Make disconnected screen reason text scrollable (#2349)

* Make disconnected screen reason text scrollable

* Remove redundant mixin.

* wrong unique

* fix max scroll having additional line-sized gap

* turns out it's the testmod fault for having an extra new line

Co-authored-by: modmuss50 <modmuss50@gmail.com>

fabric-networking-api-v1/src/client/java/net/fabricmc/fabric/mixin/networking/client/DisconnectedScreenMixin.java

@@ -0,0 +1,94 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 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.networking.client;
+
+import com.mojang.blaze3d.systems.RenderSystem;
+import org.objectweb.asm.Opcodes;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.Unique;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.Redirect;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import net.minecraft.client.font.MultilineText;
+import net.minecraft.client.gui.screen.DisconnectedScreen;
+import net.minecraft.client.gui.screen.Screen;
+import net.minecraft.client.util.math.MatrixStack;
+import net.minecraft.util.math.MathHelper;
+
+/**
+ * This mixin makes disconnect reason text scrollable.
+ */
+@Mixin(DisconnectedScreen.class)
+public abstract class DisconnectedScreenMixin extends Screen {
+	@Shadow
+	private int reasonHeight;
+
+	@Unique
+	private int actualReasonHeight;
+
+	@Unique
+	private int scroll;
+
+	@Unique
+	private int maxScroll;
+
+	private DisconnectedScreenMixin() {
+		super(null);
+	}
+
+	// Inject to right after reasonHeight is stored, to make sure the back button have correct position.
+	@Inject(method = "init", at = @At(value = "FIELD", target = "Lnet/minecraft/client/gui/screen/DisconnectedScreen;reasonHeight:I", opcode = Opcodes.PUTFIELD, shift = At.Shift.AFTER))
+	private void init(CallbackInfo ci) {
+		actualReasonHeight = reasonHeight;
+		reasonHeight = Math.min(reasonHeight, height - 100);
+		scroll = 0;
+		maxScroll = actualReasonHeight - reasonHeight;
+	}
+
+	@Redirect(method = "render", at = @At(value = "INVOKE", target = "Lnet/minecraft/client/font/MultilineText;drawCenterWithShadow(Lnet/minecraft/client/util/math/MatrixStack;II)I"))
+	private int render(MultilineText instance, MatrixStack matrixStack, int x, int y) {
+		double scale = client.getWindow().getScaleFactor();
+		RenderSystem.enableScissor(0, (int) (y * scale), (int) (width * scale), (int) (reasonHeight * scale));
+		instance.drawCenterWithShadow(matrixStack, x, y - scroll);
+		RenderSystem.disableScissor();
+
+		// Draw gradient at the top/bottom to indicate that the text is scrollable.
+		if (actualReasonHeight > reasonHeight) {
+			int startX = (width - instance.getMaxWidth()) / 2;
+			int endX = (width + instance.getMaxWidth()) / 2;
+
+			if (scroll > 0) {
+				fillGradient(matrixStack, startX, y, endX, y + 10, 0xFF000000, 0);
+			}
+
+			if (scroll < maxScroll) {
+				fillGradient(matrixStack, startX, y + reasonHeight - 10, endX, y + reasonHeight, 0, 0xFF000000);
+			}
+		}
+
+		return y + reasonHeight;
+	}
+
+	@Override
+	public boolean mouseScrolled(double mouseX, double mouseY, double amount) {
+		scroll = MathHelper.clamp(scroll - (MathHelper.sign(amount) * client.textRenderer.fontHeight * 10), 0, maxScroll);
+		return super.mouseScrolled(mouseX, mouseY, amount);
+	}
+}

fabric-networking-api-v1/src/client/resources/fabric-networking-api-v1.client.mixins.json

@@ -6,7 +6,8 @@
     "accessor.ConnectScreenAccessor",
     "accessor.MinecraftClientAccessor",
     "client.ClientLoginNetworkHandlerMixin",
-    "client.ClientPlayNetworkHandlerMixin"
+    "client.ClientPlayNetworkHandlerMixin",
+    "client.DisconnectedScreenMixin"
   ],
   "injectors": {
     "defaultRequire": 1

fabric-networking-api-v1/src/testmod/java/net/fabricmc/fabric/test/networking/disconnectscreen/DisconnectScreenTest.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2016, 2017, 2018, 2019 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.test.networking.disconnectscreen;
+
+import net.minecraft.text.Text;
+
+import net.fabricmc.api.ClientModInitializer;
+import net.fabricmc.fabric.api.client.command.v2.ClientCommandManager;
+import net.fabricmc.fabric.api.client.command.v2.ClientCommandRegistrationCallback;
+
+public class DisconnectScreenTest implements ClientModInitializer {
+	@Override
+	public void onInitializeClient() {
+		ClientCommandRegistrationCallback.EVENT.register((dispatcher, registryAccess) ->
+				dispatcher.register(ClientCommandManager.literal("disconnect_screen_test").executes(context -> {
+					StringBuilder builder = new StringBuilder("A very long disconnect reason:");
+
+					for (int i = 0; i < 100; i++) {
+						builder.append("\nLine ").append(i + 1);
+					}
+
+					context.getSource().getPlayer().networkHandler.getConnection().disconnect(Text.of(builder.toString()));
+					return 1;
+				})));
+	}
+}

fabric-networking-api-v1/src/testmod/resources/fabric.mod.json

@@ -17,6 +17,7 @@
     ],
     "client": [
       "net.fabricmc.fabric.test.networking.channeltest.NetworkingChannelClientTest",
+      "net.fabricmc.fabric.test.networking.disconnectscreen.DisconnectScreenTest",
       "net.fabricmc.fabric.test.networking.keybindreciever.NetworkingKeybindClientPacketTest",
       "net.fabricmc.fabric.test.networking.login.NetworkingLoginQueryClientTest",
       "net.fabricmc.fabric.test.networking.play.NetworkingPlayPacketClientTest"