public static GetItemsOwner ( DependencyObject element ) : |
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element | DependencyObject | |
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/// <summary> /// Measure the children /// </summary> /// <param name="availableSize">Size available</param> /// <returns>Size desired</returns> protected override Size MeasureOverride(Size availableSize) { if (ScrollOwner != null) { if (ScrollOwner.ScrollableWidth < HorizontalOffset) { SetHorizontalOffset(ScrollOwner.ScrollableWidth); } if (ScrollOwner.ScrollableHeight < VerticalOffset) { SetVerticalOffset(ScrollOwner.ScrollableHeight); } } // We need to access InternalChildren before the generator to work around a bug UIElementCollection children = InternalChildren; IItemContainerGenerator generator = ItemContainerGenerator; ItemsControl itemsControl = ItemsControl.GetItemsOwner(this); TreeViewExItem treeViewItem = itemsControl as TreeViewExItem; TreeViewEx treeView = itemsControl as TreeViewEx ?? treeViewItem.ParentTreeView; Debug(treeViewItem, "Measuring"); double maxWidth = 0; double currentYinItemSystem = 0; if (treeView.IsVirtualizing) { // never forget: virtualization of a tree is an approximation. there are some use cases which theoretically work and others // we try to get it working by estimations. See GetCachedOrEstimatedHeight for more infos. int itemCount = itemsControl.Items.Count; int firstVisibleItemIndex = 0; int lastVisibleItemIndex = itemCount; double itemTop; if (treeViewItem != null) { itemTop = treeViewItem.itemTopInTreeSystem + GetHeightOfHeader(itemsControl); } else { // get the area where items have to be visualized. This is from top to bottom of the visible space in tree system. // We add a little of offset. It seems like it improves estimation of heights. double predictionOffset = 50; double top = VerticalOffset - predictionOffset; if (top < 0) { top = 0; } treeView.realizationSpace.Top = top; treeView.realizationSpace.Bottom = VerticalOffset + availableSize.Height + predictionOffset; itemTop = GetHeightOfHeader(itemsControl); } int itemGeneratorIndex = 0; bool isPreviousItemVisible = false; IDisposable generatorRun = null; currentYinItemSystem = 0; int childHierarchyLevel = 0; if (treeViewItem != null) { childHierarchyLevel = treeViewItem.hierachyLevel + 1; } try { // iterate child items for (int i = 0; i < itemCount; i++) { double estimatedHeight = GetCachedOrEstimatedHeight(treeView, childHierarchyLevel); VerticalArea childSpace = new VerticalArea(); childSpace.Top = itemTop + currentYinItemSystem; childSpace.Bottom = childSpace.Top + estimatedHeight; // check if item is possibly visible or could become visible if someone changes expanding of siblings bool isVisibleItem = treeView.realizationSpace.IsWithin(childSpace); if (isVisibleItem) { // we have found a visible item, lets check if its the first visible item. if (!isPreviousItemVisible) { // we found a visible item, lets initialize the visible item section of the loop isPreviousItemVisible = true; firstVisibleItemIndex = i; GeneratorPosition startPos = generator.GeneratorPositionFromIndex(i); itemGeneratorIndex = (startPos.Offset == 0) ? startPos.Index : startPos.Index + 1; generatorRun = generator.StartAt(startPos, GeneratorDirection.Forward, true); } else { itemGeneratorIndex++; } // Get or create the child bool newlyRealized; TreeViewExItem child = generator.GenerateNext(out newlyRealized) as TreeViewExItem; Debug(treeViewItem, "Found visible child: " + child.DataContext); if (newlyRealized) { // Figure out if we need to insert the child at the end or somewhere in the middle AddOrInsertItemToInternalChildren(itemGeneratorIndex, child); child.ParentTreeView = treeView; generator.PrepareItemContainer(child); } else { // The child has already been created, let's be sure it's in the right spot if (child != children[itemGeneratorIndex]) { throw new InvalidOperationException("Wrong child was generated"); } } if (treeViewItem != null) { child.itemTopInTreeSystem = currentYinItemSystem + itemTop; child.hierachyLevel = treeViewItem.hierachyLevel + 1; } else { child.itemTopInTreeSystem = currentYinItemSystem; child.hierachyLevel = 1; } InvalidateMeasure(child); child.Measure(new Size(double.MaxValue, double.MaxValue)); // add real height to cache double heightOfChild = child.DesiredSize.Height; RegisterHeight(treeView, childHierarchyLevel, heightOfChild); currentYinItemSystem += child.DesiredSize.Height; // save the maximum needed width maxWidth = Math.Max(maxWidth, child.DesiredSize.Width); } else { //Debug(treeViewItem, "Found invisible child: " + i); if (isPreviousItemVisible) { // set last visible index. this is important, to cleanup not anymore used items lastVisibleItemIndex = i; isPreviousItemVisible = false; } // dispose generator run. if we do it after the whole loop, we run in multithreading issues if (generatorRun != null) { generatorRun.Dispose(); generatorRun = null; } currentYinItemSystem += GetCachedOrEstimatedHeight(treeView, childHierarchyLevel); } //Debug(treeViewItem, "Current y for " + i + ": " + currentYinItemSystem); } } finally { //just for safety if (generatorRun != null) { generatorRun.Dispose(); generatorRun = null; } } //Debug("Cleaning all items but " + firstVisibleItemIndex + " to " + lastVisibleItemIndex + " for element " + itemsControl.DataContext); CleanUpItems(firstVisibleItemIndex, lastVisibleItemIndex); } else { //Debug("Virtualization is OFF."); GeneratorPosition startPos = generator.GeneratorPositionFromIndex(0); using (generator.StartAt(startPos, GeneratorDirection.Forward, true)) { for (int i = (startPos.Offset == 0) ? startPos.Index : startPos.Index + 1; i < itemsControl.Items.Count; i++) { // Get or create the child bool newlyRealized; TreeViewExItem child = generator.GenerateNext(out newlyRealized) as TreeViewExItem; if (newlyRealized) { // Figure out if we need to insert the child at the end or somewhere in the middle AddOrInsertItemToInternalChildren(i, child); child.ParentTreeView = treeView ?? treeViewItem.ParentTreeView; generator.PrepareItemContainer(child); } child.Measure(new Size(double.MaxValue, double.MaxValue)); // now get the real height double height = child.DesiredSize.Height; // add real height to current position currentYinItemSystem += height; // save the maximum needed width maxWidth = Math.Max(maxWidth, child.DesiredSize.Width); } } } if (double.IsPositiveInfinity(maxWidth) || double.IsPositiveInfinity(currentYinItemSystem)) { throw new InvalidOperationException("???"); } Extent = new Size(maxWidth, currentYinItemSystem); Viewport = availableSize; Debug(treeViewItem, "Desired height: " + Extent.Height); return(Extent); }
/// <summary> /// Arrange the children /// </summary> /// <param name="finalSize">Size available</param> /// <returns>Size used</returns> protected override Size ArrangeOverride(Size finalSize) { ItemsControl itemsControl = ItemsControl.GetItemsOwner(this); TreeViewExItem treeViewItem = itemsControl as TreeViewExItem; TreeViewEx treeView = itemsControl as TreeViewEx ?? treeViewItem.ParentTreeView; IItemContainerGenerator generator = this.ItemContainerGenerator; //Extent = finalSize; bool foundVisibleItem = false;; double currentY = 0; if (treeView.IsVirtualizing) { //Debug("Arrange-" + itemsControl.DataContext); for (int i = 0; i < itemsControl.Items.Count; i++) { TreeViewExItem child = itemsControl.ItemContainerGenerator.ContainerFromIndex(i) as TreeViewExItem; int childHierarchyLevel = 0; if (child != null) { childHierarchyLevel = child.hierachyLevel; } if (foundVisibleItem) { if (child == null) { // other items are not visible / virtualized break; } } else { if (child != null) { // found first visible item foundVisibleItem = true; } } if (child != null) { child.Arrange(new Rect(-HorizontalOffset, currentY - VerticalOffset, finalSize.Width, child.DesiredSize.Height)); currentY += child.ActualHeight; } else { currentY += GetCachedOrEstimatedHeight(treeView, childHierarchyLevel); } } } else { for (int i = 0; i < itemsControl.Items.Count; i++) { UIElement child = itemsControl.ItemContainerGenerator.ContainerFromIndex(i) as UIElement; if (child != null) { child.Arrange(new Rect(-HorizontalOffset, currentY - VerticalOffset, finalSize.Width, child.DesiredSize.Height)); } currentY += child.DesiredSize.Height; } } return(finalSize); }