Area input and redraws

日本語

A drawing callback displays state. Change state in input callbacks or timers, then call queue_redraw_all to schedule the next draw. queue_redraw_all does not draw immediately.

x = 80.0
y = 80.0
brush = UIng::Area::Draw::Brush.new(:solid, 0.2, 0.4, 0.8, 1.0)

handler = UIng::Area::Handler.new do
  draw do |_area, params|
    params.context.fill_path(brush) do |path|
      path.add_rectangle(x, y, 24, 24)
    end
  end

  mouse_event do |area, event|
    x = event.x
    y = event.y
    area.queue_redraw_all
  end

  key_event do |area, event|
    handled = !event.up? && event.ext_key == UIng::Area::ExtKey::Left
    x -= 8 if handled
    area.queue_redraw_all if handled
    handled
  end
end

area = UIng::Area.new(handler)

Input callbacks

• mouse_event receives coordinates, button state, and modifiers.
• mouse_crossed receives pointer enter/leave changes.
• drag_broken can restore state when a drag is interrupted.
• key_event returns true when it handled the key and false otherwise.

Call begin_user_window_move and begin_user_window_resize only inside mouse_event while event.down != 0. For animation, avoid creating drawing resources every frame and redraw only after state changes.

area_analog_clock.cr and reversi.cr combine state with redraws.