学步园

public class ImageHelper {
    /**
     * 转换图片成圆形
     * @param bitmap 传入Bitmap对象
     * @return
     */
    public static Bitmap toRoundBitmap(Bitmap bitmap) {
            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;
                    bottom = width;
                    left = 0;
                    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);
            canvas.drawRoundRect(rectF, roundPx, roundPx, paint);

            paint.setXfermode( new PorterDuffXfermode(Mode. SRC_IN));
            canvas.drawBitmap(bitmap, src, dst, paint);
            return output;
    }
   
}

在Activity中调用：

    /* 将头像转为圆形 */
     Resources res = getResources();
     Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.head);
     head.setImageBitmap(ImageHelper.toRoundBitmap(bmp));