BlockCanvas: Implement drag & drop resource files from the filesystem dock

Dragging the resources from the filesystem dock shows the object's type
as "files". So, allow the "files" type in _can_drop_data() and handle it
in _drop_data(). Then, implement getting the resource's file path as a
Variable block with _drop_files() in detail. It uses the const input
parameter as the implementation to hold the resource file's path
informaiton.

https://phabricator.endlessm.com/T35712

Author: starnight

addons/block_code/code_generation/blocks_catalog.gd

@@ -302,3 +302,17 @@ static func get_property_setter_block_definition(variable: VariableDefinition) -
 	var block_def := get_variable_setter_block_definition(variable)
 	block_def.description = "Set the %s property" % variable.var_name
 	return block_def
+
+
+static func get_resource_block_definition(file_name: String) -> BlockDefinition:
+	var block_def := BlockDefinition.new()
+
+	block_def.name = &"get_resource_%s" % file_name.replace(".", "_")
+	block_def.description = "The full resource path of '%s'" % file_name
+	block_def.category = "Variables"
+	block_def.type = Types.BlockType.VALUE
+	block_def.variant_type = TYPE_STRING
+	block_def.display_template = "%s {const file_path: STRING}" % file_name
+	block_def.code_template = "{file_path}"
+
+	return block_def

addons/block_code/serialization/block_script_serialization.gd

@@ -86,7 +86,9 @@ func get_block_definition(block_name: String, arguments: Dictionary) -> BlockDef
 	var block_definition: BlockDefinition
 
 	if len(split) > 1:
-		return _get_parameter_block_definition(split[0], split[1])
+		block_definition = _get_parameter_block_definition(split[0], split[1])
+		if block_definition:
+			return block_definition
 
 	block_definition = _get_base_block_definition(block_name)
 	if block_definition != null:
@@ -97,6 +99,11 @@ func get_block_definition(block_name: String, arguments: Dictionary) -> BlockDef
 	if block_definition != null:
 		return block_definition
 
+	var file_path = arguments.get("file_path", "")
+	block_definition = _get_resource_block_definition(block_name, file_path)
+	if block_definition != null:
+		return block_definition
+
 	# FIXME: This is a workaround for old-style output block references.
 	#        These were generated ahead of time using a block name that has
 	#        a "_" before the parameter name. Now, these parameter blocks
@@ -181,6 +188,19 @@ func _get_parent_node_property_info(property_name: String) -> Dictionary:
 	return {}
 
 
+func _get_resource_block_definition(block_name: String, file_path: String) -> BlockDefinition:
+	if not block_name.begins_with("get_resource_"):
+		return null
+
+	if file_path == "":
+		return null
+
+	var file_name = file_path.get_file()
+	var block_definition := BlocksCatalog.get_resource_block_definition(file_name)
+
+	return block_definition
+
+
 func _update_block_definitions():
 	_available_blocks.clear()
 	_available_blocks.append_array(_get_inherited_block_definitions())

addons/block_code/ui/block_canvas/block_canvas.gd

@@ -87,6 +87,10 @@ func _can_drop_data(at_position: Vector2, data: Variant) -> bool:
 			return false
 		return true
 
+	# Allow dropping resource file
+	if data.get("type", "") == "files":
+		return true
+
 	var nodes: Array = data.get("nodes", [])
 	if nodes.size() != 1:
 		return false
@@ -108,6 +112,8 @@ func _drop_data(at_position: Vector2, data: Variant) -> void:
 		_drop_node(at_position, data)
 	elif data["type"] == "obj_property":
 		_drop_obj_property(at_position, data)
+	elif data["type"] == "files":
+		_drop_files(at_position, data)
 
 
 func _drop_node(at_position: Vector2, data: Variant) -> void:
@@ -148,6 +154,32 @@ func _drop_obj_property(at_position: Vector2, data: Variant) -> void:
 	reconnect_block.emit(block)
 
 
+func _drop_files(at_position: Vector2, data: Variant) -> void:
+	var resource_files = data["files"]
+	var next_position = at_position
+	var bias = 10
+
+	for file_path in resource_files:
+		# Prepare a Variable block getting the file's resource path.
+		var block_definition = _res_file_block_def(file_path)
+		var block = _context.block_script.instantiate_block(block_definition)
+		add_block(block, next_position)
+		reconnect_block.emit(block)
+
+		# Shift next block's position a little bit to avoid overlap totally.
+		next_position.x += bias
+		next_position.y += bias
+
+
+func _res_file_block_def(file_path: String) -> BlockDefinition:
+	var file_name = file_path.get_file()
+
+	var block_definition := BlocksCatalog.get_resource_block_definition(file_name)
+	block_definition.defaults = {"file_path": file_path}
+
+	return block_definition
+
+
 func add_block(block: Block, position: Vector2 = Vector2.ZERO) -> void:
 	if block is EntryBlock:
 		block.position = canvas_to_window(position).snapped(SNAP_GRID)