Support sign editing UI in 1.19.80, with APIs to allow plugins to use it

this doesn't support editing the rear side of a sign, since the 1.12 format doesn't allow us to represent the rear text, and it would necessitate API breaks to support anyway.

However, we can quite trivially support APIs for the sign GUI, which plugins can use to enable editing signs. PocketMine-MP doesn't currently permit this, since it's currently an experimental feature in 1.20, but plugins can simply use Player->openSignEditor() to mimic it.

This is, however, a byproduct of the fact that APIs needed to be added in order to facilitate the use of OpenSignPacket in 1.19.80.

src/block/BaseSign.php

@@ -97,6 +97,15 @@ abstract class BaseSign extends Transparent{
 		return parent::place($tx, $item, $blockReplace, $blockClicked, $face, $clickVector, $player);
 	}
 
+	public function onPostPlace() : void{
+		$player = $this->editorEntityRuntimeId !== null ?
+			$this->position->getWorld()->getEntity($this->editorEntityRuntimeId) :
+			null;
+		if($player instanceof Player){
+			$player->openSignEditor($this->position);
+		}
+	}
+
 	/**
 	 * Returns an object containing information about the sign text.
 	 */
@@ -110,6 +119,19 @@ abstract class BaseSign extends Transparent{
 		return $this;
 	}
 
+	/**
+	 * Sets the runtime entity ID of the player editing this sign. Only this player will be able to edit the sign.
+	 * This is used to prevent multiple players from editing the same sign at the same time, and to prevent players
+	 * from editing signs they didn't place.
+	 */
+	public function getEditorEntityRuntimeId() : ?int{ return $this->editorEntityRuntimeId; }
+
+	/** @return $this */
+	public function setEditorEntityRuntimeId(?int $editorEntityRuntimeId) : self{
+		$this->editorEntityRuntimeId = $editorEntityRuntimeId;
+		return $this;
+	}
+
 	/**
 	 * Called by the player controller (network session) to update the sign text, firing events as appropriate.
 	 *
@@ -133,6 +155,7 @@ abstract class BaseSign extends Transparent{
 		$ev->call();
 		if(!$ev->isCancelled()){
 			$this->setText($ev->getNewText());
+			$this->setEditorEntityRuntimeId(null);
 			$this->position->getWorld()->setBlock($this->position, $this);
 			return true;
 		}

src/block/tile/Sign.php

@@ -45,12 +45,18 @@ class Sign extends Spawnable{
 	public const TAG_TEXT_LINE = "Text%d"; //sprintf()able
 	public const TAG_TEXT_COLOR = "SignTextColor";
 	public const TAG_GLOWING_TEXT = "IgnoreLighting";
+	public const TAG_PERSIST_FORMATTING = "PersistFormatting"; //TAG_Byte
 	/**
 	 * This tag is set to indicate that MCPE-117835 has been addressed in whatever version this sign was created.
 	 * @see https://bugs.mojang.com/browse/MCPE-117835
 	 */
 	public const TAG_LEGACY_BUG_RESOLVE = "TextIgnoreLegacyBugResolved";
 
+	public const TAG_FRONT_TEXT = "FrontText"; //TAG_Compound
+	public const TAG_BACK_TEXT = "BackText"; //TAG_Compound
+	public const TAG_WAXED = "IsWaxed"; //TAG_Byte
+	public const TAG_LOCKED_FOR_EDITING_BY = "LockedForEditingBy"; //TAG_Long
+
 	/**
 	 * @return string[]
 	 */
@@ -118,12 +124,22 @@ class Sign extends Spawnable{
 	}
 
 	protected function addAdditionalSpawnData(CompoundTag $nbt) : void{
-		$nbt->setString(self::TAG_TEXT_BLOB, implode("\n", $this->text->getLines()));
-
-		//the following are not yet used by the server, but needed to roll back any changes to glowing state or colour
-		//if the client uses dye on the sign
-		$nbt->setInt(self::TAG_TEXT_COLOR, Binary::signInt(0xff_00_00_00));
-		$nbt->setByte(self::TAG_GLOWING_TEXT, 0);
-		$nbt->setByte(self::TAG_LEGACY_BUG_RESOLVE, 1);
+		$textPolyfill = function(CompoundTag $textTag) : CompoundTag{
+			//the following are not yet used by the server, but needed to roll back any changes to glowing state or colour
+			//if the client uses dye on the sign
+			return $textTag
+				->setInt(self::TAG_TEXT_COLOR, Binary::signInt(0xff_00_00_00))
+				->setByte(self::TAG_GLOWING_TEXT, 0)
+				->setByte(self::TAG_PERSIST_FORMATTING, 1); //TODO: not sure what this is used for
+		};
+		$nbt->setTag(self::TAG_FRONT_TEXT, $textPolyfill(CompoundTag::create()
+			->setString(self::TAG_TEXT_BLOB, implode("\n", $this->text->getLines()))
+		));
+		//TODO: this is not yet used by the server, but needed to rollback any client-side changes to the back text
+		$nbt->setTag(self::TAG_BACK_TEXT, $textPolyfill(CompoundTag::create()
+			->setString(self::TAG_TEXT_BLOB, "")
+		));
+		$nbt->setByte(self::TAG_WAXED, 0);
+		$nbt->setLong(self::TAG_LOCKED_FOR_EDITING_BY, $this->editorEntityRuntimeId ?? -1);
 	}
 }

src/network/mcpe/NetworkSession.php

@@ -60,6 +60,7 @@ use pocketmine\network\mcpe\protocol\DisconnectPacket;
 use pocketmine\network\mcpe\protocol\ModalFormRequestPacket;
 use pocketmine\network\mcpe\protocol\MovePlayerPacket;
 use pocketmine\network\mcpe\protocol\NetworkChunkPublisherUpdatePacket;
+use pocketmine\network\mcpe\protocol\OpenSignPacket;
 use pocketmine\network\mcpe\protocol\Packet;
 use pocketmine\network\mcpe\protocol\PacketDecodeException;
 use pocketmine\network\mcpe\protocol\PacketPool;
@@ -1093,6 +1094,10 @@ class NetworkSession{
 		$this->sendDataPacket(ToastRequestPacket::create($title, $body));
 	}
 
+	public function onOpenSignEditor(Vector3 $signPosition, bool $frontSide) : void{
+		$this->sendDataPacket(OpenSignPacket::create(BlockPosition::fromVector3($signPosition), $frontSide));
+	}
+
 	public function tick() : void{
 		if(!$this->isConnected()){
 			$this->dispose();

src/network/mcpe/handler/InGamePacketHandler.php

@@ -748,7 +748,7 @@ class InGamePacketHandler extends PacketHandler{
 		if(!($nbt instanceof CompoundTag)) throw new AssumptionFailedError("PHPStan should ensure this is a CompoundTag"); //for phpstorm's benefit
 
 		if($block instanceof BaseSign){
-			if(($textBlobTag = $nbt->getTag(Sign::TAG_TEXT_BLOB)) instanceof StringTag){
+			if(($textBlobTag = $nbt->getCompoundTag(Sign::TAG_FRONT_TEXT)?->getTag(Sign::TAG_TEXT_BLOB)) instanceof StringTag){
 				try{
 					$text = SignText::fromBlob($textBlobTag->getValue());
 				}catch(\InvalidArgumentException $e){

src/player/Player.php

@@ -23,6 +23,7 @@ declare(strict_types=1);
 
 namespace pocketmine\player;
 
+use pocketmine\block\BaseSign;
 use pocketmine\block\Bed;
 use pocketmine\block\BlockLegacyIds;
 use pocketmine\block\UnknownBlock;
@@ -2626,6 +2627,20 @@ class Player extends Human implements CommandSender, ChunkListener, IPlayer{
 		$this->permanentWindows = [];
 	}
 
+	/**
+	 * Opens the player's sign editor GUI for the sign at the given position.
+	 * TODO: add support for editing the rear side of the sign (not currently supported due to technical limitations)
+	 */
+	public function openSignEditor(Vector3 $position) : void{
+		$block = $this->getWorld()->getBlock($position);
+		if($block instanceof BaseSign){
+			$this->getWorld()->setBlock($position, $block->setEditorEntityRuntimeId($this->getId()));
+			$this->getNetworkSession()->onOpenSignEditor($position, true);
+		}else{
+			throw new \InvalidArgumentException("Block at this position is not a sign");
+		}
+	}
+
 	use ChunkListenerNoOpTrait {
 		onChunkChanged as private;
 		onChunkUnloaded as private;