如何获取布局的高度，以编程方式填充元素

Question

各位程序员大家好。在为 android 创建应用程序时，我遇到了一个问题。我想以编程方式创建 LinearLayout。然后我想以编程方式用不同的元素填充它。之后，我想获取此 LinearLayout 的高度以在将来使用它（例如，用于动画）并将其可见性设置为消失。我在 Activity 的 OnCreate 中执行的所有这些操作，所以如果我尝试获取高度，我得到 0。 任何人都可以帮我解决这个问题。我们将不胜感激所有建议。

更新

Gotiasits 和 Abbas 这里是代码

protected override void OnCreate(Bundle savedInstanceState)
{
    base.OnCreate(savedInstanceState);
    SetContentView(Resource.Layout.TestLayout);
    ScrollView contentScroll = FindViewById<ScrollView>(Resource.Id.contentScroll);
    LinearLayout contentContainer = FindViewById<LinearLayout>(Resource.Id.contentContainer);
    List<DetailsData> dataList = new List<DetailsData>();
    for (int i = 0; i < 3; i++)
    {
        string header = "Header " + " " + i.ToString();
        string title = "Title " + i.ToString();
        string subtitle = "Subtitle";
        string pretext = "Some words in pretext. Some words in pretext. Some words in pretext. Some words in pretext. Some words in pretext. Some words in pretext.Some words in pretext. Some words in pretext.";
        int[] images = { Resource.Drawable.detail_main1, Resource.Drawable.detail_main2, Resource.Drawable.detail_main3, Resource.Drawable.detail_main1,
            Resource.Drawable.detail_main2, Resource.Drawable.detail_main3, Resource.Drawable.detail_main1 };
        string[] features =
        {
            "OSome words in featurelist.",
            "OSome words in featurelist.",
            "OSome words in featurelist.",
            "OSome words in featurelist.",
            "OSome words in featurelist.",
            "OSome words in featurelist.",
            "OSome words in featurelist.",
            "OSome words in featurelist.",
            "OSome words in featurelist.",
            "OSome words in featurelist.",
        };
        dataList.Add(new DetailsData(i, header, title, subtitle, pretext, features, images));
    }
    testContainer = new TestContaier(this, dataList, contentContainer, contentScroll, false);
    testContainer.DataBind();
}

class TestContaier
{
    Activity _context;
    public List<DetailsData> _dataSource { get; private set; }
    LinearLayout _mainLayout;
    ScrollView _scrollContainer;
    public TestContaier(Activity context, List<HotelDetailsData> dataSource,  LinearLayout mainLayout, ScrollView scrollContainer)
    {
        _context = context;
        _dataSource = dataSource;
        _mainLayout = mainLayout;
        _firstExpanded = firstExpanded;
        _scrollContainer = scrollContainer;
    }
    public void DataBind()
    {
        bool isFirst = true;
        if (_dataSource != null)
        {
            foreach (var _dataItem in _dataSource)
            {
                TextView header = new TextView(_context)
                {
                    Text = _dataItem._header
                };
                LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MatchParent, LinearLayout.LayoutParams.WrapContent);
                header.SetTextColor(Color.ParseColor(_settings._headerTextColor));
                header.SetBackgroundColor(Color.ParseColor(_settings._headerBackgroundColor));
                header.LayoutParameters = lp;

                View contentView = _context.LayoutInflater.Inflate(Resource.Layout.DetailItem, null);
                ContentViewHolder holder = new ContentViewHolder();

                InitHolder(holder, contentView);

                FillHolder(holder, _dataItem);
                contentView.Visibility = ViewStates.Gone;
                holder.initialize(contentView);
                contentView.Tag = holder;
                header.AssociatedContent = contentView;
                _mainLayout.AddView(header);
                _mainLayout.AddView(contentView);
            }
        }
    }
    void InitHolder(ContentViewHolder holder, View view)
    {
        holder.imageSlider = view.FindViewById<ViewFlipper>(Resource.Id.imageSlider);
        holder.imagesContainer = view.FindViewById<LinearLayout>(Resource.Id.scrollImagesContainer);
        holder.detailTitle = view.FindViewById<TextView>(Resource.Id.detailTitle);
        holder.detailSubtitle = view.FindViewById<TextView>(Resource.Id.detailSubtitle);
        holder.detailPretext = view.FindViewById<TextView>(Resource.Id.detailPreText);
        holder.detailFeatureList = view.FindViewById<LinearLayout>(Resource.Id.detailFeatureList);
        holder.nextSliderButton = view.FindViewById<ImageButton>(Resource.Id.nextSliderButton);
        holder.prevSliderButton = view.FindViewById<ImageButton>(Resource.Id.prevSliderButton);
    }
    void FillHolder(AccordionContentViewHolder holder, HotelDetailsData dataItem)
    {
        /// filling holder with data
    }
}

Answer 1

线性布局需要一些时间来测量、传递给其子级并正确获取其高度。所以你必须等到它完成。这是代码

试用并运行：JAVA 代码

    linearLayout.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {

            int height = linearLayout.getMeasuredHeight();

            if( Build.VERSION.SDK_INT > 15){
                linearLayout.getViewTreeObserver().removeOnGlobalLayoutListener(this);
            } else {
                linearLayout.getViewTreeObserver().removeGlobalOnLayoutListener(this);
            }
        }
    });

为布局设置监听器，获取高度后，注销GlobalOnLayoutListener

您可以使用linearLayout.getHeight() 或linearLayout.getMeasuredHeight()。在我的测试中，两者都提供了相同的值

XAMARIN 代码

  ViewTreeObserver vto = _linearLayout.ViewTreeObserver;       
  vto.GlobalLayout += (sender, args) => {      
    var ht = linearLayout.Height;
   };

Answer 2

您最好的猜测可能是，您可以获取子项目的高度并将其乘以托管视图中的项目数，而不是尝试获取托管 (LinearLayout) 高度。

编辑：这是可能为您提供所需的解决方案。这个函数可以在onCreate()和onResume()中调用，只要它可以访问初始化的contentContainer。

 public void getHeight(){

    contentContainer.post(new Runnable() {
        @Override
        public void run() {

            int sumHeight=0;
            for(int i=0; i<contentContainer.getChildCount(); i++){
                sumHeight+=contentContainer.getChildAt(i).getHeight();
            }
            Log.d("vidi", "Layout height = " + sumHeight);
        }
    });

正如 Masked Man 很好地指出的那样，如果您的 LinearLayout 中有一些填充或边距，您可以使用 ex. contentContainer.getPaddingBottom 并将其添加到总和中。

.post(Runnable) 的目的只是推迟 Runnable 中的代码，即在 Layout 绘制完成后将这段代码排队运行。