Removed changes from druid_instance.lua. Moved navigation handler to widgets instead. Updated advanced-setup.md with the added input keys. Adjusted the comments in navigation handler module.

druid/widget/navigation_handler/navigation_handler.lua

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+-- Title: Navigation Handler
+-- Description: Adds support for navigating with keyboard and gamepad.
+-- Author: NaakkaDev <https://github.com/NaakkaDev>
+-- Widget: navigation_handler
+-- Tags: input
+-- Version: 1
+
+
+local event = require("event.event")
+local const = require("druid.const")
+
+
+---Widget force handling GUI navigation via keyboard/gamepad.
+---
+---### Setup
+---Loads the widget module:
+---`local navigation_handler = require("druid.widgets.navigation_handler.navigation_handler")`
+---
+---Create the new widget instance:
+---`self.nav = self.druid:new_widget(navigation_handler, self.my_button)`
+---
+---
+---### Example using the `on_select` event
+---```
+---local function on_select_btn(self, new, current)
+---    gui.play_flipbook(new.node, "button_selected")
+---    gui.play_flipbook(current.node, "button")
+---end
+---```
+---With `self.nav.on_select:subscribe(on_select_btn)`
+---
+---
+---### Notes
+---- `on_select` event callback params: (self, component_instance, component_instance).
+----   - **self** - Druid self context.
+----   - **new** - The component that will be selected next.
+----   - **current** - The component that is about to be de-selected.
+---- Key triggers in `input.binding` should match your setup.
+---- Used `action_id`'s are:' `key_up`, `key_down`, `key_left` and `key_right`.
+---@class druid.widget.navigation_handler: druid.widget
+---@field on_select event fun(self, component_instance, component_instance) Triggers when a new component is selected. The first component is for the newly selected and the second is for the previous component.
+---@field private _weight number The value used to control of the next button diagonal finding logic strictness.
+---@field private _tolerance number Determines how lenient the next button finding logic is. Set larger value for further diagonal navigation.
+---@field private _select_trigger hash Select trigger for the current component. Defaults to `druid.const.ACTION_SPACE`.
+---@field private _selected_triggers table Table of action_ids that can trigger the selected component. Valid only for the current button when set.
+---@field private _selected_component druid.component|druid.button|druid.slider Currently selected button instance.
+---@field private _deselect_directions table<string> The valid "escape" direction of the current selection.
+local M = {}
+
+-- Components that support navigation.
+local COMPONENTS = { "button", "slider" }
+
+
+---The constructor for the navigation_handler component.
+---@param component druid.component Current druid component that starts as selected.
+---@param tolerance number|nil How far to allow misalignment on the perpendicular axis when finding the next component.
+function M:init(component, tolerance)
+    -- Set default tolerance if not given.
+    if tolerance == nil then
+        tolerance = 250
+    end
+
+    pprint(component._component.name)
+
+    self._weight = 10
+    self._tolerance = tolerance
+    self._select_trigger = const.ACTION_SPACE
+    self._selected_triggers = {}
+    self._selected_component = component
+    self._deselect_directions = {}
+
+    -- Select the component if it's a button.
+    if component.hover then
+        component.hover:set_hover(true)
+    end
+
+    -- Events
+    self.on_select = event.create()
+end
+
+
+---@private
+---@param action_id hash Action id from on_input.
+---@param action table Action from on_input.
+---@return boolean is_consumed True if the input was consumed.
+function M:on_input(action_id, action)
+    -- Trigger an action with the selected component, e.g. button click.
+    if self:_action_id_is_trigger(action_id) and self:_selected_is_button() then
+        ---@type druid.button
+        local btn = self._selected_component
+        local is_consume = false
+
+        if action.pressed then
+            btn.is_repeated_started = false
+            btn.last_pressed_time = socket.gettime()
+            btn.on_pressed:trigger(self:get_context(), btn, self)
+            btn.can_action = true
+            return is_consume
+        end
+
+        -- While hold button, repeat rate pick from input.repeat_interval
+        if action.repeated then
+            if not btn.on_repeated_click:is_empty() and btn.can_action then
+                btn:_on_button_repeated_click()
+                return is_consume
+            end
+        end
+
+        if action.released then
+            return btn:_on_button_release() and is_consume
+        end
+
+        return not btn.disabled and is_consume
+    end
+
+    local is_left = action_id == const.ACTION_LEFT
+    local is_right = action_id == const.ACTION_RIGHT
+    local is_up = action_id == const.ACTION_UP
+    local is_down = action_id == const.ACTION_DOWN
+
+    if action.pressed then
+        ---@type druid.component|nil
+        local component = nil
+
+        if is_up then
+            component = self:_find_next_button("up")
+        elseif is_down then
+            component = self:_find_next_button("down")
+        elseif is_left then
+            component = self:_find_next_button("left")
+        elseif is_right then
+            component = self:_find_next_button("right")
+        end
+
+        if component ~= nil and component ~= self._selected_component then
+            return self:_on_new_select(component)
+        end
+    end
+
+    -- Handle chaning slider values when pressing left or right keys.
+    if (action.pressed or action.repeated)
+        and self:_selected_is_slider()
+    then
+        local is_directional = is_left or is_right or is_up or is_down
+
+        -- The action_id was not one of the directions so go no further.
+        if not is_directional then
+            return false
+        end
+
+        ---@type druid.slider
+        local slider = self._selected_component
+        local value = slider.value
+        local new_value = 0.01
+        local is_horizontal = slider.dist.x > 0
+        local negative_value = is_left or is_down
+        local positive_value = is_right or is_up
+
+        -- Reteurn if a navigation should happen instead of a value change.
+        if is_horizontal and (is_up or is_down) then
+            return false
+        elseif not is_horizontal and (is_left or is_right) then
+            return false
+        end
+
+        -- Speedup when holding the button.
+        if action.repeated and not action.pressed then
+            new_value = 0.05
+        end
+
+        if negative_value then
+            value = value - new_value
+        elseif positive_value then
+            value = value + new_value
+        end
+
+        slider:set(value)
+    end
+
+    return false
+end
+
+
+---Sets a new weight value which affects the next button diagonal finding logic.
+---@param new_value number
+---@return druid.widget.navigation_handler self
+function M:set_weight(new_value)
+    self._weight = new_value
+    return self
+end
+
+
+---Sets a new tolerance value. Can be useful when scale or window size changes.
+---@param new_value number How far to allow misalignment on the perpendicular axis when finding the next button.
+---@return druid.widget.navigation_handler self The current navigation handler instance.
+function M:set_tolerance(new_value)
+    self._tolerance = new_value
+    return self
+end
+
+
+---Set input action_id name to trigger selected component by keyboard/gamepad.
+---@param key hash|string The action_id of the input key. Example: "key_space".
+---@return druid.widget.navigation_handler self The current navigation handler instance.
+function M:set_select_trigger(key)
+    if type(key) == "string" then
+        self._select_trigger = hash(key)
+    else
+        self._select_trigger = key
+    end
+
+    return self
+end
+
+
+---Get current the trigger key for currently selected component.
+---@return hash _select_trigger The action_id of the input key.
+function M:get_select_trigger()
+    return self._select_trigger
+end
+
+
+---Set the trigger keys for the selected component. Stays valid until the selected component changes.
+---@param keys table|string|hash Supports multiple action_ids if the given value is a table with the action_id hashes or strings.
+---@return druid.widget.navigation_handler self The current navigation handler instance.
+function M:set_temporary_select_triggers(keys)
+    if type(keys) == "table" then
+        for index, value in ipairs(keys) do
+            if type(value) == "string" then
+                keys[index] = hash(value)
+            end
+        end
+        self._selected_triggers = keys
+    elseif type(keys) == "string" then
+        self._selected_triggers = { hash(keys) }
+    else
+        self._selected_triggers = { keys }
+    end
+
+    return self
+end
+
+
+---Get the currently selected component.
+---@return druid.component _selected_component Selected component, which often is a `druid.button`.
+function M:get_selected_component()
+    return self._selected_component
+end
+
+
+---Set the de-select direction for the selected button. If this is set
+---then the next button can only be in that direction.
+---@param dir string|table Valid directions: "up", "down", "left", "right". Can take multiple values as a table of strings.
+---@return druid.widget.navigation_handler self The current navigation handler instance.
+function M:set_deselect_directions(dir)
+    if type(dir) == "table" then
+        self._deselect_directions = dir
+    elseif type(dir) == "string" then
+        self._deselect_directions = { dir }
+    end
+
+    return self
+end
+
+
+---Returns true if the currently selected `druid.component` is a `druid.button`.
+---@private
+---@return boolean
+function M:_selected_is_button()
+    return self._selected_component._component.name == "button"
+end
+
+
+---Returns true if the currently selected `druid.component` is a `druid.slider`.
+---@private
+---@return boolean
+function M:_selected_is_slider()
+    return self._selected_component._component.name == "slider"
+end
+
+
+---Find the best next button based on the direction from the currently selected button.
+---@private
+---@param dir string Valid directions: "top", "bottom", "left", "right".
+---@return druid.component|nil
+function M:_find_next_button(dir)
+    ---Helper method for checking if the given direction is valid.
+    ---@param dirs table<string>
+    ---@param dir string
+    ---@return boolean
+    local function valid_direction(dirs, dir)
+        for _index, value in ipairs(dirs) do
+            if value == dir then
+                return true
+            end
+        end
+        return false
+    end
+
+    ---Helper method for checking iterating through components.
+    ---Returns true if the given component is in the table of valid components.
+    ---@param input_component druid.component
+    ---@return boolean
+    local function valid_component(input_component)
+        local component_name = input_component._component.name
+        for _index, component in ipairs(COMPONENTS) do
+            if component_name == component then
+                return true
+            end
+        end
+        return false
+    end
+
+    -- Check if the deselect direction is set and
+    -- the direction is different from it.
+    if next(self._deselect_directions) ~= nil and not valid_direction(self._deselect_directions, dir) then
+        return nil
+    end
+
+    local best_component, best_score = nil, math.huge
+    local screen_pos = gui.get_screen_position(self._selected_component.node)
+
+    -- Use the slider parent node instead of the pin node.
+    if self._selected_component._component.name == "slider" then
+        screen_pos = gui.get_screen_position(gui.get_parent(self._selected_component.node))
+    end
+
+    ---@type druid.component
+    for _, input_component in ipairs(self._meta.druid.components_interest[const.ON_INPUT]) do
+        -- GUI node of the component being iterated.
+        local node = input_component.node
+
+        -- If it is a slider component then use its parent node instead,
+        -- since the pin node moves around.
+        if input_component._component.name == "slider" then
+            node = gui.get_parent(node)
+        end
+
+        -- Only check components that are supported.
+        if input_component ~= self._selected_component and valid_component(input_component) then
+            local pos = gui.get_screen_position(node)
+            local dx, dy = pos.x - screen_pos.x, pos.y - screen_pos.y
+            local valid = false
+            local score = math.huge
+
+            if dir == "right" and dx > 0 and math.abs(dy) <= self._tolerance then
+                valid = true
+                score = dx * dx + dy * dy * self._weight
+            elseif dir == "left" and dx < 0 and math.abs(dy) <= self._tolerance then
+                valid = true
+                score = dx * dx + dy * dy * self._weight
+            elseif dir == "up" and dy > 0 and math.abs(dx) <= self._tolerance then
+                valid = true
+                score = dy * dy + dx * dx * self._weight
+            elseif dir == "down" and dy < 0 and math.abs(dx) <= self._tolerance then
+                valid = true
+                score = dy * dy + dx * dx * self._weight
+            end
+
+            if valid and score < best_score then
+                best_score = score
+                best_component = input_component
+            end
+        end
+    end
+
+    return best_component
+end
+
+
+---De-select the current selected component.
+---@private
+function M:_deselect_current()
+    if self._selected_component.hover then
+        self._selected_component.hover:set_hover(false)
+    end
+    self._selected_component = nil
+    self._selected_triggers = {}
+
+    -- The deselect direction was used so remove it.
+    if self._deselect_directions then
+        self._deselect_directions = {}
+    end
+end
+
+
+---Check if the supplied action_id can trigger the selected component.
+---@private
+---@param action_id hash
+---@return boolean
+function M:_action_id_is_trigger(action_id)
+    for _, key in ipairs(self._selected_triggers) do
+        if action_id == key then
+            return true
+        end
+    end
+
+    return action_id == self._select_trigger
+end
+
+
+---Handle new selection.
+---@private
+---@param new druid.component Instance of the selected component.
+---@return boolean
+function M:_on_new_select(new)
+    ---@type druid.component
+    local current = self._selected_component
+
+    -- De-select the current component.
+    self:_deselect_current()
+    self._selected_component = new
+
+    --- BUTTON
+    if new._component.name == "button" then
+        -- Set the active button hover state.
+        new.hover:set_hover(true)
+    end
+
+    --- SLIDER
+    if new._component.name == "slider" then
+        -- Check if the slider is horizontal, if so then
+        -- the next component should be above or below of this one.
+        if new.dist.x > 0 then
+            self:set_deselect_directions({ "up", "down" })
+        end
+
+        -- Check if the slider is vertical, if so then
+        -- the next component should be left or right of this one.
+        if new.dist.y > 0 then
+            self:set_deselect_directions({ "left, right" })
+        end
+    end
+
+    --- EVENT
+    self.on_select:trigger(self:get_context(), new, current)
+
+    return false
+end
+
+
+return M