void InitializeMeasureCache()
{
_baseItemSize = 0;
_scrollCanvasSize = new Size(0, 0);
if (_allocatedSize.Width <= 0 || _allocatedSize.Height <= 0)
{
return;
}
if (!_hasUnevenRows)
{
CollectionView !.ContentSizeUpdated();
return;
}
int n = CollectionView !.Count;
_itemSizes = new List <double>();
_cached = new List <bool>();
_accumulatedItemSizes = new List <double>();
for (int i = 0; i < n; i++)
{
_cached.Add(false);
_itemSizes.Add(BaseItemSize);
_accumulatedItemSizes.Add((i > 0 ? (_accumulatedItemSizes[i - 1] + ItemSpacing) : ItemStartPoint) + _itemSizes[i]);
}
CollectionView !.ContentSizeUpdated();
}
public void ItemRemoved(int removed)
{
if (_realizedItem.ContainsKey(removed))
{
CollectionView !.UnrealizeView(_realizedItem[removed].View);
_realizedItem.Remove(removed);
}
var items = _realizedItem.Keys.OrderBy(key => key);
foreach (var index in items)
{
if (index > removed)
{
_realizedItem[index - 1] = _realizedItem[index];
}
}
var last = items.LastOrDefault();
if (last > removed)
{
_realizedItem.Remove(last);
}
UpdateRemovedSize(removed);
_scrollCanvasSize = new Size(0, 0);
CollectionView !.ContentSizeUpdated();
}
public void SetFooter(View?footer, Size size)
{
bool contentSizeChanged = false;
if (IsHorizontal)
{
if (_footerSize.Width != size.Width)
{
contentSizeChanged = true;
}
}
else
{
if (_footerSize.Height != size.Height)
{
contentSizeChanged = true;
}
}
_footer = footer;
_footerSize = size;
if (contentSizeChanged)
{
InitializeMeasureCache();
CollectionView !.ContentSizeUpdated();
}
UpdateFooterPosition();
}
public void ItemInserted(int inserted)
{
var items = _realizedItem.Keys.OrderByDescending(key => key);
foreach (var index in items)
{
if (index >= inserted)
{
_realizedItem[index + 1] = _realizedItem[index];
}
}
if (_realizedItem.ContainsKey(inserted))
{
_realizedItem.Remove(inserted);
}
else
{
var last = items.LastOrDefault();
if (last >= inserted)
{
_realizedItem.Remove(last);
}
}
UpdateInsertedSize(inserted);
_scrollCanvasSize = new Size(0, 0);
CollectionView !.ContentSizeUpdated();
}
public void Reset()
{
foreach (var realizedItem in _realizedItem.Values.ToList())
{
CollectionView !.UnrealizeView(realizedItem.View);
}
_realizedItem.Clear();
_scrollCanvasSize = new Size(0, 0);
CollectionView !.ContentSizeUpdated();
}
public void SetHeader(View?header, Size size)
{
bool contentSizeChanged = false;
if (IsHorizontal)
{
if (_headerSize.Width != size.Width)
{
contentSizeChanged = true;
}
}
else
{
if (_headerSize.Height != size.Height)
{
contentSizeChanged = true;
}
}
_header = header;
_headerSize = size;
if (contentSizeChanged)
{
InitializeMeasureCache();
CollectionView !.ContentSizeUpdated();
}
if (_header != null)
{
var bound = new Rect(0, 0, _headerSize.Width, _headerSize.Height);
if (IsHorizontal)
{
bound.Height = _allocatedSize.Height;
}
else
{
bound.Width = _allocatedSize.Width;
}
_header.UpdateBounds(bound);
}
}
public Size GetScrollCanvasSize()
{
if (CollectionView !.Count == 0 || _allocatedSize.Width <= 0 || _allocatedSize.Height <= 0)
{
return(_allocatedSize);
}
if (_scrollCanvasSize.Width > 0 && _scrollCanvasSize.Height > 0)
{
return(_scrollCanvasSize);
}
double totalItemSize = 0;
if (_hasUnevenRows)
{
// If item source was shared between adaptors, in some case CollectionView.Count could be wrong
if (_accumulatedItemSizes.Count == 0)
{
return(_allocatedSize);
}
totalItemSize = _accumulatedItemSizes[_accumulatedItemSizes.Count - 1] + FooterSizeWithSpacing;
}
else
{
totalItemSize = (BaseItemSize + ItemSpacing) * CollectionView !.Count - ItemSpacing + ItemStartPoint + FooterSizeWithSpacing;
}
if (IsHorizontal)
{
_scrollCanvasSize = new Size(totalItemSize, _allocatedSize.Height);
}
else
{
_scrollCanvasSize = new Size(_allocatedSize.Width, totalItemSize);
}
return(_scrollCanvasSize);
}
public static void UpdateSize(this View view, Size size)
{
view.Size = size.ToNative();
}
public void SizeAllocated(Size size)
{
_allocatedSize = size;
InitializeMeasureCache();
}
public static void UpdateSize(this EvasObject view, Size size)
{
view.Resize((int)size.Width, (int)size.Height);
}
public static Size ToDP(this TSize size)
{
return(new Size(ConvertToScaledDP(size.Width), ConvertToScaledDP(size.Height)));
}
