如何在子父尺寸相同时将坐标转换为Flutter的Alignment？

我正在尝试将父容器中子组件的像素坐标（x、y）转换为Flutter的Alignment对应的x、y值。参考Flutter自带的Alignment.inscribe方法，我编写了如下TypeScript转换函数：

function convertPositionToAlignment(
  parentWidth: number,
  parentHeight: number,
  childX: number,
  childY: number,
  childWidth: number,
  childHeight: number
): AlignmentModel {
  const halfWidthDelta = (parentWidth - childWidth) / 2;
  const halfHeightDelta = (parentHeight - childHeight) / 2;

  let x;
  if (halfWidthDelta != 0) {
    x = (childX - halfWidthDelta) / halfWidthDelta;
  } else {
    x = 0;
  }
  let y;
  if (halfHeightDelta != 0) {
    y = (childY - halfHeightDelta) / halfHeightDelta;
  } else {
    y = 0;
  }

  return new AlignmentModel(new AlignmentData(x, y));
}

对比Flutter原生的Alignment.inscribe Dart函数：

/// Returns a rect of the given size, aligned within given rect as specified
/// by this alignment.
///
/// For example, a 100×100 size inscribed on a 200×200 rect using
/// [Alignment.topLeft] would be the 100×100 rect at the top left of
/// the 200×200 rect.
Rect inscribe(Size size, Rect rect) {
  final double halfWidthDelta = (rect.width - size.width) / 2.0;
  final double halfHeightDelta = (rect.height - size.height) / 2.0;
  return Rect.fromLTWH(
    rect.left + halfWidthDelta + x * halfWidthDelta,
    rect.top + halfHeightDelta + y * halfHeightDelta,
    size.width,
    size.height,
  );
}

当前代码存在边缘场景问题：当子组件尺寸与父容器完全相同时，会返回0值（如果没有判断逻辑则会出现无穷大/NaN）。但实际场景中，即使两者尺寸一致，我们也应该能得到正确的对齐值——比如下面两种场景：

VS

当前这种场景下，y轴的Alignment值会被强制设为0，但从坐标空间来看，其实可以计算出正确的对齐结果。想请教有没有方法解决这个问题？

内容的提问来源于stack exchange，提问作者Saad Ardati