dart - How can I expose a StatefulWidget's method? -

say want build statefulwidget named myslidewidget provides public instance method: animate().

when press button on parent of myslidewidget, can call myslidewidget's animate() method trigger internal slidetransition of myslidewidget.

the usage this:

class myslidewidgetdemo extends statelesswidget {    @override   widget build(buildcontext context) {     myslidewidget myslidewidget = new myslidewidget();      return new scaffold(         body: myslidewidget,         floatingactionbutton: new floatingactionbutton(           onpressed: () {             myslidewidget.animate();           },           tooltip: 'start',           child: new icon(icons.add),         ));   } } 

what wondering how encapsulate implementations of animationcontroller , _controller.forward() inside myslidewidget, user of myslidewidget can call animate().

is possible? or idea way encapsulation in flutter?

you should use animationcontroller , pass slidetransition. call controller.forward() when needed.

here sample:

    class _myhomepagestate extends state<myhomepage> tickerproviderstatemixin {    animationcontroller _controller;   animation<fractionaloffset> _slidetransitionposition;    @override   initstate() {     super.initstate();      _controller = new animationcontroller(       vsync: this,       duration: const duration(milliseconds: 2000),     );      _slidetransitionposition = new fractionaloffsettween(       begin: const fractionaloffset(0.0, -1.0),       end: const fractionaloffset(0.0, 10.0),     ).animate(new curvedanimation(       parent: _controller,       curve: curves.fastoutslowin,     ));   }    void _onpress() {     _controller.forward();   }    @override   widget build(buildcontext context) {     return new scaffold(       appbar: new appbar(         title: new text(widget.title),       ),       body: new container(         child: new slidetransition(           position: _slidetransitionposition,           child: new container(             color: colors.red,             width: 100.0,             height: 100.0,           ),         ),       ),       floatingactionbutton: new floatingactionbutton(         onpressed: _onpress,         tooltip: 'start',         child: new icon(icons.add),       ),     );   } } 

also can find examples in demos