方案1

处理Bitmap为圆形，再给ImageView设置该Bitmap

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public class Util {
    private static final int STROKE_WIDTH = 4;
    //从assets资源中获取图片
    public static Bitmap getBitmap(Context context, String filename) {
        Bitmap image = null;
        AssetManager am = context.getResources().getAssets();
        try {
            InputStream is = am.open(filename);
            image = BitmapFactory.decodeStream(is);
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return image;
    }
    public static Bitmap toRoundBitmap(Context context, String filename) {
        Bitmap bitmap = getBitmap(context, filename);
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        float roundPx;
        float left, top, right, bottom, dst_left, dst_top, dst_right, dst_bottom;
        if (width <= height) {
            roundPx = width / 2;
            top = 0;
            left = 0;
            bottom = width;
            right = width;
            height = width;
            dst_left = 0;
            dst_top = 0;
            dst_right = width;
            dst_bottom = width;
        } else {
            roundPx = height / 2;
            float clip = (width - height) / 2;
            left = clip;
            right = width - clip;
            top = 0;
            bottom = height;
            width = height;
            dst_left = 0;
            dst_top = 0;
            dst_right = height;
            dst_bottom = height;
        }
        Bitmap output = Bitmap.createBitmap(width,
                height, Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect src = new Rect((int) left, (int) top, (int) right, (int) bottom);
        final Rect dst = new Rect((int) dst_left, (int) dst_top, (int) dst_right, (int) dst_bottom);
        final RectF rectF = new RectF(dst);
        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(Color.WHITE);
        paint.setStrokeWidth(4);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, src, dst, paint);
        //画白色圆圈
        paint.reset();
        paint.setColor(Color.WHITE);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(STROKE_WIDTH);
        paint.setAntiAlias(true);
        canvas.drawCircle(width / 2, width / 2, width / 2 - STROKE_WIDTH / 2, paint);
        return output;
    }
}

方案2

自定义View继承自ImageView,在setImageDrawable()方法中把BitamapDrawable转为RoundedBitmapDrawable

bug ColorDrawable不能转化，需获取bitmap

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@Override
    public void setBackgroundDrawable(Drawable drawable) {
        if (drawable instanceof ColorDrawable) {
            Bitmap bm = Bitmap.createBitmap(getWidth(),getHeight(), Bitmap.Config.ARGB_8888);
            Paint paint = new Paint();
            paint.setAntiAlias(true);
            paint.setColor(((ColorDrawable)drawable).getColor());
            paint.setStyle(Paint.Style.FILL);
            //根据创建的bitmap新建一张画布
            Canvas canvas = new Canvas(bm);
            canvas.drawCircle(getWidth()/2,getWidth()/2,getWidth()/2,paint);
            RoundedBitmapDrawable roundedDrawable = RoundedBitmapDrawableFactory.create(getResources(),
                    bm);
            roundedDrawable.setCircular(true);
            super.setBackgroundDrawable(roundedDrawable);
        } else {
            BitmapDrawable bitmapDrawable = (BitmapDrawable) drawable;
            @SuppressWarnings("ConstantConditions")
            RoundedBitmapDrawable roundedDrawable = RoundedBitmapDrawableFactory.create(getResources(),
                    bitmapDrawable.getBitmap());
            roundedDrawable.setCircular(true);
            super.setBackgroundDrawable(roundedDrawable);
        }
    }
  • Drawable转为Bitmap的方法
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mExpandBm = Bitmap.createBitmap(mExpandDrawable.getIntrinsicWidth(),mExpandDrawable.getIntrinsicHeight(), Bitmap.Config.ARGB_8888);
           Canvas cv1 = new Canvas(mExpandBm);
           mExpandDrawable.setBounds(0,0,mExpandDrawable.getIntrinsicWidth(),mExpandDrawable.getIntrinsicHeight());
           mExpandDrawable.draw(cv1);