glide设置成圆角图片 以及解决刷新图片闪烁的问题

在项目中，我们经常会用到圆角图片，强大的glide能很简单通过自定义BitmapTransformation就能实现。

我就随便网上找了个，然鹅，发现在recyclerview的item里面，却刷新时候图片居然闪动。

后来查找官方文档

发现

对于任何 Transformation 子类，包括 BitmapTransformation，你都必须实现这三个方法，以使得磁盘和内存缓存正确地工作：

equals()
hashCode()
updateDiskCacheKey

网上很多，只是简单的裁切，而没有复写，所以，glide刷新时候会闪动一下。

~~

直接上代码：

~~

public class GlideRoundTransform extends BitmapTransformation {

        private final float radius;
        private final String ID = "com. bumptech.glide.transformations.FillSpace";
        private final byte[] ID_ByTES= ID.getBytes(CHARSET);

        public GlideRoundTransform(int dp){
           this.radius = Resources.getSystem().getDisplayMetrics().density * dp;
       }

      @Override
      protected Bitmap transform(@NonNull BitmapPool pool, @NonNull Bitmap toTransform, int outWidth, int outHeight){
          return roundCrop(pool, toTransform);
       }

    private Bitmap roundCrop(BitmapPool pool, Bitmap toTransform) {
        if (toTransform == null) {
            return null;
        }
        Bitmap result = pool.get(toTransform.getWidth(), toTransform.getHeight(), Bitmap.Config.ARGB_8888);
        if (result == null) {
            return Bitmap.createBitmap(toTransform.getWidth(), toTransform.getHeight(), Bitmap.Config.ARGB_8888);
        }

        Canvas canvas = new Canvas(result);
        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setShader(new BitmapShader(toTransform, BitmapShader.TileMode.CLAMP, BitmapShader.TileMode.CLAMP));
        RectF rectF = new RectF(0f, 0f, toTransform.getWidth(), toTransform.getHeight());
       canvas.drawRoundRect(rectF, radius, radius, paint);
       
        return result;
    }


    @Override
    public boolean equals(Object o){
        if (o instanceof GlideRoundTransform){
            GlideRoundTransform other = (GlideRoundTransform) o;
            return radius == other.radius;
        }
        return false;
    }

    @Override
    public int hashCode() {

        return Util.hashCode(ID.hashCode(),
                Util.hashCode(radius));

    }

    @Override
    public void updateDiskCacheKey(@NonNull MessageDigest messageDigest){
       messageDigest.update(ID_ByTES);
       byte[] radiusData =ByteBuffer.allocate(4).putInt((int) radius).array();messageDigest.update(radiusData);
    }

}

使用

   Glide.with(mContext)
                    .load(url)
                    .apply(new  RequestOptions()
                    .transform( new GlideRoundTransform(4)))
                    .placeholder(placeimg).fallback(placeimg)
                    .error(placeimg)
                    .into(imageView);