public override void SetLayoutVertical()
{
HandleSelfFittingAndChildrenSizeAlongAxis(1);
if (m_ProcessLayoutVertical)
{
return;
}
//对于高度限制的Item的设计，不要立刻派发布局完成，可能导致改变了宽度，需要重新计算
//一般不要设置这个属性，会导致两遍计算
if (m_NeedRecalculate)
{
m_ProcessLayoutVertical = true;
LayoutRebuilderUtility.ForceRebuildLayoutImmediate(rectTransform);
}
if (m_LayoutGroupComplete != null)
{
m_ProcessLayoutVertical = false;
m_LayoutGroupComplete.Invoke();
}
}
protected bool SetChildrenAlongAxis(bool isVertical)
{
for (int axis = 0; axis < 2; ++axis)
{
float size = rectTransform.rect.size[axis];
float startOffset = -m_TopStartPosition;
bool alongOtherAxis = (isVertical ^ (axis == 1));
if (alongOtherAxis)
{
float innerSize = size;
startOffset = 0;
for (int i = 0; i < itemViewChildren.Count; i++)
{
var child = itemViewChildren[i].ItemRectTransform;
var itemSize = LayoutUtility.GetPreferredSize(child, axis);
SetChildItemAlongAxis(child, axis, startOffset, innerSize);
if (!Mathf.Approximately(itemSize, innerSize))
{
LayoutRebuilderUtility.ForceRebuildLayoutImmediate(child);
return(true);
}
}
}
else
{
for (int i = 0; i < itemViewChildren.Count; i++)
{
var child = itemViewChildren[i].ItemRectTransform;
var itemSize = LayoutUtility.GetPreferredSize(child, axis);
SetChildItemAlongAxis(child, axis, startOffset, itemSize);
startOffset += itemSize + m_Divider;
}
}
}
return(false);
}
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;
}
}
}
public static bool IsRectTransformLayoutRebuild(RectTransform rectTransform)
{
return(!CanvasUpdateRegistry.TryRegisterCanvasElementForLayoutRebuild(LayoutRebuilderUtility.GetLayoutRebuilder(rectTransform)));
}
