Invalid curve endpoint at 1.0

[saikiranVu]

Invalid curve endpoint at 1.0

Curves must map 0.0 to near zero and 1.0 to near one but ShakeCurve mapped 1.0 to 3.6739403974420594e-16, which is near 0.0.

@OverRide
initState() {
super.initState();
streamSubscription = widget.shouldTriggerVerification.listen((isValid) => _showValidation(isValid));
controller = AnimationController(duration: const Duration(milliseconds: 500), vsync: this);
final Animation curve = CurvedAnimation(parent: controller, curve: ShakeCurve());
animation = Tween(begin: 0.0, end: ### 10.0).animate(curve)
..addStatusListener((status) {
if (status == AnimationStatus.completed) {
setState(() {
enteredPasscode = '';
controller.value = 0;
});
}
})
..addListener(() {
setState(() {
// the animation object’s value is the changed state
});
});
}

[xPutnikx]

Hi, @saikiranVu
Can you explain what is the problem? It's not really clear

[ernestowusu]

Another exception was thrown: Invalid curve endpoint at 1.0. I get this same error on IOS when a passcode is typed and the shaking animation is triggered

[maginc]

Sometimes i have same glitch, error from console:

The following assertion was thrown building LayoutBuilder:
Invalid curve endpoint at 1.0.

Curves must map 0.0 to near zero and 1.0 to near one but ShakeCurve mapped 1.0 to 3.6739403974420594e-16, which is near 0.0.
The relevant error-causing widget was: 
 OrientationBuilder file:///Users/me/AndroidStudioProjects/myapp/lib/common/pin_input_widget/passcode_screen.dart:90:16
When the exception was thrown, this was the stack: 
#0      CurvedAnimation.value.<anonymous closure> (package:flutter/src/animation/animations.dart:442:11)
#1      CurvedAnimation.value (package:flutter/src/animation/animations.dart:450:8)
#2      Animatable.evaluate (package:flutter/src/animation/tween.dart:54:66)
#3      _AnimatedEvaluation.value (package:flutter/src/animation/tween.dart:88:31)
#4      _PasscodeScreenState._buildCircles (package:myapp/common/pin_input_widget/passcode_screen.dart:196:31)
...
═══════════════════════════════════════════════════════════════════════════════```

I don't know how to replicate this, as it appears randomly.

[ssanderson]

This assertion triggers reliably for me if I enter a pin incorrectly on the PasscodeScreen using flutter_test. It looks like the issue here is that flutter's Curve class expects you to define a transform function that ranges from 0 to 1 as a function of t going from 0 to 1.

From https://api.flutter.dev/flutter/animation/Curve-class.html:

A Curve must map t=0.0 to 0.0 and t=1.0 to 1.0.

The current ShakeCurve definition is

class ShakeCurve extends Curve {
  @override
  double transform(double t) {
    //t from 0.0 to 1.0
    return sin(t * 3 * pi).abs();
  }
}

Which doesn't satisfy the required property. Specificaly sin(3 * pi).abs() is 0, not 1.

If I change the function to be sin(2.5 * pi).abs() instead, the assertion no longer triggers.

[ZephyrVentum]

Thanks, it helped to figure out what was wrong in my case. Working code for me now:

class CurveWave extends Curve {
  const CurveWave();

  @override
  double transform(double t) {
    if (t == 0) {
      return 0.01;
    } else if (t == 1) {
      return 0.99;
    }
    return math.sin(t * math.pi);
  }
}