Added EntityDamageEvent

src/main/java/net/minestom/server/entity/LivingEntity.java

@@ -4,6 +4,7 @@ import net.minestom.server.collision.BoundingBox;
 import net.minestom.server.entity.damage.DamageType;
 import net.minestom.server.entity.property.Attribute;
 import net.minestom.server.event.DeathEvent;
+import net.minestom.server.event.EntityDamageEvent;
 import net.minestom.server.event.PickupItemEvent;
 import net.minestom.server.instance.Chunk;
 import net.minestom.server.item.ItemStack;
@@ -105,18 +106,25 @@ public abstract class LivingEntity extends Entity {
     }
 
     public void damage(DamageType type, float value) {
-        if(isImmune(type)) {
+        if (isImmune(type)) {
             return;
         }
+
+        EntityDamageEvent entityDamageEvent = new EntityDamageEvent(type, value);
+        callCancellableEvent(EntityDamageEvent.class, entityDamageEvent, () -> {
+            float damage = entityDamageEvent.getDamage();
+
             EntityAnimationPacket entityAnimationPacket = new EntityAnimationPacket();
             entityAnimationPacket.entityId = getEntityId();
             entityAnimationPacket.animation = EntityAnimationPacket.Animation.TAKE_DAMAGE;
             sendPacketToViewersAndSelf(entityAnimationPacket);
-        setHealth(getHealth() - value);
+            setHealth(getHealth() - damage);
+        });
     }
 
     /**
      * Is this entity immune to the given type of damage?
+     *
      * @param type the type of damage
      * @return true iff this entity is immune to the given type of damage
      */
@@ -212,7 +220,7 @@ public abstract class LivingEntity extends Entity {
     @Override
     protected void handleVoid() {
         // Kill if in void
-        if(getInstance().isInVoid(this.position)) {
+        if (getInstance().isInVoid(this.position)) {
             damage(DamageType.VOID, 10f);
         }
     }

src/main/java/net/minestom/server/entity/Player.java

@@ -117,7 +117,7 @@ public class Player extends LivingEntity {
 
     @Override
     public void damage(DamageType type, float value) {
-        if(!isImmune(type)) {
+        if (!isImmune(type)) {
             lastDamageSource = type;
         }
         super.damage(type, value);
@@ -245,10 +245,10 @@ public class Player extends LivingEntity {
 
     @Override
     public void kill() {
-        if(!isDead()) {
+        if (!isDead()) {
             // send death message to player
             TextObject deathMessage;
-            if(lastDamageSource != null) {
+            if (lastDamageSource != null) {
                 deathMessage = lastDamageSource.buildDeathMessage();
             } else { // may happen if killed by the server without applying damage
                 deathMessage = TextBuilder.of("Killed by poor programming.").build();
@@ -258,10 +258,10 @@ public class Player extends LivingEntity {
 
             // send death message to chat
             TextObject chatMessage;
-            if(lastDamageSource != null) {
+            if (lastDamageSource != null) {
                 chatMessage = lastDamageSource.buildChatMessage(this);
             } else { // may happen if killed by the server without applying damage
-                chatMessage = TextBuilder.of(getUsername()+" was killed by poor programming.").build();
+                chatMessage = TextBuilder.of(getUsername() + " was killed by poor programming.").build();
             }
             MinecraftServer.getConnectionManager().getOnlinePlayers().forEach(player -> {
                 player.sendMessage(chatMessage);
@@ -455,7 +455,7 @@ public class Player extends LivingEntity {
 
     @Override
     public boolean isImmune(DamageType type) {
-        if(getGameMode().canTakeDamage()) {
+        if (getGameMode().canTakeDamage()) {
             return type != DamageType.VOID;
         }
         return super.isImmune(type);
@@ -659,6 +659,7 @@ public class Player extends LivingEntity {
 
     /**
      * Returns true iff this player is in creative. Used for code readability
+     *
      * @return
      */
     public boolean isCreative() {

src/main/java/net/minestom/server/entity/damage/DamageType.java

@@ -22,19 +22,19 @@ public class DamageType {
         return identifier;
     }
 
-    public TextObject buildChatMessage(Player killed) {
-        return TextBuilder.of(killed.getUsername()+" was killed by damage of type "+identifier).build();
+    public static DamageType fromProjectile(Entity shooter, Entity projectile) {
+        return new EntityProjectileDamage(shooter, projectile);
     }
 
-    public TextObject buildDeathMessage() {
-        return TextBuilder.of("Killed by damage of type "+identifier).build();
+    public TextObject buildChatMessage(Player killed) {
+        return TextBuilder.of(killed.getUsername() + " was killed by damage of type " + identifier).build();
     }
 
     public static DamageType fromPlayer(Player player) {
         return new EntityDamage(player);
     }
 
-    public static DamageType fromProjectile(Entity shooter, Entity projectile) {
-        return new EntityProjectileDamage(shooter,  projectile);
+    public TextObject buildDeathMessage() {
+        return TextBuilder.of("Killed by damage of type " + identifier).build();
     }
 }

src/main/java/net/minestom/server/event/EntityDamageEvent.java

@@ -0,0 +1,26 @@
+package net.minestom.server.event;
+
+import net.minestom.server.entity.damage.DamageType;
+
+public class EntityDamageEvent extends CancellableEvent {
+
+    private DamageType damageType;
+    private float damage;
+
+    public EntityDamageEvent(DamageType damageType, float damage) {
+        this.damageType = damageType;
+        this.damage = damage;
+    }
+
+    public DamageType getDamageType() {
+        return damageType;
+    }
+
+    public float getDamage() {
+        return damage;
+    }
+
+    public void setDamage(float damage) {
+        this.damage = damage;
+    }
+}

src/main/java/net/minestom/server/instance/Instance.java

@@ -95,6 +95,7 @@ public abstract class Instance implements BlockModifier, DataContainer {
     /**
      * Determines whether a position in the void. If true, entities should take damage and die.
      * Always returning false allow entities to survive in the void
+     *
      * @param position the position in the world
      * @return true iif position is inside the void
      */

src/main/java/net/minestom/server/network/player/PlayerConnection.java

@@ -33,6 +33,7 @@ public class PlayerConnection {
     public void sendPacket(ServerPacket serverPacket) {
         ByteBuf buffer = PacketUtils.writePacket(serverPacket);
         sendPacket(buffer);
+        buffer.release();
     }
 
     public void flush() {