android 圆角ImageView类，可设置弧度

 public class RoundImageView extends ImageView {
     private Paint paint;
     private int roundWidth = 50;
     private int roundHeight = 50;
     private Paint paint2;

     public RoundImageView(Context context, AttributeSet attrs, int defStyle) {
         super(context, attrs, defStyle);
         init(context, attrs);
     }

     public RoundImageView(Context context, AttributeSet attrs) {
         super(context, attrs);
         init(context, attrs);
     }

     public void SetRoundValue(float roundValue) {
         roundWidth = (int) roundValue;
         roundHeight = (int) roundValue;
     }

     public RoundImageView(Context context) {
         super(context);
         init(context, null);
     }

     @SuppressLint("Recycle")
     private void init(Context context, AttributeSet attrs) {

         if (attrs != null) {
             TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RoundAngleImageView);
             roundWidth = a.getDimensionPixelSize(R.styleable.RoundAngleImageView_roundWidth, roundWidth);
             roundHeight = a.getDimensionPixelSize(R.styleable.RoundAngleImageView_roundHeight, roundHeight);
         } else {
             float density = context.getResources().getDisplayMetrics().density;
             roundWidth = (int) (roundWidth * density);
             roundHeight = (int) (roundHeight * density);
         }

         paint = new Paint();
         paint.setColor(Color.WHITE);
         paint.setAntiAlias(true);
         paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));

         paint2 = new Paint();
         paint2.setXfermode(null);
     }

     @Override
     public void draw(Canvas canvas) {
         Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Config.ARGB_8888);
         Canvas canvas2 = new Canvas(bitmap);
         super.draw(canvas2);
         drawLiftUp(canvas2);
         drawRightUp(canvas2);
         drawLiftDown(canvas2);
         drawRightDown(canvas2);
         canvas.drawBitmap(bitmap, 0, 0, paint2);
         bitmap.recycle();
         bitmap = null;
     }

     private void drawLiftUp(Canvas canvas) {
         Path path = new Path();
         path.moveTo(0, roundHeight);
         path.lineTo(0, 0);
         path.lineTo(roundWidth, 0);
         path.arcTo(new RectF(0, 0, roundWidth * 2, roundHeight * 2), -90, -90);
         path.close();
         canvas.drawPath(path, paint);
     }

     private void drawLiftDown(Canvas canvas) {
         Path path = new Path();
         path.moveTo(0, getHeight() - roundHeight);
         path.lineTo(0, getHeight());
         path.lineTo(roundWidth, getHeight());
         path.arcTo(new RectF(0, getHeight() - roundHeight * 2, 0 + roundWidth * 2, getWidth()), 90, 90);
         path.close();
         canvas.drawPath(path, paint);
     }

     private void drawRightDown(Canvas canvas) {
         Path path = new Path();
         path.moveTo(getWidth() - roundWidth, getHeight());
         path.lineTo(getWidth(), getHeight());
         path.lineTo(getWidth(), getHeight() - roundHeight);
         path.arcTo(new RectF(getWidth() - roundWidth * 2, getHeight() - roundHeight * 2, getWidth(), getHeight()), 0,
                 90);
         path.close();
         canvas.drawPath(path, paint);
     }

     private void drawRightUp(Canvas canvas) {
         Path path = new Path();
         path.moveTo(getWidth(), roundHeight);
         path.lineTo(getWidth(), 0);
         path.lineTo(getWidth() - roundWidth, 0);
         path.arcTo(new RectF(getWidth() - roundWidth * 2, 0, getWidth(), 0 + roundHeight * 2), -90, 90);
         path.close();
         canvas.drawPath(path, paint);
     }

 }