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--- tutorial:propertydelegates [2020/08/14 16:57] – manymoney2
+++ tutorial:propertydelegates [2020/08/15 18:58] – [Syncing Integers with PropertyDelegates] technici4n
@@ Line 1: / Line 1: @@
 ====== Syncing Integers with PropertyDelegates ======
-In this Tutorial we will sync Integer values between the client and the Server.
+**PropertyDelegate:** A ''PropertyDelegate'' is a kind of Container which contains a specific amounts of integer values which can be read or changed.
+In this Tutorial we will sync Integer values between the client and the server, an example for this in Vanilla would be the smelting progress of a furnace.
+To understand this tutorial you need to read the first [[tutorial:screenhandler|ScreenHandler]] tutorial.
+Methods which have no code here were already shown in that tutorial.
+We will not use the [[tutorial:extendedscreenhandler|ExtendedScreenHandler]] in this tutorial any more to save us some complexity.
+====== BlockEntity ======
+As the Block class does not need to be changed at all we leave it out here.
+Our ''BlockEntity'' now implements ''Tickable'', this will provide the ''tick()'' method which gets called every tick. We use it to increase our Integer we want to sync.
+<code java [enable_line_numbers="true"] BoxBlockEntity.java>
+public class BoxBlockEntity extends BlockEntity implements NamedScreenHandlerFactory, ImplementedInventory, Tickable {
+    private final DefaultedList<ItemStack> inventory = DefaultedList.ofSize(9, ItemStack.EMPTY);
+    //this is the int we want to sync, it gets increased by one each tick
+    private int syncedInt;
+    //PropertyDelegate is an interface which we will implement inline here.
+    //It can normally contain multiple integers as data identified by the index, but in this example we only have one.
+    private final PropertyDelegate propertyDelegate = new PropertyDelegate() {
+        @Override
+        public int get(int index) {
+            return syncedInt;
+        }
+        @Override
+        public void set(int index, int value) {
+            syncedInt = value;
+        }
+        //this is supposed to return the amount of integers you have in your delegate, in our example only one
+        @Override
+        public int size() {
+            return 1;
+        }
+    };
+    public BoxBlockEntity() {
+        super(Test.BOX_BLOCK_ENTITY);
+    }
+    //From the ImplementedInventory Interface
+    @Override
+    public DefaultedList<ItemStack> getItems() {
+        return inventory;
+    }
+    //These Methods are from the NamedScreenHandlerFactory Interface
+    @Override
+    public @Nullable ScreenHandler createMenu(int syncId, PlayerInventory playerInventory, PlayerEntity player) {
+        //We provide this to the screenHandler as our class Implements Inventory
+        //Only the Server has the Inventory at the start, this will be synced to the client in the ScreenHandler
+        //Similar to the inventory: The server has the PropertyDelegate and gives it to the server instance of the screen handler directly
+        return new BoxScreenHandler(syncId, playerInventory, this,propertyDelegate);
+    }
+    @Override
+    public Text getDisplayName() {
+        return new TranslatableText(getCachedState().getBlock().getTranslationKey());
+    }
+    //increase the synced Integer by one each tick, we only do this on the server for demonstration purposes.
+    @Override
+    public void tick() {
+    if(!world.isClient)
+        syncedInt++;
+    }
+}
+</code>
+====== Our new ScreenHandler ======
+<code java [enable_line_numbers="true"] BoxScreenHandler.java>
+public class BoxScreenHandler extends ScreenHandler {
+    private final Inventory inventory;
+    PropertyDelegate propertyDelegate;
+    //This constructor gets called on the client when the server wants it to open the screenHandler,
+    //The client will call the super constructor with an empty Inventory and the screenHandler will automatically
+    //sync this empty inventory with the inventory on the server
+    //Similar to the inventory, the client will allocate an empty propertyDelegate which will be synced with the Server automatically
+    public BoxScreenHandler(int syncId, PlayerInventory playerInventory) {
+        this(syncId, playerInventory, new SimpleInventory(9),new ArrayPropertyDelegate(1));
+    }
+    //This constructor gets called from the BlockEntity on the server, the server knows the inventory of the container
+    //and can therefore directly provide it as an argument. This inventory aswell as the propertyDelegate will then be synced to the Client
+    public BoxScreenHandler(int syncId, PlayerInventory playerInventory, Inventory inventory, PropertyDelegate propertyDelegate) {
+        super(Test.BOX_SCREEN_HANDLER, syncId);
+        checkSize(inventory, 9);
+        this.inventory = inventory;
+        this.propertyDelegate = propertyDelegate;
+        //some inventories do custom logic when a player opens it.
+        inventory.onOpen(playerInventory.player);
+        //we need to tell the screenhandler about our propertyDelegate, otherwise it will not sync the data inside.
+        this.addProperties(propertyDelegate);
+        //This will place the slot in the correct locations for a 3x3 Grid. The slots exist on both server and client!
+        [...]
+    }
+    //we provide this getter for the synced integer so the Screen can access this to show it on screen
+    public int getSyncedNumber(){
+        return propertyDelegate.get(0);
+    }
+    @Override
+    public boolean canUse(PlayerEntity player) {
+        return this.inventory.canPlayerUse(player);
+    }
+    @Override
+    public ItemStack transferSlot(PlayerEntity player, int invSlot) {[...]}
+}
+</code>
+====== Showing the Information with the Screen ======
+As the screen gets the ''ScreenHandler'' in its constructor, we have access to the property delegate from above and can render the integer on screen.
+<code java [enable_line_numbers="true"] BoxScreen.java>
+public class BoxScreen extends HandledScreen<ScreenHandler> {
+    private static final Identifier TEXTURE = new Identifier("minecraft", "textures/gui/container/dispenser.png");
+    BoxScreenHandler screenHandler;
+    public BoxScreen(ScreenHandler handler, PlayerInventory inventory, Text title) {
+        super(handler, inventory, title);
+        //we save a reference to the screenhandler so we can render the number from our propertyDelegate on screen
+        screenHandler = (BoxScreenHandler) handler;
+    }
+    @Override
+    protected void drawBackground(MatrixStack matrices, float delta, int mouseX, int mouseY) {[...]}
+    @Override
+    public void render(MatrixStack matrices, int mouseX, int mouseY, float delta) {
+        //We just render our synced number somewhere in the container, this is a demonstration after all
+        //the last argument is a color code, making the font bright green
+        textRenderer.draw(matrices, Integer.toString(screenHandler.getSyncedNumber()), 0, 0, 65280);
+        renderBackground(matrices);
+        super.render(matrices, mouseX, mouseY, delta);
+        drawMouseoverTooltip(matrices, mouseX, mouseY);
+    }
+    @Override
+    protected void init() {
+        super.init();
+        // Center the title
+        titleX = (backgroundWidth - textRenderer.getWidth(title)) / 2;
+    }
+}
+</code>
+====== Result ======
+As the registration of the ''ScreenHandler'' is identical to that of the first tutorial we can see the result already!
+When the BlockEntity is placed it will increase the ''syncedInt'' by one each tick; when we look inside the container, the integer will
+automatically be synced to the client and rendered in the top left corner.
+[[https://streamable.com/7aic8q|Example Video]]
+If you want a more realistic example, you might want to have a look at ''AbstractFurnaceEntity'' and ''AbstractFurnaceScreenHandler'' in the Minecraft code.
-An Example for this in vanilla would be the smelting progress of a furnace.
-To understand this tutorial you need to read the first Screenhandler tutorial. Methods which have no code here were already shown in that tutorial