protected void UpdateView()
{
if (!m_isValid)
{
return;
}
//计算view range
Vector2 curContentPos = content.localPosition;
int minIndex = -1;
int maxIndex = -1;
switch (m_layoutDirection)
{
case LayoutDirection.Horizontal:
float minViewX = -curContentPos.x - m_layout.originSpace;
float maxViewX = minViewX + m_viewportSize.x;
minIndex = Mathf.CeilToInt(minViewX / (m_itemSize.x + m_layout.spacing)) - 1;
maxIndex = Mathf.CeilToInt(maxViewX / (m_itemSize.x + m_layout.spacing)) - 1;
break;
case LayoutDirection.Vertical:
float minViewY = curContentPos.y - m_layout.originSpace;
float maxViewY = minViewY + m_viewportSize.y;
minIndex = Mathf.CeilToInt(minViewY / (m_itemSize.y + m_layout.spacing)) - 1;
maxIndex = Mathf.CeilToInt(maxViewY / (m_itemSize.y + m_layout.spacing)) - 1;
break;
}
IndexRange viewRange = new IndexRange(minIndex, maxIndex);
viewRange.Clamp(0, m_itemIds.Count - 1);
//更新view
if (viewRange.IsInRange(m_curContentRange))
{
return;
}
int dif = m_cacheitems.Count - viewRange.count;
dif = Mathf.Max(0, dif);
int startIdx = viewRange.minIndex - dif / 2;
m_curContentRange = new IndexRange(startIdx, startIdx + m_cacheitems.Count - 1);
m_curContentRange.Clamp(0, m_itemIds.Count - 1);
showItems();
}