SDL::Joystick

Section: User Contributed Perl Documentation (3)
Updated: 2020-07-28
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NAME

SDL::Joystick -- SDL Bindings for the Joystick device  

CATEGORY

Core, Joystick  

SYNOPSIS

 use SDL;
 use SDL::Joystick;
 
 SDL::init_sub_system(SDL_INIT_JOYSTICK);
 
 die('no joystick found') unless(SDL::Joystick::num_joysticks());
     
 my $joystick = SDL::Joystick->new(0);

 

METHODS

 

num_joysticks

 int SDL::Joystick::num_joysticks( void );

Counts and returns available joysticks.  

name

 string SDL::Joystick::name( index );

Get the implementation dependent name of joystick. The "index" parameter refers to the N'th joystick on the system.

 my $num_joysticks = SDL::Joystick::num_joysticks();

 printf("%d joysticks found\n", $num_joysticks);

 for($i = 0; $i < $num_joysticks; $i++)
 {
     printf("%s\n", SDL::Joystick::name($i));
 }

 

new

 object SDL::Joystick->new( index );

Opens a joystick for use within SDL. The "index" refers to the N'th joystick in the system. A joystick must be opened before it can be used.

 # Initialize the joystick subsystem
 SDL::init_sub_system(SDL_INIT_JOYSTICK);
 
 # Check for joystick
 if(SDL::Joystick::num_joysticks() > 0)
 {
     # Open joystick
     my $joystick = SDL::Joystick->new(0);
 
     if($joystick)
     {
         printf("Opened Joystick 0\n");
         printf("Name: %s\n",              SDL::Joystick::name(0));
         printf("Number of Axes: %d\n",    SDL::Joystick::num_axes($joystick));
         printf("Number of Buttons: %d\n", SDL::Joystick::num_buttons($joystick));
         printf("Number of Balls: %d\n",   SDL::Joystick::num_balls($joystick));
     }
     else
     {
         printf("Couldn't open Joystick 0\n");
     }
 
     # Close if opened
     SDL::Joystick::close($joystick) if SDL::Joystick::opened(0);
 }

 

opened

 int SDL::Joystick::opened( index );

Determines whether a joystick has already been opened within the application. "index" refers to the N'th joystick on the system.

Returns 1 if the joystick has been opened, or 0 if it has not.  

index

 int SDL::Joystick::index( object );

Returns the "index" of a given "SDL_Joystick" structure. See SDL::Joystick::new  

num_axes

 int SDL::Joystick::num_axes( object );

Return the number of axes available from a previously opened joystick. See SDL::Joystick::new  

num_balls

 int SDL::Joystick::num_balls( object );

Return the number of trackballs available from a previously opened joystick. See SDL::Joystick::new  

num_hats

 int SDL::Joystick::num_hats( object );

Gets the number of joystick hats from a previously opened joystick. See SDL::Joystick::new  

num_buttons

 int SDL::Joystick::num_buttons( object );

Gets the number of joystick buttons from a previously opened joystick. See SDL::Joystick::new  

update

 void SDL::Joystick::update();

Updates the state(position, buttons, etc.) of all open joysticks. If joystick events have been enabled with "SDL::Joystick::event_state" then this is called automatically in the event loop.  

get_axis

"get_axis" returns the current state of the given axis on the given joystick.

On most modern joysticks the X axis is usually represented by axis 0 and the Y axis by axis 1. The value returned by "get_axis" is a signed integer (-32768 to 32767) representing the current position of the axis, it may be necessary to impose certain tolerances on these values to account for jitter.

Note: Some joysticks use axes 2 and 3 for extra buttons.

Returns a 16-bit signed integer representing the current position of the axis.

 my $joystick = SDL::Joystick->new(0);

 my $x_move   = SDL::Joystick::get_axis($joystick, 0);
 my $y_move   = SDL::Joystick::get_axis($joystick, 1);

 

get_hat

 int SDL::Joystick::get_hat( object, int );

"get_hat" returns the current state of the given "hat" on the given "joystick".

The current state is returned which is an OR'd combination of one or more of the following:

"SDL_HAT_CENTERED"
"SDL_HAT_UP"
"SDL_HAT_RIGHT"
"SDL_HAT_DOWN"
"SDL_HAT_LEFT"
"SDL_HAT_RIGHTUP"
"SDL_HAT_RIGHTDOWN"
"SDL_HAT_LEFTUP"
"SDL_HAT_LEFTDOWN"

 my $joystick = SDL::Joystick->new(0);
 
 my $position = SDL::Joystick::get_hat($joystick, 0);
 
 print("hat is in position UP\n") if $position & SDL_HAT_UP;

 

get_button

 int SDL::Joystick::get_button( object, int );

"get_button" returns the current state of the given button on the given joystick.

Returns 1 if the button is pressed. Otherwise, 0.

 my $joystick    = SDL::Joystick->new(0);
 
 my $num_buttons = SDL::Joystick::num_buttons($joystick);
 
 for(my $i = 0; $i < $num_buttons; $i++)
 {
     printf("button %d is %s\n", $i, SDL::Joystick::get_button($joystick, $i) ? 'pressed' : 'not pressed');
 }
 
 SDL::Joystick::close($joystick) if SDL::Joystick::opened(0);

 

get_ball

 int SDL::Joystick::get_ball(SDL_Joystick $joystick, int $ball, int $dx, int $dy);

Get the ball axis change.

Trackballs can only return relative motion since the last call to SDL::Joystick::get_ball, these motion deltas are placed into "dx" and "dy".

Returns 0 on success or -1 on failure

 my $delta_x  = 0;
 my $delta_y  = 0;
 my $joystick = SDL::Joystick->new(0);
 
 SDL::Joystick::update();
 
 printf("TrackBall Read Error!\n") if(SDL::JoystickGetBall($joystick, 0, $delta_x, $delta_y) == -1);
 printf("Trackball Delta- X:%d, Y:%d\n", delta_x, delta_y);

 

close

 void SDL::Joystick::close( object );

Closes a previously opened joystick. See SDL::Joystick::new

 SDL::Joystick::close($joystick) if SDL::Joystick::opened(0);

 

AUTHORS

See ``AUTHORS'' in SDL.


 

Index

NAME
CATEGORY
SYNOPSIS
METHODS
num_joysticks
name
new
opened
index
num_axes
num_balls
num_hats
num_buttons
update
get_axis
get_hat
get_button
get_ball
close
AUTHORS