NAME

Linux::Svgalib - Object Oriented Perl interface to the svgalib graphics library

SYNOPSIS

use Linux::Svgalib;

my $svga = Linux::Svgalib->new();

$svga->init();

$svga->setmode(G640x480x16);

...

$svga->setmode(TEXT);

DESCRIPTION

This module provides an Interface to a subset of the functions provided by the svgalib graphics library. Those methods that are supported are largely the graphics drawing primitives and rudimentary keyboard I/O. Specifically the graphics accelerator and blit functions are not exposed because they are rather difficult to implement a Perl interface for.

The normal course of a program using this module is create the object and then to call the init() method straight away, after that setmode() can be used to change to the appropriate graphics mode and the graphics methods can be used to draw to the screen. A program will almost always call setmode(TEXT) before execution completes in order to restore the virtual console to the state it was in before the mode was changed.

A program that fails at runtime may leave the virtual console in an unusable state - the program can make arrangements to call setmode(TEXT) in a $SIG{__DIE__} handler or END block or the textmode utility described in the svgalib documentation can be used.

In nearly all circumstances programs using Linux::Svgalib will need to be run with superuser privileges in order to initialise svgalib - this can be done by making the program setuid where that is supported or by using a program such as 'sudo'. It is strongly recommened that you switch Taint checking on with the '-T' switch to perl when running as root, you should read the perlsec manpage to learn more about this.

METHODS

new

The constructor of the class. Returns an object suitable for calling the remaining methods on.

init

Initializes the svgalib library - this is always required before any graphics operations are performed.

addmode $width, $height, $num_colors, $offset, $bytesperpixel

Adds a mode to the list of modes, with the given parameters. The function returns the mode number. If such a mode already exists on the list, its number is returned, and no mode is added.

Adding a mode to the list is not enough in order to use it. There must also be a timing line that fits that mode. This can be added either as a modeline in the config file, or with the functions addtiming

addtiming $pixelClock, $HDisplay, $HSyncStart, $HSyncEnd, $HTotal, $VDisplay, $VSyncStart, $VSyncEnd, $VTotal, $flags

Adds the given line of mode timing to the table of user timings, as if the line is in the config file. For a description of the parameter's meaning, see libvga.config(5)

changetiming $pixelClock, $HDisplay, $HSyncStart, $HSyncEnd, $HTotal, $VDisplay, $VSyncStart, $VSyncEnd, $VTotal, $flags)

Changes the value of the current timing parameters by the given values. No checks are made to see if the new timing are within monitor or card specs. See svidtune(6) for an exam­ ple of using this. See also getcurrenttiming(3)

clear

Clears the screen and sets all visible pixels to 0 (which is usually black). This is automatically done by the setmode method.

disabledriverreport

Usually svgalib prints the name of the hardware detected or forced to the screen during startup. This and other informational messages are suppressed when this method is called.

drawline $x1, $y1, $x2, $y2

Draws a line from the point ($x1, $y1) to the point ($x2, $y2) on the screen. If you exchange start and end of the line you should not expect the exactly identical set of pixel be covered by the line.

The colour of the pixels drawn is determined by that which was last set by setcolor or setrgbcolor.

drawpixel $x, $y

Sets a pixel at the point ( $x, $y) to the colour as determined by the last call to setcolor() or setrgbcolor(). For drawing a large number of pixels at one time you might want to consider drawscanline() or drawscansegment().

drawscanline $line , $colours

Draws a horizontal line over the whole screen in the line with y coordinate $line. $colours is a reference to an array containing a colour value for each pixel in the line. The pixel width of the screen should by determined before populating the array (using for instance getxdim() ) as the behaviour of undefined pixels in the array is undefined. If only a partial scan line is to be drawn that drawscansegment should be used.

drawscansegment $colours, $x, $y;

Draws a horizontal line of pixelsof the length of the array that $colours is a reference to starting at position ($x, $y). $colours is a reference to an array of integers indicating the colours of the pixels in the line drawn.

getch

Waits for a key press just like getchar(3) would. For a non blocking check for a keypress use getkey(3).

getcolors

Returns the number of colours available.

getydim

Returns the vertical size in pixels of the screen.

getxdim

Returns the horizontal size in pixels of the screen.

getcurrentchipset Returns a number representing the current SVGA chipset which was autodetected or forced. See setchipset(3).

getcurrentmode

Returns the current video mode.

getcurrenttiming

Returns a list that describes the current timing parameters:

($pixelClock,
 $HSyncStart, 
 $HSyncEnd, 
 $HTotal, 
 $VDisplay, 
 $VSyncStart, 
 $VSyncEnd, 
 $VTotal,
 $flags)

This list is suiutable to pass to changetiming() or addtiming() as parameters.

getdefaultmode

Returns the default graphics mode number from the SVGALIB_DEFAULT_MODE environment variable or an untrue value if undefined. The environment variable can either contain a mode number or a symbolic mode name.

getkey

Reads a character from the keyboard without waiting; returns false if no key pressed and the ASCII value otherwise.

getmodeinfo

Returns an object of the type Linux::Svgalib::Modeinfo which has the following methods that provide information about the current mode:

width

The width of the screen in pixels

height

The height of the screen in pixels

bytesperpixel

The number of bytes required to store pixel information.

colors

The number of colours available for simulataneous display in this mode.

linewidth

Logical scanline width in bytes. This might not be very useful.

If the given mode is out of range, undef is returned. When getmodeinfo() returns details about a certain mode, you must check if it is currently available with hasmode (3).

getmodename $mode

Will return a string representing the mode. Depending on mode it consist of a capital G followed by the amount of x pixels, followed by a lower case x, followed by the amount of y pixels, followed by a lower case x. Finally the number of different colors is appended. Here the shortcuts 32K,64K,16M, and 16M4 are used for 32768, 65536, and 16777216 are used. If the mode does not exist then the empty string will be returned.

getmodenumber $name

The reverse of the above method - parses $name and tries to find a videomode corresponding on it. $name is parsed case insensitive and should be either an integer string just giving a mode number or consist of a capital G followed by the amount of x pixels, followed by a lower case x, fol­ lowed by the amount of y pixels, followed by a lower case x. Finally the number of different colors is appended. Here the shortcuts 32K,64K,16M, and 16M4 are used for 32768, 65536, and 16777216 are used. The last refers also to 16777216 which are store in 4 bytes (highest address byte unused) for easier screen access. For unsupported values or the string "PROMPT" the value ­1 is returned. Also a irritating error message is printed to stdout. This is used during parsing the SVGALIB_DEFAULT_MODE environment variable. Probably it should not be used for anything else.

getmonitortype

This returns the monitor type configered in /etc/vga/libvga.config. The return value is one of the constants:

MON640_60 MON800_56 MON1024_43I

31.5 KHz (standard VGA): does 640x480 in 60Hz vsync. 35.1 KHz (old SVGA): does 800x600 in 56Hz vsync. 35.5 KHz (low­end SVGA, 8514): does 1024x768 in 43Hz vsync interlaced.

MON800_60 MON1024_60

37.9 KHz (SVGA): does 800x600 in 60Hz vsync. 48.3 KHz (SVGA non­interlaced): does 1024x768 in 60Hz vsync, non­interlaced.

MON1024_70 MON1024_72

56.0 KHz (SVGA high frequency): does 1024x768 in 70Hz vsync. does 1024x768 in 72Hz vsync or even better.

getpalette $index

Gets the colour from the palette with the index $index and returns a three element list relating to the red, green and blue components of that colour. The return values from this method are probably only sensible if the graphics modes supports 16 or 256 colours.

getpixel $x, $y

Returns the colour palette index of the pixel at the point ( $x, $y ).

getscansegment $x, $y, $length

returns a list describing the scan segment starting at the point ($x, $y) and of length $length - each element of the list represents a single pixel in the selected scan line.

hasmode $mode

Returns a true value if support for graphics mode $mode is available.

lastmodenumber

Returns the last video mode number available.

lockvc

Disables virtual console switching.

oktowrite

Indicates whether the program is in the console currently visible on the screen. The method is deprecated in the svgalib documentation as a means of determining whether it is safe to write to the VGA memory but as you cant do that here it is fine.

screenoff

Some SVGA chip sets will allow the turning off video signal generation and this may improve SVGA operation performance. This is almost certainly going to be unsightly and confusing to the user however.

screenon

Turn the generation of video signal back on after the use of the above method.

setcolor $colour

Set the current colour for drawing operations ( drawpixel(), drawline()) to $colour. You should only use setcolor() in 256 or less colour modes. For the other modes you must use setrgbcolor() instead.

setmode $mode

This method selects the video mode $mode and clears the screen (if it was a graphics mode).

$mode should be greater than 1 and less than or equal to lastmodenumber().

A true value will be returned on success, false otherwise.

setpalette $index, $red, $green, $blue

Sets the pallette referred to by $index to the colour described by $red, $green, $blue. This operation is only meaningful in modes with 256 or less colours.

unlockvc

Unlocks virtual console switching after a previous call to lockvc.

white

Returns the palette index of 'white' in the current graphics mode. The actual colour in the palette may not appear to be white if it has been altered with setpalette().

EXPORT

.

Exported constants

ALI
APM
ARK
ATI
BANSHEE
CHIPS
CIRRUS
EGA
ET3000
ET4000
ET6000

Graphics modes :

G1024x768x16
G1024x768x16M
G1024x768x16M32
G1024x768x256
G1024x768x32K
G1024x768x64K
G1072x600x16M
G1072x600x16M32
G1072x600x256
G1072x600x32K
G1072x600x64K
G1152x864x16
G1152x864x16M
G1152x864x16M32
G1152x864x256
G1152x864x32K
G1152x864x64K
G1280x1024x16
G1280x1024x16M
G1280x1024x16M32
G1280x1024x256
G1280x1024x32K
G1280x1024x64K
G1280x720x16M
G1280x720x16M32
G1280x720x256
G1280x720x32K
G1280x720x64K
G1360x768x16M
G1360x768x16M32
G1360x768x256
G1360x768x32K
G1360x768x64K
G1600x1200x16
G1600x1200x16M
G1600x1200x16M32
G1600x1200x256
G1600x1200x32K
G1600x1200x64K
G1800x1012x16M
G1800x1012x16M32
G1800x1012x256
G1800x1012x32K
G1800x1012x64K
G1920x1080x16M
G1920x1080x16M32
G1920x1080x256
G1920x1080x32K
G1920x1080x64K
G1920x1440x16M
G1920x1440x16M32
G1920x1440x256
G1920x1440x32K
G1920x1440x64K
G2048x1152x16M
G2048x1152x16M32
G2048x1152x256
G2048x1152x32K
G2048x1152x64K
G2048x1536x16M
G2048x1536x16M32
G2048x1536x256
G2048x1536x32K
G2048x1536x64K
G320x200x16
G320x200x16M
G320x200x16M32
G320x200x256
G320x200x32K
G320x200x64K
G320x240x16M
G320x240x16M32
G320x240x256
G320x240x256V
G320x240x32K
G320x240x64K
G320x400x16M
G320x400x16M32
G320x400x256
G320x400x256V
G320x400x32K
G320x400x64K
G320x480x16M
G320x480x16M32
G320x480x256
G320x480x32K
G320x480x64K
G360x480x256
G400x300x16M
G400x300x16M32
G400x300x256
G400x300x32K
G400x300x64K
G400x600x16M
G400x600x16M32
G400x600x256
G400x600x32K
G400x600x64K
G512x384x16M
G512x384x16M32
G512x384x256
G512x384x32K
G512x384x64K
G512x480x16M
G512x480x16M32
G512x480x256
G512x480x32K
G512x480x64K
G640x200x16
G640x350x16
G640x400x16M
G640x400x16M32
G640x400x256
G640x400x32K
G640x400x64K
G640x480x16
G640x480x16M
G640x480x16M32
G640x480x2
G640x480x256
G640x480x32K
G640x480x64K
G720x348x2
G720x540x16M
G720x540x16M32
G720x540x256
G720x540x32K
G720x540x64K
G800x600x16
G800x600x16M
G800x600x16M32
G800x600x256
G800x600x32K
G800x600x64K
G848x480x16M
G848x480x16M32
G848x480x256
G848x480x32K
G848x480x64K
G960x720x16M
G960x720x16M32
G960x720x256
G960x720x32K
G960x720x64K
TEXT

MACH32
MACH64
MON1024_43I
MON1024_60
MON1024_70
MON1024_72
MON640_60
MON800_56
MON800_60
MX
NV3
OAK
PARADISE
RAGE
RGB_MISORDERED
ROP_AND
ROP_COPY
ROP_INVERT
ROP_OR
ROP_XOR
S3
TVGA8900
UNDEFINED
VESA
VGA

AUTHOR

Jonathan Stowe , <jns@gellyfish.co.uk>

SEE ALSO

perl. svgalib