Refactors the paper bin behavior for dragging to pick up into an element (#57501)

* Drag pickup element for the paper bin behavior

* invokes async on put_in_hands to comply with the linter

* documented and like better names

* blackspace

code/datums/elements/drag_pickup.dm

@@ -0,0 +1,29 @@
+/**
+ * drag_pickup element; for allowing things to be picked up by dragging.
+ *
+ * Used for paper bins.
+ */
+/datum/element/drag_pickup
+	element_flags = ELEMENT_DETACH
+
+/datum/element/drag_pickup/Attach(datum/target)
+	if(!ismovable(target))
+		return ELEMENT_INCOMPATIBLE
+	RegisterSignal(target, COMSIG_MOUSEDROP_ONTO, .proc/pick_up)
+	return ..()
+
+/datum/element/drag_pickup/Detach(datum/source, force)
+	UnregisterSignal(source, COMSIG_MOUSEDROP_ONTO)
+	return ..()
+
+/datum/element/drag_pickup/proc/pick_up(atom/source, atom/over, mob/user)
+	SIGNAL_HANDLER
+	var/mob/living/picker = user
+	if(!istype(picker) || picker.incapacitated() || !source.Adjacent(picker))
+		return
+
+	if(over == picker)
+		INVOKE_ASYNC(picker, /mob/.proc/put_in_hands, source)
+	else if(istype(over, /atom/movable/screen/inventory/hand))
+		var/atom/movable/screen/inventory/hand/Selected_hand = over
+		picker.putItemFromInventoryInHandIfPossible(source, Selected_hand.held_index)

code/modules/paperwork/paperbin.dm

@@ -19,6 +19,7 @@
 /obj/item/paper_bin/Initialize(mapload)
 	. = ..()
 	interaction_flags_item &= ~INTERACT_ITEM_ATTACK_HAND_PICKUP
+	AddElement(/datum/element/drag_pickup)
 	if(!mapload)
 		return
 	var/obj/item/pen/P = locate(/obj/item/pen) in src.loc
@@ -26,6 +27,7 @@
 		P.forceMove(src)
 		bin_pen = P
 		update_appearance()
+	
 
 /obj/item/paper_bin/Destroy()
 	if(papers)
@@ -40,21 +42,6 @@
 		update_appearance()
 	..()
 
-/obj/item/paper_bin/MouseDrop(atom/over_object)
-	. = ..()
-	var/mob/living/M = usr
-	if(!istype(M) || M.incapacitated() || !Adjacent(M))
-		return
-
-	if(over_object == M)
-		M.put_in_hands(src)
-
-	else if(istype(over_object, /atom/movable/screen/inventory/hand))
-		var/atom/movable/screen/inventory/hand/H = over_object
-		M.putItemFromInventoryInHandIfPossible(src, H.held_index)
-
-	add_fingerprint(M)
-
 /obj/item/paper_bin/attack_paw(mob/user, list/modifiers)
 	return attack_hand(user, modifiers)
 

tgstation.dme

@@ -636,6 +636,7 @@
 #include "code\datums\elements\decal.dm"
 #include "code\datums\elements\deferred_aquarium_content.dm"
 #include "code\datums\elements\digitalcamo.dm"
+#include "code\datums\elements\drag_pickup.dm"
 #include "code\datums\elements\dryable.dm"
 #include "code\datums\elements\earhealing.dm"
 #include "code\datums\elements\embed.dm"