android - 如何在 fragment 中获取按钮的宽度/高度

Question

如何在 fragment 中获取任何 View (Button、TextView、RelativeLayout)的高度/宽度，我尝试类似的方法

 public static class FirstDemoFragment extends Fragment {

    int width,height;
    private Button button;

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_layout, container, false);
        button = (Button) view.findViewById(R.id.fragment_demo_button);

        width =  button.getWidth();
        height = button.getHeight();


        System.out.println("==== View Width : " + width);
        System.out.println("==== View height : " + height);

        width = button.getMeasuredWidth();
        height = button.getMeasuredHeight();


        System.out.println("==== View Width : " + width);
        System.out.println("==== View height : " + height);

        return view;
    }

我的layout.xml文件是

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/does_really_work_with_fragments"
    android:id="@+id/fragment_demo_button"
    android:layout_centerInParent="true" />

我对此进行了一些研究，我使用这种方法找到了 Activity 中按钮的宽度/高度。

@Override
public void onWindowFocusChanged(boolean hasFocus) {
    // TODO Auto-generated method stub
    super.onWindowFocusChanged(hasFocus);
    relMain = (RelativeLayout) findViewById(R.id.layoutMain);

    width = relMain.getMeasuredWidth();
    height = relMain.getMeasuredHeight();

    width = relMain.getWidth();
    height = relMain.getHeight();

    //System.out.println("=== Width : " + width);
    //System.out.println("=== height : " + height);


}

但是 onWindowFocusChanged() 在 android Fragment 中不可用？

Answer 1

在 Fragment 的 onCreateView 方法中尝试下面的代码:

button = (Button) view.findViewById(R.id.fragment_demo_button);   
     ViewTreeObserver vto = button.getViewTreeObserver();
        vto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
            public boolean onPreDraw() {
                button.getViewTreeObserver().removeOnPreDrawListener(this);
                Log.d("", "Height: " + button.getMeasuredHeight()+ " Width: " + button.getMeasuredWidth());
                return true;
            }
        });