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A screen is a graphical user interface that extends Screen, allowing the user to interact and fulfill some functionalities. One example of a screen is a custom config screen of your mod. Screens only exist in the client, so you must annotate them with @Environment(EnvType.CLIENT).

You may use mixins to add a into an existing screen a button that goes to your screen. But in many cases, we can implement the ModMenuApi of Mod Menu mod, and make it possible to access the screen via the config button in the Mod Menu screen. This article does document how to implement ModMenuApi.

A screen should have several “widgets”, which refer to elements in the screen. We add widgets in the init method.

@Environment(EnvType.CLIENT)
public class TutorialScreen extends Screen {
  protected TutorialScreen() {
    // The parameter is the title of the screen,
    // which will be narrated when you enter the screen.
    super(Text.literal("My tutorial screen"));
  }
 
 
  public ButtonWidget button1;
  public ButtonWidget button2;
 
  @Override
  protected void init() {
    button1 = ButtonWidget.builder(Text.literal("Button 1"), button -> {
      System.out.println("You clicked button1!");
    })
        .dimensions(width / 2 - 205, 20, 200, 20)
        .tooltip(Tooltip.of(Text.literal("Tooltip of button1")))
        .build();
    button2 = ButtonWidget.builder(Text.literal("Button 2"), button -> {
      System.out.println("You clicked button2!");
    })
        .dimensions(width / 2 + 5, 20, 200, 20)
        .tooltip(Tooltip.of(Text.literal("Tooltip of button2")))
        .build();
 
    addDrawableChild(button1);
    addDrawableChild(button2);
  }
}

The init method is called then:

• The screen is created.
• The screen is resized. Before invoking this, all existing elements are removed.

You must use add the elements to the screen via using addDrawable, addSelectableChild or addDrawableChild. The difference is:

• addDrawable: The element will be rendered, but you cannot select it, either by using mouse or keyboard.
• addSelectableChild: You can select and interact it, but it will not be rendered.
• addDrawableChild: The element will be both rendered and interactable, which is the most common case.

In the ButtonWidget.builder(…).builder(), you can specify the size and position of the button by using size and position respectively, or directly using dimensions. The tooltip specifies the tooltip, which will be rendered and narrated when your mouse hovers on, or use Tab to focus on it. Tooltip.of takes two arguments, the first to be shown, and the second (optional) to be narrated.

For versions before 1.19.3, ButtonWidget.builder(…) does not exist. In that case, please directly invoke the constructor of ButtonWidget.

Some users may instantiaze the widgets in the constructor, or the initialization. For example, they may write the code like this:

  public ButtonWidget button1 = ButtonWidget.builder(...).build();
  public ButtonWidget button2 = ButtonWidget.builder(...).build();
 
  @Override
  protected void init() {
    addDrawableChild(button1);
    addDrawableChild(button2);
  }

This is also OK. Its advantage is, if the widgets have some several states (such as the current selections of CyclingWidget, or typed text in the TextFieldWidget), they will not be reset when you resize the screen, because they will not be created again. However, when resizing, the width and height is changed, but you did not update. Therefore, in this case, you have to update the size or positions in the init method.

  @Override
  protected void init() {
    button1.setPosition(width / 2 - 205, 20);
    button2.setPosition(width / 2 + 5, 20);
 
    addDrawableChild(button1);
    addDrawableChild(button2)
  }

After adding amounts of elements, all of them are added. Some people don't care about the order they are added, because all of the widgets are rendered at the sametime. However, if you select widgets by pressing the Tab key, you may find they are focused in a messy order. Therefore, please ensure that the widgets are added in a correct order.

I accessed the screen via another screen, such as the Mod Menu screen, but when I press Esc to go back, it just jumped to the main screen, not the previous screen, why? This is because you did not specify a parent screen, and the close method just directly jumps to the main screen.

Add a parent as a parameter and field, and use it in the close method:

  private final Screen parent;
 
  protected TutorialScreen(Screen parent) {
    super(Text.literal("My tutorial screen"));
    this.parent = parent;
  }
 
  @Override
  public void close() {
    client.setScreen(parent);
  }

By default, when narration is enabled, the screen title and information of the element you hover or focus on will be narrated. If the screen requires extra narrations (for example it has some texts rendered but not added as a widget), you can override addScreenNarrations or addElementNarrations. The methods take a NarrationBuilder, in which you can use add method to add narration messages. The narration messages are divided into the following parts (NarrationPart):

• Title: The title of the screen, which is defined in the constructor. When you enter the screen, the title will be automatically narrated.
• Position: Telling you the position of the widget you are focusing on. In vanilla, it is: “Screen element %s out of %s”. Besides, if in a list widget, the following will also be narrated: “Selected list row %s out of %s”.
• Hint: This refers the tooltip of the element you focus on or hovers on. For example, the tooltip method when you create the ButtonWidget in the code above.
• Usage: In vanilla, the usage is: “Use mouse cursor or Tab button to select element”.

Besides the narration of the screen, you can also customize the narration of the element, by overriding appendNarrations method of the class of that element. The element is narrated after the narration of the screen.

In the method of appending narrations, using narrationBuilder.nextMessage() can append narrations after the current narrations, instead of replacing existing part of the narration.

[WIP]