Question

我正在尝试应用动画来折叠LinearLayout。此动画取决于LinearLayout的MeasuredHeight属性，其值大于0，但该值始终为0.

这是我正在使用的代码：

    public void Collapse()
    {
        var v = FindViewById<LinearLayout>(Resource.Id.layoutBranding);
        int initialHeight = v.MeasuredHeight; // always 0!!

        var a = new MyAnimation(v, initialHeight);

        a.Duration = (int)(initialHeight / v.Context.Resources.DisplayMetrics.Density);
        v.StartAnimation(a);
    }

MyAnimation定义为：

公共类MyAnimation：动画 { private readonly查看_view; private readonly int _initalHeight;

    public MyAnimation(View view, int initalHeight)
    {
        _view = view;
        _initalHeight = initalHeight;
    }

    protected override void ApplyTransformation(float interpolatedTime, Transformation t)
    {
        if (interpolatedTime == 1)
        {
            _view.Visibility = ViewStates.Gone;
        }
        else
        {
            _view.LayoutParameters.Height = _initalHeight - (int) (_initalHeight*interpolatedTime);
            _view.RequestLayout();
        }
    }

    public override bool WillChangeBounds()
    {
        return true;
    }
}

Answer 1

试试这个：

v.measure(View.MeasureSpec.UNSPECIFIED, View.MeasureSpec.UNSPECIFIED);


int initialHeight = v.MeasuredHeight;

Answer 2

尝试在 -

中测量视图的高度和宽度

    @Override
    public void onWindowFocusChanged(boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);
        if(hasFocus)
        {
            // Get the height and the width of the view 
        }
    }

Answer 3

直到View实际布局（在渲染之前），它的高度和宽度始终为0

如果您在onMeasure或onLayout（我认为）中测量高度，那么它应该具有非零高度

为什么MeasuredHeight始终为0，我如何获得该值？

3 个答案: