private void RectangleSelection_PointerPressed(object sender, PointerRoutedEventArgs e)
{
itemsPosition.Clear();
dataGridRows.Clear();
DependencyObjectHelpers.FindChildren <DataGridRow>(dataGridRows, uiElement); // Find visible/loaded rows
prevSelectedItems = uiElement.SelectedItems.Cast <object>().ToList(); // Save current selected items
originDragPoint = new Point(e.GetCurrentPoint(uiElement).Position.X, e.GetCurrentPoint(uiElement).Position.Y); // Initial drag point relative to the topleft corner
var verticalOffset = (scrollBar?.Value ?? 0) - uiElement.ColumnHeaderHeight;
originDragPoint.Y += verticalOffset; // Initial drag point relative to the top of the list (considering scrolled offset)
if (!e.GetCurrentPoint(uiElement).Properties.IsLeftButtonPressed || e.Pointer.PointerDeviceType == Windows.Devices.Input.PointerDeviceType.Touch)
{
// Trigger only on left click, do not trigger with touch
return;
}
var clickedRow = DependencyObjectHelpers.FindParent <DataGridRow>(e.OriginalSource as DependencyObject);
if (clickedRow != null && uiElement.SelectedItems.Contains(clickedRow.DataContext))
{
// If the item under the pointer is selected do not trigger selection rectangle
return;
}
var selectedItems = new GenericItemsCollection <object>(uiElement.SelectedItems);
selectionStrategy = e.KeyModifiers.HasFlag(VirtualKeyModifiers.Control) ?
new InvertPreviousItemSelectionStrategy(selectedItems, prevSelectedItems) :
e.KeyModifiers.HasFlag(VirtualKeyModifiers.Shift) ?
(ItemSelectionStrategy) new ExtendPreviousItemSelectionStrategy(selectedItems, prevSelectedItems) :
new IgnorePreviousItemSelectionStrategy(selectedItems);
if (clickedRow == null)
{
// If user click outside, reset selection
if (uiElement.CurrentColumn != null)
{
uiElement.CancelEdit();
}
DeselectGridCell();
selectionStrategy.HandleNoItemSelected();
}
uiElement.PointerMoved -= RectangleSelection_PointerMoved;
uiElement.PointerMoved += RectangleSelection_PointerMoved;
if (selectionChanged != null)
{
// Unsunscribe from SelectionChanged event for performance
uiElement.SelectionChanged -= selectionChanged;
}
uiElement.CapturePointer(e.Pointer);
selectionState = SelectionState.Starting;
}
private void RectangleSelection_PointerMoved(object sender, PointerRoutedEventArgs e)
{
var selectedItems = new GenericItemsCollection <object>(uiElement.SelectedItems);
var selectionStrategy = e.KeyModifiers == VirtualKeyModifiers.Control ?
(ItemSelectionStrategy) new ExtendPreviousItemSelectionStrategy(selectedItems, prevSelectedItems) :
new IgnorePreviousItemSelectionStrategy(selectedItems);
if (selectionState == SelectionState.Starting)
{
uiElement.CancelEdit();
selectionStrategy.StartSelection();
OnSelectionStarted();
selectionState = SelectionState.Active;
}
var currentPoint = e.GetCurrentPoint(uiElement);
if (currentPoint.Properties.IsLeftButtonPressed && scrollBar != null)
{
var verticalOffset = scrollBar.Value - uiElement.ColumnHeaderHeight;
var originDragPointShifted = new Point(originDragPoint.X, originDragPoint.Y - verticalOffset); // Initial drag point relative to the topleft corner
base.DrawRectangle(currentPoint, originDragPointShifted);
// 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)));
var dataGridRowsPosition = new Dictionary <DataGridRow, System.Drawing.Rectangle>();
double actualWidth = -1;
foreach (var row in dataGridRows)
{
if (row.Visibility != Visibility.Visible)
{
continue; // Skip invalid/invisible rows
}
if (actualWidth < 0)
{
var temp = new List <DataGridCell>();
Interaction.FindChildren <DataGridCell>(temp, row); // Find cells inside row
actualWidth = temp.Sum(x => x.ActualWidth); // row.ActualWidth reports incorrect width
}
var gt = row.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)actualWidth, (int)row.ActualHeight);
itemsPosition[row.DataContext] = itemRect; // Update item position
dataGridRowsPosition[row] = itemRect; // Update ui row position
}
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
// Check if there is a loaded row outside the viewport
var item = dataGridRowsPosition.OrderBy(x => x.Value.Y).SkipWhile(x => x.Value.Y <= verticalOffset + uiElement.ActualHeight).Select(x => x.Key).FirstOrDefault();
if (item == null)
{
if (dataGridRowsPosition.Any())
{
// Last loaded item is fully visible, ge thet next one from bound item source
var index = dataGridRowsPosition.OrderBy(x => x.Value.Y).Last().Key.GetIndex();
var source = (System.Collections.IList)uiElement.ItemsSource;
uiElement.ScrollIntoView(source[Math.Min(Math.Max(index + 1, 0), source.Count - 1)], null);
}
}
else
{
uiElement.ScrollIntoView(item.DataContext, null);
}
}
else if (currentPoint.Position.Y < 20)
{
// Scroll up the list if pointer is at the top
// Check if there is a loaded row outside the viewport
var item = dataGridRowsPosition.OrderBy(x => x.Value.Y).TakeWhile(x => x.Value.Y + x.Value.Height <= scrollBar.Value).Select(x => x.Key).LastOrDefault();
if (item == null)
{
if (dataGridRowsPosition.Any())
{
// First loaded item is fully visible, ge thet previous one from bound item source
var index = dataGridRowsPosition.OrderBy(x => x.Value.Y).First().Key.GetIndex();
var source = (System.Collections.IList)uiElement.ItemsSource;
uiElement.ScrollIntoView(source[Math.Min(Math.Max(index - 1, 0), source.Count - 1)], null);
}
}
else
{
uiElement.ScrollIntoView(item.DataContext, null);
}
}
}
}
