"WidgetsBinding.instance!.addPostFrameCallback((_) => yourFunction(context));" does not execute

Question

So I created a custom NavBar, when you click on the icons it runs the animations for the icon.

Problem: When starting the application the animation of a specific icon should be executed. For that i looked for a method that runs on Widget build complete.

Code I found:

void initState() {
super.initState();
WidgetsBinding.instance
    .addPostFrameCallback((_) => yourFunction(context));}

My code:

class NavBar extends StatefulWidget {
  NavBar({Key? key}) : super(key: key);

  @override
  _NavBarState createState() => _NavBarState();
}

class _NavBarState extends State<NavBar> {
  List<IconSpecs> iconSpecsLst = [
    IconSpecs(name: 'list', height: 69, width: 69),
    IconSpecs(name: 'checkmark', height: 60, width: 60),
    IconSpecs(name: 'settings', height: 60, width: 60),
  ];

  late List<RiveIcon> icons;

  @override
  void initState() {
    super.initState();
    icons = iconSpecsLst
        .map(
          (object) => RiveIcon(
            iconSpecs: object,
          ),
        )
        .toList();
    WidgetsBinding.instance!
        .addPostFrameCallback((_) => setAnimation(icons, 2));
  }

  setAnimation(List<RiveIcon> icons, int active) {
    icons[active].activeInput?.value = true;

    for (int i = 0; i < icons.length; i++) {
      if (i != active) {
        icons[i].activeInput?.value = false;
      }
    }
  }

I added it to my code but it doesn't get executed. I don't have any error message.

Andrey Gordeev · Accepted Answer · 2022-04-17 12:17:54Z

2

The callback isn't called if there's no next frame drawn.

To force draw the next frame, call ensureVisualUpdate:

WidgetsBinding.instance!.addPostFrameCallback((_) {
  setAnimation(icons, 2);
});

WidgetsBinding.instance!.ensureVisualUpdate();

edited Apr 17, 2022 at 12:17

answered Apr 8, 2022 at 7:59

Andrey Gordeev

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1 Comment

maddy Over a year ago

ensureVisualUpdate interesting

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