initAnimation method

Implementation

@override
void initAnimation(AnimationController controller) {
  // Note: This calculation is the only reason why [textStyle] is required
  final tuning = (300.0 * colors.length) *
      (textStyle!.fontSize! / 24.0) *
      0.75 *
      (textCharacters.length / 15.0);

  _fadeIn = Tween<double>(begin: 0.0, end: 1.0).animate(
    CurvedAnimation(
      parent: controller,
      curve: const Interval(0.0, 0.1, curve: Curves.easeOut),
    ),
  );

  _fadeOut = Tween<double>(begin: 1.0, end: 1.0).animate(
    CurvedAnimation(
      parent: controller,
      curve: const Interval(0.9, 1.0, curve: Curves.easeIn),
    ),
  );

  final colorShift = colors.length * tuning;
  final colorTween = textDirection == TextDirection.ltr
      ? Tween<double>(
          begin: 0.0,
          end: colorShift,
        )
      : Tween<double>(
          begin: colorShift,
          end: 0.0,
        );
  _colorShifter = colorTween.animate(
    CurvedAnimation(
      parent: controller,
      curve: const Interval(0.0, 1.0, curve: Curves.easeIn),
    ),
  );

  // With RTL, colors need to be reversed to compensate for colorTween
  // counting down instead of up.
  _colors = textDirection == TextDirection.ltr
      ? colors
      : colors.reversed.toList(growable: false);
}