GDML (Godot Markup Language)

An HTML-inspired markup language for Godot UIs.

GDML parses an xml file and generates a corresponding tree of Godot Nodes to be added to the SceneTree. Anonymous, inline scripts are allowed along with loading scripts from a context path.

Quickstart

1. Copy the ./addons/gdml/ directory to your project's addons directory
2. Load .addons/gdml/gdml.gd and instance it. A context path (the directory containing the xml files + resources) must be provided
3. Call the generate method. A file name must be provided relative to the context path
   1. e.g. var my_output: Control = gdml.generate("my_file.xml")
4. Add the output to the SceneTree

Example

my_gdml_file.xml

1. Create a CanvasLayer on layer -1 and a black ColorRect to act as the background.
2. Creates a gdml container node that holds an anonymous script.
3. A VBoxContainer is created inside the gdml node that contains a Label and a Button.
4. The Button is hooked up to the anonymous script to print "hello" when the element is pressed.

<canvas_layer gdml_props="layer: -1">
    <color_rect gdml_name="Background" gdml_style="anchor: full_rect; color: (colorN) Black"/>
</canvas_layer>

<gdml gdml_style="anchor: full_rect; margin_top: 10; margin_left: 10">
    <gdml_script>
        func say_hello():
            print("hello")
    </gdml_script>

    <v_box_container gdml_style="anchor: full_rect">
        <label>Hello label!</label>
        <button pressed="say_hello">click me</button>
    </v_box_container>
</gdml>

my_scene.gd

1. Load in gdml.gd and create a new instance. A path to the directory containing valid gdml xml files should be provided
2. gdml.generate(...) is called, specifying the main entrypoint for the output
3. The output is added as a child

extends Node

func _ready():
   var gdml = load("path_to_gdml_gd").new("path_to_folder_containing_my_gdml_file")
   
   var gui = gdml.generate("my_gdml_file.xml")
   add_child(gui)

Design Decisions

• GDML-specific properties are prepended with gdml_ in order to namespace them
• There is an implicit, global gdml node that wraps each xml file
  • This is needed since scripts can be placed at the root level
• gdml_props is an alias of gdml_style as they work in the same way (aka styles for Godot Controls are just properties)
• Context paths are used instead of res:// paths, as the library is meant to be used for runtime loaded UIs. Because of this, context paths will generally point outside of the project

3rd Party Libraries

• godot-css-theme
  • Modified to namespace the classes