crystal.Switcher

A Container which draws only one of its children at a time.

Children of a Switcher have a Basic Joint to adjust positioning preferences (padding, alignment, etc.).

Constructor

crystal.Switcher:new()

Methods

Name	Description
active_child	Returns which of its children this switcher is drawing.
set_sizing_mode	Sets how this switcher’s desired size is computed.
sizing_mode	Returns how this switcher’s desired size is computed.
switch_to	Changes which of its children this switcher is drawing.

Examples

This example implements an image carousel that can be controlled with the arrow keys (assuming they are bound to the "ui_left" and "ui_right" input actions):

local Carousel = Class("Carousel", crystal.Widget);

Carousel.init = function(self, images)
  Carousel.super.init(self);
  local switcher = self:set_child(crystal.Switcher:new());
  for _, image in ipairs(images) do
    switcher:add_child(crystal.Image:new(crystal.assets.get(image)));
  end

  local advance = function(delta, transition)
    local children = switcher:children();
    local index = table.index_of(children, switcher:active_child());
    index = index + delta;
    if index > #children then
      index = 1;
    elseif index < 1 then
      index = #children;
    end
    switcher:switch_to(switcher:child(index), transition);
  end

  switcher:bind_input("+ui_right", "always", nil, function()
    advance(1, crystal.Transition.ScrollLeft:new())
  end);

  switcher:bind_input("+ui_left", "always", nil, function()
    advance(-1, crystal.Transition.ScrollRight:new())
  end);
end

-- usage: local carousel = Carousel:new({ "cool_image.png", "other_image.png", "last_image.png" });