README: say the mod is Windows only and why the Android LeviLauncher rejects the zip

.github/workflows/android.yml

@@ -0,0 +1,58 @@
+# Builds the Android version (android/) into SplitScreenMod-android-arm64.zip / .levipack for LeviLauncher on Android.
+name: Android
+
+on:
+  pull_request:
+  push:
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write # to publish the android-latest pre-release
+    steps:
+      - uses: actions/checkout@v7
+
+      # The runner already has the Android SDK; android-actions/setup-android failed on its own sdkmanager install.
+      # NDK 28.2 is installed if missing; the runner's newest NDK is the fallback.
+      - run: |
+          sudo apt-get update
+          sudo apt-get install -y ninja-build
+          NDK="$ANDROID_HOME/ndk/28.2.13676358"
+          if [ ! -d "$NDK" ]; then
+            yes | "$ANDROID_HOME/cmdline-tools/latest/bin/sdkmanager" "ndk;28.2.13676358" > /dev/null || true
+          fi
+          if [ ! -d "$NDK" ]; then NDK="$ANDROID_NDK_LATEST_HOME"; fi
+          echo "Using NDK $NDK"
+          echo "NDK=$NDK" >> "$GITHUB_ENV"
+
+      - run: |
+          cmake -S android -B build-android -G Ninja \
+            -DCMAKE_TOOLCHAIN_FILE="$NDK/build/cmake/android.toolchain.cmake" \
+            -DANDROID_ABI=arm64-v8a -DANDROID_PLATFORM=android-28 -DANDROID_STL=c++_shared \
+            -DCMAKE_BUILD_TYPE=Release
+          cmake --build build-android --target levi_package
+
+      # The mod's resource pack (menu look, black "Choose your player" screen, texts in every language), imported
+      # into Minecraft once. Its pause menu button is for Windows only and is left out.
+      - run: |
+          cd resource_packs/SplitScreenUI
+          zip -qr ../../build-android/SplitScreenUI.mcpack . -x 'ui/pause_screen.json'
+          mkdir -p ../../build-android/package && cp ../../build-android/SplitScreenUI.mcpack ../../build-android/package/
+
+      - uses: actions/upload-artifact@v7
+        with:
+          name: ${{ github.event.repository.name }}-${{ github.sha }}-android-arm64
+          path: build-android/package/
+
+      # The newest Android build is always at the same link, so it can be downloaded straight on the phone:
+      # https://github.com/<owner>/<repo>/releases/download/android-latest/SplitScreenMod-android-arm64.zip
+      - if: github.event_name != 'pull_request'
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          gh release delete android-latest --cleanup-tag -y || true
+          gh release create android-latest build-android/SplitScreenMod-android-arm64.zip build-android/SplitScreenUI.mcpack \
+            --prerelease --target "$GITHUB_SHA" --title "Android (experimental, newest build)" \
+            --notes "Newest experimental Android build from ${GITHUB_REF_NAME} (${GITHUB_SHA::7}). Add it in LeviLauncher for Android with Mods > Add Mod, and import SplitScreenUI.mcpack into Minecraft (Settings > Global Resources) for the menus."

README.md

@@ -44,6 +44,8 @@ Minecraft Bedrock already contains split-screen (it is used on Xbox), but the Wi
 
 ## Installation
 
+> **Android:** the Windows zip does not work on Android (LeviLauncher for Android shows "Invalid ZIP Mod Package", because it needs an Android `.so`, not a Windows `.dll`). An experimental Android version is in [`android/`](android/README.md).
+
 **Easiest:** in [LeviLauncher](https://github.com/LiteLDev/LeviLauncher), open your instance's **Manage Mods**, press **Import .mcmod** and pick `SplitScreenMod.mcmod` from the [latest release](../../releases/latest).
 
 **By hand:**

android/CMakeLists.txt

@@ -0,0 +1,90 @@
+# SplitScreenMod for LeviLauncher on Android (preloader-android SDK).
+# Build: see android/README.md. The result is a .levipack (a zip) that LeviLauncher for Android imports.
+cmake_minimum_required(VERSION 3.22)
+
+project(SplitScreenModAndroid LANGUAGES CXX ASM)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+
+set(MOD_ID "SplitScreenMod" CACHE STRING "LeviLauncher mod package directory name")
+set(MOD_NAME "SplitScreenMod" CACHE STRING "LeviLauncher mod display name")
+set(MOD_AUTHOR "SnakyWarrior" CACHE STRING "LeviLauncher mod author")
+set(MOD_VERSION "0.10.3" CACHE STRING "LeviLauncher mod version")
+set(MOD_LIBRARY_NAME "SplitScreenMod" CACHE STRING "Native library name without lib prefix or .so suffix")
+set(MOD_MINECRAFT_VERSIONS "[\"1.26.*\"]" CACHE STRING "Raw JSON array for manifest minecraft_versions")
+
+if(NOT ANDROID)
+    message(FATAL_ERROR "Configure with the Android NDK toolchain file (see android/README.md)")
+endif()
+if(NOT CMAKE_ANDROID_ARCH_ABI STREQUAL "arm64-v8a")
+    message(FATAL_ERROR "Only arm64-v8a is supported, got ${CMAKE_ANDROID_ARCH_ABI}")
+endif()
+
+include(FetchContent)
+FetchContent_Declare(
+    preloader_android
+    GIT_REPOSITORY https://github.com/LiteLDev/preloader-android.git
+    GIT_TAG 0.2.2
+    SOURCE_SUBDIR cmake/preloader-sdk
+)
+FetchContent_Declare(
+    fmt
+    GIT_REPOSITORY https://github.com/fmtlib/fmt.git
+    GIT_TAG 11.2.0
+)
+set(FMT_DOC OFF CACHE BOOL "" FORCE)
+set(FMT_TEST OFF CACHE BOOL "" FORCE)
+set(FMT_INSTALL OFF CACHE BOOL "" FORCE)
+FetchContent_MakeAvailable(preloader_android fmt)
+FetchContent_GetProperties(preloader_android)
+
+# The SDK symbols are provided by the preloader that LeviLauncher has already loaded.
+option(LEVI_LINK_PRELOADER "Build and link the preloader target instead of resolving SDK symbols at runtime" ON)
+if(LEVI_LINK_PRELOADER AND NOT TARGET preloader)
+    add_subdirectory("${preloader_android_SOURCE_DIR}" "${CMAKE_BINARY_DIR}/_preloader_android")
+endif()
+
+add_library(${MOD_LIBRARY_NAME} SHARED src/main.cpp src/SplitScreen.cpp src/Elf.cpp src/InputProbe.cpp src/DeviceManagerProbe.cpp src/ControllerSplit.cpp src/FormProbe.cpp src/Menus.cpp src/VTrace.cpp src/PostTrace.cpp src/Trampolines.S src/VTrampolines.S src/PostTrampolines.S)
+target_include_directories(${MOD_LIBRARY_NAME} PRIVATE src "${preloader_android_SOURCE_DIR}/include")
+target_compile_definitions(${MOD_LIBRARY_NAME} PRIVATE SPLITSCREEN_VERSION="${MOD_VERSION}")
+target_compile_options(${MOD_LIBRARY_NAME} PRIVATE -Wall -Wextra -fvisibility=hidden -fvisibility-inlines-hidden)
+target_link_options(${MOD_LIBRARY_NAME} PRIVATE "-Wl,-z,max-page-size=16384")
+
+find_library(log-lib log REQUIRED)
+target_link_libraries(${MOD_LIBRARY_NAME} PRIVATE ${log-lib} android dl fmt::fmt)
+if(TARGET preloader)
+    target_link_libraries(${MOD_LIBRARY_NAME} PRIVATE preloader)
+else()
+    target_link_options(${MOD_LIBRARY_NAME} PRIVATE "-Wl,--unresolved-symbols=ignore-all")
+endif()
+
+add_custom_command(TARGET ${MOD_LIBRARY_NAME} POST_BUILD
+    COMMAND "${CMAKE_STRIP}" --strip-unneeded "$<TARGET_FILE:${MOD_LIBRARY_NAME}>"
+    VERBATIM
+)
+
+configure_file("${CMAKE_CURRENT_SOURCE_DIR}/manifest.json.in" "${CMAKE_CURRENT_BINARY_DIR}/manifest.json" @ONLY)
+
+# SplitScreenMod-android-arm64.levipack: a zip with SplitScreenMod/manifest.json, SplitScreenMod/libSplitScreenMod.so,
+# config/ and pack/ (the resource pack).
+# The same zip is also written as .zip, which LeviLauncher's "Add Mod" accepts.
+set(PACKAGE_ROOT "${CMAKE_CURRENT_BINARY_DIR}/package")
+set(PACKAGE_MOD_DIR "${PACKAGE_ROOT}/${MOD_ID}")
+set(PACKAGE_FILE "${CMAKE_CURRENT_BINARY_DIR}/${MOD_ID}-android-arm64.levipack")
+add_custom_target(levi_package
+    COMMAND "${CMAKE_COMMAND}" -E rm -rf "${PACKAGE_ROOT}"
+    COMMAND "${CMAKE_COMMAND}" -E make_directory "${PACKAGE_MOD_DIR}"
+    COMMAND "${CMAKE_COMMAND}" -E copy "$<TARGET_FILE:${MOD_LIBRARY_NAME}>" "${PACKAGE_MOD_DIR}/lib${MOD_LIBRARY_NAME}.so"
+    COMMAND "${CMAKE_COMMAND}" -E copy "${CMAKE_CURRENT_BINARY_DIR}/manifest.json" "${PACKAGE_MOD_DIR}/manifest.json"
+    COMMAND "${CMAKE_COMMAND}" -E copy_directory "${CMAKE_CURRENT_SOURCE_DIR}/config" "${PACKAGE_MOD_DIR}/config"
+    # the mod's resource pack, put into the game and turned on by the mod, with the Android changes from android/pack
+    COMMAND "${CMAKE_COMMAND}" -E copy_directory "${CMAKE_CURRENT_SOURCE_DIR}/../resource_packs/SplitScreenUI" "${PACKAGE_MOD_DIR}/pack"
+    COMMAND "${CMAKE_COMMAND}" -E copy_directory "${CMAKE_CURRENT_SOURCE_DIR}/pack" "${PACKAGE_MOD_DIR}/pack"
+    COMMAND "${CMAKE_COMMAND}" -E chdir "${PACKAGE_ROOT}" "${CMAKE_COMMAND}" -E tar cf "${PACKAGE_FILE}" --format=zip "${MOD_ID}"
+    COMMAND "${CMAKE_COMMAND}" -E copy "${PACKAGE_FILE}" "${CMAKE_CURRENT_BINARY_DIR}/${MOD_ID}-android-arm64.zip"
+    DEPENDS ${MOD_LIBRARY_NAME}
+    VERBATIM
+)

android/README.md

@@ -0,0 +1,40 @@
+# SplitScreenMod for Android (experimental)
+
+The Windows mod (in `src/`) cannot run on Android: it is built for LeviLamina on Windows x64, and the Android
+LeviLauncher only loads Android libraries (`.so`). This folder is a separate mod for **LeviLauncher on Android**,
+built with LeviLauncher's [preloader-android](https://github.com/LiteLDev/preloader-android) SDK.
+
+## What this version does
+
+Version 0.4 plays split screen on Android:
+
+- **Player 1 keeps the touch screen.** Press Start on a controller: a new player joins with it (player 2, 3, 4) and
+  the screen splits. Start on a controller that already plays opens that player's pause menu. A player that leaves
+  can join again with Start.
+- Every controller is a controller of its own: the game on Android sends every controller to player 1, the mod gives
+  each Android device its own controller number.
+- Split screen is on: the game keeps it off on phones it thinks are too small (`AppPlatform::allowSplitScreen`).
+
+Settings (`config/config.json`): `firstControllerIsPlayer1` gives the first controller to player 1 instead of touch.
+
+Not ported from Windows yet: the player picker, the pause menu's Split screen menu (layout, swap, remove), the P1-P4
+pictures, and the 20 second disconnect countdown. The mod still logs a lot (it is in development): everything it does
+is written to `splitscreen.log` and `Download/SplitScreenMod-android.log`.
+
+## Install
+
+Download the newest build from [releases/android-latest](../../../releases/download/android-latest/SplitScreenMod-android-arm64.zip) (always the same link) and add it in
+LeviLauncher's **Mods → Add Mod**. Start the game, enter a world, then send `Download/SplitScreenMod-android.log`.
+
+## Build
+
+Needs the Android NDK (28.2), CMake 3.22+ and Ninja:
+
+```
+cmake -S android -B build-android -G Ninja \
+  -DCMAKE_TOOLCHAIN_FILE=$ANDROID_HOME/ndk/28.2.13676358/build/cmake/android.toolchain.cmake \
+  -DANDROID_ABI=arm64-v8a -DANDROID_PLATFORM=android-28 -DANDROID_STL=c++_shared -DCMAKE_BUILD_TYPE=Release
+cmake --build build-android --target levi_package
+```
+
+The package is `build-android/SplitScreenMod-android-arm64.zip` (also as `.levipack`).

android/config/config.json

@@ -0,0 +1,7 @@
+{
+  "forceSplitScreen": true,
+  "separateControllers": true,
+  "forceSplitscreenJoin": true,
+  "firstControllerIsPlayer1": false,
+  "startJoins": true
+}

android/config/config.schema.json

@@ -0,0 +1,31 @@
+{
+  "title": "SplitScreenMod",
+  "type": "object",
+  "properties": {
+    "forceSplitScreen": {
+      "type": "boolean",
+      "title": "Turn split screen on",
+      "description": "Turns the game's split screen on when the mod can find it for certain. Turn off if the game misbehaves."
+    },
+    "separateControllers": {
+      "type": "boolean",
+      "title": "One player per controller",
+      "description": "Gives each controller its own player (the game on Android sends every controller to player 1). Turn off if controllers misbehave."
+    },
+    "forceSplitscreenJoin": {
+      "type": "boolean",
+      "title": "Let other controllers join",
+      "description": "Lets a second, third or fourth controller join as a split-screen player. Turn off if the game misbehaves."
+    },
+    "firstControllerIsPlayer1": {
+      "type": "boolean",
+      "title": "First controller plays player 1",
+      "description": "Off: player 1 keeps the touch screen and every controller joins as a new player with Start. On: the first controller plays player 1."
+    },
+    "startJoins": {
+      "type": "boolean",
+      "title": "Start joins directly",
+      "description": "On: Start on a controller without a player adds a player in a loaded world (the game shows no join prompt on Android). Off: only the game's own join prompt adds players."
+    }
+  }
+}

android/manifest.json.in

@@ -0,0 +1,9 @@
+{
+  "type": "preload-native",
+  "name": "@MOD_NAME@",
+  "author": "@MOD_AUTHOR@",
+  "version": "@MOD_VERSION@",
+  "entry": "lib@MOD_LIBRARY_NAME@.so",
+  "icon": "",
+  "minecraft_versions": @MOD_MINECRAFT_VERSIONS@
+}

android/pack/ui/pause_screen.json

@@ -0,0 +1,89 @@
+{
+  "namespace": "pause",
+
+  // Android: the Windows version's pause_screen.json with the Split screen button always shown (its bindings come from
+  // the Windows mod) and without the free-controller button. A square name-tag button in the row of small buttons
+  // under Save & Quit, styled like them. The mod handles "button.splitscreen_menu".
+  "smaller_buttons_panel/stacked_column": {
+    "modifications": [
+      {
+        "control_name": "fill_3",
+        "operation": "insert_before",
+        "value": [
+          {
+            "splitscreen_padding": {
+              "type": "panel",
+              "size": [ "2%", 0 ]
+            }
+          },
+          {
+            "splitscreen_small_button": {
+              "type": "input_panel",
+              "size": [ "100%c + 4px", 32 ],
+              "controls": [ { "splitscreen_btn@pause.splitscreen_button_small_with_tooltip": {} } ]
+            }
+          }
+        ]
+      }
+    ]
+  },
+
+  "splitscreen_icon": {
+    "type": "image",
+    "texture": "textures/items/name_tag",
+    "layer": 3,
+    "size": [ 16, 16 ]
+  },
+
+  "splitscreen_button_small@common_buttons.light_content_button": {
+    "$pressed_button_name": "button.splitscreen_menu",
+    "$focus_id": "icon_panel_main_focus",
+    "focus_change_down": "return_to_game",
+    "$button_tts_header": "splitscreen.title.menu",
+    "size": [ 24, 24 ],
+    "$button_content": "pause.splitscreen_icon",
+    "$pressed_alpha": 0.65
+  },
+
+  // the game's controller glyph, centered in the button
+  "splitscreen_free_icon": {
+    "type": "image",
+    "texture": "textures/ui/controller_glyph",
+    "layer": 3,
+    "size": [ 16, 16 ],
+    "anchor_from": "center",
+    "anchor_to": "center"
+  },
+
+  // alone in the world: take player 1's controller away so it can choose a player
+  "splitscreen_free_button_small@common_buttons.light_content_button": {
+    "$pressed_button_name": "button.splitscreen_free_controller",
+    "$default_button_texture": "textures/ui/button_red",
+    "$hover_button_texture": "textures/ui/button_red",
+    "$pressed_button_texture": "textures/ui/button_red_pressed",
+    "$focus_id": "icon_panel_main_focus",
+    "focus_change_down": "return_to_game",
+    "$button_tts_header": "splitscreen.pause.freeController",
+    "size": [ 24, 24 ],
+    "$button_content": "pause.splitscreen_free_icon",
+    "$pressed_alpha": 0.65
+  },
+
+  "splitscreen_free_button_small_with_tooltip": {
+    "type": "panel",
+    "size": [ 24, 24 ],
+    "controls": [
+      { "button@pause.splitscreen_free_button_small": {} },
+      { "tooltip_trigger@pause.icon_button_tooltip_trigger": { "$tooltip_text": "splitscreen.pause.freeController" } }
+    ]
+  },
+
+  "splitscreen_button_small_with_tooltip": {
+    "type": "panel",
+    "size": [ 24, 24 ],
+    "controls": [
+      { "button@pause.splitscreen_button_small": {} },
+      { "tooltip_trigger@pause.icon_button_tooltip_trigger": { "$tooltip_text": "splitscreen.title.menu" } }
+    ]
+  }
+}