Add Gradle build for Android

.gitignore

@@ -408,3 +408,10 @@ build[s]
 
 # Ignore autogenerated git-hash.txt file, generated for packaging purposes
 git-hash.txt
+
+# Android build bits
+.gradle/*
+android/.cxx/*
+android/build/*
+build/*
+local.properties

CMakeLists.txt

@@ -1,5 +1,21 @@
 cmake_minimum_required(VERSION 3.20)  # For using CMAKE_<LANG>_BYTE_ORDER
 
+if (CMAKE_SYSTEM_NAME STREQUAL "Android")
+  if (ANDROID_ABI MATCHES "arm64-v8a")
+    set(VCPKG_TARGET_TRIPLET "arm64-android" CACHE STRING "" FORCE)
+  elseif(ANDROID_ABI MATCHES "armeabi-v7a")
+    set(VCPKG_TARGET_TRIPLET "arm-android" CACHE STRING "" FORCE)
+  elseif(ANDROID_ABI MATCHES "x86_64")
+    set(VCPKG_TARGET_TRIPLET "x64-android" CACHE STRING "" FORCE)
+  elseif(ANDROID_ABI MATCHES "x86")
+    set(VCPKG_TARGET_TRIPLET "x86-android" CACHE STRING "" FORCE)
+  else()
+    message(FATAL_ERROR "ANDROID_ABI not set or not recognized")
+  endif()
+
+  set(ENV{ANDROID_NDK_HOME} ${CMAKE_ANDROID_NDK})
+endif()
+
 if (NOT DEFINED ENV{VCPKG_ROOT})
   message(FATAL_ERROR "
     Please set an environment variable VCPKG_ROOT

android/build.gradle

@@ -0,0 +1,63 @@
+apply plugin: 'com.android.application'
+
+def hostBuildDir = new File(rootProject.buildDir, "host")
+task configureHostTools(type: Exec) {
+    workingDir ".."
+    commandLine "cmake", "-B", hostBuildDir, "-G", "Ninja Multi-Config", "-DHOST_TOOLS_ONLY=1"
+    // intentionally do not track inputs/outputs - let cmake figure that out.
+}
+["Debug", "RelWithDebInfo"].each { buildConfig ->
+    def buildHostToolsTask = tasks.register('buildHostTools' + buildConfig, Exec) {
+        workingDir ".."
+        commandLine "cmake", "--build", hostBuildDir, "--target", "HogMaker", "--config", buildConfig
+        dependsOn configureHostTools
+        // intentionally do not track inputs/outputs - let cmake figure that out.
+    }
+    preBuild.dependsOn buildHostToolsTask
+}
+
+android {
+    namespace "com.descent3.droid"
+    compileSdkVersion 32
+    defaultConfig {
+        minSdkVersion 32
+        targetSdkVersion 32
+        versionCode 1
+        versionName "1.0"
+        externalNativeBuild {
+            cmake {
+                arguments "-DANDROID_APP_PLATFORM=android-19", "-DANDROID_STL=c++_static", "-DHogMaker_DIR=" + hostBuildDir
+                // abiFilters 'armeabi-v7a', 'arm64-v8a', 'x86', 'x86_64'
+                abiFilters 'arm64-v8a'
+            }
+        }
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+    applicationVariants.all { variant ->
+        tasks["merge${variant.name.capitalize()}Assets"]
+            .dependsOn("externalNativeBuild${variant.name.capitalize()}")
+    }
+    sourceSets {
+        main {
+            jniLibs.srcDir 'libs'
+            java.srcDirs = ['src/main/java']
+        }
+    }
+    externalNativeBuild {
+        cmake {
+            path '../CMakeLists.txt'
+        }
+    }
+    lint {
+        abortOnError false
+    }
+}
+
+dependencies {
+    implementation fileTree(include: ['*.jar'], dir: 'libs')
+}

android/proguard-rules.pro

@@ -0,0 +1,17 @@
+# Add project specific ProGuard rules here.
+# By default, the flags in this file are appended to flags specified
+# in [sdk]/tools/proguard/proguard-android.txt
+# You can edit the include path and order by changing the proguardFiles
+# directive in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# Add any project specific keep options here:
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}

android/src/main/AndroidManifest.xml

@@ -0,0 +1,86 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Replace com.test.game with the identifier of your game below, e.g.
+     com.gamemaker.game
+-->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    android:versionCode="1"
+    android:versionName="devel"
+    android:installLocation="auto">
+
+    <!-- OpenGL ES 2.0 -->
+    <uses-feature android:glEsVersion="0x00020000" />
+
+    <!-- Touchscreen support -->
+    <uses-feature
+        android:name="android.hardware.touchscreen"
+        android:required="false" />
+
+    <!-- Game controller support -->
+    <uses-feature
+        android:name="android.hardware.bluetooth"
+        android:required="false" />
+    <uses-feature
+        android:name="android.hardware.gamepad"
+        android:required="false" />
+    <uses-feature
+        android:name="android.hardware.usb.host"
+        android:required="false" />
+
+    <!-- External mouse input events -->
+    <uses-feature
+        android:name="android.hardware.type.pc"
+        android:required="false" />
+
+    <!-- Audio recording support -->
+    <!-- if you want to capture audio, uncomment this. -->
+    <!-- <uses-feature
+        android:name="android.hardware.microphone"
+        android:required="false" /> -->
+    <!-- <uses-permission android:name="android.permission.RECORD_AUDIO" /> -->
+
+    <!-- Allow access to Bluetooth devices -->
+    <!-- Currently this is just for Steam Controller support and requires setting SDL_HINT_JOYSTICK_HIDAPI_STEAM -->
+    <!-- <uses-permission android:name="android.permission.BLUETOOTH" android:maxSdkVersion="30" /> -->
+    <!-- <uses-permission android:name="android.permission.BLUETOOTH_CONNECT" /> -->
+
+    <!-- Allow access to the vibrator -->
+    <uses-permission android:name="android.permission.VIBRATE" />
+
+    <!-- Create a Java class extending SDLActivity and place it in a
+         directory under app/src/main/java matching the package, e.g. app/src/main/java/com/gamemaker/game/MyGame.java
+
+         then replace "SDLActivity" with the name of your class (e.g. "MyGame")
+         in the XML below.
+
+         An example Java class can be found in README-android.md
+    -->
+    <application android:label="@string/app_name"
+        android:icon="@mipmap/ic_launcher"
+        android:allowBackup="true"
+        android:theme="@style/AppTheme"
+        android:hardwareAccelerated="true" >
+
+        <!-- Example of setting SDL hints from AndroidManifest.xml:
+        <meta-data android:name="SDL_ENV.SDL_ACCELEROMETER_AS_JOYSTICK" android:value="0"/>
+         -->
+
+        <activity android:name="MainActivity"
+            android:label="@string/app_name"
+            android:alwaysRetainTaskState="true"
+            android:launchMode="singleInstance"
+            android:configChanges="layoutDirection|locale|orientation|uiMode|screenLayout|screenSize|smallestScreenSize|keyboard|keyboardHidden|navigation"
+            android:preferMinimalPostProcessing="true"
+            android:exported="true"
+            >
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+            <!-- Let Android know that we can handle some USB devices and should receive this event -->
+            <intent-filter>
+                <action android:name="android.hardware.usb.action.USB_DEVICE_ATTACHED" />
+            </intent-filter>
+        </activity>
+    </application>
+
+</manifest>

android/src/main/java/com/descent3/droid/MainActivity.java

@@ -0,0 +1,18 @@
+package com.descent3.droid;
+
+import org.libsdl.app.SDLActivity;
+
+public class MainActivity extends SDLActivity {
+    @Override
+    protected String[] getLibraries() {
+        return new String[] {
+            "SDL2",
+            "Descent3",
+        };
+    }
+
+    @Override
+    protected String[] getArguments() {
+        return super.getArguments();
+    }
+}

android/src/main/java/org/libsdl/app/HIDDevice.java

@@ -0,0 +1,22 @@
+package org.libsdl.app;
+
+import android.hardware.usb.UsbDevice;
+
+interface HIDDevice
+{
+    public int getId();
+    public int getVendorId();
+    public int getProductId();
+    public String getSerialNumber();
+    public int getVersion();
+    public String getManufacturerName();
+    public String getProductName();
+    public UsbDevice getDevice();
+    public boolean open();
+    public int sendFeatureReport(byte[] report);
+    public int sendOutputReport(byte[] report);
+    public boolean getFeatureReport(byte[] report);
+    public void setFrozen(boolean frozen);
+    public void close();
+    public void shutdown();
+}