BlurTransformation.java

package org.tomahawk.tomahawk_android.utils;

/**
 * Copyright (C) 2015 Wasabeef
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

import com.squareup.picasso.Transformation;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.support.v8.renderscript.Allocation;
import android.support.v8.renderscript.Element;
import android.support.v8.renderscript.RSRuntimeException;
import android.support.v8.renderscript.RenderScript;
import android.support.v8.renderscript.ScriptIntrinsicBlur;
import android.util.Log;

public class BlurTransformation implements Transformation {

    private static String TAG = BlurTransformation.class.getSimpleName();

    private static int MAX_RADIUS = 25;

    private static int DEFAULT_DOWN_SAMPLING = 1;

    private Context mContext;

    private int mRadius;

    private int mSampling;

    public BlurTransformation(Context context) {
        this(context, MAX_RADIUS, DEFAULT_DOWN_SAMPLING);
    }

    public BlurTransformation(Context context, int radius) {
        this(context, radius, DEFAULT_DOWN_SAMPLING);
    }

    public BlurTransformation(Context context, int radius, int sampling) {
        mContext = context.getApplicationContext();
        mRadius = radius;
        mSampling = sampling;
    }

    @Override
    public Bitmap transform(Bitmap source) {

        try {
            int scaledWidth = source.getWidth() / mSampling;
            int scaledHeight = source.getHeight() / mSampling;

            Bitmap bitmap = Bitmap.createBitmap(scaledWidth, scaledHeight, Bitmap.Config.ARGB_8888);

            Canvas canvas = new Canvas(bitmap);
            canvas.scale(1 / (float) mSampling, 1 / (float) mSampling);
            Paint paint = new Paint();
            paint.setFlags(Paint.FILTER_BITMAP_FLAG);
            canvas.drawBitmap(source, 0, 0, paint);

            RenderScript rs = RenderScript.create(mContext);
            Allocation input = Allocation.createFromBitmap(rs, bitmap,
                    Allocation.MipmapControl.MIPMAP_NONE, Allocation.USAGE_SCRIPT);
            Allocation output = Allocation.createTyped(rs, input.getType());
            ScriptIntrinsicBlur blur = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));

            blur.setInput(input);
            blur.setRadius(mRadius);
            blur.forEach(output);
            output.copyTo(bitmap);

            source.recycle();
            rs.destroy();

            return bitmap;
        } catch (RSRuntimeException e) {
            Log.e(TAG, "transform - ", e);
            return source;
        }
    }

    @Override
    public String key() {
        return "BlurTransformation(radius=" + mRadius + ", sampling=" + mSampling + ")";
    }
}