android - getRight、getLeft、getTop 返回零

Question

我正在使用以下代码。但是所有方法都返回零值。我知道要获得 View 的坐标，我们的 View 应该被绘制。这就是为什么我在 onResume 方法中使用代码但仍然无法正常工作的原因。有什么想法吗？

 @Override
public void onResume(){
    super.onResume();
    System.out.println("Onresume"); 
    System.out.println("tab1 - left" + btn_Tab7 .getLeft());
    System.out.println("tab1 - Top" + btn_Tab7.getTop());
    System.out.println("tab1 - right" + btn_Tab7.getRight());
    System.out.println("tab1 - bottom" + btn_Tab7.getBottom()); 
}

Answer 1

在 onResume 中调用 getLeft、getRight 还为时过早...在 onWindowFocusChanged

中执行

@Override
public void onWindowFocusChanged (boolean hasFocus){
    super.onWindowFocusChanged(hasFocus);
    if(hasFocus){
        System.out.println("onWindowFocusChanged"); 
        System.out.println("tab1 - left" + btn_Tab7 .getLeft());
        System.out.println("tab1 - Top" + btn_Tab7.getTop());
        System.out.println("tab1 - right" + btn_Tab7.getRight());
        System.out.println("tab1 - bottom" + btn_Tab7.getBottom());
    }
}

来自 onResume 的文档:

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).