private void RecycleItems(ItemLayoutInfo layoutInfo)
{
foreach (UIElement child in Children)
{
var virtualItemIndex = GetVirtualItemIndex(child);
if (virtualItemIndex < layoutInfo.FirstRealizedItemIndex || virtualItemIndex > layoutInfo.LastRealizedItemIndex)
{
var generatorPosition = _itemsGenerator.GeneratorPositionFromIndex(virtualItemIndex);
if (generatorPosition.Index >= 0)
{
try
{
_itemsGenerator.Recycle(generatorPosition, 1);
}
catch (ArgumentException)
{
//I have seen the following exception which appears to be a non-issue
// GeneratorPosition '0,10' passed to Remove does not have Offset equal to 0.
}
}
}
SetVirtualItemIndex(child, -1);
}
}
public void SetRenderInfo(IDataSourceItem item, ItemLayoutInfo info)
{
if (info != ItemLayoutInfo.Invalid)
{
this.itemSlotsRepository[item] = info;
}
}
public ItemLayoutInfo GetFreeSpot(IDataSourceItem item, bool forward)
{
if (forward && item.Previous == null || !forward && item.Next == null)
{
return(new ItemLayoutInfo());
}
//TODO Implement for backwards
double[] columnsLength = forward ? new double[this.columnCount] : Enumerable.Repeat(double.MaxValue, this.columnCount).ToArray();
var pivotItem = forward ? item.Previous : item.Next;
ItemLayoutInfo itemInfo;
List <int> foundColumns = new List <int>();
while (foundColumns.Count < this.columnCount)
{
if (pivotItem != null)
{
itemInfo = this.GetRenderInfo(pivotItem);
if (itemInfo != ItemLayoutInfo.Invalid && !foundColumns.Contains(itemInfo.ColumnIndex))
{
//Implement backward
foundColumns.Add(itemInfo.ColumnIndex);
columnsLength[itemInfo.ColumnIndex] = itemInfo.Position + itemInfo.Length;
}
pivotItem = forward ? item.Previous : item.Next;
}
}
var min = columnsLength.Min();
ItemLayoutInfo result = ItemLayoutInfo.Invalid;
for (int i = 0; i < columnsLength.Length; i++)
{
if (columnsLength[i] == min)
{
result = new ItemLayoutInfo(columnsLength[i], 0, i);
}
}
return(result);
}
private void RecycleItems(ItemLayoutInfo layoutInfo)
{
foreach (UIElement child in Children)
{
var virtualItemIndex = GetVirtualItemIndex(child);
if (virtualItemIndex < layoutInfo.FirstRealizedItemIndex || virtualItemIndex > layoutInfo.LastRealizedItemIndex)
{
var generatorPosition = _itemsGenerator.GeneratorPositionFromIndex(virtualItemIndex);
if (generatorPosition.Index >= 0)
{
_itemsGenerator.Recycle(generatorPosition, 1);
}
}
SetVirtualItemIndex(child, -1);
}
}
private void RecycleItems(ItemLayoutInfo layoutInfo)
{
foreach (UIElement child in Children)
{
var virtualItemIndex = GetVirtualItemIndex(child);
var cacheLength = GetCacheLength(this);
var cacheUnit = GetCacheLengthUnit(this);
double multipler;
switch (cacheUnit)
{
case VirtualizationCacheLengthUnit.Pixel:
multipler = Orientation == Orientation.Vertical ? 1d / _itemWidth : 1d / _itemHeight;
break;
case VirtualizationCacheLengthUnit.Item:
multipler = 1d;
break;
case VirtualizationCacheLengthUnit.Page:
multipler = layoutInfo.LastRealizedItemIndex - layoutInfo.FirstRealizedItemIndex + 1;
break;
default:
throw new ArgumentOutOfRangeException();
}
if (virtualItemIndex < layoutInfo.FirstRealizedItemIndex - cacheLength.CacheBeforeViewport * multipler ||
virtualItemIndex > layoutInfo.LastRealizedItemIndex + cacheLength.CacheAfterViewport * multipler)
{
var generatorPosition = _itemsGenerator.GeneratorPositionFromIndex(virtualItemIndex);
if (generatorPosition.Index >= 0)
{
_itemsGenerator.Recycle(generatorPosition, 1);
}
}
SetVirtualItemIndex(child, -1);
}
}
private void RecycleItems(ItemLayoutInfo layoutInfo)
{
foreach (UIElement child in Children)
{
int virtualItemIndex = GetVirtualItemIndex(child);
if (virtualItemIndex < layoutInfo.FirstRealizedItemIndex ||
virtualItemIndex > layoutInfo.LastRealizedItemIndex)
{
GeneratorPosition generatorPosition = _itemsGenerator.GeneratorPositionFromIndex(virtualItemIndex);
if (generatorPosition.Index >= 0)
{
_itemsGenerator.Recycle(generatorPosition, 1);
}
}
SetVirtualItemIndex(child, RecycledIndex);
}
}
private void RecycleItems(ItemLayoutInfo layoutInfo) {
foreach (UIElement child in Children) {
var virtualItemIndex = GetVirtualItemIndex(child);
var cacheLength = GetCacheLength(this);
var cacheUnit = GetCacheLengthUnit(this);
double multipler;
switch (cacheUnit) {
case VirtualizationCacheLengthUnit.Pixel:
multipler = Orientation == Orientation.Vertical ? 1d / _itemWidth : 1d / _itemHeight;
break;
case VirtualizationCacheLengthUnit.Item:
multipler = 1d;
break;
case VirtualizationCacheLengthUnit.Page:
multipler = layoutInfo.LastRealizedItemIndex - layoutInfo.FirstRealizedItemIndex + 1;
break;
default:
throw new ArgumentOutOfRangeException();
}
if (virtualItemIndex < layoutInfo.FirstRealizedItemIndex - cacheLength.CacheBeforeViewport * multipler
|| virtualItemIndex > layoutInfo.LastRealizedItemIndex + cacheLength.CacheAfterViewport * multipler) {
var generatorPosition = _itemsGenerator.GeneratorPositionFromIndex(virtualItemIndex);
if (generatorPosition.Index >= 0) {
_itemsGenerator.Recycle(generatorPosition, 1);
}
}
SetVirtualItemIndex(child, -1);
}
}
private void RecycleItems(ItemLayoutInfo layoutInfo)
{
foreach (UIElement child in Children)
{
var virtualItemIndex = GetVirtualItemIndex(child);
if (virtualItemIndex < layoutInfo.FirstRealizedItemIndex || virtualItemIndex > layoutInfo.LastRealizedItemIndex)
{
var generatorPosition = _itemsGenerator.GeneratorPositionFromIndex(virtualItemIndex);
if (generatorPosition.Index >= 0)
{
try
{
_itemsGenerator.Recycle(generatorPosition, 1);
}
catch (ArgumentException)
{
//I have seen the following exception which appears to be a non-issue
// GeneratorPosition '0,10' passed to Remove does not have Offset equal to 0.
}
}
}
SetVirtualItemIndex(child, -1);
}
}
protected override Size MeasureOverride(Size availableSize)
{
_isInMeasure = true;
if (_itemsControl != null)
{
_childLayouts.Clear();
ExtentInfo extentInfo = GetExtentInfo(availableSize, ItemHeight);
EnsureScrollOffsetIsWithinConstrains(extentInfo);
ItemLayoutInfo layoutInfo = GetLayoutInfo(availableSize, ItemHeight, extentInfo);
RecycleItems(layoutInfo);
// Determine where the first item is in relation to previously realized items
GeneratorPosition generatorStartPosition =
_itemsGenerator.GeneratorPositionFromIndex(layoutInfo.FirstRealizedItemIndex);
int visualIndex = 0;
double currentX = layoutInfo.FirstRealizedItemLeft;
double currentY = layoutInfo.FirstRealizedLineTop;
var availableItemSize = new Size(ItemWidth, ItemHeight);
using (_itemsGenerator.StartAt(generatorStartPosition, GeneratorDirection.Forward, true))
{
for (int itemIndex = layoutInfo.FirstRealizedItemIndex;
itemIndex <= layoutInfo.LastRealizedItemIndex;
itemIndex++, visualIndex++)
{
bool newlyRealized;
var child = (UIElement)_itemsGenerator.GenerateNext(out newlyRealized);
SetVirtualItemIndex(child, itemIndex);
if (newlyRealized)
{
InsertInternalChild(visualIndex, child);
}
else
{
// check if item needs to be moved into a new position in the Children collection
if (visualIndex < Children.Count)
{
if (Children[visualIndex] != child)
{
int childCurrentIndex = Children.IndexOf(child);
if (childCurrentIndex >= 0)
{
RemoveInternalChildRange(childCurrentIndex, 1);
}
InsertInternalChild(visualIndex, child);
}
}
else
{
// we know that the child can't already be in the children collection
// because we've been inserting children in correct visualIndex order,
// and this child has a visualIndex greater than the Children.Count
AddInternalChild(child);
}
}
// only prepare the item once it has been added to the visual tree
_itemsGenerator.PrepareItemContainer(child);
child.Measure(availableItemSize);
_childLayouts.Add(child, new Rect(currentX, currentY, ItemWidth, ItemHeight));
if (currentX + ItemWidth * 2 >= availableSize.Width)
{
// wrap to a new line
currentY += ItemHeight;
currentX = 0;
}
else
{
currentX += ItemWidth;
}
}
}
RemoveRedundantChildren();
UpdateScrollInfo(availableSize, extentInfo);
}
Size desiredSize = GetPanelDesiredSize(availableSize);
_isInMeasure = false;
return(desiredSize);
}