/// <summary>
/// Realize indexed item.
/// </summary>
/// <param name="index"> Index position of realizing item </param>
internal virtual RecyclerViewItem RealizeItem(int index)
{
object context = InternalItemSource.GetItem(index);
// Check DataTemplate is Same!
if (ItemTemplate is DataTemplateSelector)
{
// Need to implements for caching of selector!
}
else
{
// pop item
RecyclerViewItem item = PopRecycleCache(ItemTemplate);
if (item != null)
{
DecorateItem(item, index, context);
return(item);
}
}
object content = DataTemplateExtensions.CreateContent(ItemTemplate, context, (BindableObject)this) ?? throw new Exception("Template return null object.");
if (content is RecyclerViewItem)
{
RecyclerViewItem item = (RecyclerViewItem)content;
ContentContainer.Add(item);
DecorateItem(item, index, context);
return(item);
}
else
{
throw new Exception("Template content must be type of ViewItem");
}
}
protected virtual void MeasureChild(RecyclerView parent, RecyclerViewItem child)
{
if (parent == null)
{
throw new ArgumentNullException(nameof(parent));
}
if (child == null)
{
throw new ArgumentNullException(nameof(child));
}
if (child.Layout == null)
{
return;
}
//FIXME: This measure can be restricted size of child to be less than parent size.
// but our parent can be not calculated yet, also some child can be bigger than it's parent size,
// so we use implicit value 9999 as restricted specification.
MeasureSpecification childWidthMeasureSpec = LayoutGroup.GetChildMeasureSpecification(
new MeasureSpecification(new LayoutLength(9999), MeasureSpecification.ModeType.Exactly),
new LayoutLength(0),
new LayoutLength(child.WidthSpecification));
MeasureSpecification childHeightMeasureSpec = LayoutGroup.GetChildMeasureSpecification(
new MeasureSpecification(new LayoutLength(9999), MeasureSpecification.ModeType.Exactly),
new LayoutLength(0),
new LayoutLength(child.HeightSpecification));
child.Layout.Measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
protected virtual void MeasureChild(RecyclerView parent, RecyclerViewItem child)
{
if (parent == null)
{
throw new ArgumentNullException(nameof(parent));
}
if (child == null)
{
throw new ArgumentNullException(nameof(child));
}
if (child.Layout == null)
{
return;
}
//FIXME: This measure can be restricted size of child to be less than parent size.
// but in some multiple-line TextLabel can be long enough to over the it's parent size.
MeasureSpecification childWidthMeasureSpec = LayoutGroup.GetChildMeasureSpecification(
new MeasureSpecification(new LayoutLength(parent.Size.Width - parent.Padding.Start - parent.Padding.End - child.Margin.Start - child.Margin.End), MeasureSpecification.ModeType.Exactly),
new LayoutLength(0),
new LayoutLength(child.WidthSpecification));
MeasureSpecification childHeightMeasureSpec = LayoutGroup.GetChildMeasureSpecification(
new MeasureSpecification(new LayoutLength(parent.Size.Height - parent.Padding.Top - parent.Padding.Bottom - child.Margin.Top - child.Margin.Bottom), MeasureSpecification.ModeType.Exactly),
new LayoutLength(0),
new LayoutLength(child.HeightSpecification));
child.Layout.Measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
private void DecorateItem(RecyclerViewItem item, int index, object context)
{
item.Index = index;
item.ParentItemsView = this;
item.Template = (ItemTemplate as DataTemplateSelector)?.SelectDataTemplate(InternalItemSource.GetItem(index), this) ?? ItemTemplate;
item.BindingContext = context;
item.Relayout += OnItemRelayout;
}
protected virtual RecyclerViewItem PopRecycleCache(DataTemplate Template)
{
for (int i = 0; i < RecycleCache.Count; i++)
{
RecyclerViewItem item = RecycleCache[i];
if (item.Template == Template)
{
RecycleCache.Remove(item);
item.Show();
return(item);
}
}
return(null);
}
public override void NotifyItemSizeChanged(RecyclerViewItem item)
{
if (item == null)
{
throw new ArgumentNullException(nameof(item));
}
if (!IsInitialized ||
(colView.SizingStrategy == ItemSizingStrategy.MeasureFirst &&
item.Index != 0) ||
(item.Index < 0))
{
return;
}
float PrevSize, CurrentSize;
if (item.Index == (colView.InternalItemSource.Count - 1))
{
PrevSize = ScrollContentSize - ItemPosition[item.Index];
}
else
{
PrevSize = ItemPosition[item.Index + 1] - ItemPosition[item.Index];
}
CurrentSize = (IsHorizontal ? item.Size.Width : item.Size.Height);
if (CurrentSize != PrevSize)
{
if (colView.SizingStrategy == ItemSizingStrategy.MeasureAll)
{
ItemSize[item.Index] = CurrentSize;
}
else
{
StepCandidate = CurrentSize;
}
}
if (ItemSizeChanged == -1)
{
ItemSizeChanged = item.Index;
}
else
{
ItemSizeChanged = Math.Min(ItemSizeChanged, item.Index);
}
//ScrollContentSize += Diff; UpdateOnce?
}
public override View RequestNextFocusableView(View currentFocusedView, View.FocusDirection direction, bool loopEnabled)
{
if (currentFocusedView == null)
{
throw new ArgumentNullException(nameof(currentFocusedView));
}
View nextFocusedView = null;
int targetSibling = -1;
switch (direction)
{
case View.FocusDirection.Left:
{
targetSibling = IsHorizontal ? currentFocusedView.SiblingOrder - 1 : targetSibling;
break;
}
case View.FocusDirection.Right:
{
targetSibling = IsHorizontal ? currentFocusedView.SiblingOrder + 1 : targetSibling;
break;
}
case View.FocusDirection.Up:
{
targetSibling = IsHorizontal ? targetSibling : currentFocusedView.SiblingOrder - 1;
break;
}
case View.FocusDirection.Down:
{
targetSibling = IsHorizontal ? targetSibling : currentFocusedView.SiblingOrder + 1;
break;
}
}
if (targetSibling > -1 && targetSibling < Container.Children.Count)
{
RecyclerViewItem candidate = Container.Children[targetSibling] as RecyclerViewItem;
if (candidate.Index >= 0 && candidate.Index < colView.InternalItemSource.Count)
{
nextFocusedView = candidate;
}
}
return(nextFocusedView);
}
protected virtual bool PushRecycleCache(RecyclerViewItem item)
{
if (item == null)
{
throw new ArgumentNullException(nameof(item));
}
if (RecycleCache.Count >= CacheMax)
{
return(false);
}
if (item.Template == null)
{
return(false);
}
item.Hide();
item.Index = -1;
RecycleCache.Add(item);
return(true);
}
/// <summary>
/// Unrealize indexed item.
/// </summary>
/// <param name="item"> Target item for unrealizing </param>
/// <param name="recycle"> Allow recycle. default is true </param>
internal virtual void UnrealizeItem(RecyclerViewItem item, bool recycle = true)
{
item.Index = -1;
item.ParentItemsView = null;
// Remove BindingContext null set for performance improving.
//item.BindingContext = null;
item.IsPressed = false;
item.IsSelected = false;
item.IsEnabled = true;
// Remove Update Style on default for performance improving.
//item.UpdateState();
item.Relayout -= OnItemRelayout;
if (!recycle || !PushRecycleCache(item))
{
//ContentContainer.Remove(item);
Utility.Dispose(item);
}
}
/// <summary>
/// Unrealize indexed item.
/// </summary>
/// <param name="item"> Target item for unrealizing </param>
/// <param name="recycle"> Allow recycle. default is true </param>
internal virtual void UnrealizeItem(RecyclerViewItem item, bool recycle = true)
{
if (item == null)
{
return;
}
item.Index = -1;
item.ParentItemsView = null;
item.BindingContext = null;
item.IsPressed = false;
item.IsSelected = false;
item.IsEnabled = true;
item.UpdateState();
item.Relayout -= OnItemRelayout;
if (!recycle || !PushRecycleCache(item))
{
//ContentContainer.Remove(item);
Utility.Dispose(item);
}
}
public virtual void NotifyItemSizeChanged(RecyclerViewItem item)
{
}
public override void Initialize(RecyclerView view)
{
colView = view as CollectionView;
if (colView == null)
{
throw new ArgumentException("LinearLayouter only can be applied CollectionView.", nameof(view));
}
// 1. Clean Up
foreach (RecyclerViewItem item in VisibleItems)
{
colView.UnrealizeItem(item, false);
}
VisibleItems.Clear();
ItemPosition.Clear();
ItemSize.Clear();
groups.Clear();
FirstVisible = 0;
LastVisible = 0;
IsHorizontal = (colView.ScrollingDirection == ScrollableBase.Direction.Horizontal);
RecyclerViewItem header = colView?.Header;
RecyclerViewItem footer = colView?.Footer;
float width, height;
int count = colView.InternalItemSource.Count;
if (header != null)
{
MeasureChild(colView, header);
width = header.Layout != null?header.Layout.MeasuredWidth.Size.AsRoundedValue() : 0;
height = header.Layout != null?header.Layout.MeasuredHeight.Size.AsRoundedValue() : 0;
headerSize = IsHorizontal ? width : height;
hasHeader = true;
colView.UnrealizeItem(header);
}
else
{
hasHeader = false;
}
if (footer != null)
{
MeasureChild(colView, footer);
width = footer.Layout != null?footer.Layout.MeasuredWidth.Size.AsRoundedValue() : 0;
height = footer.Layout != null?footer.Layout.MeasuredHeight.Size.AsRoundedValue() : 0;
footerSize = IsHorizontal ? width : height;
footer.Index = count - 1;
hasFooter = true;
colView.UnrealizeItem(footer);
}
else
{
hasFooter = false;
}
//No Internal Source exist.
if (count == (hasHeader ? (hasFooter ? 2 : 1) : 0))
{
return;
}
int firstIndex = hasHeader ? 1 : 0;
if (colView.IsGrouped)
{
isGrouped = true;
if (colView.GroupHeaderTemplate != null)
{
while (!colView.InternalItemSource.IsGroupHeader(firstIndex))
{
firstIndex++;
}
//must be always true
if (colView.InternalItemSource.IsGroupHeader(firstIndex))
{
RecyclerViewItem groupHeader = colView.RealizeItem(firstIndex);
firstIndex++;
if (groupHeader == null)
{
throw new Exception("[" + firstIndex + "] Group Header failed to realize!");
}
// Need to Set proper height or width on scroll direction.
if (groupHeader.Layout == null)
{
width = groupHeader.WidthSpecification;
height = groupHeader.HeightSpecification;
}
else
{
MeasureChild(colView, groupHeader);
width = groupHeader.Layout.MeasuredWidth.Size.AsRoundedValue();
height = groupHeader.Layout.MeasuredHeight.Size.AsRoundedValue();
}
//Console.WriteLine("[NUI] GroupHeader Size {0} :{0}", width, height);
// pick the StepCandidate.
groupHeaderSize = IsHorizontal ? width : height;
colView.UnrealizeItem(groupHeader);
}
}
else
{
groupHeaderSize = 0F;
}
if (colView.GroupFooterTemplate != null)
{
int firstFooter = firstIndex;
while (!colView.InternalItemSource.IsGroupFooter(firstFooter))
{
firstFooter++;
}
//must be always true
if (colView.InternalItemSource.IsGroupFooter(firstFooter))
{
RecyclerViewItem groupFooter = colView.RealizeItem(firstFooter);
if (groupFooter == null)
{
throw new Exception("[" + firstFooter + "] Group Footer failed to realize!");
}
// Need to Set proper height or width on scroll direction.
if (groupFooter.Layout == null)
{
width = groupFooter.WidthSpecification;
height = groupFooter.HeightSpecification;
}
else
{
MeasureChild(colView, groupFooter);
width = groupFooter.Layout.MeasuredWidth.Size.AsRoundedValue();
height = groupFooter.Layout.MeasuredHeight.Size.AsRoundedValue();
}
// pick the StepCandidate.
groupFooterSize = IsHorizontal ? width : height;
colView.UnrealizeItem(groupFooter);
}
}
else
{
groupFooterSize = 0F;
}
}
else
{
isGrouped = false;
}
bool failed = false;
//Final Check of FirstIndex
while (colView.InternalItemSource.IsHeader(firstIndex) ||
colView.InternalItemSource.IsGroupHeader(firstIndex) ||
colView.InternalItemSource.IsGroupFooter(firstIndex))
{
if (colView.InternalItemSource.IsFooter(firstIndex))
{
StepCandidate = 0F;
failed = true;
break;
}
firstIndex++;
}
if (!failed)
{
RecyclerViewItem sizeDeligate = colView.RealizeItem(firstIndex);
if (sizeDeligate == null)
{
// error !
throw new Exception("Cannot create content from DatTemplate.");
}
sizeDeligate.BindingContext = colView.InternalItemSource.GetItem(firstIndex);
// Need to Set proper height or width on scroll direction.
if (sizeDeligate.Layout == null)
{
width = sizeDeligate.WidthSpecification;
height = sizeDeligate.HeightSpecification;
}
else
{
MeasureChild(colView, sizeDeligate);
width = sizeDeligate.Layout.MeasuredWidth.Size.AsRoundedValue();
height = sizeDeligate.Layout.MeasuredHeight.Size.AsRoundedValue();
}
//Console.WriteLine("[NUI] Layout Size {0} :{0}", width, height);
// pick the StepCandidate.
StepCandidate = IsHorizontal ? width : height;
if (StepCandidate == 0)
{
StepCandidate = 1; //????
}
colView.UnrealizeItem(sizeDeligate);
}
float Current = 0.0F;
IGroupableItemSource source = colView.InternalItemSource;
GroupInfo currentGroup = null;
for (int i = 0; i < count; i++)
{
if (colView.SizingStrategy == ItemSizingStrategy.MeasureAll)
{
if (i == 0 && hasHeader)
{
ItemSize.Add(headerSize);
}
else if (i == count - 1 && hasFooter)
{
ItemSize.Add(footerSize);
}
else if (source.IsGroupHeader(i))
{
ItemSize.Add(groupHeaderSize);
}
else if (source.IsGroupFooter(i))
{
ItemSize.Add(groupFooterSize);
}
else
{
ItemSize.Add(StepCandidate);
}
}
if (isGrouped)
{
if (i == 0 && hasHeader)
{
//ItemPosition.Add(Current);
Current += headerSize;
}
else if (i == count - 1 && hasFooter)
{
//ItemPosition.Add(Current);
Current += footerSize;
}
else
{
//GroupHeader must always exist in group usage.
if (source.IsGroupHeader(i))
{
currentGroup = new GroupInfo()
{
GroupParent = source.GetGroupParent(i),
//hasHeader = true,
//hasFooter = false,
StartIndex = i,
Count = 1,
GroupSize = groupHeaderSize,
GroupPosition = Current
};
currentGroup.ItemPosition.Add(0);
groups.Add(currentGroup);
Current += groupHeaderSize;
}
//optional
else if (source.IsGroupFooter(i))
{
//currentGroup.hasFooter = true;
currentGroup.Count++;
currentGroup.GroupSize += groupFooterSize;
currentGroup.ItemPosition.Add(Current - currentGroup.GroupPosition);
Current += groupFooterSize;
}
else
{
currentGroup.Count++;
currentGroup.GroupSize += StepCandidate;
currentGroup.ItemPosition.Add(Current - currentGroup.GroupPosition);
Current += StepCandidate;
}
}
}
else
{
ItemPosition.Add(Current);
if (i == 0 && hasHeader)
{
Current += headerSize;
}
else if (i == count - 1 && hasFooter)
{
Current += footerSize;
}
else
{
Current += StepCandidate;
}
}
}
ScrollContentSize = Current;
if (IsHorizontal)
{
colView.ContentContainer.SizeWidth = ScrollContentSize;
}
else
{
colView.ContentContainer.SizeHeight = ScrollContentSize;
}
base.Initialize(view);
//Console.WriteLine("[NUI] Init Done, StepCnadidate{0}, Scroll{1}", StepCandidate, ScrollContentSize);
}
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");
}
}
public override void Initialize(RecyclerView view)
{
colView = view as CollectionView;
if (colView == null)
{
throw new ArgumentException("GridLayouter only can be applied CollectionView.", nameof(view));
}
// 1. Clean Up
foreach (RecyclerViewItem item in VisibleItems)
{
colView.UnrealizeItem(item, false);
}
VisibleItems.Clear();
groups.Clear();
FirstVisible = 0;
LastVisible = 0;
IsHorizontal = (colView.ScrollingDirection == ScrollableBase.Direction.Horizontal);
RecyclerViewItem header = colView?.Header;
RecyclerViewItem footer = colView?.Footer;
float width, height;
int count = colView.InternalItemSource.Count;
int pureCount = count - (header ? 1 : 0) - (footer ? 1 : 0);
// 2. Get the header / footer and size deligated item and measure the size.
if (header != null)
{
MeasureChild(colView, header);
width = header.Layout != null?header.Layout.MeasuredWidth.Size.AsRoundedValue() : 0;
height = header.Layout != null?header.Layout.MeasuredHeight.Size.AsRoundedValue() : 0;
headerSize = IsHorizontal ? width : height;
hasHeader = true;
colView.UnrealizeItem(header);
}
if (footer != null)
{
MeasureChild(colView, footer);
width = footer.Layout != null?footer.Layout.MeasuredWidth.Size.AsRoundedValue() : 0;
height = footer.Layout != null?footer.Layout.MeasuredHeight.Size.AsRoundedValue() : 0;
footerSize = IsHorizontal ? width : height;
footer.Index = count - 1;
hasFooter = true;
colView.UnrealizeItem(footer);
}
int firstIndex = header ? 1 : 0;
if (colView.IsGrouped)
{
isGrouped = true;
if (colView.GroupHeaderTemplate != null)
{
while (!colView.InternalItemSource.IsGroupHeader(firstIndex))
{
firstIndex++;
}
//must be always true
if (colView.InternalItemSource.IsGroupHeader(firstIndex))
{
RecyclerViewItem groupHeader = colView.RealizeItem(firstIndex);
firstIndex++;
if (groupHeader == null)
{
throw new Exception("[" + firstIndex + "] Group Header failed to realize!");
}
// Need to Set proper hieght or width on scroll direciton.
if (groupHeader.Layout == null)
{
width = groupHeader.WidthSpecification;
height = groupHeader.HeightSpecification;
}
else
{
MeasureChild(colView, groupHeader);
width = groupHeader.Layout.MeasuredWidth.Size.AsRoundedValue();
height = groupHeader.Layout.MeasuredHeight.Size.AsRoundedValue();
}
//Console.WriteLine("[NUI] GroupHeader Size {0} :{0}", width, height);
// pick the StepCandidate.
groupHeaderSize = IsHorizontal ? width : height;
colView.UnrealizeItem(groupHeader);
}
}
else
{
groupHeaderSize = 0F;
}
if (colView.GroupFooterTemplate != null)
{
int firstFooter = firstIndex;
while (!colView.InternalItemSource.IsGroupFooter(firstFooter))
{
firstFooter++;
}
//must be always true
if (colView.InternalItemSource.IsGroupFooter(firstFooter))
{
RecyclerViewItem groupFooter = colView.RealizeItem(firstFooter);
if (groupFooter == null)
{
throw new Exception("[" + firstFooter + "] Group Footer failed to realize!");
}
// Need to Set proper hieght or width on scroll direciton.
if (groupFooter.Layout == null)
{
width = groupFooter.WidthSpecification;
height = groupFooter.HeightSpecification;
}
else
{
MeasureChild(colView, groupFooter);
width = groupFooter.Layout.MeasuredWidth.Size.AsRoundedValue();
height = groupFooter.Layout.MeasuredHeight.Size.AsRoundedValue();
}
// pick the StepCandidate.
groupFooterSize = IsHorizontal ? width : height;
colView.UnrealizeItem(groupFooter);
}
}
else
{
groupFooterSize = 0F;
}
}
else
{
isGrouped = false;
}
bool failed = false;
//Final Check of FirstIndex
while (colView.InternalItemSource.IsHeader(firstIndex) ||
colView.InternalItemSource.IsGroupHeader(firstIndex) ||
colView.InternalItemSource.IsGroupFooter(firstIndex))
{
if (colView.InternalItemSource.IsFooter(firstIndex))
{
StepCandidate = 0F;
failed = true;
break;
}
firstIndex++;
}
sizeCandidate = new Size2D(0, 0);
if (!failed)
{
// Get Size Deligate. FIXME if group exist index must be changed.
RecyclerViewItem sizeDeligate = colView.RealizeItem(firstIndex);
if (sizeDeligate == null)
{
throw new Exception("Cannot create content from DatTemplate.");
}
sizeDeligate.BindingContext = colView.InternalItemSource.GetItem(firstIndex);
// Need to Set proper hieght or width on scroll direciton.
if (sizeDeligate.Layout == null)
{
width = sizeDeligate.WidthSpecification;
height = sizeDeligate.HeightSpecification;
}
else
{
MeasureChild(colView, sizeDeligate);
width = sizeDeligate.Layout.MeasuredWidth.Size.AsRoundedValue();
height = sizeDeligate.Layout.MeasuredHeight.Size.AsRoundedValue();
}
//Console.WriteLine("[NUI] item Size {0} :{1}", width, height);
// pick the StepCandidate.
StepCandidate = IsHorizontal ? width : height;
spanSize = IsHorizontal ? Convert.ToInt32(Math.Truncate((double)(colView.Size.Height / height))) :
Convert.ToInt32(Math.Truncate((double)(colView.Size.Width / width)));
sizeCandidate = new Size2D(Convert.ToInt32(width), Convert.ToInt32(height));
colView.UnrealizeItem(sizeDeligate);
}
if (StepCandidate < 1)
{
StepCandidate = 1;
}
if (spanSize < 1)
{
spanSize = 1;
}
if (isGrouped)
{
float Current = 0.0F;
IGroupableItemSource source = colView.InternalItemSource;
GroupInfo currentGroup = null;
for (int i = 0; i < count; i++)
{
if (i == 0 && hasHeader)
{
Current += headerSize;
}
else if (i == count - 1 && hasFooter)
{
Current += footerSize;
}
else
{
//GroupHeader must always exist in group usage.
if (source.IsGroupHeader(i))
{
currentGroup = new GroupInfo()
{
GroupParent = source.GetGroupParent(i),
StartIndex = i,
Count = 1,
GroupSize = groupHeaderSize,
GroupPosition = Current
};
groups.Add(currentGroup);
Current += groupHeaderSize;
}
//optional
else if (source.IsGroupFooter(i))
{
//currentGroup.hasFooter = true;
currentGroup.Count++;
currentGroup.GroupSize += groupFooterSize;
Current += groupFooterSize;
}
else
{
currentGroup.Count++;
int index = i - currentGroup.StartIndex - 1; // groupHeader must always exist.
if ((index % spanSize) == 0)
{
currentGroup.GroupSize += StepCandidate;
Current += StepCandidate;
}
}
}
}
ScrollContentSize = Current;
}
else
{
// 3. Measure the scroller content size.
ScrollContentSize = StepCandidate * Convert.ToInt32(Math.Ceiling((double)pureCount / (double)spanSize));
if (hasHeader)
{
ScrollContentSize += headerSize;
}
if (hasFooter)
{
ScrollContentSize += footerSize;
}
}
if (IsHorizontal)
{
colView.ContentContainer.SizeWidth = ScrollContentSize;
}
else
{
colView.ContentContainer.SizeHeight = ScrollContentSize;
}
base.Initialize(colView);
//Console.WriteLine("Init Done, StepCnadidate{0}, spanSize{1}, Scroll{2}", StepCandidate, spanSize, ScrollContentSize);
}
/// <inheritdoc/>
public override void NotifyItemSizeChanged(RecyclerViewItem item)
{
// All Item size need to be same in grid!
// if you want to change item size, change dataTemplate to re-initing.
return;
}
/// <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");
}