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Creating UI using Java and KubeJS is mostly the same. This page will introduce the basic workflow of creating and using a UI.

The entire UI creation and usage pipeline consists of the following steps:

1. Create UI widget and layout (1)

   1. Create buttons and item slots, set their positions...

2. Bind UI functional logic (1)

   1. Add logic to be executed when a button is clicked, bind inventory to item slots...

3. Display the UI (1)

   1. Open the GUI when right-clicking an item, open the GUI when right-clicking a block...

Technically, the UI function binding and UI widget creation processes happen simultaneously, as many controls provide constructors that bind functions at the same time.

On this page, we separate step 1 and step 2 in the code examples to provide a clearer understanding of how the UI works.

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Create UI Widgets and Layout

Let's begin with a WigetGroup, which is a container of child widgtes. Therefore, we create a WidgetGroup as a root widget. Check all widgets here.

Then, we add a Label and a Button into it.

public WidgetGroup createUI() {
    // create a root container
    var root = new WidgetGroup();
    root.setSize(100, 100);
    root.setBackground(ResourceBorderTexture.BORDERED_BACKGROUND);

    // create a label and a button
    var label = new LabelWidget();
    label.setSelfPosition(20, 20);
    label.setText("Hello, World!");
    var button = new ButtonWidget();
    button.setSelfPosition(20, 60);
    button.setSize(60, 20);
    // prepare button textures
    var backgroundImage = ResourceBorderTexture.BUTTON_COMMON;
    var hoverImage = backgroundImage.copy().setColor(ColorPattern.CYAN.color);
    var textAbove = new TextTexture("Click me!");
    button.setButtonTexture(backgroundImage, textAbove);
    button.setClickedTexture(hoverImage, textAbove);

    // add the label and button to the root container
    root.addWidgets(label, button);
    return root;
}

function createUI() {
    // create a root container
    let root = new WidgetGroup();
    root.setSize(100, 100);
    root.setBackground(ResourceBorderTexture.BORDERED_BACKGROUND);

    // create a label and a button
    let label = new LabelWidget();
    label.setSelfPosition(20, 20);
    label.setText("Hello, World!");
    let button = new ButtonWidget();
    button.setSelfPosition(20, 60);
    button.setSize(60, 20);
    // prepare button textures
    let backgroundImage = ResourceBorderTexture.BUTTON_COMMON;
    let hoverImage = backgroundImage.copy().setColor(ColorPattern.CYAN.color);
    let textAbove = new TextTexture("Click me!");
    button.setButtonTexture(backgroundImage, textAbove);
    button.setClickedTexture(hoverImage, textAbove);

    // add the label and button to the root container
    root.addWidgets(label, button);
    return root;
}

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Bind UI functional logic

After the creation of the ui, we should implement the logic of the ui. For example, we want to click the button to change the label text.

public WidgetGroup createUI() {
    // creation of the ui
    // ....

    // click logic
    AtomicInteger counter = new AtomicInteger(0);
    button.setOnPressCallback(clickData -> {
        label.setText("Clicked " + counter.incrementAndGet() + " times!");
    });

    return root;
}

function createUI() {
    // creation of the ui
    // ....

    // click logic
    let counter = 0;
    button.setOnPressCallback(clickData => {
        counter++;
        label.setText("Clicked " + counter + " times!");
    });

    return root;
}

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Display the UI

Now, let's display the ui we create! We need to specify a UI Factory to display the ui, which maintains the lifecycle of the ui.

There are four steps:

1. open ui
2. create UI in server side
3. notify to open UI
4. create UI in remote side

UI Factory will help handle the step 3. Therefore, user should define WHEN to trigger step 1, and WHAT to be createed in step 2 and step 4. In general, the UI created on the server side and the remote side is the same in most cases.

LDLib provides two built-in factories:

1. Block Entity UI Factory
2. Held Item UI Factory

Block Entity UI Factory

This factory allows user to open the ui from a block.

Java

1. Java user should implement IUIHolder.Block for your own BlockEntity and implement the method createUI(Player entityPlayer).

2. Call the method BlockEntityUIFactory.INSTANCE.openUI() when you want to open the ui.

KubeJS

KubeJS user can do the same thing in an easy way. User can even open the ui for the block (without entity), but less accessibility compared with Java.

1. KubeJS user should use LDLibUI.block(ui_name, e => {}) to create the ui by the given ui_name.
2. Call the method BlockUIFactory.INSTANCE.openUI(player, pos, ui_name) when you want to open the ui.

public class TestBlockEntity extends BlockEntity implements IUIHolder {

    public void onPlayerUse(Player player) {
        // step 1 here.
        if (player instanceof ServerPlayer serverPlayer) {
            BlockEntityUIFactory.INSTANCE.openUI(this, serverPlayer);
        }
    }

    private WidgetGroup createUI() {
        // ....
    }

    @Override
    public ModularUI createUI(Player entityPlayer) {
        // step 2 and step 4 here 
        return new ModularUI(createUI(), this, entityPlayer);
    }
}

// server script

BlockEvents.rightClicked('test_block_ui', event => { 
    // step 1 here.
    BlockUIFactory.INSTANCE.openUI(event.player, event.block.pos, "test_block_ui");
})

function createUI() {
    // ....
}

LDLibUI.block("test_block_ui", e => { 
    // step 2 and step 4 here 

    // let level = e.level
    // let pos = e.pos
    // let block = e.block
    // let player = e.player

    var ui = createUI();
    e.success(ui);
})

Held Item UI Factory

This factory allows user to open the ui from the held item.

Java

1. Java user should implement IUIHolder.Item for your own Item and implement the method createUI(Player entityPlayer, HeldItemUIFactory.HeldItemHolder holder).

2. Call the method HeldItemUIFactory.INSTANCE.openUI() when you want to open the ui.

KubeJS

KubeJS user can do the same thing in an easy way. User can even open the ui for the block (without entity), but less accessibility compared with Java.

1. KubeJS user should use LDLibUI.item(ui_name, e => {}) to create the ui by the given ui_name.
2. Call the method ItemUIFactory.INSTANCE.openUI(player, hand, ui_name) when you want to open the ui.

public class TestItem implements IUIHolder.Item {
    @Override
    public InteractionResult useOn(UseOnContext context) {
        // step 1 here.
        if (context.getPlayer() instanceof ServerPlayer serverPlayer) {
            HeldItemUIFactory.INSTANCE.openUI(serverPlayer, context.getHand());
        }
        return InteractionResult.SUCCESS;
    }

    private WidgetGroup createUI() {
        // ....
    }

    @Override
    public ModularUI createUI(Player entityPlayer, HeldItemUIFactory.HeldItemHolder holder) {
        // step 2 and step 4
        return new ModularUI(createUI(), holder, entityPlayer);
    }
}

// server script

ItemEvents.firstRightClicked('minecraft:stick', event => {
    // step 1 here.
    ItemUIFactory.INSTANCE.openUI(event.player, event.hand, "test_item_ui");
})

function createUI() {
    // ....
}

LDLibUI.item("test_item_ui", e => {
    // step 2 and step 4

    // let player = e.player
    // let hand = e.hand
    // let held = e.held

    var ui = createUI();
    e.success(ui);
})