Viewport/Canvas scaler for Godot 4

canvas_scaler.gd

extends Node

"""
Viewport scaling for Godot 4
It's supposed to work similar to Unity's CanvasScaler set to
"Match Width or Height"
It's best to stick this to an autoloaded node.
"""

@export var enable := true
@export_range(0.0, 1.0) var width_height_factor = 0.5

var _default_size = Vector2.ZERO


func _ready():
	if enable:
		_default_size.x = ProjectSettings.get_setting("display/window/size/viewport_width")
		_default_size.y = ProjectSettings.get_setting("display/window/size/viewport_height")
		get_viewport().connect("size_changed", _update_viewport_size)
		_update_viewport_size()


func _exit_tree():
	if enable:
		get_tree().disconnect("size_changed", _update_viewport_size)


func _update_viewport_size():
	if enable:
		var viewport_size = Vector2(get_viewport().size.x, get_viewport().size.y)
		var size_ratio = viewport_size / _default_size
		var width_weight = 1.0 - width_height_factor
		var height_weight = width_height_factor
		var v_scale = (size_ratio.x * width_weight) + (size_ratio.y * height_weight)
		get_tree().root.content_scale_size = get_viewport().size / v_scale