How to blur background images in Android

This is an easy way to blur Images Efficiently with Android's RenderScript that I found on this article

1. Create a Class called BlurBuilder

   public class BlurBuilder {
     private static final float BITMAP_SCALE = 0.4f;
     private static final float BLUR_RADIUS = 7.5f;
   
     public static Bitmap blur(Context context, Bitmap image) {
       int width = Math.round(image.getWidth() * BITMAP_SCALE);
       int height = Math.round(image.getHeight() * BITMAP_SCALE);
   
       Bitmap inputBitmap = Bitmap.createScaledBitmap(image, width, height, false);
       Bitmap outputBitmap = Bitmap.createBitmap(inputBitmap);
   
       RenderScript rs = RenderScript.create(context);
       ScriptIntrinsicBlur theIntrinsic = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
       Allocation tmpIn = Allocation.createFromBitmap(rs, inputBitmap);
       Allocation tmpOut = Allocation.createFromBitmap(rs, outputBitmap);
       theIntrinsic.setRadius(BLUR_RADIUS);
       theIntrinsic.setInput(tmpIn);
       theIntrinsic.forEach(tmpOut);
       tmpOut.copyTo(outputBitmap);
   
       return outputBitmap;
     }
   }
   

2. Copy any image to your drawable folder

3. Use BlurBuilder in your activity like this:

   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       requestWindowFeature(Window.FEATURE_NO_TITLE);
       getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
               WindowManager.LayoutParams.FLAG_FULLSCREEN);
       setContentView(R.layout.activity_login);
   
       mContainerView = (LinearLayout) findViewById(R.id.container);
       Bitmap originalBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.background);
       Bitmap blurredBitmap = BlurBuilder.blur( this, originalBitmap );
       mContainerView.setBackground(new BitmapDrawable(getResources(), blurredBitmap));
   

4. Renderscript is included into support v8 enabling this answer down to api 8. To enable it using gradle include these lines into your gradle file (from this answer)

   defaultConfig {
       ...
       renderscriptTargetApi *your target api*
       renderscriptSupportModeEnabled true
   }
   

5. Result

The easiest way to do that is use a library. Take a look at this one: https://github.com/wasabeef/Blurry

With the library you only need to do this:

Blurry.with(context)
  .radius(10)
  .sampling(8)
  .color(Color.argb(66, 255, 255, 0))
  .async()
  .onto(rootView);

You can use:

Glide.with(getContext()).load(R.mipmap.bg)
     .apply(bitmapTransform(new BlurTransformation(22)))
     .into((ImageView) view.findViewById(R.id.imBg));

This requires the following addition to your build.gradle file:

implementation 'jp.wasabeef:glide-transformations:4.0.0'