如何在颤动中检测键盘完成动画

Question

In my page I have textfield and when tap in textfield open keyboard, Now I want know when finished keyboard open animation. When I use any packages about keyboard, keyboard visible property becomes true when starting animation.

Answer 1

You can add listener to the class you want to observe. For example

     class KeyboardTogglePage extends StatefulWidget {
        @override
        _KeyboardTogglePageState createState() => _KeyboardTogglePageState();
      }
    
     class _KeyboardTogglePageState extends State<KeyboardTogglePage>
          with WidgetsBindingObserver {
        @override
        void initState() {
          super.initState();
          WidgetsBinding.instance.addObserver(this);
        }
    
        @override
        void dispose() {
          WidgetsBinding.instance.removeObserver(this);
          super.dispose();
        }
    
        var isKeyboardOpen = false;
    
        ///
        /// This routine is invoked when the window metrics have changed.
        ///
        @override
        void didChangeMetrics() {
          final value = MediaQuery.of(context).viewInsets.bottom;
          if (value > 0) {
            if (isKeyboardOpen) {
              _onKeyboardChanged(false);
            }
            isKeyboardOpen = false;
          } else {
            isKeyboardOpen = true;
            _onKeyboardChanged(true);
          }
        }
    
        _onKeyboardChanged(bool isVisible) {
          if (isVisible) {
            print("KEYBOARD VISIBLE");
          } else {
            print("KEYBOARD HIDDEN");
          }
        }
    
        @override
        Widget build(BuildContext context) {
          return Container(
            child: Center(
              child: TextField(),
            ),
          );
        }
      }

Credit from here. https://stackoverflow.com/a/52140861/11612628