android - 获取 ListView / View 中第一项的可见高度

Question

我需要在 listivew 中获取页眉的可见高度。如何在 Listview(Header) 或任何 View 中获取第一项的高度。

我尝试了下面给出的方法，但这些方法给我的是项目的原始高度，而不是可见高度。

 view.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
 @SuppressLint("NewApi")
 @SuppressWarnings("deprecation")
 @Override
  public void onGlobalLayout() {
   //now we can retrieve the width and height
   int width = view.getWidth();
   int height = view.getHeight();
   //...
   //do whatever you want with them
   //...
   //this is an important step not to keep receiving callbacks:
   //we should remove this listener
   //I use the function to remove it based on the api level!

if(android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.JELLY_BEAN)
    view.getViewTreeObserver().removeOnGlobalLayoutListener(this);
   else
    view.getViewTreeObserver().removeGlobalOnLayoutListener(this);
  }
 });

和

view.measure(MeasureSpec.UNSPECIFIED, MeasureSpec.UNSPECIFIED);
int widht = view.getMeasuredWidth();
int height = view.getMeasuredHeight();

还有这个

DisplayMetrics metrics = new DisplayMetrics();
      getWindowManager().getDefaultDisplay().getMetrics(metrics); height =
      metrics.heightPixels; width = metrics.widthPixels;

但没有得到任何结果。提前致谢

Answer 1

你可以试试这个。让你的布局文件如下:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/rl_container"
    android:layout_height="match_parent" 
    android:layout_width="match_parent">

    <ListView
        android:id="@+id/sample_list_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
</RelativeLayout>

在您的 Activity java 文件中:

ListView mListView = (ListView) findViewById(R.id.sample_list_view);
mListView.setAdapter(mAdapter);

// add header view.
// Let "mHeaderView" is a header view inflated from some layout file
mListView.addHeaderView(mHeaderView);

// let your listview's parent view (in layout file) is a relative layout
// with id = "rl_container" as shown in above XML layout file
RelativeLayout rlContainer = (RelativeLayout)findViewById(R.id.rl_container);

// To find visible height of the first item (header in this case)
// mListView.getChildAt(i) return view of the ith child from top.
// header is considered to be as 0th child.
// not sure about multiple headers. but it should be same.
View childView = mListView.getChildAt(0);

// visible height is bottom cordinate of the child view - top cordinate of the list view's parent container.
// here I am considering list view as the top child of its parent container.
// code can be modified accordingly to consider margins from top.
int visibleHeight = childView.getBottom() - rlContainer.getTop();
if(visibleHeight < 0) {
    //then item is not visible
}

它对我有用，因为我在我的项目中使用它。欢迎提出意见和建议。