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);
    }

}