[0.2.0] add pick item callback (#82)

src/main/java/net/fabricmc/fabric/api/block/ContextSensitivePickable.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.api.block;
+
+import net.minecraft.block.BlockState;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.hit.HitResult;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.BlockView;
+
+public interface ContextSensitivePickable {
+	ItemStack getPickStack(BlockState state, BlockView view, BlockPos pos, /* nullable */ PlayerEntity player, /* nullable */ HitResult result);
+}

src/main/java/net/fabricmc/fabric/api/entity/ContextSensitivePickable.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.api.entity;
+
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.hit.HitResult;
+
+public interface ContextSensitivePickable {
+	ItemStack getPickStack(/* nullable */ PlayerEntity player, /* nullable */ HitResult result);
+}

src/main/java/net/fabricmc/fabric/api/event/client/player/ClientPickItemCallback.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.api.event.client.player;
+
+import net.fabricmc.fabric.api.event.Event;
+import net.fabricmc.fabric.api.event.EventFactory;
+import net.minecraft.entity.player.PlayerEntity;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.hit.HitResult;
+
+/**
+ * This interaction event is called on the CLIENT SIDE ONLY when the player
+ * attempts to pick up an item.
+ *
+ * Use {@link Container} to change the picked stack. Return true if you
+ * wish for execution to continue, return false to cancel the item picking
+ * operation (for example, if you want to route to the server side, etc.)
+ */
+public interface ClientPickItemCallback {
+	public static final class Container {
+		private ItemStack stack;
+
+		public Container(ItemStack stack) {
+			this.stack = stack;
+		}
+
+		public ItemStack getStack() {
+			return stack;
+		}
+
+		public void setStack(ItemStack stack) {
+			this.stack = stack;
+		}
+	}
+
+	public static final Event<ClientPickItemCallback> EVENT = EventFactory.arrayBacked(ClientPickItemCallback.class,
+		(listeners) -> (player, result, container) -> {
+			for (ClientPickItemCallback event : listeners) {
+				if (!event.pick(player, result, container)) {
+					return false;
+				}
+			}
+
+			return true;
+		}
+	);
+
+	boolean pick(PlayerEntity player, HitResult result, Container container);
+}

src/main/java/net/fabricmc/fabric/impl/FabricAPIClientInitializer.java

@@ -17,10 +17,18 @@
 package net.fabricmc.fabric.impl;
 
 import net.fabricmc.api.ClientModInitializer;
+import net.fabricmc.fabric.api.block.ContextSensitivePickable;
+import net.fabricmc.fabric.api.event.client.player.ClientPickItemCallback;
 import net.fabricmc.fabric.api.network.ClientSidePacketRegistry;
 import net.fabricmc.fabric.impl.client.gui.ScreenProviderRegistryImpl;
 import net.fabricmc.fabric.impl.registry.RegistrySyncManager;
+import net.minecraft.block.BlockState;
 import net.minecraft.client.MinecraftClient;
+import net.minecraft.entity.Entity;
+import net.minecraft.util.hit.BlockHitResult;
+import net.minecraft.util.hit.EntityHitResult;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.world.BlockView;
 
 public class FabricAPIClientInitializer implements ClientModInitializer {
 	@Override
@@ -30,6 +38,26 @@ public class FabricAPIClientInitializer implements ClientModInitializer {
 			RegistrySyncManager.receivePacket(ctx, buf, !MinecraftClient.getInstance().isInSingleplayer());
 		});
 
+		ClientPickItemCallback.EVENT.register(((player, result, container) -> {
+			if (result instanceof BlockHitResult) {
+				BlockView view = player.getEntityWorld();
+				BlockPos pos = ((BlockHitResult) result).getBlockPos();
+				BlockState state = view.getBlockState(pos);
+
+				if (state.getBlock() instanceof ContextSensitivePickable) {
+					container.setStack(((ContextSensitivePickable) state.getBlock()).getPickStack(state, view, pos, player, result));
+				}
+			} else if (result instanceof EntityHitResult) {
+				Entity entity = ((EntityHitResult) result).getEntity();
+
+				if (entity instanceof net.fabricmc.fabric.api.entity.ContextSensitivePickable) {
+					container.setStack(((net.fabricmc.fabric.api.entity.ContextSensitivePickable) entity).getPickStack(player, result));
+				}
+			}
+
+			return true;
+		}));
+
 		((ScreenProviderRegistryImpl) ScreenProviderRegistryImpl.INSTANCE).init();
 	}
 }

src/main/java/net/fabricmc/fabric/mixin/events/playerinteraction/MixinMinecraftClient.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2016, 2017, 2018 FabricMC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.fabricmc.fabric.mixin.events.playerinteraction;
+
+import net.fabricmc.fabric.api.event.client.player.ClientPickItemCallback;
+import net.minecraft.client.MinecraftClient;
+import net.minecraft.item.ItemStack;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.ModifyVariable;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+@Mixin(MinecraftClient.class)
+public class MixinMinecraftClient {
+	private boolean fabric_itemPickCancelled;
+
+	@ModifyVariable(at = @At(value = "INVOKE", target = "Lnet/minecraft/item/ItemStack;isEmpty()Z", ordinal = 2), method = "doItemPick", ordinal = 0)
+	public ItemStack modifyItemPick(ItemStack stack) {
+		ClientPickItemCallback.Container ctr = new ClientPickItemCallback.Container(stack);
+		//noinspection ConstantConditions
+		MinecraftClient client = (MinecraftClient) (Object) this;
+
+		boolean toContinue = ClientPickItemCallback.EVENT.invoker().pick(client.player, client.hitResult, ctr);
+		if (!toContinue) {
+			fabric_itemPickCancelled = true;
+			return ItemStack.EMPTY;
+		} else {
+			fabric_itemPickCancelled = false;
+			return ctr.getStack();
+		}
+	}
+
+	@Inject(at = @At(value = "INVOKE", target = "Lnet/minecraft/item/ItemStack;isEmpty()Z", ordinal = 2), method = "doItemPick", cancellable = true)
+	public void cancelItemPick(CallbackInfo info) {
+		if (fabric_itemPickCancelled) {
+			fabric_itemPickCancelled = false;
+			info.cancel();
+		}
+	}
+}

src/main/resources/net.fabricmc.fabric.mixins.client.json

@@ -16,6 +16,7 @@
     "client.render.MixinItemColorMap",
     "client.texture.MixinSpriteAtlasTexture",
     "events.playerinteraction.MixinClientPlayerInteractionManager",
+    "events.playerinteraction.MixinMinecraftClient",
     "events.tick.MixinMinecraftClient",
     "networking.MixinClientPlayNetworkHandler",
     "registry.client.MixinBlockColorMap",