporated.''
.PP
.SH "OPTIONS"
Normally you'd invoke zgv as plain `\fBzgv\fR'. However, you can directly
specify files to view or a start directory on the command-line. In
addition, there are various options.
.PP
(If you're new to zgv, you should probably skip the rest of this section
for now and come back to it later.)
.PP
The general format of the zgv command-line goes roughly like this:
.PP
zgv [\fIoptions\fR] [\fIstart-dir\fR | \fIfile\fR [\fIfile2\fR ...]]
.br
.PP
Two types of options are supported --- the traditional Unix
single-letter options, and GNU-style long options. Both forms are listed
in the table below, but not all long options have single-letter
equivalents.
.PP
Note that all options are processed after any configuration file(s).
Config file settings are just like the long-option names below minus the
`\fB--\fR' (see \fBConfiguring zgv\fR), though a few command-line options
are not permitted as config file settings (e.g. `\fBhelp\fR'), and vice
versa.
.PP
Here's what the options do:
.PP
`\fB-A\fR'
.RS
.RE
`\fB--auto-animate\fR'
.RS
Automatically animate multiple-image GIF files (see \fBMultiple-image
GIF Animation\fR). This limits your viewing options greatly, but can be
handy for slideshows and the like.
.PP
.RE
`\fB--auto-mode-fit\fR'
.RS
Automatically switch modes to suit image size.
.PP
.RE
`\fB--auto-mode-fit-diff \fIdiff\fR\fR'
.RS
When choosing an auto-mode-fit mode, add \fIdiff\fR to each mode's
width and height. For example, with a value of 20 any picture up to
820x620 will be displayed in an 800x600 mode if possible. If
\fIdiff\fR is negative, for example -20, the effect is reversed; any
picture above 780x580 will be displayed in a mode with a resolution
higher than 800x600 if possible.
.PP
.RE
`\fB-p\fR'
.RS
.RE
`\fB--avoid-single-progress\fR'
.RS
Don't show progress indicator when loading a single file from the
command-line.
.PP
.RE
`\fB--black-background\fR'
.RS
Try to use a black (or nearest-to-black) background when in 8-bit modes.
This can be quite nice for consistency's sake when viewing (say) a
mixture of GIFs and JPEGs, but the extra pass over the loaded image
slows things down slightly.
.PP
.RE
`\fB-b\fR'
.RS
.RE
`\fB--block-cursor\fR'
.RS
Use a blocky outline cursor in the selector, which is rather unsubtle
but more obvious.
.PP
.RE
`\fB--brightness \fIadjust_val\fR\fR'
.RS
Specify how much to add to colour values to change brightness (default
0). Values less than zero decrease brightness, values greater than zero
increase it. Brightness is applied after contrast by default.
.PP
.RE
`\fB--centre\fR'
.RS
.RE
`\fB--center\fR'
.RS
(Normally enabled, use e.g. `\fB--centre=off\fR' to disable.) By default
zgv centres pictures smaller than the screen, in whichever dimensions
they are smaller. This setting gives you a way to disable this, so that
pictures always start in the top-left.
			
.RE
`\fB--clear-screen-on-exit\fR'
.RS
Clear the screen on exit. (Normally, zgv leaves the original screen
contents intact.)
.PP
.RE
`\fB--col-black \fIr g b\fR\fR'
.RS
Set colour used for `black' (text) in selector; RGB values should be in
the range 0-63 for this and the other colour settings below, and the
three numbers should be quoted, e.g. `\fB--col-black "10 20 30"\fR'.
.PP
.RE
`\fB--col-dark \fIr g b\fR\fR'
.RS
Set colour used for lowlights in selector.
.PP
.RE
`\fB--col-light \fIr g b\fR\fR'
.RS
Set colour used for highlights in selector.
.PP
.RE
`\fB--col-medium \fIr g b\fR\fR'
.RS
Set colour used for background in selector.
.PP
.RE
`\fB--col-tagged \fIr g b\fR\fR'
.RS
Set colour used for tagged files in selector.
.PP
.RE
`\fB--contrast \fImultiplier\fR\fR'
.RS
Specify how much to multiply colour values by to change contrast
(default 1.0). zgv multiplies each colour's difference from grey by this
number; values less than one decrease contrast, values greater than one
increase it. Negative values are also allowed, and act in a similar way,
but with the picture's colours inverted. Contrast is applied before
brightness by default.
.PP
.RE
`\fB--delete-single-prompt\fR'
.RS
(Normally enabled, use `\fB--delete-single-prompt=off\fR' to disable.) If
disabled, don't prompt for confirmation when deleting a single file.
.PP
.RE
`\fB--delete-tagged-prompt\fR'
.RS
(Normally enabled, use `\fB--delete-tagged-prompt=off\fR' to disable.)
If disabled, don't prompt for confirmation when deleting all tagged
files.
.PP
.RE
`\fB--dither-16col-fast\fR'
.RS
(Normally enabled, use `\fB--dither-16col-fast=off\fR' to disable.) By
default, zgv uses a (reasonably fast) ordered dither when displaying a
dithered colour image in 640x480x4 mode. But if you disable this
setting, it uses error-diffused dithering (which looks better but is
rather noticeably slower).
.PP
.RE
`\fB--dither-hicol\fR'
.RS
If enabled, use dithering in `high-colour' modes, i.e. 15/16-bit
modes. This makes colour gradients smoother, but slows things down
quite a bit.
.PP
.RE
`\fB--fake-cols\fR'
.RS
(Normally enabled, use `\fB--fake-cols=off\fR' to disable.) If disabled,
don't fake extra greyscales and colour depth in 8-bit modes.
See \fBIncreased Greyscales\fR, for details.
.PP
.RE
`\fB--force-fs-16col\fR'
.RS
Force the use of the 640x480 16-colour mode for the selector.
.PP
.RE
`\fB-j\fR'
.RS
.RE
`\fB--force-viewer-8bit\fR'
.RS
Force all images to be loaded as 8-bit. Normally zgv will load 24-bit
images (e.g. colour JPEGs) as 24-bit if you have any modes capable of
displaying the image in 15, 16, 24, or 32-bit colour.
.PP
.RE
`\fB--fs-16col-colour-thumbnails\fR'
.RS
.RE
`\fB--fs-16col-color-thumbnails\fR'
.RS
Use low-quality colour thumbnail pictures when the file selector is
using 640x480 16-colour mode. Normally zgv uses higher-quality
monochrome thumbnails in this situation.
.PP
.RE
`\fB--fs-ignore-old-pos\fR'
.RS
Don't recall previous cursor position in a directory when returning to
it later. (This mechanism only applies when changing directory
`normally'; jumping directly to another dir with `\fBG\fR' never does such
a save/restore (see \fBChanging Directory\fR).)
.PP
.RE
`\fB--fs-magic\fR'
.RS
Use `magic number'-type identification to determine which files should
be listed in the file selector. This is more accurate, but very much
slower. See \fBFile Type Identification\fR, for a discussion of the
tradeoffs involved.
.PP
.RE
`\fB--fs-perfect-cols\fR'
.RS
Don't change thumbnail colours when using the file selector to make the
rest of the selector look right. See \fBThumbnail Issues\fR.
.PP
.RE
`\fB--fs-slow-thumbnail-update\fR'
.RS
`Walk' through the directory when updating thumbnails, moving the cursor
over every single picture whether it needs updating or not. Normally,
zgv completely skips any pictures which don't need updating, which makes
it considerably faster on large directories and/or slow machines.
.PP
.RE
`\fB--fs-small-text\fR'
.RS
Reduce the size of the filename text in the selector. You may find this
useful if you think the text is too big, or if you'd like to see more of
the filename without having to press `\fB:\fR'.
.PP
.RE
`\fB--fs-start-mode \fImodespec\fR\fR'
.RS
Specify the video mode zgv should start off using for the file
selector. (The default is 640x480x8 if possible, otherwise 640x480x4.)
The `modespec' should be the width, height, and depth in quotes, e.g.
`\fB"640 480 8"\fR'. See \fBVideo Modes\fR, for details of precisely what
this means. The specified depth is actually ignored in this case, as
you can only choose 8-bit modes for the selector.
.PP
.RE
`\fB-t\fR'
.RS
.RE
`\fB--fs-thick-text\fR'
.RS
Thicken the text (filenames etc.) in the file selector (and elsewhere).
(Note that if \fIline-text\fR has been enabled, then
\fIfs-thick-text\fR only has an effect if \fIblock-cursor\fR is on as
well.)
.PP
.RE
`\fB--fullscreen\fR'
.RS
(Normally enabled, use `\fB--fullscreen=off\fR' to disable.) This
option only applies when using the SDL backend. By default, zgv
generally uses the entire screen for its display. But if you disable
this option, it tries to run in a window when possible (e.g. when
running under X). Note that zgv won't be able to fill the screen in
modes it doesn't natively support, in either case.
.PP
.RE
`\fB-G \fIval\fR\fR'
.RS
.RE
`\fB--gamma \fIval\fR\fR'
.RS
Set the gamma adjustment used (see \fBGamma Adjustment\fR). This also sets
the `initial value' used when resetting the gamma adjustment. The
default is 1.0, i.e. no adjustment.
.PP
.RE
`\fB--gnulitically-correct\fR'
.RS
GNU has \fIPOSIXLY_CORRECT\fR for compatibility with silly POSIX
misfeatures, and zgv has...
.PP
.RE
`\fB-h\fR'
.RS
.RE
`\fB--help\fR'
.RS
Display a list of options and a terse description of what the options
do.
.PP
.RE
`\fB-i\fR'
.RS
.RE
`\fB--ignore-errors\fR'
.RS
When loading a single file from the command-line, ignore (some) errors.
Only meaningful for PNG currently.
.PP
.RE
`\fB--jpeg-index-style \fIstyle\fR\fR'
.RS
Specify how to read JPEGs when creating thumbnails. Style `\fB1\fR' is
the quickest, but sometimes generates rather fuzzy/blocky thumbnails;
`\fB2\fR' is fairly cautious (and the default), but still quite fast;
`\fB3\fR' is an extremely cautious and slow method.
.PP
.RE
`\fB-J \fItype\fR\fR'
.RS
.RE
`\fB--jpeg-speed \fItype\fR\fR'
.RS
Set JPEG speed/quality tradeoff. Type `\fB1\fR' is slow but accurate;
`\fB2\fR' is faster but not as accurate (and the default); `\fB3\fR' is
the fastest but the least accurate.
.PP
.RE
`\fB--line-text\fR'
.RS
Draw text by drawing lines rather than using bitmap fonts. This looks
worse but is faster.
.PP
.RE
`\fB-M\fR'
.RS
.RE
`\fB--mouse\fR'