private void HandleSelfFittingAndChildrenSizeAlongAxis(int axis)
{
FitMode fitting = (axis == 0 ? horizontalFit : verticalFit);
if (fitting != FitMode.Unconstrained)
{
m_Tracker.Add(this, rectTransform,
(axis == 0 ? DrivenTransformProperties.SizeDeltaX : DrivenTransformProperties.SizeDeltaY));
rectTransform.SetSizeWithCurrentAnchors((RectTransform.Axis)axis, GetTotalPreferredSize(axis));
}
SelfSizeRatioMode sizeRatioMode = (axis == 0 ? selfSizeWidthRatio : selfSizeHeightRatio);
if (sizeRatioMode != SelfSizeRatioMode.Unconstrained)
{
bool needRebuild = false;
if (sizeRatioMode == SelfSizeRatioMode.RelativeParent && rectTransform.parent != null &&
rectTransform.parent is RectTransform)
{
//如果是限制在父对象内部，则限制的区域为
//父对象的宽和高减去limitPadding的水平和竖直间隔范围内
float preferred = LayoutUtility.GetPreferredSize(rectTransform.parent as RectTransform, axis) - (axis == 0 ? limitPadding.horizontal : limitPadding.vertical);
preferred = Mathf.Max(0, preferred);
preferred = axis == 0
? Mathf.Clamp(GetTotalPreferredSize(axis), m_MinWidthRatio * preferred, m_MaxWidthRatio * preferred)
: Mathf.Clamp(GetTotalPreferredSize(axis), m_MinHeightRatio * preferred, m_MaxHeightRatio * preferred);
m_Tracker.Add(this, rectTransform,
(axis == 0 ? DrivenTransformProperties.SizeDeltaX : DrivenTransformProperties.SizeDeltaY));
needRebuild = axis == 1 && (m_NeedRebuildCurrentFrame != Time.frameCount) && !Mathf.Approximately(preferred, GetTotalPreferredSize(1));
rectTransform.SetSizeWithCurrentAnchors((RectTransform.Axis)axis, preferred);
SetLayoutInputForAxis(preferred, preferred, -1, axis);
}
else if (sizeRatioMode == SelfSizeRatioMode.FixedSize)
{
float preferred = (axis == 0 ? fixedSize.x: fixedSize.y) - (axis == 0 ? limitPadding.horizontal : limitPadding.vertical);
preferred = axis == 0
? Mathf.Clamp(GetTotalPreferredSize(axis), m_MinWidthRatio * preferred, m_MaxWidthRatio * preferred)
: Mathf.Clamp(GetTotalPreferredSize(axis), m_MinHeightRatio * preferred, m_MaxHeightRatio * preferred);
m_Tracker.Add(this, rectTransform,
(axis == 0 ? DrivenTransformProperties.SizeDeltaX : DrivenTransformProperties.SizeDeltaY));
needRebuild = axis == 1 && (m_NeedRebuildCurrentFrame != Time.frameCount) && !Mathf.Approximately(preferred, GetTotalPreferredSize(1));
rectTransform.SetSizeWithCurrentAnchors((RectTransform.Axis)axis, preferred);
SetLayoutInputForAxis(preferred, preferred, -1, axis);
}
if (needRebuild)
{
//高度约束导致高度变化的情况下，需要重新计算布局，因为可能宽度也变了，但是宽度是提前算的，不重新算，会导致得到错误的值
m_NeedRebuildCurrentFrame = Time.frameCount;
LayoutRebuilderUtility.MarkLayoutForImmediateRebuild(rectTransform);
return;
}
}
}
