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RectangleSelection_ListViewBase.cs
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RectangleSelection_ListViewBase.cs
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using Files.Uwp.Helpers.XamlHelpers;
using Microsoft.Toolkit.Uwp.UI;
using System;
using System.Collections.Generic;
using System.Linq;
using Windows.Foundation;
using Windows.System;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Shapes;
namespace Files.Uwp.UserControls.Selection
{
public class RectangleSelection_ListViewBase : RectangleSelection
{
private ListViewBase uiElement;
private ScrollViewer scrollViewer;
private SelectionChangedEventHandler selectionChanged;
private DispatcherQueueTimer timer;
private Point originDragPoint;
private Dictionary<object, System.Drawing.Rectangle> itemsPosition;
private List<object> prevSelectedItems;
private List<object> prevSelectedItemsDrag;
private ItemSelectionStrategy selectionStrategy;
public RectangleSelection_ListViewBase(ListViewBase uiElement, Rectangle selectionRectangle, SelectionChangedEventHandler selectionChanged = null)
{
this.uiElement = uiElement;
this.selectionRectangle = selectionRectangle;
this.selectionChanged = selectionChanged;
itemsPosition = new Dictionary<object, System.Drawing.Rectangle>();
timer = DispatcherQueue.GetForCurrentThread().CreateTimer();
InitEvents(null, null);
}
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 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);
}
if (selectionChanged != null)
{
// Restore and trigger SelectionChanged event
uiElement.SelectionChanged -= selectionChanged;
uiElement.SelectionChanged += selectionChanged;
var currentSelectedItemsDrag = uiElement.SelectedItems.Cast<object>().ToList();
if (prevSelectedItemsDrag == null || !prevSelectedItemsDrag.SequenceEqual(currentSelectedItemsDrag))
{
// Trigger SelectionChanged event if the selection has changed
selectionChanged(sender, null);
prevSelectedItemsDrag = currentSelectedItemsDrag;
}
}
}
}
private void RectangleSelection_PointerPressed(object sender, PointerRoutedEventArgs e)
{
if (scrollViewer == null)
{
return;
}
itemsPosition.Clear();
scrollViewer.ViewChanged -= ScrollViewer_ViewChanged;
scrollViewer.ViewChanged += ScrollViewer_ViewChanged;
originDragPoint = new Point(e.GetCurrentPoint(uiElement).Position.X, e.GetCurrentPoint(uiElement).Position.Y); // Initial drag point relative to the topleft corner
prevSelectedItems = uiElement.SelectedItems.Cast<object>().ToList(); // Save current selected items
var verticalOffset = scrollViewer.VerticalOffset;
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;
}
FetchItemsPosition();
selectionStrategy = e.KeyModifiers.HasFlag(VirtualKeyModifiers.Control) ?
new InvertPreviousItemSelectionStrategy(uiElement.SelectedItems, prevSelectedItems) :
e.KeyModifiers.HasFlag(VirtualKeyModifiers.Shift) ?
(ItemSelectionStrategy)new ExtendPreviousItemSelectionStrategy(uiElement.SelectedItems, prevSelectedItems) :
new IgnorePreviousItemSelectionStrategy(uiElement.SelectedItems);
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 FetchItemsPosition()
{
var verticalOffset = scrollViewer.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;
}
}
private void ScrollViewer_ViewChanged(object sender, ScrollViewerViewChangedEventArgs e)
{
if (!timer.IsRunning)
{
timer.Debounce(FetchItemsPosition, TimeSpan.FromMilliseconds(1000));
}
}
private void RectangleSelection_PointerReleased(object sender, PointerRoutedEventArgs e)
{
Canvas.SetLeft(selectionRectangle, 0);
Canvas.SetTop(selectionRectangle, 0);
selectionRectangle.Width = 0;
selectionRectangle.Height = 0;
uiElement.PointerMoved -= RectangleSelection_PointerMoved;
scrollViewer.ViewChanged -= ScrollViewer_ViewChanged;
uiElement.ReleasePointerCapture(e.Pointer);
if (selectionChanged != null)
{
// Restore and trigger SelectionChanged event
uiElement.SelectionChanged -= selectionChanged;
uiElement.SelectionChanged += selectionChanged;
if (prevSelectedItems == null || !uiElement.SelectedItems.SequenceEqual(prevSelectedItems))
{
// Trigger SelectionChanged event if the selection has changed
selectionChanged(sender, null);
}
}
if (selectionState == SelectionState.Active || e.OriginalSource is ListViewBase)
{
// Always trigger SelectionEnded to focus the file list when clicking on the empty space (#2977)
OnSelectionEnded();
}
selectionStrategy = null;
selectionState = SelectionState.Inactive;
prevSelectedItemsDrag = null;
e.Handled = true;
}
private void RectangleSelection_SizeChanged(object sender, object e)
{
if (scrollViewer == null)
{
scrollViewer = DependencyObjectHelpers.FindChild<ScrollViewer>(uiElement, sv => sv.VerticalScrollMode != ScrollMode.Disabled);
}
if (scrollViewer != null)
{
uiElement.SizeChanged -= RectangleSelection_SizeChanged;
}
}
private void InitEvents(object sender, RoutedEventArgs e)
{
if (!uiElement.IsLoaded)
{
uiElement.Loaded += InitEvents;
}
else
{
uiElement.Loaded -= InitEvents;
uiElement.PointerPressed += RectangleSelection_PointerPressed;
uiElement.PointerReleased += RectangleSelection_PointerReleased;
uiElement.PointerCaptureLost += RectangleSelection_PointerReleased;
uiElement.PointerCanceled += RectangleSelection_PointerReleased;
scrollViewer = DependencyObjectHelpers.FindChild<ScrollViewer>(uiElement, sv => sv.VerticalScrollMode != ScrollMode.Disabled);
if (scrollViewer == null)
{
uiElement.SizeChanged += RectangleSelection_SizeChanged;
}
}
}
}
}