I think i actually got it to work lmaooo

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

@@ -27,7 +27,9 @@ package org.geysermc.geyser.api.bedrock.camera;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.geysermc.geyser.api.bedrock.gui.GuiElement;
 import org.geysermc.geyser.api.connection.GeyserConnection;
+import org.geysermc.geyser.api.bedrock.gui.GuiData;
 
 import java.util.Set;
 import java.util.UUID;
@@ -150,7 +152,9 @@ public interface CameraData {
      * Hides a {@link GuiElement} on the client's side.
      *
      * @param element the {@link GuiElement} to hide
+     * @deprecated Use {@link GuiData#hideElement(GuiElement...)} instead
      */
+    @Deprecated
     void hideElement(@NonNull GuiElement... element);
 
     /**
@@ -161,20 +165,26 @@ public interface CameraData {
      * If no elements are specified, this will reset all currently hidden elements
      *
      * @param element the {@link GuiElement} to reset
+     * @deprecated Use {@link GuiData#resetElement(GuiElement...)} instead
      */
+    @Deprecated
     void resetElement(@NonNull GuiElement @Nullable... element);
 
     /**
      * Determines whether a {@link GuiElement} is currently hidden.
      *
      * @param element the {@link GuiElement} to check
+     * @deprecated Use {@link GuiData#isHudElementHidden(GuiElement)} instead
      */
+    @Deprecated
     boolean isHudElementHidden(@NonNull GuiElement element);
 
     /**
      * Returns the currently hidden {@link GuiElement}s.
      *
      * @return an unmodifiable view of all currently hidden {@link GuiElement}s
+     * @deprecated Use {@link GuiData#hiddenElements()} instead
      */
+    @Deprecated
     @NonNull Set<GuiElement> hiddenElements();
 }

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

@@ -25,36 +25,31 @@
 
 package org.geysermc.geyser.api.bedrock.camera;
 
+import org.geysermc.geyser.api.bedrock.gui.GuiData;
+
 /**
  * Represent GUI elements on the players HUD display.
- * These can be hidden using {@link CameraData#hideElement(GuiElement...)},
+ * These can be hidden using {@link GuiData#hideElement(org.geysermc.geyser.api.bedrock.gui.GuiElement...)},
- * and one can reset their visibility using {@link CameraData#resetElement(GuiElement...)}.
+ * and one can reset their visibility using {@link GuiData#resetElement(org.geysermc.geyser.api.bedrock.gui.GuiElement...)}.
+ * @deprecated use {@link org.geysermc.geyser.api.bedrock.gui.GuiElement}
  */
-public class GuiElement {
+public class GuiElement extends org.geysermc.geyser.api.bedrock.gui.GuiElement {
-    public static final GuiElement PAPER_DOLL = new GuiElement(0);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement PAPER_DOLL = org.geysermc.geyser.api.bedrock.gui.GuiElement.PAPER_DOLL;
-    public static final GuiElement ARMOR = new GuiElement(1);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement ARMOR = org.geysermc.geyser.api.bedrock.gui.GuiElement.ARMOR;
-    public static final GuiElement TOOL_TIPS = new GuiElement(2);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement TOOL_TIPS = org.geysermc.geyser.api.bedrock.gui.GuiElement.TOOL_TIPS;
-    public static final GuiElement TOUCH_CONTROLS = new GuiElement(3);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement TOUCH_CONTROLS = org.geysermc.geyser.api.bedrock.gui.GuiElement.TOUCH_CONTROLS;
-    public static final GuiElement CROSSHAIR = new GuiElement(4);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement CROSSHAIR = org.geysermc.geyser.api.bedrock.gui.GuiElement.CROSSHAIR;
-    public static final GuiElement HOTBAR = new GuiElement(5);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement HOTBAR = org.geysermc.geyser.api.bedrock.gui.GuiElement.HOTBAR;
-    public static final GuiElement HEALTH = new GuiElement(6);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement HEALTH = org.geysermc.geyser.api.bedrock.gui.GuiElement.HEALTH;
-    public static final GuiElement PROGRESS_BAR = new GuiElement(7);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement PROGRESS_BAR = org.geysermc.geyser.api.bedrock.gui.GuiElement.PROGRESS_BAR;
-    public static final GuiElement FOOD_BAR = new GuiElement(8);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement FOOD_BAR = org.geysermc.geyser.api.bedrock.gui.GuiElement.FOOD_BAR;
-    public static final GuiElement AIR_BUBBLES_BAR = new GuiElement(9);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement AIR_BUBBLES_BAR = org.geysermc.geyser.api.bedrock.gui.GuiElement.AIR_BUBBLES_BAR;
-    public static final GuiElement VEHICLE_HEALTH = new GuiElement(10);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement VEHICLE_HEALTH = org.geysermc.geyser.api.bedrock.gui.GuiElement.VEHICLE_HEALTH;
-    public static final GuiElement EFFECTS_BAR = new GuiElement(11);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement EFFECTS_BAR = org.geysermc.geyser.api.bedrock.gui.GuiElement.EFFECTS_BAR;
-    public static final GuiElement ITEM_TEXT_POPUP = new GuiElement(12);
+    public static final org.geysermc.geyser.api.bedrock.gui.GuiElement ITEM_TEXT_POPUP = org.geysermc.geyser.api.bedrock.gui.GuiElement.ITEM_TEXT_POPUP;
 
-    private GuiElement(int id) {
+    public GuiElement(int id) {
-        this.id = id;
+        super(id);
-    }
-
-    private final int id;
-
-    /**
-     * Internal use only; don't depend on these values being consistent.
-     */
-    public int id() {
-        return this.id;
     }
 }
+

api/src/main/java/org/geysermc/geyser/api/connection/GeyserConnection.java

@@ -31,6 +31,7 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 import org.geysermc.api.connection.Connection;
 import org.geysermc.geyser.api.bedrock.camera.CameraData;
 import org.geysermc.geyser.api.bedrock.camera.CameraShake;
+import org.geysermc.geyser.api.bedrock.gui.GuiData;
 import org.geysermc.geyser.api.command.CommandSource;
 import org.geysermc.geyser.api.entity.EntityData;
 import org.geysermc.geyser.api.entity.type.GeyserEntity;
@@ -60,6 +61,14 @@ public interface GeyserConnection extends Connection, CommandSource {
      */
     @NonNull EntityData entities();
 
+    /**
+     * Exposes the {@link GuiData} for this connection.
+     * It allows you to hide GUI elements, and send notification toasts.
+     *
+     * @return the GuiData for this connection.
+     */
+    @NonNull GuiData gui();
+
     /**
      * @param javaId the Java entity ID to look up.
      * @return a {@link GeyserEntity} if present in this connection's entity tracker.

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

@@ -47,7 +47,7 @@ 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.api.bedrock.gui.GuiElement;
 import org.geysermc.geyser.session.GeyserSession;
 import org.geysermc.mcprotocollib.protocol.data.game.entity.player.GameMode;
 
@@ -302,22 +302,4 @@ public class GeyserCameraData implements CameraData {
     public @NonNull Set<GuiElement> hiddenElements() {
         return Collections.unmodifiableSet(hiddenHudElements);
     }
-
-    /**
-     * Deals with hiding hud elements while in spectator.
-     *
-     * @param currentlySpectator whether the player is currently in spectator mode
-     * @param newGameMode the new GameMode to switch to
-     */
-    public void handleGameModeChange(boolean currentlySpectator, GameMode newGameMode) {
-        if (newGameMode == GameMode.SPECTATOR) {
-            if (!currentlySpectator) {
-                hideElement(SPECTATOR_HIDDEN_ELEMENTS);
-            }
-        } else {
-            if (currentlySpectator) {
-                resetElement(SPECTATOR_HIDDEN_ELEMENTS);
-            }
-        }
-    }
 }

core/src/main/java/org/geysermc/geyser/impl/gui/GeyserGuiData.java

@@ -71,8 +71,18 @@ public class GeyserGuiData implements GuiData {
     private final Set<GuiElement> hiddenHudElements = new HashSet<>();
 
     @Override
-    public void hideElement(@NotNull @NonNull GuiElement... element) {
+    public void hideElement(@NonNull GuiElement... elements) {
+        Objects.requireNonNull(elements);
+        SetHudPacket packet = new SetHudPacket();
+        packet.setVisibility(HudVisibility.HIDE);
+        Set<HudElement> elementSet = packet.getElements();
 
+        for (GuiElement element : elements) {
+            this.hiddenHudElements.add(element);
+            elementSet.add(HUD_ELEMENT_VALUES[element.id()]);
+        }
+
+        session.sendUpstreamPacket(packet);
     }
 
     @Override

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

@@ -71,6 +71,7 @@ import org.geysermc.geyser.Constants;
 import org.geysermc.geyser.GeyserImpl;
 import org.geysermc.geyser.api.bedrock.camera.CameraData;
 import org.geysermc.geyser.api.bedrock.camera.CameraShake;
+import org.geysermc.geyser.api.bedrock.gui.GuiData;
 import org.geysermc.geyser.api.connection.GeyserConnection;
 import org.geysermc.geyser.api.entity.EntityData;
 import org.geysermc.geyser.api.entity.type.GeyserEntity;
@@ -94,6 +95,7 @@ import org.geysermc.geyser.erosion.AbstractGeyserboundPacketHandler;
 import org.geysermc.geyser.erosion.GeyserboundHandshakePacketHandler;
 import org.geysermc.geyser.impl.camera.CameraDefinitions;
 import org.geysermc.geyser.impl.camera.GeyserCameraData;
+import org.geysermc.geyser.impl.gui.GeyserGuiData;
 import org.geysermc.geyser.inventory.Inventory;
 import org.geysermc.geyser.inventory.PlayerInventory;
 import org.geysermc.geyser.inventory.recipe.GeyserRecipe;
@@ -559,6 +561,9 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
 
     private final GeyserEntityData entityData;
 
+    private final GeyserGuiData guiData;
+
+
     private MinecraftProtocol protocol;
 
     public GeyserSession(GeyserImpl geyser, BedrockServerSession bedrockServerSession, EventLoop eventLoop) {
@@ -582,8 +587,10 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
         this.structureBlockCache = new StructureBlockCache();
         this.tagCache = new TagCache();
         this.worldCache = new WorldCache(this);
+
         this.cameraData = new GeyserCameraData(this);
         this.entityData = new GeyserEntityData(this);
+        this.guiData = new GeyserGuiData(this);
 
         this.worldBorder = new WorldBorder(this);
 
@@ -1310,7 +1317,7 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
     public void setGameMode(GameMode newGamemode) {
         boolean currentlySpectator = this.gameMode == GameMode.SPECTATOR;
         this.gameMode = newGamemode;
-        this.cameraData.handleGameModeChange(currentlySpectator, newGamemode);
+        this.guiData.handleGameModeChange(currentlySpectator, newGamemode);
     }
 
     /**
@@ -2023,6 +2030,11 @@ public class GeyserSession implements GeyserConnection, GeyserCommandSource {
         return this.entityData;
     }
 
+    @Override
+    public @NonNull GuiData gui() {
+        return this.guiData;
+    }
+
     @Override
     public void shakeCamera(float intensity, float duration, @NonNull CameraShake type) {
         this.cameraData.shakeCamera(intensity, duration, type);

core/src/main/java/org/geysermc/geyser/translator/protocol/java/JavaUpdateAdvancementsTranslator.java

@@ -84,11 +84,7 @@ public class JavaUpdateAdvancementsTranslator extends PacketTranslator<Clientbou
                     String frameType = advancement.getDisplayData().getAdvancementType().toString().toLowerCase(Locale.ROOT);
                     String frameTitle = advancement.getDisplayColor() + MinecraftLocale.getLocaleString("advancements.toast." + frameType, session.locale());
                     String advancementName = MessageTranslator.convertMessage(advancement.getDisplayData().getTitle(), session.locale());
-
+                    session.gui().sendToast(frameTitle, advancementName);
-                    ToastRequestPacket toastRequestPacket = new ToastRequestPacket();
-                    toastRequestPacket.setTitle(frameTitle);
-                    toastRequestPacket.setContent(advancementName);
-                    session.sendUpstreamPacket(toastRequestPacket);
                 }
             }
         }