Serialization: Reuse serialized resources

Add a resource property to blocks. The resource will be updated before
building the tree.

This mitigates having a huge diff in scenes with blocks for minimum
changes like moving a block in the canvas.

Author: manuq

addons/block_code/ui/block_canvas/block_canvas.gd

@@ -40,6 +40,8 @@ var zoom: float:
 	get:
 		return _window.scale.x
 
+var _undo_redo: EditorUndoRedoManager
+
 signal reconnect_block(block: Block)
 signal add_block_code
 signal open_scene
@@ -170,24 +172,29 @@ func load_tree(parent: Node, node: SerializedBlockTreeNode):
 		load_tree(scene.get_node(c[0]), c[1])
 
 
-func get_canvas_block_trees() -> SerializedBlockTreeNodeArray:
-	var block_trees := SerializedBlockTreeNodeArray.new()
+func rebuild_block_trees(undo_redo):
+	_undo_redo = undo_redo
+	_current_bsd.block_trees.array = []
 	for c in _window.get_children():
-		block_trees.array.append(build_tree(c))
-
-	return block_trees
+		_current_bsd.block_trees.array.append(build_tree(c))
 
 
 func build_tree(block: Block) -> SerializedBlockTreeNode:
-	var n = SerializedBlockTreeNode.new()
-	n.serialized_block = SerializedBlock.new(block.get_block_class(), block.get_serialized_props())
+	var path_child_pairs = []
+	block.update_resources(_undo_redo)
 
 	for snap in find_snaps(block):
-		for c in snap.get_children():
-			if c is Block:  # Make sure to not include preview
-				n.path_child_pairs.append([block.get_path_to(snap), build_tree(c)])
+		for child in snap.get_children():
+			if not child is Block:  # Make sure to not include preview
+				continue
+			path_child_pairs.append([block.get_path_to(snap), build_tree(child)])
+
+	if block.resource.path_child_pairs != path_child_pairs:
+		_undo_redo.add_undo_property(block.resource, "path_child_pairs", block.resource.path_child_pairs)
+		block.resource.path_child_pairs = path_child_pairs
+		_undo_redo.add_do_property(block.resource, "path_child_pairs", block.resource.path_child_pairs)
 
-	return n
+	return block.resource
 
 
 func find_snaps(node: Node) -> Array:

addons/block_code/ui/blocks/block/block.gd

@@ -26,6 +26,9 @@ signal modified
 ## The scope of the block (statement of matching entry block)
 @export var scope: String = ""
 
+## The resource containing the block properties and the snapped blocks
+@export var resource: SerializedBlockTreeNode
+
 
 func _ready():
 	mouse_filter = Control.MOUSE_FILTER_IGNORE
@@ -61,6 +64,19 @@ func get_instruction_node() -> InstructionTree.TreeNode:
 	return node
 
 
+func update_resources(undo_redo: EditorUndoRedoManager):
+	if resource == null:
+		var serialized_block = SerializedBlock.new(get_block_class(), get_serialized_props())
+		resource = SerializedBlockTreeNode.new(serialized_block)
+		return
+
+	var serialized_props = get_serialized_props()
+	if serialized_props != resource.serialized_block.serialized_props:
+		undo_redo.add_undo_property(resource.serialized_block, "serialized_props", resource.serialized_block.serialized_props)
+		resource.serialized_block.serialized_props = serialized_props
+		undo_redo.add_do_property(resource.serialized_block, "serialized_props", resource.serialized_block.serialized_props)
+
+
 # Override this method to add more serialized properties
 func get_serialized_props() -> Array:
 	return serialize_props(["block_name", "label", "color", "block_type", "position", "scope"])

addons/block_code/ui/main_panel.gd

@@ -139,17 +139,14 @@ func save_script():
 		_current_block_code_node.block_script = block_script
 		undo_redo.add_do_property(_current_block_code_node, "block_script", _current_block_code_node.block_script)
 
-	undo_redo.add_undo_property(_current_block_code_node.block_script, "block_trees", _current_block_code_node.block_script.block_trees)
-	undo_redo.add_undo_property(_current_block_code_node.block_script, "generated_script", _current_block_code_node.block_script.generated_script)
-
-	var block_trees := _block_canvas.get_canvas_block_trees()
+	_block_canvas.rebuild_block_trees(undo_redo)
 	var generated_script = _block_canvas.generate_script_from_current_window(block_script)
-	block_script.block_trees = block_trees
-	block_script.generated_script = generated_script
+	if generated_script != block_script.generated_script:
+		undo_redo.add_undo_property(_current_block_code_node.block_script, "generated_script", _current_block_code_node.block_script.generated_script)
+		block_script.generated_script = generated_script
+		undo_redo.add_do_property(_current_block_code_node.block_script, "generated_script", _current_block_code_node.block_script.generated_script)
 	block_script.version = Constants.CURRENT_DATA_VERSION
 
-	undo_redo.add_do_property(_current_block_code_node.block_script, "block_trees", block_trees)
-	undo_redo.add_do_property(_current_block_code_node.block_script, "generated_script", generated_script)
 	undo_redo.commit_action()