Add API to show/hide GUI elements

We can also use this for a nicer looking spectator mode GUI :)

api/src/main/java/org/geysermc/geyser/api/bedrock/camera/CameraData.java

@@ -145,4 +145,50 @@ public interface CameraData {
      * @return whether the camera is currently locked
      */
     boolean isCameraLocked();
+
+    /**
+     * Hides a {@link GuiElement} on the client's side.
+     *
+     * @param element the {@link GuiElement} to hide
+     */
+    void hideElement(@NonNull GuiElement element);
+
+    /**
+     * Hides a set of {@link GuiElement}'s on the client's side.
+     *
+     * @param elements the {@link Set<GuiElement>} to hide
+     */
+    void hideElements(@NonNull Set<GuiElement> elements);
+
+    /**
+     * Resets a {@link GuiElement} on the client's side.
+     * This makes the client decide on its own - e.g. based on client settings -
+     * whether to show or hide the gui element.
+     *
+     * @param element the {@link GuiElement} to reset
+     */
+    void resetElement(@NonNull GuiElement element);
+
+    /**
+     * Resets a set of {@link GuiElement} on the client's side.
+     * This makes the client decide on its own - e.g. based on client settings -
+     * whether to show or hide the gui elements.
+     *
+     * @param elements the {@link Set<GuiElement>} to reset
+     */
+    void resetElements(@NonNull Set<GuiElement> elements);
+
+    /**
+     * Determines whether a {@link GuiElement} is currently hidden.
+     *
+     * @param element the {@link GuiElement} to check
+     */
+    boolean isHudElementHidden(@NonNull GuiElement element);
+
+    /**
+     * Returns the currently hidden {@link GuiElement}.
+     *
+     * @return an immutable set of all currently hidden {@link GuiElement}s
+     */
+    @NonNull Set<GuiElement> hiddenElements();
 }

api/src/main/java/org/geysermc/geyser/api/bedrock/camera/GuiElement.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2024 GeyserMC. http://geysermc.org
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ * @author GeyserMC
+ * @link https://github.com/GeyserMC/Geyser
+ */
+
+package org.geysermc.geyser.api.bedrock.camera;
+
+public enum GuiElement {
+    PAPER_DOLL,
+    ARMOR,
+    TOOL_TIPS,
+    TOUCH_CONTROLS,
+    CROSSHAIR,
+    HOTBAR,
+    HEALTH,
+    PROGRESS_BAR,
+    FOOD_BAR,
+    AIR_BUBBLES_BAR,
+    VEHICLE_HEALTH,
+    EFFECTS_BAR,
+    ITEM_TEXT_POPUP
+}

core/src/main/java/org/geysermc/geyser/impl/camera/GeyserCameraData.java

@@ -32,16 +32,29 @@ import org.cloudburstmc.math.vector.Vector2f;
 import org.cloudburstmc.math.vector.Vector3f;
 import org.cloudburstmc.protocol.bedrock.data.CameraShakeAction;
 import org.cloudburstmc.protocol.bedrock.data.CameraShakeType;
+import org.cloudburstmc.protocol.bedrock.data.HudElement;
+import org.cloudburstmc.protocol.bedrock.data.HudVisibility;
 import org.cloudburstmc.protocol.bedrock.data.camera.CameraEase;
 import org.cloudburstmc.protocol.bedrock.data.camera.CameraFadeInstruction;
 import org.cloudburstmc.protocol.bedrock.data.camera.CameraSetInstruction;
 import org.cloudburstmc.protocol.bedrock.packet.CameraInstructionPacket;
 import org.cloudburstmc.protocol.bedrock.packet.CameraShakePacket;
 import org.cloudburstmc.protocol.bedrock.packet.PlayerFogPacket;
-import org.geysermc.geyser.api.bedrock.camera.*;
+import org.cloudburstmc.protocol.bedrock.packet.SetHudPacket;
+import org.geysermc.geyser.api.bedrock.camera.CameraData;
+import org.geysermc.geyser.api.bedrock.camera.CameraEaseType;
+import org.geysermc.geyser.api.bedrock.camera.CameraFade;
+import org.geysermc.geyser.api.bedrock.camera.CameraPerspective;
+import org.geysermc.geyser.api.bedrock.camera.CameraPosition;
+import org.geysermc.geyser.api.bedrock.camera.CameraShake;
+import org.geysermc.geyser.api.bedrock.camera.GuiElement;
 import org.geysermc.geyser.session.GeyserSession;
 
-import java.util.*;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Objects;
+import java.util.Set;
+import java.util.UUID;
 
 public class GeyserCameraData implements CameraData {
 
@@ -57,6 +70,11 @@ public class GeyserCameraData implements CameraData {
 
     private final Set<UUID> cameraLockOwners = new HashSet<>();
 
+    /**
+     * All currently hidden HUD elements
+     */
+    private final Set<GuiElement> hiddenHudElements = new HashSet<>();
+
     public GeyserCameraData(GeyserSession session) {
         this.session = session;
     }
@@ -223,4 +241,66 @@ public class GeyserCameraData implements CameraData {
     public boolean isCameraLocked() {
         return !this.cameraLockOwners.isEmpty();
     }
+
+    @Override
+    public void hideElement(@NonNull GuiElement element) {
+        Objects.requireNonNull(element);
+        this.hiddenHudElements.add(element);
+
+        SetHudPacket packet = new SetHudPacket();
+        packet.setVisibility(HudVisibility.HIDE);
+        packet.getElements().add(HudElement.values()[element.ordinal()]);
+        session.sendUpstreamPacket(packet);
+    }
+
+    @Override
+    public void hideElements(@NonNull Set<GuiElement> elements) {
+        Objects.requireNonNull(elements);
+        this.hiddenHudElements.removeAll(elements);
+
+        SetHudPacket packet = new SetHudPacket();
+        packet.setVisibility(HudVisibility.HIDE);
+        Set<HudElement> elementSet = packet.getElements();
+        elements.forEach((element) -> elementSet.add(HudElement.values()[element.ordinal()]));
+        session.sendUpstreamPacket(packet);
+    }
+
+    @Override
+    public void resetElement(@NonNull GuiElement element) {
+        Objects.requireNonNull(element);
+        this.hiddenHudElements.remove(element);
+
+        SetHudPacket packet = new SetHudPacket();
+        packet.setVisibility(HudVisibility.RESET);
+        packet.getElements().add(HudElement.values()[element.ordinal()]);
+        session.sendUpstreamPacket(packet);
+    }
+
+    @Override
+    public void resetElements(@NonNull Set<GuiElement> elements) {
+        Objects.requireNonNull(elements);
+        this.hiddenHudElements.removeAll(elements);
+
+        // This is unfortunate, but resetting multiple elements doesn't work otherwise
+        if (!hiddenHudElements.isEmpty()) {
+            elements.forEach(this::resetElement);
+            return;
+        }
+
+        SetHudPacket packet = new SetHudPacket();
+        packet.setVisibility(HudVisibility.RESET);
+        packet.getElements().addAll(Set.of(HudElement.values()));
+        session.sendUpstreamPacket(packet);
+    }
+
+    @Override
+    public boolean isHudElementHidden(@NonNull GuiElement element) {
+        Objects.requireNonNull(element);
+        return this.hiddenHudElements.contains(element);
+    }
+
+    @Override
+    public @NonNull Set<GuiElement> hiddenElements() {
+        return Set.copyOf(hiddenHudElements);
+    }
 }

core/src/main/java/org/geysermc/geyser/session/GeyserSession.java

@@ -28,6 +28,7 @@ package org.geysermc.geyser.session;
 import com.github.steveice10.mc.auth.data.GameProfile;
 import com.github.steveice10.mc.auth.exception.request.RequestException;
 import com.github.steveice10.mc.auth.service.MsaAuthenticationService;
+import org.geysermc.geyser.api.bedrock.camera.GuiElement;
 import org.geysermc.mcprotocollib.protocol.MinecraftConstants;
 import org.geysermc.mcprotocollib.protocol.MinecraftProtocol;
 import org.geysermc.mcprotocollib.protocol.data.ProtocolState;
@@ -288,7 +289,6 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
      */
     private volatile boolean closed;
 
-    @Setter
     private GameMode gameMode = GameMode.SURVIVAL;
 
     /**
@@ -581,6 +581,19 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
 
     private MinecraftProtocol protocol;
 
+    /**
+     * A set of elements to hide when the player is in spectator mode.
+     * Helps with tidying up the GUI; Java-style.
+     */
+    private static final Set<GuiElement> SPECTATOR_HUD = Set.of(
+            GuiElement.AIR_BUBBLES_BAR,
+            GuiElement.ARMOR,
+            GuiElement.HEALTH,
+            GuiElement.FOOD_BAR,
+            GuiElement.PROGRESS_BAR,
+            GuiElement.TOOL_TIPS
+    );
+
     public GeyserSession(GeyserImpl geyser, BedrockServerSession bedrockServerSession, EventLoop eventLoop) {
         this.geyser = geyser;
         this.upstream = new UpstreamSession(bedrockServerSession);
@@ -1321,6 +1334,22 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
         }
     }
 
+    public void setGameMode(GameMode newGamemode) {
+        boolean currentlySpectator = gameMode == GameMode.SPECTATOR;
+        this.gameMode = newGamemode;
+
+        // Hide/Unhide GUI elements as needed
+        if (newGamemode == GameMode.SPECTATOR) {
+            if (!currentlySpectator) {
+                this.cameraData.hideElements(SPECTATOR_HUD);
+            }
+        } else {
+            if (currentlySpectator) {
+                this.cameraData.resetElements(SPECTATOR_HUD);
+            }
+        }
+    }
+
     /**
      * Adjusts speed if the player is crawling.
      *