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Blur an image

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This example demonstrates how to use Renderscript API to blur an image (using Bitmap). This example uses ScriptInstrinsicBlur provided by android Renderscript API (API >= 17). 

public class BlurProcessor {
    
    private RenderScript rs;
    private Allocation inAllocation;
    private Allocation outAllocation;
    private int width;
    private int height;

    private ScriptIntrinsicBlur blurScript;

    public BlurProcessor(RenderScript rs) {
        this.rs = rs;
    }
    
    public void initialize(int width, int height) {
        blurScript = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
        blurScript.setRadius(7f); // Set blur radius. 25 is max

        if (outAllocation != null) {
            outAllocation.destroy();
            outAllocation = null;
        }
        
        // Bitmap must have ARGB_8888 config for this type
        Type bitmapType = new Type.Builder(rs, Element.RGBA_8888(rs))
            .setX(width)
            .setY(height)
            .setMipmaps(false) // We are using MipmapControl.MIPMAP_NONE
            .create();
        
        // Create output allocation
        outAllocation = Allocation.createTyped(rs, bitmapType);

        // Create input allocation with same type as output allocation
        inAllocation = Allocation.createTyped(rs, bitmapType);
    }

    public void release() {
        
        if (blurScript != null) {
            blurScript.destroy();
            blurScript = null;
        }
    
        if (inAllocation != null) {
            inAllocation.destroy();
            inAllocation = null;
        }

        if (outAllocation != null) {
            outAllocation.destroy();
            outAllocation = null;
        }
    }

    public Bitmap process(Bitmap bitmap, boolean createNewBitmap) {
        if (bitmap.getWidth() != width || bitmap.getHeight() != height) {
            // Throw error if required
            return null;
        }
        
        // Copy data from bitmap to input allocations
        inAllocation.copyFrom(bitmap);

        // Set input for blur script
        blurScript.setInput(inAllocation);

        // process and set data to the output allocation
        blurScript.forEach(outAllocation);
        
        if (createNewBitmap) {
            Bitmap returnVal = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
            outAllocation.copyTo(returnVal);
            return returnVal;
        }

        outAllocation.copyTo(bitmap);
        return bitmap;
    }
}

Each script has a kernel which processes the data and it is generally invoked via forEach method. 

public class BlurActivity extends AppCompatActivity {
    private BlurProcessor blurProcessor;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        // setup layout and other stuff

        
        blurProcessor = new BlurProcessor(Renderscript.create(getApplicationContext()));
    }

    private void loadImage(String path) {
        // Load image to bitmap
        Bitmap bitmap = loadBitmapFromPath(path);
        
        // Initialize processor for this bitmap
        blurProcessor.release();
        blurProcessor.initialize(bitmap.getWidth(), bitmap.getHeight());
        
        // Blur image
        Bitmap blurImage = blurProcessor.process(bitmap, true); // Use newBitamp as false if you don't want to create a new bitmap
    }
}

This concluded the example here. It is advised to do the processing in a background thread.

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RenderScript:
* RenderScript
* Getting Started
* Blur a View
* Blur an image
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