horizontal method

Transform horizontal(double aniValue, int index, double page, Widget child,)

Implementation

Transform horizontal(double aniValue, int index, double page, Widget child) {
  var alignment = Alignment.centerRight;
  var value = 1 - aniValue;
  if (page >= index) {
    /// _pageController.page > index 向右滑动 划出下一页 下一页可见
    return Transform(
      transform: Matrix4.identity()
        ..setEntry(3, 2, -0.001)
        ..rotateY(math.pi / -2 * value),
      alignment: alignment,
      child: child,
    );
  } else {
    /// _pageController.page < index 向下滑动 划出上一页
    alignment = Alignment.centerLeft;
    var angle = originAngle - originAngle * aniValue;
    return Transform(
      transform: Matrix4.identity()
        ..setEntry(3, 2, 0.001)
        ..scale(initialScale + 0.2 * aniValue, initialScale + 0.2 * aniValue, 1)
        ..rotateY(angle.clamp(0, math.pi / 2)),
      alignment: alignment,
      child: Opacity(opacity: .5 + .5 * aniValue.abs(), child: child),
    );
  }
}