如何检测下拉菜单是否显示在android中的微调器上方或下方？

Question

我正在设计spinner看起来自定义我想要的是当微调器弹出下拉到微调器下面我想使用popupbackground图像不同而当它弹出窗口上方我想使用弹出窗口不同

这是我的Xml代码:

 <Spinner
    android:id="@+id/spinner1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:spinnerMode="dropdown"
    android:popupBackground="@drawable/spinnerbottombg"
    android:overlapAnchor="false"
    android:drawSelectorOnTop="false"

    />

现在问题是我怎么知道微调器打开它上面或下面的下拉列表

Answer 1

我深入挖掘PopupWindow,发现你的要求可以通过

StateListDrawable

以下代码将解释一切 -

activity_main.xml中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context="com.mmbarno.dummyalertdialog.MainActivity">

   <Spinner
       android:id="@+id/spinner"
       android:layout_width="match_parent"
       android:layout_height="wrap_content"
       android:spinnerMode="dropdown"
       android:overlapAnchor="false"
       android:drawSelectorOnTop="false" />
</RelativeLayout>

popup_bg_above.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
   android:shape="rectangle">
   <solid android:color="#FF4081" />
</shape>

popup_bg_below.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
   android:shape="rectangle">
   <solid android:color="#3F51B5" />
</shape>

最后在MainActivity.java中

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Spinner spinner = (Spinner) findViewById(R.id.spinner);
    spinner.setPopupBackgroundDrawable(getPopupBg());
    populateSpinner();
}

private void populateSpinner() {
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
            R.array.planets_array, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setAdapter(adapter);
}

private StateListDrawable getPopupBg() {
    StateListDrawable states = new StateListDrawable();
    int identifier = Resources.getSystem().getIdentifier("state_above_anchor", "attr", "android");
    states.addState(new int[] {identifier}, ContextCompat.getDrawable(this, R.drawable.popup_bg_below));
    states.addState(new int[]{}, ContextCompat.getDrawable(this, R.drawable.popup_bg_above));
    return states;
}

希望您的要求得到满足.我和ScrollView一起在不同的场景中测试了它.它完美无缺.