helium/core/element.lua

--[[ Element superclass ]]
local path = string.sub(..., 1, string.len(...) - string.len(".core.element"))
local helium = require(path .. ".dummy")

---@class context
local context = {}
context.__index = context

local activeContext

---@param elem element
function context.new(elem)
	local ctx = setmetatable({view = elem.view, element = elem}, context)

	return ctx
end

function context:bubbleUpdate()
	self.element.settings.pendingUpdate  = true
	self.element.settings.needsRendering = true

	if self.parentCtx then
		self.parentCtx:bubbleUpdate()
	end
end

function context:set()
	if activeContext then
		self.parentCtx = activeContext

		self.absX      = self.parentCtx.absX + self.view.x
		self.absY      = self.parentCtx.absY + self.view.y

		activeContext  = self
	else
		self.absX      = self.view.x
		self.absY      = self.view.y

		activeContext  = self
	end
end

function context:unset()
	if self.parentCtx then
		activeContext = self.parentCtx
	else
		activeContext = nil
	end
end

---@class element
local element = {}
element.__index = element

setmetatable(element,{
		__call = function(cls, ...)
			local self
			local func, loader = ...
			if type(func)=='function' then
				self = setmetatable({}, element)
				self.renderer  = ...
				self.classless = true
			elseif type(cls)=='table' then
				self = setmetatable({}, cls)
				self.classless = false
			end

			if loader then
				local function f(newFunc)
					self:reLoader(newFunc)
				end
				loader(f)
			end

			self:new()

			return self
		end
	})

--Dummy functions
function element:renderer() print('no renderer') end

function element:updater() end

function element:constructor() end


--Control functions
--The new function that should be used for element creation
function element:new()
	local dimensions
	--save the parameters
	self.parameters = {}

	--The element canvas
	self.canvas = nil

	--Internal settings
	self.settings = {
		isSetup              = false,
		pendingUpdate        = true,
		needsRendering       = true,
		calculatedDimensions = true,
		inserted             = false
	}

	self.view = {
		x = 0,
		y = 0,
		w = 10,
		h = 10,
	}

	if self.classless then
		self.classlessState = {}
		self.classlessData  = {}
	end
end

--Hotswapping code
function element:reLoader(newFunc)
	self.renderer = newFunc
	self.context:bubbleUpdate()
end

--Called once dimensions are validated
function element:setup()
	self.state =
		setmetatable(
		{},
		{
			__index = function(t, index)
				return self.baseState[index]
			end,
			__newindex = function(t, index, val)
				if self.baseState[index] ~= val then
					self.baseState[index] = val
					self.context:bubbleUpdate()
				end
			end
		}
	)

	self.parameters =
		setmetatable(
		{},
		{
			__index = function(t, index)
				return self.baseParams[index] or nil
			end,
			__newindex = function(t, index, val)
				if self.baseParams[index] ~= val then
					self.baseParams[index] = val
					self.context:bubbleUpdate()
				end
			end
		}
	)

	self.canvas = love.graphics.newCanvas(self.view.w, self.view.h)

	self.quad = love.graphics.newQuad(0, 0, self.view.w, self.view.h, self.view.w, self.view.h)

	--Context makes sure element internals don't have to worry about absolute coordinates
	self.inputContext = helium.input.newContext(self)
	self.context = context.new(self)

	self.settings.isSetup = true

	--Classless rendering
	if self.classless then
		self.classlessData.loadEffect = function (func)
			if self.classlessData.loaded and self.classlessData.loadCaptured then
				return self.classlessData.loadCaptured
			elseif not self.classlessData.loaded then
				self.classlessData.loadCaptured = func()
				self.classlessData.loaded = true
				if self.classlessData.loadCaptured then
					return self.classlessData.loadCaptured
				end
			end
		end
		---@param initial any
		---@return any
		---@return function
		self.classlessData.useState = function (initial)
			self.settings.indice = self.settings.indice + 1
			local indice         = self.settings.indice

			if self.classlessState[indice] and self.classlessState[indice].state then
				return self.classlessState[indice].state, self.classlessState[indice].setState
			else
				self.classlessState[indice]       = {}
				self.classlessState[indice].state = initial

				self.classlessState[indice].setState  = function(set)
					self.classlessState[indice].state = set
					self.context:bubbleUpdate()
				end

				self.classlessState[indice].getState = function()
					return self.classlessState[indice].state
				end
				return self.classlessState[indice].state, self.classlessState[indice].setState, self.classlessState[indice].getState
			end
		end
	end
end

function element:classlessRender()
	self.inputContext:set()
	self.settings.indice = 0
	if type(self.renderer)=='function' then
		local denv = getfenv(self.renderer)
		denv['useState']   = self.classlessData.useState
		denv['loadEffect'] = self.classlessData.loadEffect

		local status,err = pcall(self.renderer,self.parameters, self.view.w, self.view.h)

		if not status then
			love.graphics.setColor(1,0,0)
			love.graphics.rectangle('line',0,0,self.view.w,self.view.h)
			love.graphics.setColor(1,1,1)
			love.graphics.printf("Error: "..err,0,0,self.view.w)
		end

		denv['useState']   = nil
		denv['loadEffect'] = nil
	elseif type(self.renderer)=='string' then
			love.graphics.setColor(1,0,0)
			love.graphics.rectangle('line',0,0,self.view.w,self.view.h)
			love.graphics.setColor(1,1,1)
			love.graphics.printf("Error: "..self.renderer,0,0,self.view.w)
	end
	self.inputContext:unset()
end

function element:renderWrapper()
	local cnvs = love.graphics.getCanvas()
	love.graphics.setCanvas({self.canvas, stencil = true})

	love.graphics.clear()

	if self.classless and self.parameters then
		self:classlessRender()
		self.settings.pendingUpdate = false
	else
		self:renderer()
	end

	love.graphics.setCanvas(cnvs)
end

function element:externalRender()
	self.context:set()

	if self.settings.needsRendering then
		self:renderWrapper()
		self.settings.needsRendering = false
	end

	love.graphics.setColor(1,1,1)
	love.graphics.draw(self.canvas, self.quad, self.view.x, self.view.y)

	self.context:unset()
end

function element:externalUpdate()
	if self.settings.pendingUpdate then
		if self.updater then
			self:updater()
		end

		self.settings.needsRendering = true
		self.settings.pendingUpdate  = false
	end
end

--External functions
--Acts as the entrypoint for beginning rendering
---@param params any
---@param x number
---@param y number
---@param w number
---@param h number
function element:draw(params, x, y, w, h)
	self.view.x = x or self.view.x
	self.view.y = y or self.view.y
	self.view.w = w or self.view.w
	self.view.h = h or self.view.h

	if params then
		if type(params)=='table' and self.baseParams then
			helium.utils.tableMerge(params, self.parameters)
		elseif self.baseParams==nil then
			self.baseParams = params
		else
			self.parameters = params
		end

	end

	if not self.settings.isSetup then
		self:setup()
	end

	if activeContext then
		self:externalRender()
	elseif not self.settings.inserted then
		self.settings.inserted = true
		table.insert(helium.elementBuffer, self)
	end
end

function element:undraw()
	self.settings.remove  = true
	self.settings.isSetup = false
end

return element