Add app icon for macOS and Windows

src/client/java/net/imaginefun/ImagineFunUtilsClient.java

@@ -8,6 +8,8 @@
 import net.imaginefun.networking.ClientCustomPacketListenerImpl;
 import net.imaginefun.networking.HandshakePayload;
 import net.imaginefun.servers.ServerListPopulator;
+import net.imaginefun.windowicon.DockIconHandler;
+import net.minecraft.client.multiplayer.ServerData;
 
 public class ImagineFunUtilsClient implements ClientModInitializer {
 
@@ -24,8 +26,18 @@ public void onInitializeClient() {
 				.map(mod -> mod.getMetadata().getVersion().getFriendlyString())
 				.orElse("unknown");
 			ClientPlayNetworking.send(new HandshakePayload(version));
+
+			ServerData server = client.getCurrentServer();
+			if (server != null && server.ip != null) {
+				String host = server.ip.toLowerCase().split(":")[0];
+				if (host.endsWith(".imaginefun.net")) {
+					DockIconHandler.apply();
+				}
+			}
 		});
 
+		ClientPlayConnectionEvents.DISCONNECT.register((handler, client) -> DockIconHandler.reset());
+
 	}
 
     public ClientCustomPacketListener getClientCustomPacketListener() {

src/client/java/net/imaginefun/windowicon/DockIconHandler.java

@@ -0,0 +1,219 @@
+package net.imaginefun.windowicon;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.ByteBuffer;
+
+import org.lwjgl.glfw.GLFW;
+import org.lwjgl.glfw.GLFWImage;
+import org.lwjgl.system.JNI;
+import org.lwjgl.system.MemoryStack;
+import org.lwjgl.system.MemoryUtil;
+import org.lwjgl.system.macosx.ObjCRuntime;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import com.mojang.blaze3d.platform.IconSet;
+import com.mojang.blaze3d.platform.NativeImage;
+
+import net.minecraft.SharedConstants;
+import net.minecraft.client.Minecraft;
+
+/**
+ * Replaces the OS window icon (macOS Dock, Windows taskbar) with the ImagineFun logo
+ * while connected to an ImagineFun server, and restores the vanilla icon on disconnect.
+ *
+ * <p>Two code paths because GLFW's {@code glfwSetWindowIcon} is documented as a no-op on
+ * macOS — Cocoa requires {@code [NSApplication setApplicationIconImage:]} via the
+ * Objective-C runtime.
+ *
+ * <p>Must be called <em>after</em> the GLFW window exists; calling during
+ * {@code onInitializeClient} is too early because window creation overwrites the icon.
+ */
+public final class DockIconHandler {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger("ImagineFunDockIcon");
+    private static final String ICON_RESOURCE = "/assets/imaginefunutils/dock-icon.png";
+
+    private enum Os { MAC, WIN, OTHER }
+
+    private static final Os OS;
+    static {
+        String os = System.getProperty("os.name", "").toLowerCase();
+        if (os.contains("mac") || os.contains("darwin")) {
+            OS = Os.MAC;
+        } else if (os.contains("win")) {
+            OS = Os.WIN;
+        } else {
+            OS = Os.OTHER;
+        }
+    }
+
+    private static boolean applied = false;
+    private static long savedMacIcon = 0;
+
+    private DockIconHandler() {}
+
+    public static void apply() {
+        if (applied) return;
+        switch (OS) {
+            case MAC -> applyMac();
+            case WIN -> applyGlfw();
+            case OTHER -> {}
+        }
+    }
+
+    public static void reset() {
+        if (!applied) return;
+        switch (OS) {
+            case MAC -> resetMac();
+            case WIN -> resetGlfw();
+            case OTHER -> {}
+        }
+    }
+
+    private static byte[] readIconBytes() throws IOException {
+        try (InputStream in = DockIconHandler.class.getResourceAsStream(ICON_RESOURCE)) {
+            if (in == null) {
+                throw new IOException("missing classpath resource: " + ICON_RESOURCE);
+            }
+            return in.readAllBytes();
+        }
+    }
+
+    private static void applyMac() {
+        try {
+            byte[] pngBytes = readIconBytes();
+
+            long msgSend = ObjCRuntime.getLibrary().getFunctionAddress("objc_msgSend");
+            if (msgSend == 0) {
+                LOGGER.warn("objc_msgSend not found; cannot set Dock icon");
+                return;
+            }
+
+            long nsAppClass = ObjCRuntime.objc_getClass("NSApplication");
+            long selSharedApp = ObjCRuntime.sel_registerName("sharedApplication");
+            long app = JNI.invokePPP(nsAppClass, selSharedApp, msgSend);
+
+            long selGetIcon = ObjCRuntime.sel_registerName("applicationIconImage");
+            savedMacIcon = JNI.invokePPP(app, selGetIcon, msgSend);
+
+            long nsDataClass = ObjCRuntime.objc_getClass("NSData");
+            long selDataWithBytesLength = ObjCRuntime.sel_registerName("dataWithBytes:length:");
+
+            long pngPtr = MemoryUtil.nmemAlloc(pngBytes.length);
+            try {
+                for (int i = 0; i < pngBytes.length; i++) {
+                    MemoryUtil.memPutByte(pngPtr + i, pngBytes[i]);
+                }
+
+                long nsData = JNI.invokePPPP(
+                    nsDataClass, selDataWithBytesLength, pngPtr, pngBytes.length, msgSend);
+                if (nsData == 0) {
+                    LOGGER.warn("Failed to create NSData from PNG bytes");
+                    return;
+                }
+
+                long nsImageClass = ObjCRuntime.objc_getClass("NSImage");
+                long selAlloc = ObjCRuntime.sel_registerName("alloc");
+                long selInitWithData = ObjCRuntime.sel_registerName("initWithData:");
+
+                long nsImageRaw = JNI.invokePPP(nsImageClass, selAlloc, msgSend);
+                long nsImage = JNI.invokePPPP(nsImageRaw, selInitWithData, nsData, msgSend);
+                if (nsImage == 0) {
+                    LOGGER.warn("Failed to create NSImage from PNG data");
+                    return;
+                }
+
+                long selSetIcon = ObjCRuntime.sel_registerName("setApplicationIconImage:");
+                JNI.invokePPPV(app, selSetIcon, nsImage, msgSend);
+
+                applied = true;
+                LOGGER.info("Replaced macOS Dock icon with ImagineFun logo");
+            } finally {
+                MemoryUtil.nmemFree(pngPtr);
+            }
+        } catch (Exception e) {
+            LOGGER.warn("Failed to set macOS Dock icon", e);
+        }
+    }
+
+    private static void resetMac() {
+        try {
+            long msgSend = ObjCRuntime.getLibrary().getFunctionAddress("objc_msgSend");
+            if (msgSend == 0) return;
+
+            long nsAppClass = ObjCRuntime.objc_getClass("NSApplication");
+            long selSharedApp = ObjCRuntime.sel_registerName("sharedApplication");
+            long app = JNI.invokePPP(nsAppClass, selSharedApp, msgSend);
+
+            long selSetIcon = ObjCRuntime.sel_registerName("setApplicationIconImage:");
+            JNI.invokePPPV(app, selSetIcon, savedMacIcon, msgSend);
+
+            applied = false;
+            LOGGER.info("Restored original macOS Dock icon");
+        } catch (Exception e) {
+            LOGGER.warn("Failed to restore macOS Dock icon", e);
+        }
+    }
+
+    private static void applyGlfw() {
+        NativeImage image = null;
+        ByteBuffer pixels = null;
+        try (InputStream in = DockIconHandler.class.getResourceAsStream(ICON_RESOURCE)) {
+            if (in == null) {
+                LOGGER.warn("Dock icon resource missing: {}", ICON_RESOURCE);
+                return;
+            }
+            image = NativeImage.read(in);
+            int w = image.getWidth();
+            int h = image.getHeight();
+
+            // GLFW expects RGBA bytes in memory order; NativeImage.getPixel returns
+            // 0xAARRGGBB packed ints, so unpack and rewrite as R,G,B,A bytes.
+            pixels = MemoryUtil.memAlloc(w * h * 4);
+            for (int y = 0; y < h; y++) {
+                for (int x = 0; x < w; x++) {
+                    int argb = image.getPixel(x, y);
+                    pixels.put((byte) ((argb >> 16) & 0xFF));
+                    pixels.put((byte) ((argb >> 8) & 0xFF));
+                    pixels.put((byte) (argb & 0xFF));
+                    pixels.put((byte) ((argb >> 24) & 0xFF));
+                }
+            }
+            pixels.flip();
+
+            try (MemoryStack stack = MemoryStack.stackPush()) {
+                GLFWImage glfwImg = GLFWImage.malloc(stack);
+                glfwImg.set(w, h, pixels);
+                GLFWImage.Buffer buf = GLFWImage.malloc(1, stack);
+                buf.put(0, glfwImg);
+                buf.position(0);
+                long handle = Minecraft.getInstance().getWindow().handle();
+                GLFW.glfwSetWindowIcon(handle, buf);
+            }
+
+            applied = true;
+            LOGGER.info("Replaced window icon with ImagineFun logo");
+        } catch (Exception e) {
+            LOGGER.warn("Failed to set window icon", e);
+        } finally {
+            if (pixels != null) MemoryUtil.memFree(pixels);
+            if (image != null) image.close();
+        }
+    }
+
+    private static void resetGlfw() {
+        try {
+            Minecraft mc = Minecraft.getInstance();
+            IconSet set = SharedConstants.getCurrentVersion().stable()
+                ? IconSet.RELEASE
+                : IconSet.SNAPSHOT;
+            mc.getWindow().setIcon(mc.getVanillaPackResources(), set);
+            applied = false;
+            LOGGER.info("Restored vanilla window icon");
+        } catch (Exception e) {
+            LOGGER.warn("Failed to restore window icon", e);
+        }
+    }
+}