Implement layer and frame dragging and dropping to re-arrange them in the timeline

Part of #306

src/UI/Timeline/CelButton.gd

@@ -128,13 +128,13 @@ func get_drag_data(_position) -> Array:
 	button.add_child(texture_rect)
 	set_drag_preview(button)
 
-	return [frame, layer]
+	return ["Cel", frame, layer]
 
 
 func can_drop_data(_pos, data) -> bool:
-	if typeof(data) == TYPE_ARRAY:
-		var new_frame = data[0]
-		var new_layer = data[1]
+	if typeof(data) == TYPE_ARRAY and data[0] == "Cel":
+		var new_frame = data[1]
+		var new_layer = data[2]
 		if Global.current_project.frames[frame] in Global.current_project.layers[layer].linked_cels or Global.current_project.frames[new_frame] in Global.current_project.layers[new_layer].linked_cels:
 			# If the cel we're dragging or the cel we are targeting are linked, don't allow dragging
 			return false
@@ -145,8 +145,8 @@ func can_drop_data(_pos, data) -> bool:
 
 
 func drop_data(_pos, data) -> void:
-	var new_frame = data[0]
-	var new_layer = data[1]
+	var new_frame = data[1]
+	var new_layer = data[2]
 
 	var this_frame_new_cels = Global.current_project.frames[frame].cels.duplicate()
 	var new_frame_new_cels

src/UI/Timeline/FrameButton.gd

@@ -69,3 +69,44 @@ func change_frame_order(rate : int) -> void:
 	Global.current_project.undo_redo.add_undo_method(Global, "undo")
 	Global.current_project.undo_redo.add_do_method(Global, "redo")
 	Global.current_project.undo_redo.commit_action()
+
+
+func get_drag_data(_position) -> Array:
+	var button := Button.new()
+	button.rect_size = rect_size
+	button.theme = Global.control.theme
+	button.text = text
+	set_drag_preview(button)
+
+	return ["Frame", frame]
+
+
+func can_drop_data(_pos, data) -> bool:
+	if typeof(data) == TYPE_ARRAY:
+		return data[0] == "Frame"
+	else:
+		return false
+
+
+func drop_data(_pos, data) -> void:
+	var new_frame = data[1]
+	if frame == new_frame:
+		return
+
+	var new_frames : Array = Global.current_project.frames.duplicate()
+	var temp = new_frames[frame]
+	new_frames[frame] = new_frames[new_frame]
+	new_frames[new_frame] = temp
+
+	Global.current_project.undo_redo.create_action("Change Frame Order")
+	Global.current_project.undo_redo.add_do_property(Global.current_project, "frames", new_frames)
+
+	if Global.current_project.current_frame == frame:
+		Global.current_project.undo_redo.add_do_property(Global.current_project, "current_frame", new_frame)
+		Global.current_project.undo_redo.add_undo_property(Global.current_project, "current_frame", Global.current_project.current_frame)
+
+	Global.current_project.undo_redo.add_undo_property(Global.current_project, "frames", Global.current_project.frames)
+
+	Global.current_project.undo_redo.add_undo_method(Global, "undo")
+	Global.current_project.undo_redo.add_do_method(Global, "redo")
+	Global.current_project.undo_redo.commit_action()

src/UI/Timeline/LayerButton.gd

@@ -3,20 +3,16 @@ extends Button
 
 
 var layer := 0
-var visibility_button : BaseButton
-var lock_button : BaseButton
-var linked_button : BaseButton
-var label : Label
-var line_edit : LineEdit
+
+onready var visibility_button : BaseButton = find_node("VisibilityButton")
+onready var lock_button : BaseButton = find_node("LockButton")
+onready var linked_button : BaseButton = find_node("LinkButton")
+onready var label : Label = find_node("Label")
+onready var line_edit : LineEdit = find_node("LineEdit")
 
 
 func _ready() -> void:
 	rect_min_size.y = Global.animation_timeline.cel_size
-	visibility_button = find_node("VisibilityButton")
-	lock_button = find_node("LockButton")
-	linked_button = find_node("LinkButton")
-	label = find_node("Label")
-	line_edit = find_node("LineEdit")
 
 	var layer_buttons = find_node("LayerButtons")
 	for child in layer_buttons.get_children():
@@ -87,3 +83,50 @@ func _on_LinkButton_pressed() -> void:
 		# If button is pressed and there are no linked cels in the layer
 		Global.current_project.layers[layer].linked_cels.append(Global.current_project.frames[Global.current_project.current_frame])
 		Global.current_project.layers[layer].frame_container.get_child(Global.current_project.current_frame)._ready()
+
+
+func get_drag_data(_position) -> Array:
+	var button := Button.new()
+	button.rect_size = rect_size
+	button.theme = Global.control.theme
+	button.text = label.text
+	set_drag_preview(button)
+
+	return ["Layer", layer]
+
+
+func can_drop_data(_pos, data) -> bool:
+	if typeof(data) == TYPE_ARRAY:
+		return data[0] == "Layer"
+	else:
+		return false
+
+
+func drop_data(_pos, data) -> void:
+	var new_layer = data[1]
+	if layer == new_layer:
+		return
+
+	var new_layers : Array = Global.current_project.layers.duplicate()
+	var temp = new_layers[layer]
+	new_layers[layer] = new_layers[new_layer]
+	new_layers[new_layer] = temp
+
+	Global.current_project.undo_redo.create_action("Change Layer Order")
+	for f in Global.current_project.frames:
+		var new_cels : Array = f.cels.duplicate()
+		var temp_canvas = new_cels[layer]
+		new_cels[layer] = new_cels[new_layer]
+		new_cels[new_layer] = temp_canvas
+		Global.current_project.undo_redo.add_do_property(f, "cels", new_cels)
+		Global.current_project.undo_redo.add_undo_property(f, "cels", f.cels)
+
+	if Global.current_project.current_layer == layer:
+		Global.current_project.undo_redo.add_do_property(Global.current_project, "current_layer", new_layer)
+		Global.current_project.undo_redo.add_undo_property(Global.current_project, "current_layer", Global.current_project.current_layer)
+	Global.current_project.undo_redo.add_do_property(Global.current_project, "layers", new_layers)
+	Global.current_project.undo_redo.add_undo_property(Global.current_project, "layers", Global.current_project.layers)
+
+	Global.current_project.undo_redo.add_undo_method(Global, "undo")
+	Global.current_project.undo_redo.add_do_method(Global, "redo")
+	Global.current_project.undo_redo.commit_action()