Add item-based subclass of SyncedGuiDescription

1 files changed, 63 insertions, 0 deletions

diff --git a/src/main/java/io/github/cottonmc/cotton/gui/ItemSyncedGuiDescription.java b/src/main/java/io/github/cottonmc/cotton/gui/ItemSyncedGuiDescription.java
new file mode 100644
index 0000000..bdf3479
--- /dev/null
+++ b/src/main/java/io/github/cottonmc/cotton/gui/ItemSyncedGuiDescription.java
@@ -0,0 +1,63 @@
+package io.github.cottonmc.cotton.gui;
+
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.entity.player.PlayerInventory;
+import net.minecraft.inventory.StackReference;
+import net.minecraft.item.ItemStack;
+import net.minecraft.screen.ScreenHandlerType;
+
+import java.util.Objects;
+
+/**
+ * A {@link SyncedGuiDescription} for an {@linkplain ItemStack item stack}
+ * in an {@linkplain net.minecraft.inventory.Inventory inventory}.
+ *
+ * <p>The owning item is represented with a {@link StackReference}, which can be
+ * an item in an entity's inventory or a block's container, or any other reference
+ * to an item stack.
+ *
+ * <p>If the owning item stack changes in any way, the screen closes by default (see {@link #canUse(PlayerEntity)}).
+ *
+ * @since 7.0.0
+ */
+public class ItemSyncedGuiDescription extends SyncedGuiDescription {
+	/**
+	 * A reference to the owning item stack of this GUI.
+	 */
+	protected final StackReference owner;
+
+	/**
+	 * The initial item stack of this GUI. This stack must <strong>not</strong> be mutated!
+	 */
+	protected final ItemStack ownerStack;
+
+	/**
+	 * Constructs an {@code ItemSyncedGuiDescription}.
+	 *
+	 * @param type            the screen handler type
+	 * @param syncId          the sync ID
+	 * @param playerInventory the inventory of the player viewing this GUI description
+	 * @param owner           a reference to the owning item stack of this GUI description
+	 */
+	public ItemSyncedGuiDescription(ScreenHandlerType<?> type, int syncId, PlayerInventory playerInventory, StackReference owner) {
+		super(type, syncId, playerInventory);
+		this.owner = Objects.requireNonNull(owner, "Owner cannot be null");
+		this.ownerStack = owner.get().copy();
+	}
+
+	/**
+	 * {@inheritDoc}
+	 *
+	 * <p>The default implementation for {@code ItemSyncedGuiDescription} returns {@code true} if and only if
+	 * the {@linkplain #owner current owning item stack} is {@linkplain ItemStack#areEqual fully equal}
+	 * to the {@linkplain #ownerStack original owner}.
+	 *
+	 * <p>If the item NBT is intended to change, subclasses should override this method to only check
+	 * the item and the count. Those subclasses should also take care to respond properly
+	 * to any NBT changes in the owning item stack.
+	 */
+	@Override
+	public boolean canUse(PlayerEntity entity) {
+		return ItemStack.areEqual(ownerStack, owner.get());
+	}
+}