Update readme, code cleanup

README.md

@@ -43,7 +43,7 @@ https://github.com/Insality/defold-tweener/archive/refs/tags/3.zip
 
 ### Global Update Frequency
 
-Optionally, you can setup global default update freqency in your game.project. It's `60` by default.
+Optionally, you can setup global default update frequency in your game.project. It's `60` by default.
 
 Add next `tweener` section to your `game.project` in text mode:
 
@@ -57,7 +57,8 @@ update_frequency = 60
 ### Quick API Reference
 
 ```lua
-local tween_function = tweener.linear or go.EASING_LINEAR or gui.EASING_LINEAR or {0, 0.2, 0.4, 0.8, 0.9, 1}
+-- Tween function can be a string, a predefined easing function, or a custom easing function
+local tween_function = "linear" or tweener.linear or go.EASING_LINEAR or gui.EASING_LINEAR or {0, 0.2, 0.4, 0.8, 0.9, 1}
 
 tweener.tween(tween_function, from, to, time, callback, [dt])
 tweener.ease(tween_function, from, to, time, time_elapsed)
@@ -92,7 +93,7 @@ This function initiates a tween operation immediately. Here's how to use it:
   - `dt` (optional): The time interval for updating the tween, in seconds.
 
 - **Return Value:**
-  - `timer_id`: A timer id from `timer.delay` if you wish to cancel the tween.
+  - `tweener_id`: A tweener id from `timer.delay` if you wish to cancel the tween.
 
 - **Usage Example:**
 
@@ -108,6 +109,7 @@ end)
 local tween_id = tweener.tween({0, 0.2, 0.4, 0.8, 0.9, 1}, 0, 100, 1.5, function(value, is_final_call)
 	print("Tween value: " .. value)
 end)
+
 -- You can cancel the tween by calling tweener.cancel
 tweener.cancel(tween_id)
 ```

tweener/tweener.lua

@@ -3,7 +3,7 @@ local UPDATE_FREQUENCY = sys.get_config_int("tweener.update_frequency", 60)
 ---@class tweener
 local M = {}
 
----@alias easing_function (fun(current: number, from: number, to: number, time: number): number)|constant|number[]
+---@alias easing_function (fun(current: number, from: number, to: number, time: number): number)|string|constant|number[]
 
 ---@class hash
 ---@class constant
@@ -13,20 +13,6 @@ local TYPE_TABLE = "table"
 local TYPE_USERDATA = "userdata"
 
 
----@param easing number[]|vector @The array of easing values, Example: {0, 0.5, 1, 2, 1}. Must have at least two elements.
----@return easing_function @The easing function
-local function get_custom_ease(easing)
-	local sample_count = #easing
-	if sample_count < 2 then
-		error("Easing table must have at least two elements.")
-	end
-
-	return function(t, b, c, d)
-		return M.custom_ease(easing, t, b, c, d)
-	end
-end
-
-
 ---Starts a tweening operation.
 ---@param easing_function easing_function
 ---@param from number
@@ -42,7 +28,12 @@ function M.tween(easing_function, from, to, time, callback, update_delta_time)
 	easing_function = M.DEFOLD_EASINGS[easing_function] or M[easing_function] or easing_function
 	local easing_type = type(easing_function)
 	if easing_type == TYPE_USERDATA or easing_type == TYPE_TABLE then
-		easing_function = get_custom_ease(easing_function --[[@as vector]])
+		---@cast easing_function number[]
+		local custom_easing = function(t, b, c, d)
+			return M.custom_ease(easing_function, t, b, c, d)
+		end
+
+		easing_function = custom_easing
 	end
 
 	local time_elapsed = 0
@@ -89,6 +80,7 @@ function M.ease(easing_function, from, to, time, time_elapsed)
 		---@cast easing_function number[]
 		return M.custom_ease(easing_function, time_elapsed, from, to - from, time)
 	end
+
 	return easing_function(time_elapsed, from, to - from, time)
 end
 
@@ -113,15 +105,20 @@ function M.custom_ease(easing, t, b, c, d)
 		error("Division by zero: 'd' must not be zero.")
 	end
 
+	local sample_count = #easing
+	if sample_count < 2 then
+		error("Easing table must have at least two elements.")
+	end
+
 	local time_progress = t / d
 	if time_progress >= 1 then
-		return (c + b) * easing[#easing]
+		return (c + b) * easing[sample_count]
 	end
 	if time_progress <= 0 then
 		return b * easing[1]
 	end
 
-	local sample_index = #easing - 1
+	local sample_index = sample_count - 1
 	local index1 = math.floor(time_progress * sample_index)
 	local index2 = math.min(index1 + 1, sample_index)