Ported touch support to Godot 4 (#323)

Co-authored-by: jacketsj <[email protected]>

Author: m-GDEV

lorien/InfiniteCanvas/PanZoomCamera.gd

@@ -19,6 +19,12 @@ var _zoom_active := false
 var _current_zoom_level := 1.0
 var _start_mouse_pos := Vector2(0.0, 0.0)
 
+# -------------------------------------------------------------------------------------------------
+var _touch_events = {}
+var _touch_last_drag_distance := 0.0
+var _touch_last_drag_median := Vector2.ZERO
+var _multidrag_valid = false
+
 # -------------------------------------------------------------------------------------------------
 func set_zoom_level(zoom_level: float) -> void:
 	_current_zoom_level = _to_nearest_zoom_step(zoom_level)
@@ -35,6 +41,49 @@ func do_center(screen_space_center_point: Vector2) -> void:
 	get_viewport().warp_mouse(screen_space_center)
 	_do_pan(delta)
 
+	
+func touch_event(event):
+	# Keep track of the fingers on the screen
+	if event is InputEventScreenTouch:
+		if event.pressed:
+			_touch_events[event.index] = event
+			_multidrag_valid = false
+		else:
+			_touch_events.erase(event.index)
+			#_touch_last_drag_distance = 0
+		get_viewport().set_input_as_handled()
+
+	if event is InputEventScreenDrag:
+		_touch_events[event.index] = event
+		# At least one fing drag
+		if _touch_events.size() == 1:
+			_do_pan(event.relative)
+		if _touch_events.size() == 2:
+			var events = []
+			for key in _touch_events.keys():
+				events.append(_touch_events.get(key))
+
+			var median_point = Vector2.ZERO
+			for e in events:
+				median_point += e.position
+			median_point /= events.size()
+			if _multidrag_valid:
+				_do_pan(median_point - _touch_last_drag_median)
+			_touch_last_drag_median = median_point
+			median_point = get_canvas_transform().affine_inverse() * median_point
+			median_point = get_global_transform().affine_inverse() * median_point
+
+			var drag_distance = events[0].position.distance_to(events[1].position)
+			var delta = (drag_distance - _touch_last_drag_distance) * _current_zoom_level / 800
+			if _multidrag_valid:
+				_zoom_canvas(_current_zoom_level + delta, median_point)
+			_touch_last_drag_distance = drag_distance
+			_multidrag_valid = true
+		get_viewport().set_input_as_handled()
+
+func _input(event):
+	touch_event(event)
+
 # -------------------------------------------------------------------------------------------------
 func tool_event(event: InputEvent) -> void:
 	if _is_input_enabled:

lorien/project.godot

@@ -260,6 +260,7 @@ canvas_pan_key={
 [input_devices]
 
 pen_tablet/driver.windows="wintab"
+pointing/emulate_mouse_from_touch=false
 
 [locale]