CATEGORY¶

Core, Events

pump_events¶

Pumps the event loop, gathering events from the input devices.

        pump_events();

pump_events gathers all the pending input information from devices and places it on the event queue. Without calls to pump_events no events would ever be placed on the queue. Often the need for calls to pump_events is hidden from the user since "poll_event" and "wait_event" implicitly call pump_events. However, if you are not polling or waiting for events (e.g. you are filtering them), then you must call pump_events to force an event queue update.

peep_events (event, num_events, action, mask)¶

Checks the event queue for messages and optionally returns them.

        my $num_peep_events = SDL::Events::peep_events($event, 127, SDL_PEEKEVENT, SDL_ALLEVENTS);

If action is SDL_ADDEVENT, up to num_events events will be added to the back of the event queue.

If action is SDL_PEEKEVENT, up to num_events events at the front of the event queue, matching mask, will be returned and will not be removed from the queue.

If action is SDL_GETEVENT, up to num_events events at the front of the event queue, matching mask, will be returned and will be removed from the queue.

The mask parameter is a bitwise OR of SDL::Events::SDL_EVENTMASK(event_type), for all event types you are interested in

This function is thread-safe.

You may have to call pump_events before calling this function. Otherwise, the events may not be ready to be filtered when you call peep_events.

Examples of mask:

SDL_EVENTMASK (SDL_KEYUP)

(SDL_EVENTMASK (SDL_MOUSEBUTTONDOWN) | SDL_EVENTMASK (SDL_MOUSEBUTTONUP))

SDL_ALLEVENTS

SDL_KEYUPMASK

SDL_ALLEVENTS ^ SDL_QUITMASK

RETURN

Number of Events actually stored or -1 if there was an error

poll_event($event)¶

Polls for currently pending events.

If $event is not NULL, the next event is removed from the queue and stored in the SDL::Event structure pointed to by $event.

As this function implicitly calls pump_events, you can only call this function in the thread that set the video mode with SDL::Video::set_video_mode.

RETURN

Returns 1 if there are any pending events, or 0 if there are none available.

push_event($event)¶

Pushes an event onto the event queue

The event queue can actually be used as a two way communication channel. Not only can events be read from the queue, but the user can also push their own events onto it. event is a pointer to the event structure you wish to push onto the queue. The event is copied into the queue, and the caller may dispose of the memory pointed to after push_event returns.

Note: Pushing device input events onto the queue doesn't modify the state of the device within SDL.

This function is thread safe, and can be called from other threads safely.

RETURN

Returns 0 on success or -1 if the event couldn't be pushed.

wait_event($event)¶

Waits indefinitely for the next available $event, returning 0 if there was an error while waiting for events, 1 otherwise.

If $event is not NULL, the next event is removed from the queue and stored in $event.

As this function implicitly calls SDL_PumpEvents, you can only call this function in the thread that SDL::Video::set_video_mode.

RETURN

0 if there was an error while waiting for events, 1 otherwise

set_event_filter¶

Sets up a filter to process all events

        my $filter = sub { if($_[0]->type == SDL_ACTIVEEVENT){ return 0} else{ return 1; }};
        SDL::Events::set_event_filter($filter);

PARAMETER

set_event_filter takes a coderef that it checks all events again. The callback gets a event in the stack

        sub { my $event_to_test = shift; ...}

to filter the event return a 0, to pass the filter return a 1.

One Caveat is if you are filtering SDL_QUIT the event will be filtered if it is non-interrupt call ( Window closes normally ). If it is a interrupt SDL_QUIT it will be process on the next event poll.

Events pushed onto to the queue with SDL::Events::push_events or SDL::Events::peep_events do not get filtered.

This callback may run in a different thread.

get_key_state¶

Get a snapshot of the current keyboard state

        my $keys_ref = SDL::Events::get_key_state();
        print $keys_ref->[SDLK_RETURN]; # 1 if pressed , 0 if not pressed

Use SDL::Events::pump_events to update the state array.

This function gives you the current state after all events have been processed, so if a key or button has been pressed and released before you process events, then the pressed state will never show up in the get_key_state call.

This function doesn't take into account whether shift has been pressed or not.

get_mod_state¶

Get the state of the modifier keys

Returns the current state of modifier keys

Return value is an OR'd combination of KMOD_*

 SDL::Events::pump_events; #get latest mod_state in buffers
 my $mod_state = SDL::Events::get_mod_state();
 # Check which ones are pressed with 
 # no mod pressed?
 
 print 'no_mod' if  ( $mod_state & KMOD_NONE );
 # CTRL or ALT 
 print 'ctrl alt' if ($mod_state & KMOD_CTRL || $mod_state & KMOD_ALT );

MOD VALUES

KMOD_NONE

KMOD_LSHIFT

KMOD_RSHIFT

KMOD_LCTRL

KMOD_RCTRL

KMOD_LALT

KMOD_RALT

KMOD_LMETA

KMOD_RMETA

KMOD_NUM

KMOD_CAPS

KMOD_MODE

KMOD_CTRL

same as KMOD_LCTRL|KMOD_RCTRL

KMOD_SHIFT

same as KMOD_LSHIFT|KMOD_RSHIFT

KMOD_ALT

same as KMOD_LALT|KMOD_RALT

KMOD_META

same as KMOD_LMETA|KMOD_RMETA

set_mod_state¶

Get the state of the modifier keys

The inverse of SDL::Events::get_mod_state allows you to impose modifier key states on your application.

Simply pass your desired modifier states into $modstate. This value can be a OR'd combination of any KMOD* constant.

 my $modstate = KMOD_LMETA | KMOD_LSHIFT;

Any KMOD_* constant see SDL::Events::get_mod_state for constants.
SDL::Events::set_mod_state( $modstate );

event_state¶

Allows you to set the state of processing certain events

 SDL::Events::event_state( $type, $state );

A list of $type(s) can be found in SDL::Event

STATES

SDL_IGNORE

The event of $type will be automatically dropper from the event queue and will not be filtered.

SDL_ENABLE

The event of $type will be processed normally. This is default.

SDL_QUERY

The current processing state of the $type will be returned

get_key_name¶

Gets the name of the a SDL virtual keysym

 my $event = SDL::Event->new();
 while( SDL::Events::poll_event($event) )
 {
   my $key = $event->key_sym;
   $key_str = SDL::Events::get_key_name($key);
 }

Returns a string with the name of the key sym.

enable_unicode¶

Enable/Disable UNICODE translation

  my $previous_translation_mode = SDL::Events::enable_unicode( 1 ); #enable
     $previous_translation_mode = SDL::Events::enable_unicode( 0 ); #disables

To obtain the character codes corresponding to received keyboard events, Unicode translation must first be turned on using this function. The translation incurs a slight overhead for each keyboard event and is therefore disabled by default. For each subsequently received key down event, the unicode member of the SDL::Event::key_sym provided structure will be then contain the corresponding character code, or otherwise zero.

A value of 1 for enabling, 0 for disabling and -1 for unchanged. -1 is useful for querying the current translation mode.

Only key press events will be translated not release events.

Returns the previous translation mode as (1,0).

enable_key_repeat¶

Sets keyboard repeat rate

 my $success = SDL::Events::enable_key_repeat( $delay, $interval );

Enables or disables the keyboard repeat rate. $delay specifies how long the key must be pressed before it begins repeating, it then repeats at the speed specified by $interval. Both $delay and $interval are expressed in milliseconds.

Setting $delay to 0 disables key repeating completely. Good default values are SDL_DEFAULT_REPEAT_DELAY and SDL_DEFAULT_REPEAT_INTERVAL.

Return 0 on success and -1 on fail.

get_mouse_state¶

Retrieves the current state of the mouse

  my ($mask,$x,$y) = @{ SDL::Events::get_mouse_state( ) };
  print 'Button Left pressed' if ($mask & SDL_BUTTON_LMASK);    
  print 'Button Right pressed' if ($mask & SDL_BUTTON_RMASK);   
  print 'Button Middle pressed' if ($mask & SDL_BUTTON_MMASK);  
  print $x.','.$y;

The current button state is returned as a button $bitmask, which can be tested using the the above constants

get_relative_mouse_state¶

Retrieves the current relative state of the mouse

  my ($mask,$x,$y) = @{ SDL::Events::get_mouse_state( ) };
  print 'Button Left pressed' if ($mask & SDL_BUTTON_LMASK);    
  print 'Button Right pressed' if ($mask & SDL_BUTTON_RMASK);   
  print 'Button Middle pressed' if ($mask & SDL_BUTTON_MMASK);  
  print $x.','.$y; # this is relative to the last position of the mouse

The current button state is returned as a button $bitmask, which can be tested using the the above constants

get_app_state¶

Gets the state of the application

        my $app_state = SDL::Events::get_app_state();

The $app_state is a bitwise combination of:

SDL_APPMOUSEFOCUS

Application has mouse focus

        warn 'mouse focus' if $app_state & SDL_APPMOUSEFOCUS
    

SDL_APPINPUTFOCUS

Application has keyboard focus

        warn 'keyboard focus' if $app_state & SDL_APPINPUTFOCUS
    

SDL_APPACTIVE

Application is visible

        warn 'Application Visible' if $app_state & SDL_APPACTIVE
    

joystick_event_state¶

Enable/disable joystick event polling

        my $status = SDL::Events::joystick_event_state( $state );

This function is used to enable or disable joystick event processing. With joystick event processing disabled you will have to update joystick states with SDL::Joystick::update and read the joystick information manually. $state can be:

SDL_QUERY

SDL_ENABLE

SDL_IGNORE

Joystick event handling is default. Even if joystick event processing is enabled, individual joysticks must be opened before they generate events

Warning: Calling this function may delete all events currently in SDL's event queue.

If $state is SDL_QUERY then the current state is returned, otherwise the new processing state is returned.