Android: Allow building of native libraries inside Android Studio / Gradle

Source/Android/.gitignore

@@ -39,4 +39,5 @@ tasks.xml
 gradle/
 build/
 *.so
-*.iml
+*.iml
+build.properties

Source/Android/app/build.gradle

@@ -41,6 +41,10 @@ android {
             applicationIdSuffix ".debug"
             versionNameSuffix '-debug'
             jniDebuggable true
+
+            tasks.withType(JavaCompile) {
+                compileTask -> compileTask.dependsOn(compileNative)
+            }
         }
     }
 }
@@ -58,3 +62,53 @@ dependencies {
     // For loading huge screenshots from the disk.
     compile 'com.squareup.picasso:picasso:2.5.2'
 }
+
+task setupCMake(type: Exec) {
+    // Check if a build properties file exists.
+    def propsFile = rootProject.file("build.properties")
+
+    // If it does, call CMake.
+    if (propsFile.canRead()) {
+        // Read the properties file's contents.
+        def buildProperties = new Properties()
+        buildProperties.load(new FileInputStream(propsFile))
+
+        mkdir('build/' + buildProperties.abi)
+        workingDir 'build/' + buildProperties.abi
+
+        executable 'cmake'
+
+        args "-DANDROID=true",
+                "-DANDROID_NATIVE_API_LEVEL=android-18",
+                "-DCMAKE_TOOLCHAIN_FILE=../../../android.toolchain.cmake",
+                "../../../../..",
+                "-DGIT_EXECUTABLE=" + buildProperties.gitPath,
+                "-DANDROID_NDK=" + buildProperties.ndkPath,
+                "-DANDROID_TOOLCHAIN_NAME=" + buildProperties.toolchain,
+                "-DANDROID_ABI=" + buildProperties.abi
+    } else {
+        executable 'echo'
+        args 'No build.properties found; skipping CMake.'
+    }
+}
+
+task compileNative(type: Exec, dependsOn: 'setupCMake') {
+    // Check if a build properties file exists.
+    def propsFile = rootProject.file("build.properties")
+
+    // If it does, call make.
+    if (propsFile.canRead()) {
+        // Read the properties file's contents.
+        def buildProperties = new Properties()
+        buildProperties.load(new FileInputStream(propsFile))
+
+        workingDir 'build/' + buildProperties.abi
+
+        executable 'make'
+
+        args buildProperties.makeArgs
+    } else {
+        executable 'echo'
+        args 'No build.properties found; skipping native build.'
+    }
+}