Add ClientInformationUpdatedEvent (neoforged#1365)

patches/net/minecraft/server/network/ServerGamePacketListenerImpl.java.patch

@@ -100,14 +100,22 @@
                          }
 
                          @Override
-@@ -1753,7 +_,7 @@
+@@ -1753,13 +_,15 @@
      @Override
      public void handlePlayerAbilities(ServerboundPlayerAbilitiesPacket p_9887_) {
          PacketUtils.ensureRunningOnSameThread(p_9887_, this, this.player.serverLevel());
 -        this.player.getAbilities().flying = p_9887_.isFlying() && this.player.getAbilities().mayfly;
 +        this.player.getAbilities().flying = p_9887_.isFlying() && this.player.mayFly();
      }
 
+     @Override
+     public void handleClientInformation(ServerboundClientInformationPacket p_301979_) {
+         PacketUtils.ensureRunningOnSameThread(p_301979_, this, this.player.serverLevel());
++        net.minecraft.server.level.ClientInformation oldInfo = this.player.clientInformation();
+         this.player.updateOptions(p_301979_.information());
++        net.neoforged.neoforge.common.NeoForge.EVENT_BUS.post(new net.neoforged.neoforge.event.entity.player.ClientInformationUpdatedEvent(this.player, oldInfo, p_301979_.information()));
+     }
+
      @Override
 @@ -1812,7 +_,7 @@
              this.connection

src/main/java/net/neoforged/neoforge/event/entity/player/ClientInformationUpdatedEvent.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) NeoForged and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.neoforged.neoforge.event.entity.player;
+
+import net.minecraft.server.level.ClientInformation;
+import net.minecraft.server.level.ServerPlayer;
+import net.neoforged.neoforge.common.NeoForge;
+
+/**
+ * ClientInformationUpdatedEvent is fired when a player changes server-synced client options,
+ * specifically those in {@link net.minecraft.server.level.ClientInformation}.
+ * <p>
+ * This event is fired on the {@link NeoForge#EVENT_BUS}.
+ **/
+public class ClientInformationUpdatedEvent extends PlayerEvent {
+    private final ClientInformation oldInformation;
+    private final ClientInformation updatedInformation;
+
+    public ClientInformationUpdatedEvent(ServerPlayer player, ClientInformation oldInfo, ClientInformation newInfo) {
+        super(player);
+        this.oldInformation = oldInfo;
+        this.updatedInformation = newInfo;
+    }
+
+    @Override
+    public ServerPlayer getEntity() {
+        return (ServerPlayer) super.getEntity();
+    }
+
+    /**
+     * Returns the new client info to be applied to the player.
+     * Sometimes the client resends unchanged options, so if that matters
+     * for your use case, check equality with {@link #getOldInformation()}.
+     *
+     * @return updated information
+     */
+    public ClientInformation getUpdatedInformation() {
+        return this.updatedInformation;
+    }
+
+    /**
+     * Returns the existing client info from to the player.
+     * <p>
+     * May be blank or defaulted initial data on first event call for a player instance.
+     *
+     * @return updated information
+     */
+    public ClientInformation getOldInformation() {
+        return this.oldInformation;
+    }
+}

tests/src/main/java/net/neoforged/neoforge/oldtest/entity/player/ClientInformationUpdatedTest.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright (c) NeoForged and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.neoforged.neoforge.oldtest.entity.player;
+
+import net.minecraft.network.chat.Component;
+import net.neoforged.fml.common.Mod;
+import net.neoforged.neoforge.common.NeoForge;
+import net.neoforged.neoforge.event.entity.player.ClientInformationUpdatedEvent;
+
+/**
+ * Tests the client info update event by telling a player their new and old info on updates.
+ * Easiest thing to test is change your language or view distance.
+ */
+@Mod(ClientInformationUpdatedTest.MOD_ID)
+public class ClientInformationUpdatedTest {
+    public static final String MOD_ID = "client_information_updated_test";
+
+    public ClientInformationUpdatedTest() {
+        NeoForge.EVENT_BUS.addListener((ClientInformationUpdatedEvent event) -> {
+            event.getEntity().sendSystemMessage(Component.literal("old: " + event.getOldInformation()));
+            event.getEntity().sendSystemMessage(Component.literal("new: " + event.getUpdatedInformation()));
+        });
+    }
+}

tests/src/main/resources/META-INF/neoforge.mods.toml

@@ -246,5 +246,7 @@ modId="player_spawn_phantoms_event_test"
 modId="conditional_codec_test"
 [[mods]]
 modId="may_fly_attribute_item"
+[[mods]]
+modId="client_information_updated_test"
 
 # ADD ABOVE THIS LINE