Size IVirtualizingLayoutOverrides.ArrangeOverride(VirtualizingLayoutContext context, Size finalSize)
{
return(ArrangeOverride(context, finalSize));
}
void IVirtualizingLayoutOverrides.UninitializeForContextCore(VirtualizingLayoutContext context)
{
UninitializeForContextCore(context);
}
Size IVirtualizingLayoutOverrides.MeasureOverride(VirtualizingLayoutContext context, Size availableSize)
{
return(MeasureOverride(context, availableSize));
}
protected virtual Size ArrangeOverride(VirtualizingLayoutContext context, Size finalSize)
{
// Do not throw. If the layout decides to arrange its
// children during measure, then an ArrangeOverride is not required.
return(finalSize);
}
protected virtual void OnItemsChangedCore(VirtualizingLayoutContext context, object source, NotifyCollectionChangedEventArgs args)
{
InvalidateMeasure();
}
protected internal abstract Size MeasureOverride(VirtualizingLayoutContext context, Size availableSize);
protected virtual Size MeasureOverride(VirtualizingLayoutContext context, Size availableSize)
{
throw new NotImplementedException();
}
public VirtualLayoutContextAdapter(VirtualizingLayoutContext virtualizingContext)
{
m_virtualizingContext = new WeakReference <VirtualizingLayoutContext>(virtualizingContext);
}
public ChildrenCollection(VirtualizingLayoutContext context)
{
m_context = context;
}
protected override Size ArrangeOverride(VirtualizingLayoutContext context, Size finalSize)
{
return(ArrangeLayoutFunc != null?ArrangeLayoutFunc(finalSize, context) : default(Size));
}
public void InitializeForContext(VirtualizingLayoutContext context, IFlowLayoutAlgorithmDelegates callbacks)
{
m_algorithmCallbacks = callbacks;
m_context = context;
m_elementManager.SetContext(context);
}
protected override Size MeasureOverride(VirtualizingLayoutContext context, Size availableSize)
{
return(MeasureLayoutFunc != null?MeasureLayoutFunc(availableSize, context) : default(Size));
}
internal void OnLineArranged(int startIndex, int countInLine, double lineSize, VirtualizingLayoutContext context)
{
// If we do not have any estimation information, use the line for estimation.
// If we do have some estimation information, don't account for the last line which is quite likely
// different from the rest of the lines and can throw off estimation.
if (TotalLinesMeasured == 0 || startIndex + countInLine != context.ItemCount)
{
int estimationBufferIndex = startIndex % m_lineSizeEstimationBuffer.Count;
bool alreadyMeasured = m_lineSizeEstimationBuffer[estimationBufferIndex] != 0;
if (!alreadyMeasured)
{
++TotalLinesMeasured;
}
TotalLineSize -= m_lineSizeEstimationBuffer[estimationBufferIndex];
TotalLineSize += lineSize;
m_lineSizeEstimationBuffer[estimationBufferIndex] = lineSize;
TotalItemsPerLine -= m_itemsPerLineEstimationBuffer[estimationBufferIndex];
TotalItemsPerLine += countInLine;
m_itemsPerLineEstimationBuffer[estimationBufferIndex] = countInLine;
}
}
public void SetContext(VirtualizingLayoutContext virtualContext)
{
m_context = virtualContext;
}
void IVirtualizingLayoutOverrides.OnItemsChangedCore(VirtualizingLayoutContext context, object source, NotifyCollectionChangedEventArgs args)
{
OnItemsChangedCore(context, source, args);
}
protected virtual void UninitializeForContextCore(VirtualizingLayoutContext context)
{
}
internal void UninitializeForContext(VirtualizingLayoutContext context)
{
FlowAlgorithm.UninitializeForContext(context);
}
protected internal virtual void InitializeForContextCore(VirtualizingLayoutContext context)
{
}
