Android StackBlur is a library that can perform a blurry effect on a Bitmap based on a gradient or radius, and return the result. The library is based on the code of Mario Klingemann.

The library is compatible for Android versions 1.5 (so pretty much compatible with every device).

A library and a sample application are provided with the code.

• Mario Klingemann developed the original algorithm and gave me the idea to port it to Android.
• Manuel Peinado Gallego has generously pointed me out some other sources working on the same area.
• Nicolas Pomepuy pointed me out to his really useful article on the topic.
• Dr-Emann for his contribution adding RenderScript and Muiltithreading support.

Download the library with git. When it has been imported into your project. First initialize your StackBlurManager to load a sample image:

    stackBlurManager = new StackBlurManager(getBitmapFromAsset(this, "android_platform_256.png"));

Process using a certain radius with the following line:

    stackBlurManager.process(progress*5);

and finally obtain the image and load it into an ImageView or any other component:

    imageView.setImageBitmap(_stackBlurManager.returnBlurredImage() );

If you want to use the native code (NDK), first you need to compile the native files. Move to the folder where you have the project, and call:

    ndk-build

If everything goes alright, you will compile and generate a library object, libblur.so, in the folder libs. For more information regarding the NDK framework, please click here. Then, from the code you just need to code:

    stackBlurManager.processNatively(progress*5);

The function processNatively(int radius) return the image already blurry. This code is 25-30 times faster as the Java code.

If you want to use RenderScript, you can do it by using:

   stackBlurManager.processRenderScript(progress*5);

• 10.02.2014: Added Multithreading support thanks to Dr-Emann
• 27.01.2014: Added Benchmarking, bug fixing thanks to Dr-Emann
• 10.01.2014: Added RenderScript support thanks to Dr-Emann
• 04.12.2013: Added support for NDK blurry, much faster.
• 02.12.2013: Solved the issue #1, provoking an ArrayOutOfBoundsException.
• 08.09.2013: Added support for Gradle
• 19.08.2013: Added support for Alpha blurring

As soon as I get some free time I want to add the following features:

• Uploading to MavenCentral
• Support for PNG9
• Unit tests

If you want to colaborate with the project, feel free to submit a pull request!

Also, if you have used Android StackBlur on your app and you let me know, I can link it from here :)

Enrique López Mañas - eenriquelopez@gmail.com