Class: SlideField::Animator

Inherits:
Object
  • Object
show all
Defined in:
lib/slidefield/animator.rb

Instance Method Summary collapse

Constructor Details

#initialize(layout_size) ⇒ Animator

Returns a new instance of Animator.



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# File 'lib/slidefield/animator.rb', line 2

def initialize(layout_size)
  @layout_size = layout_size
  reset
end

Instance Method Details

#frame(*args) ⇒ Object 



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# File 'lib/slidefield/animator.rb', line 16

def frame(*args)
  struct = Struct.new :time, :current?, :forward?
  @frame = struct.new *args
  yield
  @frame = nil
end

#need_redraw? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/slidefield/animator.rb', line 7

def need_redraw?
  @animations.each {|k,v| return true if v.enabled }
  @animations.empty?
end

#reset ⇒ Object 



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# File 'lib/slidefield/animator.rb', line 12

def reset
  @animations = {}
end

#transform(obj) ⇒ Object 



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# File 'lib/slidefield/animator.rb', line 23

def transform(obj)
  raise "Can not animate outside a frame" unless @frame

  tr_struct = Struct.new :skip_draw?, :x_offset, :y_offset, :scale, :opacity
  tr = tr_struct.new false, 0, 0, 1.0, 1.0

  anim = animation_for obj.ancestor(:animation)

  # no animation
  return tr if anim.nil?

  # direction disabled
  cur_direction = @frame.forward? ? @frame.current? : !@frame.current?
  dir_enabled = cur_direction ? anim.enter : anim.leave
  anim.enabled = false unless dir_enabled

  elapsed = @frame.time - anim.start_time
  position = elapsed / anim.duration
  anim.enabled = false if position > 1.0

  # animation finished
  unless anim.enabled
    tr[:skip_draw?] = !@frame.current? # don't draw the previous slide anymore
    return tr
  end

  width, height = @layout_size

  case anim.name
  when "fade"
    if @frame.current?
      tr.opacity = position
    else
      tr.opacity = 1.0 - position
    end
  when "slide right"
    tr.x_offset = slide_offset position, width, false
  when "slide left"
    tr.x_offset = slide_offset position, width, true
  when "slide down"
    tr.y_offset = slide_offset position, height, false
  when "slide up"
    tr.y_offset = slide_offset position, height, true
  when "zoom"
    if @frame.current?
      tr.scale = position
    else
      tr.scale = 1.0 - position
    end
  else
    # the validator has missed ?!
    # TODO: validate at interpret time
    raise SlideField::RuntimeError,
      "Unsupported animation '#{anim.name}'"
  end

  tr
end