private RadSize MeasureHorizontally(RadSize availableSize, double offset, double bufferScale)
{
//TODO: add buffer here
var context = new MeasureContext()
{
Offset = offset,
BufferScale = bufferScale
};
context.InitializeForHorizontalMeasure(this.Layout, availableSize);
this.AvailableLength = context.AvailableLength;
if (this.IsBufferNeeded)
{
context.FirstVisibleIndex = this.GenerateTopBufferItems(context.FirstVisibleIndex, context.AvailableLength, context.Offset, context);
context.LastVisibleIndex = context.FirstVisibleIndex;
}
this.MeasureForward(ref context);
//TODO: Investigate the case with maximizing and incorrect scroll offset.
if (context.AvailableLength - context.ForwardGeneratedLength > ListViewModel.DoubleArithmetics.Ceiling(1d / IndexStorage.PrecisionMultiplier))
{
if (this.viewportItemsCount < this.Layout.VisibleLineCount)
{
// perform the measure logic again, since this difference will most probably occur when the Index tree is cleared before the measure pass
this.RecycleLocally();
context.InitializeForHorizontalMeasure(this.Layout, availableSize);
if (this.IsBufferNeeded)
{
context.FirstVisibleIndex = this.GenerateTopBufferItems(context.FirstVisibleIndex, context.AvailableLength, context.Offset, context);
context.LastVisibleIndex = context.FirstVisibleIndex;
}
this.MeasureForward(ref context);
}
}
this.MeasureBackwards(ref context);
if (this.IsBufferNeeded)
{
this.GenerateBottomBufferItems(context.LastVisibleIndex, context.AvailableLength, context);
}
var desiredSize = this.ComputeDesiredSize(context);
this.Layout.UpdateAverageLength(context.FirstVisibleIndex, context.LastVisibleIndex);
return(desiredSize);
}
private RadSize MeasureHorizontally(RadSize availableSize, double offset, int frozenElementsCount)
{
var context = new MeasureContext()
{
Offset = offset
};
if (frozenElementsCount > 0)
{
var frozenGeneratedContext = this.MeasureHorizontalFrozenElements(availableSize, frozenElementsCount);
context.InitializeForHorizontalMeasure(this, availableSize, frozenGeneratedContext);
}
else
{
context.InitializeForHorizontalMeasure(this, availableSize);
}
this.AvailableLength = context.AvailableLength;
this.MeasureForward(ref context);
if (context.AvailableLength - context.ForwardGeneratedLength > GridModel.DoubleArithmetics.Ceiling(1d / IndexStorage.PrecisionMultiplier))
{
if (context.FirstVisibleIndex + this.ViewportItemCount < this.layout.VisibleLineCount)
{
// perform the measure logic again, since this difference will most probably occur when the Index tree is cleared before the measure pass
this.RecycleLocally();
context.InitializeForHorizontalMeasure(this, availableSize);
this.MeasureForward(ref context);
}
}
context.FirstVisibleIndex -= this.owner.FrozenColumnCount;
this.MeasureBackwards(ref context);
var desiredSize = new RadSize(context.GeneratedLength, context.MaxLength);
desiredSize.Width = Math.Min(desiredSize.Width, context.AvailableLength);
desiredSize.Height = Math.Min(desiredSize.Height, GridModel.DoubleArithmetics.Ceiling(availableSize.Height));
this.Layout.UpdateAverageLength(context.FirstVisibleIndex, context.LastVisibleIndex);
return(desiredSize);
}
private MeasureContext MeasureHorizontalFrozenElements(RadSize availableSize, int frozenContainersCount)
{
var context = new MeasureContext();
context.InitializeForHorizontalMeasure(this, availableSize);
if (frozenContainersCount == 0)
{
return(context);
}
var firstContainerDesiredSize = new RadSize();
var lastContainerDesiredSize = new RadSize();
using (var itemInfos = this.layout.GetLines(context.FirstVisibleIndex, true).GetEnumerator())
{
if (itemInfos.MoveNext())
{
firstContainerDesiredSize = this.GenerateContainer(itemInfos.Current);
context.ForwardGeneratedLength = context.GetLength(firstContainerDesiredSize);
context.MaxLength = Math.Max(context.MaxLength, context.GetOppositeLength(firstContainerDesiredSize));
// Take the length portion of the indexed element that is not currently in viewport.
this.HiddenPixels = GridModel.DoubleArithmetics.Floor(context.ForwardGeneratedLength * (context.Index % 1));
context.ForwardGeneratedLength -= this.HiddenPixels;
context.ForwardGeneratedLength = GridModel.DoubleArithmetics.Ceiling(context.ForwardGeneratedLength);
lastContainerDesiredSize = firstContainerDesiredSize;
this.ViewportItemCount++;
}
while (frozenContainersCount - 1 > context.LastVisibleIndex && GridModel.DoubleArithmetics.IsLessThan(context.ForwardGeneratedLength, context.AvailableLength) && itemInfos.MoveNext())
{
context.LastVisibleIndex++;
lastContainerDesiredSize = this.GenerateContainer(itemInfos.Current);
context.ForwardGeneratedLength += context.GetLength(lastContainerDesiredSize);
context.MaxLength = Math.Max(context.MaxLength, context.GetOppositeLength(lastContainerDesiredSize));
this.ViewportItemCount++;
}
}
return(context);
}
