fix: item lines not showing to players upon joining (#204)

src/main/java/eu/decentsoftware/holograms/api/Settings.java

@@ -42,6 +42,12 @@ public class Settings {
     public static int DEFAULT_LRU_CACHE_SIZE = 500;
     @Key("allow-placeholders-inside-animations")
     public static boolean ALLOW_PLACEHOLDERS_INSIDE_ANIMATIONS = false;
+    @Key(value = "defaults.minimum-ticks-lived-item-line", min = 0)
+    public static int DEFAULT_MINIMUM_TICKS_LIVED_ITEM_LINE = 40;
+    @Key(value = "defaults.limit-hologram-updates-per-tick")
+    public static boolean LIMIT_HOLOGRAM_UPDATES_PER_TICK = true;
+    @Key(value = "defaults.maximum-hologram-updates-per-tick", min = 1)
+    public static int MAXIMUM_HOLOGRAM_UPDATES_PER_TICK = 10;
 
     public static Map<String, String> CUSTOM_REPLACEMENTS = ImmutableMap.<String, String>builder()
             .put("[x]", "\u2588")

src/main/java/eu/decentsoftware/holograms/api/holograms/Hologram.java

@@ -633,21 +633,21 @@ public boolean show(@NonNull Player player, int pageIndex) {
             if (page != null && page.size() > 0 && canShow(player) && isInDisplayRange(player)) {
                 if (isVisible(player)) {
                     hide(player);
+                    return true; // Skip a tick before updating, should fix the previous issue with clients desyncing.
                 }
-                if (Version.after(8)) {
-                    showPageTo(player, page, pageIndex);
-                } else {
-                    // We need to run the task later on older versions as, if we don't, it causes issues with some holograms *randomly* becoming invisible.
-                    // I *think* this is from despawning and spawning the entities (with the same ID) in the same tick.
-                    S.sync(() -> showPageTo(player, page, pageIndex), 0L);
-                }
+
+                showPageTo(player, page, pageIndex);
                 return true;
             }
             return false;
         }
     }
 
     private void showPageTo(@NonNull Player player, @NonNull HologramPage page, int pageIndex) {
+        if (page.getLines().stream().anyMatch(line -> line.shouldAwaitDisplay(player))) {
+            return;
+        }
+
         page.getLines().forEach(line -> line.show(player));
         // Add player to viewers
         viewerPages.put(player.getUniqueId(), pageIndex);

src/main/java/eu/decentsoftware/holograms/api/holograms/HologramLine.java

@@ -409,6 +409,7 @@ public void show(Player... players) {
             if (parent != null && parent.getParent().isHideState(player)) {
                 continue;
             }
+
             if (!isVisible(player) && canShow(player) && isInDisplayRange(player)) {
                 switch (type) {
                     case TEXT:
@@ -571,4 +572,8 @@ public boolean canShow(@NonNull Player player) {
         return super.canShow(player) && (parent == null || parent.getParent().canShow(player));
     }
 
+    // Could be considered hacky but it works?
+    public boolean shouldAwaitDisplay(Player player) {
+        return (type == HologramLineType.ICON || type == HologramLineType.HEAD) && player.getTicksLived() < Settings.DEFAULT_MINIMUM_TICKS_LIVED_ITEM_LINE;
+    }
 }

src/main/java/eu/decentsoftware/holograms/api/holograms/HologramManager.java

@@ -53,10 +53,18 @@ public HologramManager(DecentHolograms decentHolograms) {
 
     @Override
     public synchronized void tick() {
+        final Map<UUID, Integer> updates = new LinkedHashMap<>();
+
         for (Hologram hologram : Hologram.getCachedHolograms()) {
             if (hologram.isEnabled()) {
                 for (Player player : Bukkit.getOnlinePlayers()) {
-                    updateVisibility(player, hologram);
+                    if (Settings.LIMIT_HOLOGRAM_UPDATES_PER_TICK && updates.getOrDefault(player.getUniqueId(), 0) >= Settings.MAXIMUM_HOLOGRAM_UPDATES_PER_TICK) {
+                        continue;
+                    }
+
+                    if (updateVisibility(player, hologram) && Settings.LIMIT_HOLOGRAM_UPDATES_PER_TICK) {
+                        updates.put(player.getUniqueId(), updates.getOrDefault(player.getUniqueId(), 0) + 1);
+                    }
                 }
             }
         }
@@ -68,24 +76,34 @@ public void updateVisibility(@NonNull Player player) {
         }
     }
 
-    public void updateVisibility(@NonNull Player player, @NonNull Hologram hologram) {
+    /**
+     * Update the visibility of the hologram for the given player.
+     *
+     * @param player - The player to update the visibility for.
+     * @param hologram - The hologram to update the visibility for.
+     * @return True if the hologram was shown, false otherwise.
+     */
+    public boolean updateVisibility(@NonNull Player player, @NonNull Hologram hologram) {
         if (hologram.isDisabled()) {
-            return;
+            return false;
         }
 
         // Determine the player's display state of this hologram.
         if (hologram.isHideState(player) || (!hologram.isDefaultVisibleState() && !hologram.isShowState(player))) {
             if (hologram.isVisible(player)) {
                 hologram.hide(player);
             }
-            return;
+            return false;
         }
 
         if (!hologram.isVisible(player) && hologram.canShow(player) && hologram.isInDisplayRange(player)) {
             hologram.show(player, hologram.getPlayerPage(player));
+            return true;
         } else if (hologram.isVisible(player) && !(hologram.canShow(player) && hologram.isInDisplayRange(player))) {
             hologram.hide(player);
         }
+
+        return false;
     }
 
     /**

src/main/java/eu/decentsoftware/holograms/api/listeners/PlayerListener.java

@@ -24,7 +24,6 @@ public PlayerListener(DecentHolograms decentHolograms) {
     @EventHandler(priority = EventPriority.MONITOR)
     public void onJoin(PlayerJoinEvent e) {
         Player player = e.getPlayer();
-        S.async(() -> decentHolograms.getHologramManager().updateVisibility(player));
         decentHolograms.getPacketListener().hook(player);
         if (decentHolograms.isUpdateAvailable() && player.hasPermission("dh.admin")) {
             Lang.sendUpdateMessage(player);