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);
}

}