Druid-Extension/docs_md/02-creating_custom_components.md
2020-03-22 12:17:06 +03:00

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# Creating custom components
## Overview
Druid allows you to create your custom components from druid basic components or other custom components
## Custom components
Basic custom component template looks like this:
```lua
local const = require("druid.const")
local component = require("druid.component")
local M = component.create("name_your_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
return M
```
Add your custom component to druid via `druid.register`
```lua
local druid = require("druid.druid")
local my_component = require("my.amazing.component")
local function init(self)
druid.register("my_component", 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:
```lua
-- 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
```