给任意布局加圆角

public class CornersView extends LinearLayout {
private float roundLayoutRadius;
private Path roundPath;
private RectF rectF;

public CornersView(Context context) {
    this(context, null);
}

public CornersView(Context context, AttributeSet attrs) {
    super(context, attrs);

    TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.RoundLayout);
    roundLayoutRadius = typedArray.getDimensionPixelSize(R.styleable.RoundLayout_roundLayoutRadius, (int) roundLayoutRadius);
    typedArray.recycle();

    init();
}

private void init() {
    setWillNotDraw(false);//如果你继承的是ViewGroup,注意此行,否则draw方法是不会回调的;
    roundPath = new Path();
    rectF = new RectF();
}

private void setRoundPath() {
    //添加一个圆角矩形到path中, 如果要实现任意形状的View, 只需要手动添加path就行
    roundPath.addRoundRect(rectF, roundLayoutRadius, roundLayoutRadius, Path.Direction.CW);
}


public void setRoundLayoutRadius(float roundLayoutRadius) {
    this.roundLayoutRadius = roundLayoutRadius;
    setRoundPath();
    postInvalidate();
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    super.onLayout(changed, l, t, r, b);
    rectF.set(0, 0, getMeasuredWidth(), getMeasuredHeight());
}

@Override
protected void onDraw(Canvas canvas) {
    setRoundPath();
    if (roundLayoutRadius > 0f) {
        canvas.clipPath(roundPath);
    }
    super.onDraw(canvas);
}

public static int dip2px(Context context, float dipValue) {
    final float scale = context.getResources().getDisplayMetrics().density;
    return (int) (dipValue * scale + 0.5f);
}

}

如果没有实现圆角，有可能是里面的布局和这一层有padding或者margin值