Add API for client-side signs (#11903)

paper-server/patches/sources/net/minecraft/server/network/ServerGamePacketListenerImpl.java.patch

@@ -2486,7 +2486,7 @@
              } else if (flag && flag2) {
                  if (this.dropSpamThrottler.isUnderThreshold()) {
                      this.dropSpamThrottler.increment();
-@@ -1895,11 +_,24 @@
+@@ -1895,15 +_,38 @@
  
      @Override
      public void handleSignUpdate(ServerboundSignUpdatePacket packet) {
@@ -2512,6 +2512,20 @@
          this.player.resetLastActionTime();
          ServerLevel serverLevel = this.player.serverLevel();
          BlockPos pos = packet.getPos();
+         if (serverLevel.hasChunkAt(pos)) {
++            // Paper start - Add API for client-side signs
++            if (!new io.papermc.paper.event.packet.UncheckedSignChangeEvent(
++                this.player.getBukkitEntity(),
++                io.papermc.paper.util.MCUtil.toPosition(pos),
++                packet.isFrontText() ? org.bukkit.block.sign.Side.FRONT : org.bukkit.block.sign.Side.BACK,
++                filteredText.stream().<net.kyori.adventure.text.Component>map(line -> net.kyori.adventure.text.Component.text(line.raw())).toList())
++                .callEvent()) {
++                return;
++            }
++            // Paper end - Add API for client-side signs
+             if (!(serverLevel.getBlockEntity(pos) instanceof SignBlockEntity signBlockEntity)) {
+                 return;
+             }
 @@ -1915,14 +_,32 @@
      @Override
      public void handlePlayerAbilities(ServerboundPlayerAbilitiesPacket packet) {

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java

@@ -12,6 +12,8 @@ import io.papermc.paper.configuration.GlobalConfiguration;
 import io.papermc.paper.entity.LookAnchor;
 import io.papermc.paper.entity.PaperPlayerGiveResult;
 import io.papermc.paper.entity.PlayerGiveResult;
+import io.papermc.paper.math.Position;
+import io.papermc.paper.util.MCUtil;
 import it.unimi.dsi.fastutil.shorts.ShortArraySet;
 import it.unimi.dsi.fastutil.shorts.ShortSet;
 import java.io.ByteArrayOutputStream;
@@ -73,6 +75,7 @@ import net.minecraft.network.protocol.game.ClientboundHurtAnimationPacket;
 import net.minecraft.network.protocol.game.ClientboundLevelEventPacket;
 import net.minecraft.network.protocol.game.ClientboundLevelParticlesPacket;
 import net.minecraft.network.protocol.game.ClientboundMapItemDataPacket;
+import net.minecraft.network.protocol.game.ClientboundOpenSignEditorPacket;
 import net.minecraft.network.protocol.game.ClientboundPlayerInfoRemovePacket;
 import net.minecraft.network.protocol.game.ClientboundPlayerInfoUpdatePacket;
 import net.minecraft.network.protocol.game.ClientboundRemoveMobEffectPacket;
@@ -3037,6 +3040,13 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         CraftSign.openSign(sign, this, side);
     }
 
+    @Override
+    public void openVirtualSign(Position block, Side side) {
+        if (this.getHandle().connection == null) return;
+
+        this.getHandle().connection.send(new ClientboundOpenSignEditorPacket(MCUtil.toBlockPos(block), side == Side.FRONT));
+    }
+
     @Override
     public void showDemoScreen() {
         if (this.getHandle().connection == null) return;