EventQueue provides a simple way to manage SDL’s events, allowing the application to detect keyboard presses, mouse movements and clicks, joystick movement, etc. You can also post custom events to the EventQueue to help manage the game state.
In Rubygame 2.4 and later, you can call enable_new_style_events to make EventQueue fetch the new event classes (in the Rubygame::Events module). Otherwise, the old classes will be used, for backwards compatibility.
If you wish to ignore all events of a certain class, append those classes the instance variable @ignore (accessors are provided). You can ignore as many classes of events as you want, but make sure you don’t ignore ALL event classes, or the user won’t be able to control the game!
If the program has to pause and wait for an event (for example, if the player must press a button to begin playing), you might find the wait method to be convenient.
Alias for each
Iterate through all events in the EventQueue, yielding them one at a time to the given block. The EventQueue is flushed after all events have been yielded. You can use peek_each if you want to keep the events.
If the internal variable @autofetch is true, this method will call fetch_sdl_events once before iterating.
# File lib/rubygame/queue.rb, line 108 def each( &block ) fetch_sdl_events if @autofetch _old_each( &block ) self.clear end
If you call this method, the new event classes will be used. Otherwise, the old classes will be used, for backwards compatibility.
# File lib/rubygame/queue.rb, line 82 def enable_new_style_events @new_style_events = true end
Posts pending SDL hardware events to the EventQueue. Only one EventQueue should call this method per application, and only if you are not using Rubygame#fetch_sdl_events to manually process events! Otherwise, some events may be removed from SDL’s event stack before they can be properly processed!
# File lib/rubygame/queue.rb, line 127 def fetch_sdl_events if @new_style_events self.push( Rubygame::Events.fetch_sdl_events() ) else Rubygame.deprecated("Rubygame::EventQueue with old event classes", "3.0") self.push( Rubygame.fetch_sdl_events() ) end end
Alias for push
Wait for an event to be posted, then return that event. If there is already an event in the queue, this method will immediately return that event. Events that are ignored will not trigger the return.
This method takes this argument:
|time:||how long (in milliseconds) to delay between each check for new events. Defaults to 10 ms.|
If a block is given to this method, it will be run after each unsuccessful check for new events. This method will pass to the block the number of times it has checked for new events.
If the internal variable @autofetch is true, this method will call fetch_sdl_events before every check for new events.
Please be cautious when using this method, as it is rather easy to cause an infinite loop. Two ways an infinite loop might occur are:
# File lib/rubygame/queue.rb, line 159 def wait(delay=10, &block) iterations = 0 if block_given? loop do fetch_sdl_events() if @autofetch if self.length >= 1 s = self.shift return s unless s == nil end yield iterations iterations += 1 Rubygame::Clock.delay(delay) end else loop do fetch_sdl_events() if @autofetch s = self.shift return s unless s == nil iterations += 1 Rubygame::Clock.delay(delay) end end end