Rewrite data slots using observable properties

Author: Juuxel

src/main/java/io/github/cottonmc/cotton/gui/impl/DataSlotImpl.java

@@ -1,59 +1,38 @@
 package io.github.cottonmc.cotton.gui.impl;
 
-import net.fabricmc.fabric.api.event.Event;
-import net.fabricmc.fabric.api.event.EventFactory;
-
 import io.github.cottonmc.cotton.gui.SyncedGuiDescription;
 import io.github.cottonmc.cotton.gui.networking.DataSlot;
 import io.github.cottonmc.cotton.gui.networking.NetworkDirection;
 import io.github.cottonmc.cotton.gui.networking.ScreenMessageKey;
-
-import java.util.Objects;
+import io.github.cottonmc.cotton.gui.widget.data.ObservableProperty;
 
 public final class DataSlotImpl<T> implements DataSlot<T> {
 	private final SyncedGuiDescription owner;
 	private final ScreenMessageKey<T> key;
-	private T value;
+	private final ObservableProperty<T> value;
 	private final NetworkDirection networkDirection;
-	private final Event<ChangeListener<T>> valueChangedEvent;
 	private boolean dirty = false;
 
 	public DataSlotImpl(SyncedGuiDescription owner, ScreenMessageKey<T> key, T initialValue, NetworkDirection networkDirection) {
 		this.owner = owner;
 		this.key = key;
-		this.value = initialValue;
+		this.value = ObservableProperty.of(initialValue).name("value").build();
+		this.value.addListener((property, from, to) -> dirty = true);
 		this.networkDirection = networkDirection;
-		this.valueChangedEvent = EventFactory.createArrayBacked(ChangeListener.class, listeners -> (dataSlot, value) -> {
-			for (ChangeListener<T> listener : listeners) {
-				listener.onValueChanged(dataSlot, value);
-			}
-		});
 	}
 
-	public T get() {
+	@Override
+	public ObservableProperty<T> valueProperty() {
 		return value;
 	}
 
-	public void set(T value) {
-		if (!Objects.equals(this.value, value)) {
-			this.value = value;
-			dirty = true;
-			valueChangedEvent.invoker().onValueChanged(this, value);
-		}
-	}
-
 	public void checkAndSendUpdate() {
 		if (dirty) {
-			owner.getNetworking(networkDirection.from()).send(key, value);
+			owner.getNetworking(networkDirection.from()).send(key, value.get());
 			dirty = false;
 		}
 	}
 
-	@Override
-	public Event<ChangeListener<T>> getValueChangedEvent() {
-		return valueChangedEvent;
-	}
-
 	@Override
 	public ScreenMessageKey<T> getKey() {
 		return key;

src/main/java/io/github/cottonmc/cotton/gui/networking/DataSlot.java

@@ -1,7 +1,6 @@
 package io.github.cottonmc.cotton.gui.networking;
 
-import net.fabricmc.fabric.api.event.Event;
-
+import io.github.cottonmc.cotton.gui.widget.data.ObservableProperty;
 import org.jetbrains.annotations.ApiStatus;
 
 /**
@@ -31,35 +30,50 @@
  * }
  *
  * // You can listen to data slot updates on both sides:
- * myData.getValueChangedEvent().register((dataSlot, value) -> {
- * 	   System.out.println("updated data: " + value);
+ * myData.addChangeListener((dataSlot, from, to) -> {
+ *     System.out.println("updated data: " + value);
  * });
  * }
  *
+ * @properties
  * @param <T> the data slot content type
  * @see io.github.cottonmc.cotton.gui.SyncedGuiDescription#registerDataSlot(ScreenMessageKey, Object, NetworkDirection)
  * @since 13.1.0
  */
 @ApiStatus.NonExtendable
 public interface DataSlot<T> {
+	/**
+	 * Returns the current value of the data slot.
+	 * The result is an <em>observable property</em> that can be modified and listened to.
+	 *
+	 * @return the {@code value} property
+	 */
+	ObservableProperty<T> valueProperty();
+
 	/**
 	 * {@return the current value of the data slot}
 	 */
-	T get();
+	default T get() {
+		return valueProperty().get();
+	}
 
 	/**
 	 * Sets the current value of the data slot.
-	 * If it's not equal to the previous value,
-	 * {@link #getValueChangedEvent()} will be triggered.
 	 *
 	 * @param value the new value
 	 */
-	void set(T value);
+	default void set(T value) {
+		valueProperty().set(value);
+	}
 
 	/**
-	 * {@return an event triggered when this data slot's value changes}
+	 * Adds a change listener to this data slot.
+	 *
+	 * @param listener the added listener
 	 */
-	Event<ChangeListener<T>> getValueChangedEvent();
+	default void addChangeListener(ChangeListener<T> listener) {
+		valueProperty().addListener((property, from, to) -> listener.onValueChanged(this, from, to));
+	}
 
 	/**
 	 * {@return the key of the message that syncs this data slot}
@@ -73,7 +87,7 @@ public interface DataSlot<T> {
 	NetworkDirection getNetworkDirection();
 
 	/**
-	 * A listener for {@link #getValueChangedEvent()}.
+	 * A listener for data slot value changes.
 	 *
 	 * @param <T> the data slot content type
 	 */
@@ -83,8 +97,9 @@ interface ChangeListener<T> {
 		 * Called when a data slot's value changes.
 		 *
 		 * @param dataSlot the data slot for which the event was triggered
-		 * @param value    the new value
+		 * @param from     the old value
+		 * @param to       the new value
 		 */
-		void onValueChanged(DataSlot<T> dataSlot, T value);
+		void onValueChanged(DataSlot<T> dataSlot, T from, T to);
 	}
 }

src/main/java/io/github/cottonmc/cotton/gui/widget/WWidget.java

@@ -493,7 +493,7 @@ public boolean canHover() {
 
 	/**
 	 * Returns whether the user is hovering over this widget.
-	 * The result is an <i>observable property</i> that can be modified and listened to.
+	 * The result is an <em>observable property</em> that can be modified and listened to.
 	 *
 	 * <p>This property takes into account {@link #isWithinBounds(int, int)} to check
 	 * if the cursor is within the bounds, as well as {@link #canHover()} to enable hovering at all.

src/testMod/java/io/github/cottonmc/test/TestDescription.java

@@ -104,9 +104,9 @@ public TestDescription(ScreenHandlerType<?> type, int syncId, PlayerInventory pl
 		// The button will never be yellow! Initial values won't be synced.
 		buttonColor = registerDataSlot(BUTTON_COLOR_DATA_SLOT, 0xFF_FFFF00, NetworkDirection.CLIENT_TO_SERVER);
 
-		buttonLabel.getValueChangedEvent().register((dataSlot, value) -> buttonA.setLabel(value));
-		buttonColor.getValueChangedEvent().register((dataSlot, value) -> {
-			buttonB.setLabel(buttonB.getLabel().copy().withColor(value));
+		buttonLabel.addChangeListener((dataSlot, from, to) -> buttonA.setLabel(to));
+		buttonColor.addChangeListener((dataSlot, from, to) -> {
+			buttonB.setLabel(buttonB.getLabel().copy().withColor(to));
 		});
 
 		getNetworking(NetworkSide.SERVER).receive(TEST_MESSAGE, Codec.INT, value -> {