方法得到的视图返回位置0 [英] Methods to get position of view returns 0

问题描述

这个问题已经被问了好几次，但每个人都给出了，为什么发生这种情况的原因（即布局奠定了之前发生计算）。但我需要这个解决方案。我试过 getBottom（）; ，共达（）; ， getLocationOnScreen将（INT []的位置）; 。但是，所有返回值零（0）。我甚至尝试在 ONSTART（）给这些; ，以便有时间布局铺设，但没有运气。 这是我的code：

This question has been asked several times, but everyone gives the reason for why this occurs (i.e. calculation occurs before the layout is laid). But I need the solution for this. I tried getBottom();, getTop();, getLocationOnScreen(int[] location);. But all returns the value Zero (0). I even tried giving these in onStart();, to give time for layout to be laid, but no luck. Here is my code:

TextView tv;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    tv = (TextView) findViewById(R.id.textView1);
    Log.d("getBottom   :", Integer.toString(tv.getBottom()));
    Log.d("gettop      :", Integer.toString(tv.getTop()));

    int[] location = new int[2];
    tv.getLocationOnScreen(location);
    Log.d("getlocationonscreen values :", Integer.toString(location[0])+"  "+Integer.toString(location[1]));
}
@Override
protected void onStart() {
    Log.d("getBottom in onStart :", Integer.toString(tv.getBottom()));
    Log.d("gettop in onStart    :", Integer.toString(tv.getTop()));

    int[] location = new int[2];
    tv.getLocationOnScreen(location);
    Log.d("getlocationonscreen in onStart :", Integer.toString(location[0])+"  "+Integer.toString(location[1]));
    super.onStart();
}

布局XML：

Layout XML:

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

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="156dp"
    android:text="Medium Text"
    android:textAppearance="?android:attr/textAppearanceMedium" />

</RelativeLayout>

此外，我对重复的问题深表歉意。先谢谢了。

Again, I apologize for repeating the question. Thanks in advance.

推荐答案

您把测量中的<一个href="http://developer.android.com/reference/android/app/Activity.html#onWindowFocusChanged%28boolean%29"><$c$c>onWindowFocusChanged()-method.
正如文件指出：

You put the 'measuring' in the onWindowFocusChanged()-method.
As the documentation states:

这是这种活性是否是对用户可见的最佳指标。

This is the best indicator of whether this activity is visible to the user.

您也可以把它放在<一href="http://developer.android.com/reference/android/app/Activity.html#onResume%28%29"><$c$c>onResume()这是在申请前的最后一个步骤是完全在屏幕上和主动，但是：

You could also put it in the onResume() which is the last step before the application is completely on screen and active, however:

请记住，onResume不是你的活动是对用户可见的最佳指标;一个系统窗口，如键盘锁可能是在前面。使用onWindowFocusChanged（布尔值）要肯定知道您的活动是用户可见的（例如，恢复一个游戏）。

Keep in mind that onResume is not the best indicator that your activity is visible to the user; a system window such as the keyguard may be in front. Use onWindowFocusChanged(boolean) to know for certain that your activity is visible to the user (for example, to resume a game).

如果尚未显示的窗口/视图但不保证，它有其测量结果，因此，previous方法会更好。

If the window/view has not yet been displayed there is no guarantee that it has its measurements, thus the previous method would be better.

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