zgv.texi

一个利用SDL语言来实现svgalib函数的示例程序

@kindex Alt-t (Selector)
@itemx Alt-t
Sort by last-modified date/time. The newest files are listed last.

@kindex Alt-e (Selector)
@item Alt-e
Sort by extension.
@end table


@node  File Selector Toggles, Other File Sel Commands, Changing the Sorting Order, The File Selector
@comment  node-name,  next,  previous,  up
@section File Selector Toggles

@cindex file selector toggles
@cindex file selector, run-time configuration of
@cindex file selector, options in
@cindex options in file selector
@cindex thumbnails, toggling display of
@cindex scrollbar, toggling
@cindex slideshows, toggling randomised
@cindex slideshows, toggling looping
@cindex listing files without extensions
@cindex extensions, listing files without
@cindex magic number, listing files based on

Various aspects of the file selector's behaviour can be configured while
zgv is running, by using these toggle commands (which enable the feature
if it was previously disabled, and vice versa).

These settings can also be altered using command-line options
(@pxref{Invoking zgv}) and/or config file settings (@pxref{Configuring
zgv}).

@table @kbd
@kindex v (Selector)
@item v
Toggle display of thumbnails (default is on). The without-thumbnails
display can sometimes be useful for navigating around large directories
(many filenames are shown onscreen at once), and it is of course faster.

@kindex s (Selector)
@item s
Toggle scrollbar on/off (default is on). The scrollbar shows which part
and which proportion of the list is currently being shown onscreen, and
when mouse support is enabled can be used to move around the list.

@kindex S (Selector)
@itemx S
Toggle shuffling (randomising) of slideshows. @xref{Slideshows}.

@kindex L (Selector)
@item L
Toggle looping in slideshows. @xref{Slideshows}.

@kindex Alt-m (Selector)
@item Alt-m
Toggle use of `magic numbers' (identifiers at the start of a file) to
pick which files in a directory to list in the selector. The usual
method of doing this is based on the file's extension (@pxref{File Type
Identification}, which is much faster but won't catch e.g. files without
extensions.

@kindex c (Selector)
@item c
If the file selector is running in 16-colour mode (it usually doesn't
unless zgv has no choice --- @pxref{16-colour File Selector}), toggle
between greyscale (default) and colour thumbnails.
@end table


@node  Other File Sel Commands, Showing More Files, File Selector Toggles, The File Selector
@comment  node-name,  next,  previous,  up
@section Other File Sel Commands

@c since this section is a vague compendium of stuff, we have index
@c entries for each bit.
@c delete
@cindex deleting a file
@cindex file, deleting a
@c colon
@cindex file, showing full filename of
@cindex showing a full filename
@cindex complete filename, showing a
@cindex entire filename, showing an
@cindex file, showing size of
@cindex showing the size of a file
@cindex size, showing a file's
@cindex file, showing date/time of
@cindex date, showing a file's
@cindex time, showing a file's
@cindex mtime, showing a file's
@cindex last-modified date/time, showing a file's
@cindex permissions, showing a file's
@cindex owner, showing a file's
@c ^L
@cindex directory, rereading
@cindex rereading a directory
@cindex scanning a directory again
@c K
@cindex disabling mouse
@cindex turning off the mouse
@cindex pointer, removing the mouse
@cindex killing mouse
@cindex mouse, disabling
@c Alt-f
@cindex file count
@cindex showing the number of files
@cindex displaying the number of files
@cindex number of files, showing the
@cindex tagged files, showing number of

@c XXX this intro bit is clunky as hell!

There are some other commands in the file selector which don't easily
fit anywhere else. Here they are:

@table @kbd
@kindex Delete (Selector)
@item Delete
Delete (only) the file the cursor is on. Asks for confirmation (unless
this is disabled, @pxref{Configuring zgv}). It also deletes the file's
thumbnail, if it has one. @xref{Copying/Moving/Deleting Files}, for a
more general command which deletes all tagged files.

@c Since colons aren't allowed in index entries, saying `Colon' is
@c pretty much the best I can do. :-/
@c NB: the listing of `;' in body text rather than as an itemx is
@c *deliberate* - I'd rather not encourage using that, as it's not
@c consistent across the selector and viewer (while `:' is).
@c
@kindex colon (Selector)
@item :
@kindex ; (Selector)
Show various details about the file the cursor is on; the (full)
filename, the size in kilobytes, width/height if recorded in any
thumbnail, last-modified date, etc. You can also use the @kbd{;} key to
get this.

@kindex Alt-f (Selector)
@item Alt-f
Show the number of (picture) files in the current directory, and the
number of tagged files (@pxref{Tagging}).

@kindex ^L (Selector)
@item ^L
@kindex ^R (Selector)
@itemx ^R
Rescan the directory contents, and redraw the screen.

@kindex K (Selector)
@item K
Kill mouse --- disable mouse for the rest of this zgv session. (It
prompts to check if you really want to do so.) This can be useful if you
have the mouse enabled in a config file, so that zgv always starts up
with the mouse on, but you're currently using just the keyboard. In such
a situation the mouse pointer can be a bit annoying. This command lets
you disable the mouse completely for the current zgv process.
@end table


@node  Showing More Files, 16-colour File Selector, Other File Sel Commands, The File Selector
@comment  node-name,  next,  previous,  up
@section Showing More Files

@c This is a tough concept to get a firm hold of, so we cover an absurd
@c number of bases here. :-)
@c
@c these go for a `more files' approach:
@cindex file selector, showing more files in the
@cindex file selector, video modes in the
@cindex showing more files in the selector
@cindex more files in the selector, showing
@c these talk about video modes:
@cindex selector video modes
@cindex video modes in the selector
@cindex modes in selector, video
@cindex screen, resolution of selector
@cindex display, resolution of selector

The file selector normally runs at a relatively low resolution
(640x480), meaning it can only show 20 thumbnails at once. This keeps
the selector running at a reasonable speed even on slow machines.

If you have a faster machine, however, and your video card has
256-colour modes with higher resolutions than 640x480 (@pxref{Video
Modes}), you may want to see more thumbnails onscreen at once.

(zgv tends not to look as `right' in such modes as it does in the usual
640x480, but apart from that it's much the same.)

@table @kbd
@kindex F1 (Selector)
@item F1
Select 640x480 mode. This is the default.

@kindex F2 (Selector)
@item F2
Select 800x600 mode.

@kindex F3 (Selector)
@item F3
Select 1024x768 mode.

@kindex F4 (Selector)
@item F4
Select 1280x1024 mode.
@end table

If you want to change the default mode used in the file selector, use
the @samp{fs-start-mode} config file setting (@pxref{Configuring zgv}).
For example, to use 800x600 by default, you'd use @samp{fs-start-mode
800 600 8}.

Note these modes are subject to the same checks as in the viewer --- in
particular, this means that the file selector obeys the viewer's
@samp{mode-good}, @samp{mode-bad}, etc. settings. @xref{Config
Variables}.

Finally, if you have no 640x480 256-colour mode, or if
@samp{force-fs-16col} has been set, the 640x480 16-colour mode is all
that is available.


@node  16-colour File Selector,  , Showing More Files, The File Selector
@comment  node-name,  next,  previous,  up
@section 16-colour File Selector

@c the most obvious thing people will notice about a 16-col selector is
@c that it's (by default) grey, so most of these concentrate on that.
@cindex file selector, generic VGA
@cindex file selector, 16-colour
@cindex file selector, monochrome
@cindex file selector, grey
@cindex 16-colour file selector
@cindex file selector, monochrome
@cindex monochrome file selector
@cindex black-and-white file selector
@cindex grey file selector

The file selector normally operates in a 256-colour mode (by default,
the 640x480 one). However, the original VGA cards didn't have this mode,
and SVGA cards not supported by svgalib won't have it as far as zgv is
concerned either.

For such cards, zgv supports a more limited and slower file selector
which works in 640x480 16-colour mode. It should be easy to tell which
zgv is using --- if thumbnails appear in monochrome rather than colour
(and the files are colour pictures ;-)) then it's running in 16-colour
mode. (Another hint is that 16-colour mode has an extra border around
the edge of the screen which 256-colour mode probably won't have.)

As you might imagine, having 240 fewer colours makes things difficult.
The default way of coping with this is the greyscale thumbnails (eleven
grey levels are used), which are reasonably fast and quite faithful to
the originals. If you'd prefer less accurate --- but colour ---
thumbnails (eight colours are used, with dithering and increased
contrast), you can press @kbd{c} to toggle between the two, or set zgv
up to default to using colour thumbnails instead with
@samp{fs-16col-colour-thumbnails on} in a config file
(@pxref{Configuring zgv}).

(For those of you out there who have a 640x480 256-colour mode, but feel
you're missing out by not seeing this 16-colour file selector :-), you
can force zgv to use it by using the @samp{--force-fs-16col} option.)


@node  The Viewer, xzgv Compatibility, The File Selector, Top
@comment  node-name,  next,  previous,  up
@chapter The Viewer

@cindex the viewer
@cindex using the viewer
@cindex viewer, using the

When a picture is being shown onscreen, you're in the viewer. This
section describes what you can do while viewing the picture.

@menu
* Exiting the Viewer::          Usually returns you to the file selector.
* Big Pictures::                Scrolling, zoom mode, and auto-mode-fit.
* Scaling::                     Making the picture appear larger.
* Mirror and Rotate::           Distorting your sense of reality on a budget.
* Brightness and Contrast::     You can have zgv alter the picture
                                  to change the brightness or contrast.
* Gamma Adjustment::            If a picture looks unexpectedly dark or
                                  bright, chances are you need to tweak this.
* Increased Greyscales::        Normally, zgv tries to fake some extra
                                  greyscales.
* Changing Picture::            You can change the currently-viewed
                                  picture without returning to the file
                                  selector.
* File Details::                Seeing the file's name, size, etc.
* Pausing Slideshows::          You can temporarily stop a slideshow.
* Multiple-image GIF Animation::  Now you too can have digitised flip
                                  books in your very own home.
* Video Modes::                 The pixels that make up the displayed
                                  picture can have different physical
                                  sizes and `depths'; change video mode
                                  to change these attributes.
@end menu


@node  Exiting the Viewer, Big Pictures, The Viewer, The Viewer
@comment  node-name,  next,  previous,  up
@section Exiting the Viewer

@cindex exiting the viewer
@cindex quitting the viewer
@cindex leaving the viewer
@cindex returning to file selector
@cindex file selector, returning to

Exiting the viewer is simple:

@table @kbd
@kindex Esc (Viewer)
@item Esc
@kindex x (Viewer)
@itemx x
Exit the viewer.

If you got to the viewer from the file selector, you're returned there;
if you bypassed the file selector (by running zgv with a file (or files)
to view specified on the command-line --- @pxref{Invoking zgv}) then
exiting the viewer also exits zgv.
@end table


@node  Big Pictures, Scaling, Exiting the Viewer, The Viewer
@comment  node-name,  next,  previous,  up
@section Big Pictures

@cindex dealing with big pictures
@cindex pictures, big
@cindex large pictures
@cindex big pictures
@cindex small screen, coping with a

A picture may well be too large to fit entirely on the screen. There are
two general ways to see the whole of the picture, and in addition to
those, you may be able to fit more on by choosing a different video mode
(@pxref{Video Modes}), either manually or by using auto-mode-fit.

(For multi-resolution Photo-CD files, there is yet another alternative
approach (@pxref{Supported File Formats}).)

@menu
* Scrolling::                   Moving around the picture.
* Zoom Mode::                   Fitting the picture to the screen.
* Auto-mode-fit::               Automated video mode switching.
@end menu

@node  Scrolling, Zoom Mode, Big Pictures, Big Pictures
@comment  node-name,  next,  previous,  up
@subsection Scrolling

@cindex scrolling
@cindex panning
@cindex viewer, scrolling in the
@cindex picture, moving around a
@cindex viewer, moving around in the
@cindex moving around the picture

Scrolling is the default approach to handling big pictures in zgv. When
the viewer is started up, the top-left of the