didChangeMetrics method
窗口尺寸变化回调 当窗口尺寸变化时被调用，通常是旋转设备或者是窗口大小调整时。
Called when the window size changes (e.g., device rotation or resizing).
Implementation
@override
void didChangeMetrics() {
super.didChangeMetrics();
loge("Window metrics changed");
}