public async static Task ScrollToItem(this ListViewBase listViewBase, object item)
{
bool isVirtualizing = default(bool);
double previousHorizontalOffset = default(double), previousVerticalOffset = default(double);
// get the ScrollViewer withtin the ListView/GridView
var scrollViewer = listViewBase?.GetScrollViewer();
// get the SelectorItem to scroll to
var selectorItem = listViewBase?.ContainerFromItem(item) as SelectorItem;
// when it's null, means virtualization is on and the item hasn't been realized yet
if (selectorItem == null && listViewBase != null && scrollViewer != null)
{
isVirtualizing = true;
previousHorizontalOffset = scrollViewer?.HorizontalOffset ?? 0.0;
previousVerticalOffset = scrollViewer?.VerticalOffset ?? 0.0;
// call task-based ScrollIntoViewAsync to realize the item
await listViewBase?.ScrollIntoViewAsync(item);
// this time the item shouldn't be null again
selectorItem = (SelectorItem)listViewBase?.ContainerFromItem(item);
}
// calculate the position object in order to know how much to scroll to
var transform = selectorItem?.TransformToVisual((UIElement)scrollViewer?.Content);
var position = transform?.TransformPoint(new Point(0, 0)) ?? new Point(0, 0);
// when virtualized, scroll back to previous position without animation
if (isVirtualizing)
{
await scrollViewer?.ChangeViewAsync(previousHorizontalOffset, previousVerticalOffset, true);
}
// scroll to desired position with animation!
scrollViewer?.ChangeView(position.X, position.Y - scrollViewer?.ActualHeight / 2, null);
}
public async static Task ScrollToItem2(this ListViewBase listViewBase, object item, VerticalAlignment alignment, bool highlight, double?pixel = null)
{
var scrollViewer = listViewBase.GetScrollViewer();
if (scrollViewer == null)
{
return;
}
//listViewBase.SelectionMode = ListViewSelectionMode.Single;
//listViewBase.SelectedItem = item;
var selectorItem = listViewBase.ContainerFromItem(item) as SelectorItem;
if (selectorItem == null)
{
// call task-based ScrollIntoViewAsync to realize the item
await listViewBase.ScrollIntoViewAsync(item);
// this time the item shouldn't be null again
selectorItem = (SelectorItem)listViewBase.ContainerFromItem(item);
}
if (selectorItem == null)
{
return;
}
// calculate the position object in order to know how much to scroll to
var transform = selectorItem.TransformToVisual((UIElement)scrollViewer.Content);
var position = transform.TransformPoint(new Point(0, 0));
if (alignment == VerticalAlignment.Top)
{
if (pixel is double adjust)
{
position.Y -= adjust;
}
}
else if (alignment == VerticalAlignment.Center)
{
position.Y -= (listViewBase.ActualHeight - selectorItem.ActualHeight) / 2d;
}
else if (alignment == VerticalAlignment.Bottom)
{
position.Y -= listViewBase.ActualHeight - selectorItem.ActualHeight;
if (pixel is double adjust)
{
position.Y += adjust;
}
}
// scroll to desired position with animation!
scrollViewer.ChangeView(position.X, position.Y, null, alignment != VerticalAlignment.Center);
if (highlight)
{
var bubble = selectorItem.Descendants <MessageBubble>().FirstOrDefault() as MessageBubble;
if (bubble == null)
{
return;
}
bubble.Highlight();
}
}
private void RectangleSelection_PointerMoved(object sender, PointerRoutedEventArgs e)
{
if (scrollViewer == null)
{
return;
}
var currentPoint = e.GetCurrentPoint(uiElement);
var verticalOffset = scrollViewer.VerticalOffset;
if (selectionState == SelectionState.Starting)
{
if (!HasMovedMinimalDelta(originDragPoint.X, originDragPoint.Y - verticalOffset, currentPoint.Position.X, currentPoint.Position.Y))
{
return;
}
// Clear selected items once if the pointer is pressed and moved
selectionStrategy.StartSelection();
OnSelectionStarted();
selectionState = SelectionState.Active;
}
if (currentPoint.Properties.IsLeftButtonPressed)
{
var originDragPointShifted = new Point(originDragPoint.X, originDragPoint.Y - verticalOffset); // Initial drag point relative to the topleft corner
base.DrawRectangle(currentPoint, originDragPointShifted, uiElement);
// Selected area considering scrolled offset
var rect = new System.Drawing.Rectangle((int)Canvas.GetLeft(selectionRectangle), (int)Math.Min(originDragPoint.Y, currentPoint.Position.Y + verticalOffset), (int)selectionRectangle.Width, (int)Math.Abs(originDragPoint.Y - (currentPoint.Position.Y + verticalOffset)));
foreach (var item in uiElement.Items.ToList().Except(itemsPosition.Keys))
{
var listViewItem = (FrameworkElement)uiElement.ContainerFromItem(item); // Get ListViewItem
if (listViewItem == null)
{
continue; // Element is not loaded (virtualized list)
}
var gt = listViewItem.TransformToVisual(uiElement);
var itemStartPoint = gt.TransformPoint(new Point(0, verticalOffset)); // Get item position relative to the top of the list (considering scrolled offset)
var itemRect = new System.Drawing.Rectangle((int)itemStartPoint.X, (int)itemStartPoint.Y, (int)listViewItem.ActualWidth, (int)listViewItem.ActualHeight);
itemsPosition[item] = itemRect;
}
foreach (var item in itemsPosition.ToList())
{
try
{
if (rect.IntersectsWith(item.Value))
{
selectionStrategy.HandleIntersectionWithItem(item.Key);
}
else
{
selectionStrategy.HandleNoIntersectionWithItem(item.Key);
}
}
catch (ArgumentException)
{
// Item is not present in the ItemsSource
itemsPosition.Remove(item);
}
}
if (currentPoint.Position.Y > uiElement.ActualHeight - 20)
{
// Scroll down the list if pointer is at the bottom
var scrollIncrement = Math.Min(currentPoint.Position.Y - (uiElement.ActualHeight - 20), 40);
scrollViewer.ChangeView(null, verticalOffset + scrollIncrement, null, false);
}
else if (currentPoint.Position.Y < 20)
{
// Scroll up the list if pointer is at the top
var scrollIncrement = Math.Min(20 - currentPoint.Position.Y, 40);
scrollViewer.ChangeView(null, verticalOffset - scrollIncrement, null, false);
}
}
}
public async static Task ScrollToItem(this ListViewBase listViewBase, object item, SnapPointsAlignment alignment, bool highlight, double?pixel = null)
{
// get the ScrollViewer withtin the ListView/GridView
var scrollViewer = listViewBase.GetScrollViewer();
// get the SelectorItem to scroll to
var selectorItem = listViewBase.ContainerFromItem(item) as SelectorItem;
// when it's null, means virtualization is on and the item hasn't been realized yet
if (selectorItem == null)
{
// call task-based ScrollIntoViewAsync to realize the item
await listViewBase.ScrollIntoViewAsync(item);
// this time the item shouldn't be null again
selectorItem = (SelectorItem)listViewBase.ContainerFromItem(item);
}
if (selectorItem == null)
{
return;
}
// calculate the position object in order to know how much to scroll to
var transform = selectorItem.TransformToVisual((UIElement)scrollViewer.Content);
var position = transform.TransformPoint(new Point(0, 0));
if (alignment == SnapPointsAlignment.Near)
{
if (pixel is double adjust)
{
position.Y -= adjust;
}
}
else if (alignment == SnapPointsAlignment.Center)
{
position.Y -= (listViewBase.ActualHeight - selectorItem.ActualHeight) / 2d;
}
else if (alignment == SnapPointsAlignment.Far)
{
position.Y -= listViewBase.ActualHeight - selectorItem.ActualHeight;
if (pixel is double adjust)
{
position.Y += adjust;
}
}
// scroll to desired position with animation!
scrollViewer.ChangeView(position.X, position.Y, null, alignment != SnapPointsAlignment.Center);
if (highlight)
{
var bubble = selectorItem.Descendants <MessageBubble>().FirstOrDefault() as MessageBubble;
if (bubble == null)
{
return;
}
bubble.Highlight();
}
}
private void View_PointerMoved(object sender, PointerRoutedEventArgs e)
{
if (IsEnabled && e.Pointer.PointerDeviceType == PointerDeviceType.Mouse && e.GetCurrentPoint(View).Properties.IsLeftButtonPressed)
{
if (Interlocked.Exchange(ref Locker, 1) == 0)
{
try
{
Point RelativeEndPoint = e.GetCurrentPoint(View).Position;
SrcollIfNeed(RelativeEndPoint);
Point AbsEndPoint = new Point(RelativeEndPoint.X + InnerScrollView.HorizontalOffset, RelativeEndPoint.Y + InnerScrollView.VerticalOffset);
Point RelativeStartPoint = new Point(AbsStartPoint.X - InnerScrollView.HorizontalOffset, AbsStartPoint.Y - InnerScrollView.VerticalOffset);
DrawRectangleInCanvas(RelativeStartPoint, RelativeEndPoint);
if (Math.Abs(RelativeStartPoint.X - RelativeEndPoint.X) >= 20 && Math.Abs(RelativeStartPoint.Y - RelativeEndPoint.Y) >= 20)
{
List <FileSystemStorageItemBase> VisibleList = new List <FileSystemStorageItemBase>();
if (View is ListView)
{
ItemsStackPanel VirtualPanel = View.ItemsPanelRoot as ItemsStackPanel;
for (int i = VirtualPanel.FirstVisibleIndex; i <= VirtualPanel.LastVisibleIndex; i++)
{
VisibleList.Add(View.Items[i] as FileSystemStorageItemBase);
}
}
else
{
ItemsWrapGrid VirtualPanel = View.ItemsPanelRoot as ItemsWrapGrid;
for (int i = VirtualPanel.FirstVisibleIndex; i <= VirtualPanel.LastVisibleIndex; i++)
{
VisibleList.Add(View.Items[i] as FileSystemStorageItemBase);
}
}
foreach (FileSystemStorageItemBase Item in VisibleList.Except(AbsItemLocationRecord.Select((Rec) => Rec.Key)))
{
if (View.ContainerFromItem(Item) is SelectorItem Selector)
{
AbsItemLocationRecord.Add(new KeyValuePair <FileSystemStorageItemBase, Rect>(Item, Selector.TransformToVisual(View).TransformBounds(new Rect(InnerScrollView.HorizontalOffset, InnerScrollView.VerticalOffset, Selector.ActualWidth, Selector.ActualHeight))));
}
}
Rect AbsBoxSelectionRect = new Rect(Math.Min(AbsStartPoint.X, AbsEndPoint.X), Math.Min(AbsStartPoint.Y, AbsEndPoint.Y), Math.Abs(AbsStartPoint.X - AbsEndPoint.X), Math.Abs(AbsStartPoint.Y - AbsEndPoint.Y));
foreach (KeyValuePair <FileSystemStorageItemBase, Rect> Pair in AbsItemLocationRecord)
{
Rect Intersect = RectHelper.Intersect(AbsBoxSelectionRect, Pair.Value);
if (!Intersect.IsEmpty && Intersect.Width > 0 && Intersect.Height > 0)
{
if (!View.SelectedItems.Contains(Pair.Key))
{
View.SelectedItems.Add(Pair.Key);
}
}
else
{
View.SelectedItems.Remove(Pair.Key);
}
}
}
}
catch (Exception ex)
{
LogTracer.Log(ex);
}
finally
{
_ = Interlocked.Exchange(ref Locker, 0);
}
}
}
}
private void View_PointerMoved(object sender, PointerRoutedEventArgs e)
{
if (AllowProcess && e.Pointer.PointerDeviceType == PointerDeviceType.Mouse && e.GetCurrentPoint(View).Properties.IsLeftButtonPressed)
{
if (Interlocked.Exchange(ref Locker, 1) == 0)
{
try
{
Point RelativeEndPoint = e.GetCurrentPoint(View).Position;
SrcollIfNeed(RelativeEndPoint);
Point RelativeStartPoint = new Point(AbsStartPoint.X - InnerScrollView.HorizontalOffset, AbsStartPoint.Y - InnerScrollView.VerticalOffset);
DrawRectangleInCanvas(RelativeStartPoint, RelativeEndPoint);
GeneralTransform AbsToWindowTransform = View.TransformToVisual(Window.Current.Content);
Rect SelectedRect = new Rect(RelativeStartPoint, RelativeEndPoint);
if (SelectedRect.Width >= 20 && SelectedRect.Height >= 20)
{
IEnumerable <FileSystemStorageItemBase> SelectedList = VisualTreeHelper.FindElementsInHostCoordinates(AbsToWindowTransform.TransformBounds(SelectedRect), View).OfType <SelectorItem>().Select((Item) => Item.Content as FileSystemStorageItemBase);
foreach (FileSystemStorageItemBase Item in View.SelectedItems.OfType <FileSystemStorageItemBase>().Except(SelectedList).Where((Item) => (View.ContainerFromItem(Item) as SelectorItem).IsVisibleOnContainer(View)))
{
View.SelectedItems.Remove(Item);
}
foreach (FileSystemStorageItemBase Item in SelectedList.Except(View.SelectedItems.OfType <FileSystemStorageItemBase>()))
{
View.SelectedItems.Add(Item);
}
}
}
catch (Exception ex)
{
LogTracer.Log(ex);
}
finally
{
_ = Interlocked.Exchange(ref Locker, 0);
}
}
}
}
