少造轮子之--android高斯模糊，使用简单，带渐变！！！

简单粗暴，
使用方法：BitmapBlurUtil.getInstance().setImageBlurBitmap(…);
完整代码：

import android.content.Context;
import android.graphics.Bitmap;
import android.os.Build;
import android.os.Handler;
import android.os.Looper;
import android.renderscript.Allocation;
import android.renderscript.Element;
import android.renderscript.RenderScript;
import android.renderscript.ScriptIntrinsicBlur;
import android.view.animation.AlphaAnimation;
import android.view.animation.DecelerateInterpolator;
import android.widget.ImageView;

import java.lang.ref.WeakReference;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;


/**
 * Created by hucanhui on 2017/11/13.
 */

public class BitmapBlurUtil {
    private static final float BITMAP_SCALE = 1f;//图片缩放值
    private static final int BLUR_RADIUS = 20;//模糊度
    private Handler handler;
    private ExecutorService executorService;
    private volatile static BitmapBlurUtil instance;

    private BitmapBlurUtil(){
        handler = new Handler(Looper.getMainLooper());
        executorService = Executors.newCachedThreadPool();
    }

    public synchronized static BitmapBlurUtil getInstance(){
        if (instance == null)
        synchronized (BitmapBlurUtil.class){
            if (instance == null){
                instance = new BitmapBlurUtil();
            }
        }
        return instance;
    }

    private Bitmap blur(Context context, Bitmap bitmap) {
        return blur(context, bitmap, BITMAP_SCALE, BLUR_RADIUS);
    }

    private Bitmap blur(Context context, Bitmap bitmap, float bitmap_scale) {
        return blur(context, bitmap, bitmap_scale, BLUR_RADIUS);
    }

    private Bitmap blur(Context context, Bitmap bitmap, int blur_radius) {
        return blur(context, bitmap, BITMAP_SCALE, blur_radius);
    }

    public void setImageBlurBitmap(Context context, ImageView imageView, Bitmap bitmap){
        setImageBlurBitmap(context, imageView, bitmap, BITMAP_SCALE, BLUR_RADIUS);
    }

    public void setImageBlurBitmap(Context context, ImageView imageView, Bitmap bitmap, float bitmap_scale){
        setImageBlurBitmap(context, imageView, bitmap, bitmap_scale, BLUR_RADIUS);
    }

    public void setImageBlurBitmap(Context context, ImageView imageView, Bitmap bitmap, int blur_radius){
        setImageBlurBitmap(context, imageView, bitmap, BITMAP_SCALE, blur_radius);
    }

    /**
     *
     * @param context
     * @param imageView
     * @param bitmap
     * @param bitmap_scale 需要缩放的倍数 图片压缩后可加快速度
     * @param blur_radius 模糊度 越大越模糊
     */
    public void setImageBlurBitmap(Context context, final ImageView imageView, final Bitmap bitmap, final float bitmap_scale, final int blur_radius) {
        if (bitmap == null || context == null) return;
        final WeakReference<Context> weakReference = new WeakReference<Context>(context);
        executorService.execute(new Runnable() {
            @Override
            public void run() {
                if (weakReference.get() != null){
                    final Bitmap blurBitmap = blur(weakReference.get(), bitmap, bitmap_scale, blur_radius);
                    handler.post(new Runnable() {
                        @Override
                        public void run() {
                            if (imageView != null && weakReference.get() != null){
                                imageView.setImageBitmap(blurBitmap);
                                AlphaAnimation fadeImage = new AlphaAnimation(0.0F, 1.0F);
                                fadeImage.setDuration(300);
                                fadeImage.setInterpolator(new DecelerateInterpolator());
                                imageView.startAnimation(fadeImage);
                            }
                        }
                    });
                }
            }
        });
    }

    /**
     * 该方法耗时 最好放异步执行
     * @param context
     * @param bitmap
     * @param bitmap_scale
     * @param blur_radius
     * @return
     */
    private Bitmap blur(Context context, Bitmap bitmap, float bitmap_scale, int blur_radius) {
        //先对图片进行压缩然后再blur 缩短时间
        Bitmap inputBitmap = bitmap;
        if (bitmap_scale < 1){
            inputBitmap = Bitmap.createScaledBitmap(bitmap, Math.round(bitmap.getWidth() * bitmap_scale),
                    Math.round(bitmap.getHeight() * bitmap_scale), false);
        }
        Bitmap outputBitmap;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {//rendScript只适用于Build.VERSION_CODES大于17
            //创建空的Bitmap用于输出
            outputBitmap = Bitmap.createBitmap(inputBitmap);
            //初始化Renderscript
            RenderScript rs = RenderScript.create(context);
            ScriptIntrinsicBlur theIntrinsic = ScriptIntrinsicBlur.create(rs, Element.U8_4(rs));
            //native层分配内存空间
            Allocation tmpIn = Allocation.createFromBitmap(rs, inputBitmap);
            Allocation tmpOut = Allocation.createFromBitmap(rs, outputBitmap);
            //设置blur的半径然后进行blur
            theIntrinsic.setRadius(blur_radius);
            theIntrinsic.setInput(tmpIn);
            theIntrinsic.forEach(tmpOut);
            //拷贝blur后的数据到java缓冲区中
            tmpOut.copyTo(outputBitmap);
            //销毁Renderscript
            rs.destroy();
        } else {
            //兼容低版本
            outputBitmap = fastblur(inputBitmap, blur_radius);
        }
        return outputBitmap;
    }

    private static Bitmap fastblur(Bitmap sentBitmap, int radius) {
        Bitmap bitmap = sentBitmap.copy(sentBitmap.getConfig(), true);
        if(radius < 1) {
            return null;
        } else {
            int w = bitmap.getWidth();
            int h = bitmap.getHeight();
            int[] pix = new int[w * h];
            bitmap.getPixels(pix, 0, w, 0, 0, w, h);
            int wm = w - 1;
            int hm = h - 1;
            int wh = w * h;
            int div = radius + radius + 1;
            int[] r = new int[wh];
            int[] g = new int[wh];
            int[] b = new int[wh];
            int[] vmin = new int[Math.max(w, h)];
            int divsum = div + 1 >> 1;
            divsum *= divsum;
            int[] dv = new int[256 * divsum];

            int i;
            for(i = 0; i < 256 * divsum; ++i) {
                dv[i] = i / divsum;
            }

            int yi = 0;
            int yw = 0;
            int[][] stack = new int[div][3];
            int r1 = radius + 1;

            int rsum;
            int gsum;
            int bsum;
            int x;
            int y;
            int p;
            int stackpointer;
            int stackstart;
            int[] sir;
            int rbs;
            int routsum;
            int goutsum;
            int boutsum;
            int rinsum;
            int ginsum;
            int binsum;
            for(y = 0; y < h; ++y) {
                bsum = 0;
                gsum = 0;
                rsum = 0;
                boutsum = 0;
                goutsum = 0;
                routsum = 0;
                binsum = 0;
                ginsum = 0;
                rinsum = 0;

                for(i = -radius; i <= radius; ++i) {
                    p = pix[yi + Math.min(wm, Math.max(i, 0))];
                    sir = stack[i + radius];
                    sir[0] = (p & 16711680) >> 16;
                    sir[1] = (p & '\uff00') >> 8;
                    sir[2] = p & 255;
                    rbs = r1 - Math.abs(i);
                    rsum += sir[0] * rbs;
                    gsum += sir[1] * rbs;
                    bsum += sir[2] * rbs;
                    if(i > 0) {
                        rinsum += sir[0];
                        ginsum += sir[1];
                        binsum += sir[2];
                    } else {
                        routsum += sir[0];
                        goutsum += sir[1];
                        boutsum += sir[2];
                    }
                }

                stackpointer = radius;

                for(x = 0; x < w; ++x) {
                    r[yi] = dv[rsum];
                    g[yi] = dv[gsum];
                    b[yi] = dv[bsum];
                    rsum -= routsum;
                    gsum -= goutsum;
                    bsum -= boutsum;
                    stackstart = stackpointer - radius + div;
                    sir = stack[stackstart % div];
                    routsum -= sir[0];
                    goutsum -= sir[1];
                    boutsum -= sir[2];
                    if(y == 0) {
                        vmin[x] = Math.min(x + radius + 1, wm);
                    }

                    p = pix[yw + vmin[x]];
                    sir[0] = (p & 16711680) >> 16;
                    sir[1] = (p & '\uff00') >> 8;
                    sir[2] = p & 255;
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
                    rsum += rinsum;
                    gsum += ginsum;
                    bsum += binsum;
                    stackpointer = (stackpointer + 1) % div;
                    sir = stack[stackpointer % div];
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
                    rinsum -= sir[0];
                    ginsum -= sir[1];
                    binsum -= sir[2];
                    ++yi;
                }

                yw += w;
            }

            for(x = 0; x < w; ++x) {
                bsum = 0;
                gsum = 0;
                rsum = 0;
                boutsum = 0;
                goutsum = 0;
                routsum = 0;
                binsum = 0;
                ginsum = 0;
                rinsum = 0;
                int yp = -radius * w;

                for(i = -radius; i <= radius; ++i) {
                    yi = Math.max(0, yp) + x;
                    sir = stack[i + radius];
                    sir[0] = r[yi];
                    sir[1] = g[yi];
                    sir[2] = b[yi];
                    rbs = r1 - Math.abs(i);
                    rsum += r[yi] * rbs;
                    gsum += g[yi] * rbs;
                    bsum += b[yi] * rbs;
                    if(i > 0) {
                        rinsum += sir[0];
                        ginsum += sir[1];
                        binsum += sir[2];
                    } else {
                        routsum += sir[0];
                        goutsum += sir[1];
                        boutsum += sir[2];
                    }

                    if(i < hm) {
                        yp += w;
                    }
                }

                yi = x;
                stackpointer = radius;

                for(y = 0; y < h; ++y) {
                    pix[yi] = -16777216 & pix[yi] | dv[rsum] << 16 | dv[gsum] << 8 | dv[bsum];
                    rsum -= routsum;
                    gsum -= goutsum;
                    bsum -= boutsum;
                    stackstart = stackpointer - radius + div;
                    sir = stack[stackstart % div];
                    routsum -= sir[0];
                    goutsum -= sir[1];
                    boutsum -= sir[2];
                    if(x == 0) {
                        vmin[y] = Math.min(y + r1, hm) * w;
                    }

                    p = x + vmin[y];
                    sir[0] = r[p];
                    sir[1] = g[p];
                    sir[2] = b[p];
                    rinsum += sir[0];
                    ginsum += sir[1];
                    binsum += sir[2];
                    rsum += rinsum;
                    gsum += ginsum;
                    bsum += binsum;
                    stackpointer = (stackpointer + 1) % div;
                    sir = stack[stackpointer];
                    routsum += sir[0];
                    goutsum += sir[1];
                    boutsum += sir[2];
                    rinsum -= sir[0];
                    ginsum -= sir[1];
                    binsum -= sir[2];
                    yi += w;
                }
            }

            bitmap.setPixels(pix, 0, w, 0, 0, w, h);
            return bitmap;
        }
    }
}

来源：CSDN

作者：辉son

链接：https://blog.csdn.net/u014798175/article/details/79570401