/// <summary>
/// Handles the PreviewMouseLeftButtonDown event on the drag source.
/// </summary>
/// <param name="sender">The sender.</param>
/// <param name="e">The event args.</param>
private void DragSourcePreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
this.sourceItemsControl = (TreeListBox)sender;
var visual = e.OriginalSource as Visual;
this.topWindow = Window.GetWindow(this.sourceItemsControl);
this.initialMousePosition = e.GetPosition(this.topWindow);
this.sourceItemContainer = visual != null
? this.sourceItemsControl.ContainerFromElement(visual) as TreeListBoxItem
: null;
if (this.sourceItemContainer != null)
{
this.draggedData = new List <IDragSource>();
this.draggedData.Add(this.sourceItemContainer.DataContext);
// todo: how to drag multiple items?
// must set e.Handled = true to avoid items being deselected
// foreach (var si in sourceItemsControl.SelectedItems) this.draggedData.Add(si);
}
else
{
this.draggedData = null;
}
}
/// <summary>
/// Handles the PreviewMouseLeftButtonDown event on the drag source.
/// </summary>
/// <param name="sender">
/// The sender.
/// </param>
/// <param name="e">
/// The event args.
/// </param>
private void DragSourcePreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
this.sourceItemsControl = (TreeListBox)sender;
var visual = e.OriginalSource as Visual;
this.topWindow = Window.GetWindow(this.sourceItemsControl);
this.initialMousePosition = e.GetPosition(this.topWindow);
this.sourceItemContainer = visual != null
? this.sourceItemsControl.ContainerFromElement(visual) as TreeListBoxItem
: null;
if (this.sourceItemContainer != null)
{
this.draggedData = new List<IDragSource>();
this.draggedData.Add(this.sourceItemContainer.DataContext);
// todo: how to drag multiple items?
// must set e.Handled = true to avoid items being deselected
// foreach (var si in sourceItemsControl.SelectedItems) this.draggedData.Add(si);
}
else
{
this.draggedData = null;
}
}
/// <summary>
/// Decides the drop target.
/// </summary>
/// <param name="e">The event args.</param>
private void DecideDropTarget(DragEventArgs e)
{
// If the types of the dragged data and ItemsControl's source are compatible,
// there are 3 situations to have into account when deciding the drop target:
// 1. mouse is over an items container
// 2. mouse is over the empty part of an ItemsControl, but ItemsControl is not empty
// 3. mouse is over an empty ItemsControl.
// The goal of this method is to decide on the values of the following properties:
// targetItemContainer, insertionIndex and isInFirstHalf.
int targetItemsControlCount = this.targetItemsControl.Items.Count;
var draggedItems = e.Data.GetData(this.format.Name) as IList;
if (targetItemsControlCount > 0)
{
this.hasVerticalOrientation = true;
this.targetItemContainer =
this.targetItemsControl.ContainerFromElement((DependencyObject)e.OriginalSource) as TreeListBoxItem;
if (this.targetItemContainer != null)
{
Point positionRelativeToItemContainer = e.GetPosition(this.targetItemContainer);
double relativePosition = GetRelativePosition(
this.targetItemContainer, positionRelativeToItemContainer, this.hasVerticalOrientation);
this.isInFirstHalf = relativePosition < 0.5;
if (relativePosition > 0.3 && relativePosition < 0.7)
{
this.dropPosition = DropPosition.Add;
}
else
{
this.dropPosition = relativePosition < 0.5
? DropPosition.InsertBefore
: DropPosition.InsertAfter;
}
}
else
{
this.targetItemContainer = this.targetItemsControl.ContainerFromIndex(targetItemsControlCount - 1);
this.isInFirstHalf = false;
this.dropPosition = DropPosition.InsertAfter;
}
}
else
{
this.targetItemContainer = null;
this.dropPosition = DropPosition.InsertBefore;
}
if (this.targetItemContainer != null && draggedItems != null)
{
var dropTarget = this.targetItemContainer.DataContext as IDropTarget;
foreach (var draggedItem in draggedItems)
{
var dragSource = draggedItem as IDragSource;
if ((dragSource == null || !dragSource.IsDraggable) ||
(dropTarget == null || !dropTarget.CanDrop(dragSource, this.dropPosition, (DragDropEffect)e.Effects)))
{
this.targetItemContainer = null;
e.Effects = DragDropEffects.None;
return;
}
}
}
}
/// <summary>
/// Expands the specified item.
/// </summary>
/// <param name="item">
/// The item.
/// </param>
internal void Expand(TreeListBoxItem item)
{
if (this.isPreparingContainer)
{
// cannot expand when preparing the container
// add the item to a queue, and expand later
this.expandItems.Enqueue(item);
if (!this.isSubscribedToRenderingEvent)
{
CompositionTarget.Rendering += this.CompositionTargetRendering;
this.isSubscribedToRenderingEvent = true;
}
return;
}
if (item.Content == null || item.Children == null)
{
return;
}
lock (this)
{
int i0 = this.Items.IndexOf(item.Content) + 1;
foreach (var child in item.Children)
{
if (this.Items.Contains(child))
{
Debug.WriteLine("TreeListBox bug.");
continue;
}
this.Items.Insert(i0++, child);
this.parentContainerMap[child] = item;
}
}
}
/// <summary>
/// Decides the drop target.
/// </summary>
/// <param name="e">
/// The event args.
/// </param>
private void DecideDropTarget(DragEventArgs e)
{
// If the types of the dragged data and ItemsControl's source are compatible,
// there are 3 situations to have into account when deciding the drop target:
// 1. mouse is over an items container
// 2. mouse is over the empty part of an ItemsControl, but ItemsControl is not empty
// 3. mouse is over an empty ItemsControl.
// The goal of this method is to decide on the values of the following properties:
// targetItemContainer, insertionIndex and isInFirstHalf.
int targetItemsControlCount = this.targetItemsControl.Items.Count;
var draggedItems = e.Data.GetData(this.format.Name) as IList;
if (targetItemsControlCount > 0)
{
this.hasVerticalOrientation = true;
this.targetItemContainer =
this.targetItemsControl.ContainerFromElement((DependencyObject)e.OriginalSource) as TreeListBoxItem;
if (this.targetItemContainer != null)
{
Point positionRelativeToItemContainer = e.GetPosition(this.targetItemContainer);
double relativePosition = GetRelativePosition(
this.targetItemContainer, positionRelativeToItemContainer, this.hasVerticalOrientation);
this.isInFirstHalf = relativePosition < 0.5;
if (relativePosition > 0.3 && relativePosition < 0.7)
{
this.dropPosition = DropPosition.Add;
}
else
{
this.dropPosition = relativePosition < 0.5
? DropPosition.InsertBefore
: DropPosition.InsertAfter;
}
}
else
{
this.targetItemContainer = this.targetItemsControl.ContainerFromIndex(targetItemsControlCount - 1);
this.isInFirstHalf = false;
this.dropPosition = DropPosition.InsertAfter;
}
}
else
{
this.targetItemContainer = null;
this.dropPosition = DropPosition.InsertBefore;
}
if (this.targetItemContainer != null && draggedItems != null)
{
var dropTarget = this.targetItemContainer.DataContext as IDropTarget;
bool copy = (e.Effects & DragDropEffects.Copy) != 0;
foreach (var draggedItem in draggedItems)
{
var dragSource = draggedItem as IDragSource;
if ((dragSource == null || !dragSource.IsDraggable)
|| (dropTarget == null || !dropTarget.CanDrop(dragSource, this.dropPosition, copy)))
{
this.targetItemContainer = null;
e.Effects = DragDropEffects.None;
return;
}
}
}
}
/// <summary>
/// Handles child collection changes.
/// </summary>
/// <param name="parent">
/// The parent.
/// </param>
/// <param name="e">
/// The <see cref="System.Collections.Specialized.NotifyCollectionChangedEventArgs"/> instance containing the event data.
/// </param>
internal void ChildCollectionChanged(TreeListBoxItem parent, NotifyCollectionChangedEventArgs e)
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Remove:
case NotifyCollectionChangedAction.Move:
foreach (var item in e.OldItems)
{
var container = this.ContainerFromItem(item);
if (container != null && container.IsExpanded)
{
container.IsExpanded = false;
}
this.Items.Remove(item);
}
break;
case NotifyCollectionChangedAction.Reset:
var itemsToRemove = new List<TreeListBoxItem>();
foreach (var item in this.Items)
{
var container = this.ContainerFromItem(item);
if (container == null || !ReferenceEquals(container.ParentItem, parent))
{
continue;
}
itemsToRemove.Add(container);
}
foreach (var container in itemsToRemove)
{
if (container.IsExpanded)
{
container.IsExpanded = false;
}
this.Items.Remove(container.Content);
}
parent.IsExpanded = false;
parent.HasItems = false;
break;
case NotifyCollectionChangedAction.Replace:
// todo: remove old items and child items
throw new NotImplementedException();
}
switch (e.Action)
{
case NotifyCollectionChangedAction.Move:
case NotifyCollectionChangedAction.Add:
if (parent.IsExpanded)
{
int i;
if (e.NewStartingIndex + e.NewItems.Count < parent.Children.Count)
{
// inserted items
var followingChild = parent.Children[e.NewStartingIndex + e.NewItems.Count];
i = this.Items.IndexOf(followingChild);
}
else
{
// added items
var parentSibling = parent.GetNextSibling();
if (parentSibling == null)
{
// No sibling found, so add at the end of the list.
i = this.Items.Count;
}
else
{
// Found the sibling, so add the items before this item.
i = this.Items.IndexOf(parentSibling.Content);
//// int i0 = this.ItemContainerGenerator.IndexFromContainer(parentSibling);
}
}
if (i < 0)
{
Debug.WriteLine("TreeListBox bug.");
}
else
{
foreach (var item in e.NewItems)
{
this.parentContainerMap[item] = parent;
if (this.Items.Contains(item))
{
Debug.WriteLine("TreeListBox bug.");
}
this.Items.Insert(i++, item);
}
}
}
break;
case NotifyCollectionChangedAction.Replace:
for (int i = 0; i < e.NewItems.Count; i++)
{
this.Items[e.NewStartingIndex + i] = e.NewItems[i];
}
// todo: add new items and child items
throw new NotImplementedException();
}
parent.HasItems = parent.Children.Cast<object>().Any();
}
/// <summary>
/// Collapses the specified item.
/// </summary>
/// <param name="item">
/// The item.
/// </param>
internal void Collapse(TreeListBoxItem item)
{
if (item.Children == null)
{
return;
}
foreach (var child in item.Children)
{
var childContainer = this.ContainerFromItem(child);
if (childContainer != null)
{
if (childContainer.IsExpanded)
{
childContainer.IsExpanded = false;
}
if (childContainer.IsSelected)
{
childContainer.IsSelected = false;
}
}
this.Items.Remove(child);
}
}
/// <summary>
/// Inserts the specified items in the tree.
/// </summary>
/// <param name="parentContainer">The parent container.</param>
/// <param name="newItems">The new items.</param>
/// <param name="newStartingIndex">New index of the starting.</param>
private void InsertItems(TreeListBoxItem parentContainer, IList newItems, int newStartingIndex)
{
// Find the index where the new items should be added
int i;
if (newStartingIndex + newItems.Count < parentContainer.Children.Count)
{
// inserted items
var followingChild = parentContainer.Children[newStartingIndex + newItems.Count];
i = this.Items.IndexOf(followingChild);
}
else
{
// added items
var parentSibling = parentContainer.GetNextSibling();
if (parentSibling == null)
{
// No sibling found, so add at the end of the list.
i = this.Items.Count;
}
else
{
// Found the sibling, so add the items before this item.
i = this.Items.IndexOf(parentSibling.Content);
}
}
if (i < 0)
{
#if !DEBUG
throw new InvalidOperationException("Could not get parent index in TreeListBox.");
#else
System.Diagnostics.Trace.WriteLine("Could not get parent index in TreeListBox.");
#endif
}
foreach (var item in newItems)
{
this.InsertItem(i, item, parentContainer.Content);
}
}
/// <summary>
/// Expands the specified container.
/// </summary>
/// <param name="container">The container to expand.</param>
internal void Expand(TreeListBoxItem container)
{
if (this.isPreparingContainer)
{
// cannot expand when preparing the container
// add the item to a queue, and expand later
this.expandItemQueue.Enqueue(container);
if (!this.isSubscribedToRenderingEvent)
{
CompositionTarget.Rendering += this.CompositionTargetRendering;
this.isSubscribedToRenderingEvent = true;
}
return;
}
if (container.Content == null || container.Children == null)
{
return;
}
lock (this)
{
int i0 = this.Items.IndexOf(container.Content) + 1;
var parent = container.Content;
foreach (var child in container.Children)
{
this.InsertItem(i0++, child, parent);
}
}
}
/// <summary>
/// Handles child collection changes.
/// </summary>
/// <param name="parentContainer">The parent container.</param>
/// <param name="e">The <see cref="System.Collections.Specialized.NotifyCollectionChangedEventArgs" /> instance containing the event data.</param>
internal void ChildCollectionChanged(TreeListBoxItem parentContainer, NotifyCollectionChangedEventArgs e)
{
switch (e.Action)
{
case NotifyCollectionChangedAction.Remove:
case NotifyCollectionChangedAction.Move:
case NotifyCollectionChangedAction.Replace:
this.RemoveItems(e.OldItems);
break;
case NotifyCollectionChangedAction.Reset:
this.RemoveItems(this.Items);
parentContainer.IsExpanded = false;
parentContainer.HasItems = false;
break;
}
switch (e.Action)
{
case NotifyCollectionChangedAction.Move:
case NotifyCollectionChangedAction.Add:
case NotifyCollectionChangedAction.Replace:
if (parentContainer.IsExpanded)
{
this.InsertItems(parentContainer, e.NewItems, e.NewStartingIndex);
}
break;
}
parentContainer.HasItems = parentContainer.Children.Cast<object>().Any();
}
/// <summary>
/// Subscribes for changes on the specified collection.
/// </summary>
/// <param name="parent">The parent.</param>
/// <param name="collection">The collection to observe.</param>
private void SubscribeForCollectionChanges(TreeListBoxItem parent, IEnumerable collection)
{
if (this.ParentTreeListBox == null)
{
throw new InvalidOperationException("Parent not set.");
}
var cc = collection as INotifyCollectionChanged;
if (cc != null)
{
var parentTreeListBox = this.ParentTreeListBox;
this.collectionChangedHandler = (s, e) => parentTreeListBox.ChildCollectionChanged(parent, e);
cc.CollectionChanged += this.collectionChangedHandler;
}
}
/// <summary>
/// Subscribes for collection changes.
/// </summary>
/// <param name="parent">
/// The parent.
/// </param>
/// <param name="collection">
/// The collection.
/// </param>
private void SubscribeForCollectionChanges(TreeListBoxItem parent, IEnumerable collection)
{
var cc = collection as INotifyCollectionChanged;
if (cc != null)
{
this.collectionChangedHandler = (s, e) => this.ParentTreeListBox.ChildCollectionChanged(parent, e);
cc.CollectionChanged += this.collectionChangedHandler;
}
}
