Android实现高斯模糊

实现思路是结合Glide和RenderScript来实现高斯模糊的效果

1.在Module的build.gradle的defaultConfig标签下配置

renderscriptTargetApi 19
renderscriptSupportModeEnabled true

2.引用Glide的问题这里就不多提了，直接上Glide的实现代码

 public static void displayBlurImg(Context context,String url,ImageView imageView) {
     Glide.with(context)
              .load(url)
              .placeholder(R.drawable.image_smile)
              .error(R.drawable.image_smile)
              .crossFade(1000)
              .bitmapTransform(new BlurTransformation(context,23,4)) // “23”：设置模糊度(在0.0到25.0之间)，默认”25";"4":图片缩放比例,默认“1”。
              .into(imageView);
}

3.实现的关键就是这个转换器BlurTransformation

public class BlurTransformation implements Transformation {
    private static int MAX_RADIUS = 25;
    private static int DEFAULT_DOWN_SAMPLING = 1;

    private Context mContext;
    private BitmapPool mBitmapPool;

    private int mRadius;
    private int mSampling;

    public BlurTransformation(Context context) {
        this(context, Glide.get(context).getBitmapPool(), MAX_RADIUS, DEFAULT_DOWN_SAMPLING);
    }

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

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

    public BlurTransformation(Context context, int radius) {
        this(context, Glide.get(context).getBitmapPool(), radius, DEFAULT_DOWN_SAMPLING);
    }

    public BlurTransformation(Context context, BitmapPool pool, int radius, int sampling) {
        mContext = context;
        mBitmapPool = pool;
        mRadius = radius;
        mSampling = sampling;
    }

    public BlurTransformation(Context context, int radius, int sampling) {
        mContext = context;
        mBitmapPool = Glide.get(context).getBitmapPool();
        mRadius = radius;
        mSampling = sampling;
    }

    @Override
    public Resource transform(Resource resource, int outWidth, int outHeight) {
        Bitmap source = resource.get();

        int width = source.getWidth();
        int height = source.getHeight();
        int scaledWidth = width / mSampling;
        int scaledHeight = height / mSampling;

        Bitmap bitmap = mBitmapPool.get(scaledWidth, scaledHeight, Bitmap.Config.ARGB_8888);
        if (bitmap == null) {
            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);
        RenderScriptGaussianBlur rsBlur = new RenderScriptGaussianBlur(mContext);
        bitmap = rsBlur.blur(mRadius, bitmap);
        rsBlur.destroy();
        return BitmapResource.obtain(bitmap, mBitmapPool);
    }

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

最后实现的效果是这样的