Creating custom components

Overview

Druid allows you to create your custom components from druid basic components or other custom components.

Every component is the children of Basic Druid component. Read the [basic component API here].(https://insality.github.io/druid/modules/component.html), Methods of basic components you can call via self:{method_name}

Custom components

Basic custom component template looks like this:

local const = require("druid.const")
local component = require("druid.component")

local M = component.create("my_component")

-- Component constructor
function M.init(self, ...)
end

-- Call only if exist interest: const.ON_UPDATE
function M.update(self, dt)
end

-- Call only if exist interest: const.ON_INPUT or const.ON_INPUT_HIGH
function M.on_input(self, action_id, action)
end

-- Call only if exist interest: const.ON_MESSAGE
function M.on_message(self, message_id, message, sender)
end

-- Call only if component with ON_CHANGE_LANGUAGE interest
function M.on_change_language(self)
end

-- Call only if component with ON_LAYOUT_CHANGE interest
function M.on_layout_change(self)
end

-- Call, if input was capturing before this component
-- Example: scroll is start scrolling, so you need unhover button
function M.on_input_interrupt(self)
end

-- Call on component remove or on druid:final
function M.on_remove(self)
end

return M

Add your custom component to druid via druid.register

local druid = require("druid.druid")
local my_component = require("my.amazing.component")

function init(self)
	druid.register("my_component", my_component)
end

Registering make new function with "new_{component_name}". In our example it will be: druid:new_my_component().

Or you can create component without registering with druid:create(my_component_module)

As component registered, you can create your component with next code:

local druid = require("druid.druid")
local my_component = require("my.amazing.component")

function init(self)
	self.druid = druid.new(self)

	local my_component = self.druid:new_my_component(...)
	-- or --
	local my_component = self.druid:create(my_component, ...)
end

Interest

Interest - is a way to indicate what events your component will respond to. There is next interests in druid:

ON_MESSAGE - component will receive messages from on_message
ON_UPDATE - component will be updated from update
ON_INPUT_HIGH - component will receive input from on_input, before other components with ON_INPUT
ON_INPUT - component will receive input from on_input, after other components with ON_INPUT_HIGH
ON_CHANGE_LANGUAGE - will call on_change_language function on language change trigger
ON_LAYOUT_CHANGED will call on_layout_change function on layout change trigger

Best practice on custom components

On each component recommended describe component scheme in next way:

-- Component module
local component = require("druid.component")

local M = component.create("your_component")

local SCHEME = {
	ROOT = "root",
	ITEM = "item",
	TITLE = "title"
}

function M.init(self, template_name, node_table)
	-- If component use template, setup it:
	self:set_template(template_name)

	-- If component was cloned with gui.clone_tree, pass his nodes
	self:set_nodes(node_table)

	-- helper can get node from gui/template/table
	local root = self:get_node(SCHEME.ROOT)

	-- This component can spawn another druid components:
	local druid = self:get_druid()

	-- Button self on callback is self of _this_ component
	local button = druid:new_button(...)

	-- helper can return you the component style for current component
	-- It return by component name from 
	local my_style = self:get_style()
end

Power of using templates

You can use one component, but creating and customizing templates for them. Templates only requires to match the component scheme.

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