Class: Rubygame::EventQueue

Inherits:
Array
  • Object
show all
Defined in:
lib/rubygame/queue.rb

Overview

EventQueue to help manage the game state.

For basic usage, create a #new EventQueue with autofetch, then call the #each method once per game loop, passing a block which handles events. See the sample applications for examples of this.

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.

It is **strongly recommended** that you use the new event classes. The old classes are deprecated as of Rubygame 2.4, and will be removed entirely in Rubygame 3.0.

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.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize {|_self| ... } ⇒ EventQueue

Create a new EventQueue.

Yields:

  • (_self)

Yield Parameters:



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# File 'lib/rubygame/queue.rb', line 63

def initialize()
  @autofetch = true
  @ignore = []
  @new_style_events = false
  yield self if block_given?
end

Instance Attribute Details

#autofetch ⇒ Object

Whether to fetch SDL events automatically when #each and #wait are used. Enabled by default.



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# File 'lib/rubygame/queue.rb', line 60

def autofetch
  @autofetch
end

#ignore ⇒ Object

Array of classes to be ignored by #push.



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# File 'lib/rubygame/queue.rb', line 56

def ignore
  @ignore
end

Instance Method Details

#each(&block) ⇒ Object

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.



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# File 'lib/rubygame/queue.rb', line 108

def each( &block )
  fetch_sdl_events if @autofetch
  _old_each( &block )
  self.clear
end

#enable_new_style_events ⇒ Object

Enable new-style events. These are the event classes in the Rubygame::Events module, which were added in Rubygame 2.4.

If you call this method, the new event classes will be used. Otherwise, the old classes will be used, for backwards compatibility.

It is **strongly recommended** that you use the new event classes. The old classes are deprecated as of Rubygame 2.4, and will be removed entirely in Rubygame 3.0.



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# File 'lib/rubygame/queue.rb', line 82

def enable_new_style_events
  @new_style_events = true
end

#fetch_sdl_events ⇒ Object

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!



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# 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

#peek_each(&block) ⇒ Object

Like #each, but doesn’t remove the events from the queue after iterating.



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# File 'lib/rubygame/queue.rb', line 116

def peek_each( &block )
  fetch_sdl_events if @autofetch
  _old_each( &block )
end

#push(*events) ⇒ Object Also known as: post

Append events to the EventQueue. Silently ignores events whose class is in @ignore.



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# File 'lib/rubygame/queue.rb', line 89

def push(*events)
  events = events.flatten.delete_if {|e| @ignore.include?(e.class)}
  events.each do |e|
    super( e )
  end
end

#wait(delay = 10, &block) ⇒ Object

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:

  1. Waiting for an SDL event when @autofetch is disabled. (This is not a problem if the block will post an event.)

  2. Waiting for any event when all possible event types are ignored.



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# 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