public override void RequestLayout(float scrollPosition, bool force = false)
{
// Layouting is only possible after once it initialized.
if (!IsInitialized)
{
return;
}
int LastIndex = colView.InternalItemSource.Count - 1;
if (!force && PrevScrollPosition == Math.Abs(scrollPosition))
{
return;
}
PrevScrollPosition = Math.Abs(scrollPosition);
if (ItemSizeChanged >= 0)
{
for (int i = ItemSizeChanged; i <= LastIndex; i++)
{
UpdatePosition(i);
}
ScrollContentSize = ItemPosition[LastIndex - 1] + GetItemSize(LastIndex);
}
int prevFirstVisible = FirstVisible;
int prevLastVisible = LastVisible;
(float X, float Y)visibleArea = (PrevScrollPosition,
PrevScrollPosition + (IsHorizontal ? colView.Size.Width : colView.Size.Height)
);
// 1. Set First/Last Visible Item Index.
(int start, int end) = FindVisibleItems(visibleArea);
FirstVisible = start;
LastVisible = end;
// 2. Unrealize invisible items.
List <RecyclerViewItem> unrealizedItems = new List <RecyclerViewItem>();
foreach (RecyclerViewItem item in VisibleItems)
{
if (item.Index < FirstVisible || item.Index > LastVisible)
{
//Console.WriteLine("[NUI] Unrealize{0}!", item.Index);
unrealizedItems.Add(item);
colView.UnrealizeItem(item);
}
}
VisibleItems.RemoveAll(unrealizedItems.Contains);
// 3. Realize and placing visible items.
for (int i = FirstVisible; i <= LastVisible; i++)
{
RecyclerViewItem item = null;
// 4. Get item if visible or realize new.
if (i >= prevFirstVisible && i <= prevLastVisible)
{
item = GetVisibleItem(i);
if (item)
{
continue;
}
}
if (item == null)
{
item = colView.RealizeItem(i);
}
VisibleItems.Add(item);
// 5. Placing item.
float posX = 0F, posY = 0F;
if (isGrouped)
{
//isHeader?
if (colView.Header == item)
{
posX = 0F;
posY = 0F;
}
else if (colView.Footer == item)
{
posX = (IsHorizontal ? ScrollContentSize - item.SizeWidth : 0F);
posY = (IsHorizontal ? 0F : ScrollContentSize - item.SizeHeight);
}
else
{
GroupInfo gInfo = GetGroupInfo(i);
posX = (IsHorizontal ? gInfo.GroupPosition + gInfo.ItemPosition[i - gInfo.StartIndex] : 0F);
posY = (IsHorizontal ? 0F : gInfo.GroupPosition + gInfo.ItemPosition[i - gInfo.StartIndex]);
}
}
else
{
posX = (IsHorizontal ? ItemPosition[i] : 0F);
posY = (IsHorizontal ? 0F : ItemPosition[i]);
}
item.Position = new Position(posX, posY);
//Console.WriteLine("[NUI] ["+item+"]["+item.Index+"] :: ["+item.Position.X+", "+item.Position.Y+"] ==== \n");
}
}
/// <summary>
/// This is called to find out where items are lain out according to current scroll position.
/// </summary>
/// <param name="scrollPosition">Scroll position which is calculated by ScrollableBase</param>
/// <param name="force">boolean force flag to layouting forcely.</param>
public override void RequestLayout(float scrollPosition, bool force = false)
{
// Layouting is only possible after once it intialized.
if (!IsInitialized)
{
return;
}
int LastIndex = colView.InternalItemSource.Count;
if (!force && PrevScrollPosition == Math.Abs(scrollPosition))
{
return;
}
PrevScrollPosition = Math.Abs(scrollPosition);
int prevFirstVisible = FirstVisible;
int prevLastVisible = LastVisible;
bool IsHorizontal = (colView.ScrollingDirection == ScrollableBase.Direction.Horizontal);
(float X, float Y)visibleArea = (PrevScrollPosition,
PrevScrollPosition + (IsHorizontal ? colView.Size.Width : colView.Size.Height)
);
//Console.WriteLine("[NUI] itemsView [{0},{1}] [{2},{3}]", colView.Size.Width, colView.Size.Height, colView.ContentContainer.Size.Width, colView.ContentContainer.Size.Height);
// 1. Set First/Last Visible Item Index.
(int start, int end) = FindVisibleItems(visibleArea);
FirstVisible = start;
LastVisible = end;
//Console.WriteLine("[NUI] {0} :visibleArea before [{1},{2}] after [{3},{4}]", scrollPosition, prevFirstVisible, prevLastVisible, FirstVisible, LastVisible);
// 2. Unrealize invisible items.
List <RecyclerViewItem> unrealizedItems = new List <RecyclerViewItem>();
foreach (RecyclerViewItem item in VisibleItems)
{
if (item.Index < FirstVisible || item.Index > LastVisible)
{
//Console.WriteLine("[NUI] Unrealize{0}!", item.Index);
unrealizedItems.Add(item);
colView.UnrealizeItem(item);
}
}
VisibleItems.RemoveAll(unrealizedItems.Contains);
//Console.WriteLine("Realize Begin [{0} to {1}]", FirstVisible, LastVisible);
// 3. Realize and placing visible items.
for (int i = FirstVisible; i <= LastVisible; i++)
{
//Console.WriteLine("[NUI] Realize!");
RecyclerViewItem item = null;
// 4. Get item if visible or realize new.
if (i >= prevFirstVisible && i <= prevLastVisible)
{
item = GetVisibleItem(i);
if (item)
{
continue;
}
}
if (item == null)
{
item = colView.RealizeItem(i);
}
VisibleItems.Add(item);
(float x, float y) = GetItemPosition(i);
// 5. Placing item.
item.Position = new Position(x, y);
//Console.WriteLine("[NUI] ["+item.Index+"] ["+item.Position.X+", "+item.Position.Y+" ==== \n");
}
//Console.WriteLine("Realize Done");
}