Allow to scroll database screen without selecting item on touch-down.

1 files changed, 79 insertions, 55 deletions

diff --git a/touch_scroll.gd b/touch_scroll.gd
index ea92087..f2aeca7 100644
--- a/touch_scroll.gd
+++ b/touch_scroll.gd
@@ -1,66 +1,90 @@
 extends Control
 
+const VELOCITY_DECAYING_FACTOR: float = 5.5
+const DRAG_THRESHOLD_CM: float = 0.250
 
-func _gui_input(event: InputEvent):
-#func _input(event: InputEvent):
-#	return
-	if event is InputEventScreenDrag:
-		self.v_scroll.value -= event.relative.y
-#	accept_event()
+var pointer: Dictionary
+var anchor: float
+var offset: float
+var screen_dpcm: float
+
+onready var target: Control = get_parent()
+onready var target_scroll: VScrollBar = get_parent().get_v_scroll()
+
+
+func _ready():
+	pointer = {
+		index = -1,
+		initial_position = Vector2.ZERO,
+		current_position = Vector2.ZERO,
+		velocity = Vector2.ZERO,
+		was_dragged = false,
+		is_active = false,
+	}
+	screen_dpcm = float(OS.get_screen_dpi()) / 2.54
 
-#func _gui_input(event):
-#	accept_event()
-#	get_tree().set_input_as_handled()
-#	if event is InputEventScreenDrag:
-#		get_parent().v_scroll.value -= event.relative.y
 
+func _process(delta: float):
+	if pointer.is_active:
+		var dragged_distance: float = - (pointer.current_position.y - pointer.initial_position.y)
+		offset = anchor + dragged_distance
+		self.target_scroll.value = offset
+	elif pointer.velocity.length() > 0.5:
+		pointer.velocity *= clamp((1.0 - VELOCITY_DECAYING_FACTOR * delta), 0.0, 1.0)
+		offset -= pointer.velocity.y * delta
+		self.target_scroll.value = offset
 
-export(float) var drag_threshold = 5
-onready var touch_enabled = OS.has_touchscreen_ui_hint()
-onready var v_scroll = get_parent().get_v_scroll()
 
-var dragging = false
-var pressed = false
-var last_event
-# must be _input, as _gui_input has bugs, with no touch.pressed = false events
-# see: https://github.com/godotengine/godot/issues/16761
-func _input_disabled(event):
-#func _gui_input(event):
+func _gui_input(event: InputEvent):
+	
+	# @DAM A bug on GODOT-3.X makes events from non-mouse-emulated pointers (index > 0) unreliable.
+	if event is InputEventScreenTouch || event is InputEventScreenDrag:
+		if event.index != 0:
+			return
+	
+	if event is InputEventScreenTouch && (pointer.is_active == false || pointer.index == event.index):
+		var touch := event as InputEventScreenTouch
+		pointer.is_active = event.pressed
+		pointer.current_position = touch.position
+		if pointer.is_active:
+			pointer.index = touch.index
+			pointer.initial_position = touch.position
+			anchor = self.target_scroll.value
+		else:
+			if pointer.was_dragged == false: # Click detected.
+				simulate_gui_click()
+			pointer.index = -1
+			pointer.was_dragged = false
 	
-	if not visible:
-		return
+	if event is InputEventScreenDrag && event.index == pointer.index:
+		var drag := event as InputEventScreenDrag
+		pointer.current_position = drag.position
+		pointer.velocity = drag.speed
+		if pointer.current_position.distance_to(pointer.initial_position) / screen_dpcm > DRAG_THRESHOLD_CM:
+			pointer.was_dragged = true
 
-	if not touch_enabled:
-		return
 
-	if event is InputEventScreenDrag:
-		accept_event()
-		if event.speed == Vector2():
-			# we're on a device and speed is broken
-			# see: https://github.com/godotengine/godot/issues/3623
-			event.speed = event.relative
-		if abs(event.speed.y) >= drag_threshold:
-			# scroll the list
-			dragging = true
-			v_scroll.value -= event.relative.y
-		return
+func simulate_gui_click():
+	
+	var position := self.get_global_mouse_position() - target.rect_global_position
+	
+	var event_touch := InputEventScreenTouch.new()
+	event_touch.index = 0
+	event_touch.position = position
+	
+	var event_mouse := InputEventMouseButton.new()
+	event_mouse.button_index = BUTTON_LEFT
+	event_mouse.button_mask = BUTTON_MASK_LEFT
+	event_mouse.position = position
+	
+	event_mouse.pressed = true
+	event_touch.pressed = true
+	target._gui_input(event_mouse)
+	target._gui_input(event_touch)
+	
+	event_mouse.pressed = false
+	event_touch.pressed = false
+	target._gui_input(event_mouse)
+	target._gui_input(event_touch)
+
 
-	if event is InputEventScreenTouch:
-		if event.index == 0:
-			accept_event()
-			if dragging && event.pressed == false:
-				# prints("end drag")
-				dragging = false
-				pressed = false
-			else:
-				if event.pressed && pressed == false:
-					# prints("touch start")
-					pressed = true
-					# TODO: prevent select highlight
-				elif !event.pressed && pressed == true:
-					# prints("touch end and accept")
-					pressed = false
-					var ev = InputEventAction.new()
-					ev.action = "ui_accept"
-					ev.pressed = true
-					Input.parse_input_event(ev)