Add configuration for including the library as a git submodule

.gitignore

@@ -9,6 +9,7 @@ gradle.properties
 *.apk
 *.ap_
 *.jar
+.externalNativeBuild
 
 # files for the dex VM
 *.dex

JniBitmapOperationsLibrary/build.gradle

@@ -27,7 +27,11 @@ android {
         }
     }
 
-
+    externalNativeBuild {
+        ndkBuild {
+            path 'jni/Android.mk'
+        }
+    }
 
 /*
     task buildNative(type: Exec, description: 'Compile JNI source via NDK') {

README.md

@@ -80,6 +80,29 @@ Just import the whole cloned project and run the sample.
 
 #### Further configuring and using as the library
 
+#### Option 1
+ 1. Add this repository as a git submodule. For these instructions we added in a folder named `AndroidJniBitmapOperations`
+ 2. Add the following lines to your `settings.gradle` file
+
+    ```
+    include ':JniBitmapOperationsLibrary'
+    project(':JniBitmapOperationsLibrary').projectDir = new File(settingsDir, '../AndroidJniBitmapOperations/JniBitmapOperationsLibrary')
+    ```
+ 3. Add the following lines to your top level `build.gradle` file inside the `buildscript` section. Replace the versions with whatever your project is using as needed.
+
+    ```
+    // Variables for JniBitmapOperationsLibrary
+    ext.propCompileSdkVersion = 23
+    ext.propBuildToolsVersion = "27.0.3"
+    ```
+ 4. Add the following lines to your app `build.gradle` file inside the `dependancies` section
+
+    ```
+    implementation project(':JniBitmapOperationsLibrary')
+    ```
+
+#### Option 2
+
  1. Copy `JniBitmapOperationsLibrary.cpp` into `src/main/jni` directory:
 
     ![Studio folder structure](https://s3.amazonaws.com/uploads.hipchat.com/22412/120721/qZyoFrgpUnFmnHu/upload.png)

build.gradle

@@ -7,9 +7,10 @@
 buildscript {
     repositories {
         mavenCentral()
+        google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:1.2.3'
+        classpath 'com.android.tools.build:gradle:3.1.2'
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files