android - 关于 ViewGroup.requestLayout()

Question

我有一个像这样的自定义viewGroup

public class CustomLinearLayout extends LinearLayout {
public CustomLinearLayout(Context context) {
    super(context);
}

public CustomLinearLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
}

@Override
protected void onWindowVisibilityChanged(int visibility) {
    super.onWindowVisibilityChanged(visibility);
    requestLayout();
    System.out.println("right after request layout");
}

@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
    super.onLayout(changed, l, t, r, b);
    System.out.println("on layout");
}

当我运行这个应用程序时，我发现了这样的日志: 怎么会这样？ onLayout() 在 System.out.println("right after request layout"); 之后运行。谁能告诉我为什么？

Answer 1

来自此处的文档:http://developer.android.com/reference/android/view/View.html#requestLayout()

"Call this when something has changed which has invalidated the layout of this view. This will schedule a layout pass of the view tree."

requestLayout() 调用仅安排布局传递，但不会立即执行。