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ScrollViewerSelectorBehavior.cs
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ScrollViewerSelectorBehavior.cs
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using Microsoft.Xaml.Interactivity;
using System;
using System.Diagnostics;
using System.Linq;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using System.Threading;
using Windows.Devices.Input;
using Windows.Foundation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Input;
using WinRTXamlToolkit.Controls.Extensions;
namespace PowerMapView.Views.Behaviors
{
public class ScrollViewerSelectorBehavior : DependencyObject, IBehavior
{
public DependencyObject AssociatedObject { get; private set; }
private ScrollViewer AssociatedViewer
{
get { return (ScrollViewer)this.AssociatedObject; }
}
private Selector AssociatedSelector
{
get { return _associatedSelector ?? (_associatedSelector = this.AssociatedObject.GetFirstDescendantOfType<Selector>()); }
}
private Selector _associatedSelector;
private CompositeDisposable disposer;
public void Attach(DependencyObject associatedObject)
{
this.AssociatedObject = associatedObject as ScrollViewer;
if (this.AssociatedObject == null)
{
Debug.WriteLine("Associated object is not ScrollViewer!");
return;
}
AssociatedViewer.Loaded += OnLoaded;
disposer = new CompositeDisposable();
}
public void Detach()
{
if (this.AssociatedObject == null)
return;
AssociatedViewer.Loaded -= OnLoaded;
disposer.Dispose();
}
private void OnLoaded(object sender, RoutedEventArgs e)
{
ViewerSize = new Size(AssociatedViewer.ActualWidth, AssociatedViewer.ActualHeight);
// ViewChanged event
disposer.Add(
Observable.FromEventPattern<ScrollViewerViewChangedEventArgs>(
h => AssociatedViewer.ViewChanged += h,
h => AssociatedViewer.ViewChanged -= h)
.Throttle(TimeSpan.FromMilliseconds(100)) // 100 msec throttling
.ObserveOn(SynchronizationContext.Current)
.Subscribe(e_ => SaveInViewerCenterPosition()));
// SizeChanged event
disposer.Add(
Observable.FromEvent<SizeChangedEventHandler, SizeChangedEventArgs>(
h => (sender_, e_) => h(e_),
h => AssociatedViewer.SizeChanged += h,
h => AssociatedViewer.SizeChanged -= h)
.Subscribe(e_ => RestoreInViewerCenterPosition()));
// Tapped event
StartListenTap();
// Manipulation events (alternative)
StartListenManipulation();
//// Pointer events (alternative)
//StartListenPointer();
}
#region Common
public Size ViewerSize
{
get { return (Size)GetValue(ViewerSizeProperty); }
set { SetValue(ViewerSizeProperty, value); }
}
public static readonly DependencyProperty ViewerSizeProperty =
DependencyProperty.Register(
"ViewerSize",
typeof(Size),
typeof(ScrollViewerSelectorBehavior),
new PropertyMetadata(default(Size)));
public float ViewerZoomFactor
{
get { return (float)GetValue(ViewerZoomFactorProperty); }
set { SetValue(ViewerZoomFactorProperty, value); }
}
public static readonly DependencyProperty ViewerZoomFactorProperty =
DependencyProperty.Register(
"ViewerZoomFactor",
typeof(float),
typeof(ScrollViewerSelectorBehavior),
new PropertyMetadata(0F));
public Point InSelectorCenterPosition
{
get { return (Point)GetValue(InSelectorCenterPositionProperty); }
set { SetValue(InSelectorCenterPositionProperty, value); }
}
public static readonly DependencyProperty InSelectorCenterPositionProperty =
DependencyProperty.Register(
"InSelectorCenterPosition",
typeof(Point),
typeof(ScrollViewerSelectorBehavior),
new PropertyMetadata(default(Point)));
public bool IsViewerInitiating
{
get { return (bool)GetValue(IsViewerInitiatingProperty); }
set { SetValue(IsViewerInitiatingProperty, value); }
}
public static readonly DependencyProperty IsViewerInitiatingProperty =
DependencyProperty.Register(
"IsViewerInitiating",
typeof(bool),
typeof(ScrollViewerSelectorBehavior),
new PropertyMetadata(
false, // Default must be false.
(d, e) =>
{
if (!(bool)e.NewValue)
((ScrollViewerSelectorBehavior)d).RestoreInViewerCenterPosition();
}));
private bool isInitial = true;
private void RestoreInViewerCenterPosition()
{
if ((ViewerZoomFactor == 0F) || (InSelectorCenterPosition == default(Point)))
return;
var inViewerCenterPosition = new Point(AssociatedViewer.ActualWidth / 2D, AssociatedViewer.ActualHeight / 2D);
RestoreInViewerPosition(inViewerCenterPosition, InSelectorCenterPosition, ViewerZoomFactor, isInitial);
isInitial = false;
Debug.WriteLine($"Restored center position and zoom factor. {InSelectorCenterPosition}");
}
private void RestoreInViewerPosition(Point inViewerPosition, Point inSelectorPosition, float viewerZoomFactor, bool checkesItemInViewport = false)
{
var offsetX = inSelectorPosition.X * viewerZoomFactor - inViewerPosition.X;
var offsetY = inSelectorPosition.Y * viewerZoomFactor - inViewerPosition.Y;
if (checkesItemInViewport)
{
var left = offsetX / viewerZoomFactor;
var right = left + AssociatedViewer.ActualWidth / viewerZoomFactor;
var top = offsetY / viewerZoomFactor;
var bottom = top + AssociatedViewer.ActualHeight / viewerZoomFactor;
var existsItemInViewport = AssociatedSelector.GetDescendantsOfType<SelectorItem>()
.Select(item => item.TransformToVisual(AssociatedSelector).TransformPoint(default(Point)))
.Any(position => (left < position.X) && (position.X < right) && (top < position.Y) && (position.Y < bottom));
if (!existsItemInViewport)
return;
}
try
{
AssociatedViewer.ChangeView(offsetX, offsetY, viewerZoomFactor);
}
catch (Exception ex)
{
Debug.WriteLine($"Failed to restore position and zoom factor.\r\n{ex}");
}
}
private void SaveInViewerCenterPosition()
{
var inViewerCenterPosition = new Point(AssociatedViewer.ActualWidth / 2D, AssociatedViewer.ActualHeight / 2D);
InSelectorCenterPosition = ConvertToInSelectorPosition(inViewerCenterPosition, AssociatedViewer.ZoomFactor);
ViewerZoomFactor = AssociatedViewer.ZoomFactor;
Debug.WriteLine($"Saved center position and zoom factor. {InSelectorCenterPosition}");
}
private Point ConvertToInSelectorPosition(Point inViewerPosition, float viewerZoomFactor)
{
var selectorPosition = AssociatedSelector.TransformToVisual(AssociatedViewer).TransformPoint(default(Point));
var offsetX = (inViewerPosition.X - selectorPosition.X) / viewerZoomFactor;
var offsetY = (inViewerPosition.Y - selectorPosition.Y) / viewerZoomFactor;
return new Point(offsetX, offsetY);
}
#endregion
#region Zoom(Tap)
public ZoomDirectionMode ZoomDirection
{
get { return (ZoomDirectionMode)GetValue(ZoomDirectionProperty); }
set { SetValue(ZoomDirectionProperty, value); }
}
public static readonly DependencyProperty ZoomDirectionProperty =
DependencyProperty.Register(
"ZoomDirection",
typeof(ZoomDirectionMode),
typeof(ScrollViewerSelectorBehavior),
new PropertyMetadata(default(ZoomDirectionMode)));
private void StartListenTap()
{
disposer.Add(
Observable.FromEventPattern<TappedEventHandler, TappedRoutedEventArgs>(
h => h.Invoke,
h => AssociatedViewer.Tapped += h,
h => AssociatedViewer.Tapped -= h)
.Subscribe(x => OnTapped(x.Sender, x.EventArgs)));
}
private void OnTapped(object sender, TappedRoutedEventArgs e)
{
try
{
var inViewerPosition = e.GetPosition((FrameworkElement)sender);
var inSelectorPosition = ConvertToInSelectorPosition(inViewerPosition, AssociatedViewer.ZoomFactor);
switch (ZoomDirection)
{
case ZoomDirectionMode.ZoomIn:
e.Handled = true;
ZoomIn(inViewerPosition, inSelectorPosition);
break;
case ZoomDirectionMode.ZoomOut:
e.Handled = true;
ZoomOut(inViewerPosition, inSelectorPosition);
break;
}
}
catch (Exception ex)
{
Debug.WriteLine($"Failed to handle zoom tapped event.\r\n{ex}");
}
}
private const double zoomNotchFactor = 0.18F;
private void ZoomIn(Point inViewerPosition, Point inSelectorPosition)
{
var factor = Math.Min(9F, AssociatedViewer.ZoomFactor * (float)(1D + zoomNotchFactor));
RestoreInViewerPosition(inViewerPosition, inSelectorPosition, factor);
Debug.WriteLine($"Zoomed in: Factor:{factor} InViewerPosition: {inViewerPosition} inSelectorPosition: {inSelectorPosition}");
}
private void ZoomOut(Point inViewerPosition, Point inSelectorPosition)
{
var factor = Math.Max(1F, AssociatedViewer.ZoomFactor / (float)(1D + zoomNotchFactor));
RestoreInViewerPosition(inViewerPosition, inSelectorPosition, factor);
Debug.WriteLine($"Zoomed in: Factor:{factor} InViewerPosition: {inViewerPosition} InSelectorPosition: {inSelectorPosition}");
}
#endregion
#region Move/Zoom(Manipulation)
private void StartListenManipulation()
{
var manipulationStarted = Observable.FromEvent<ManipulationStartedEventHandler, ManipulationStartedRoutedEventArgs>(
h => (sender, e) => h(e),
h => AssociatedViewer.ManipulationStarted += h,
h => AssociatedViewer.ManipulationStarted -= h)
.Where(e => e.PointerDeviceType == PointerDeviceType.Mouse);
var manipulationDelta = Observable.FromEvent<ManipulationDeltaEventHandler, ManipulationDeltaRoutedEventArgs>(
h => (sender, e) => h(e),
h => AssociatedViewer.ManipulationDelta += h,
h => AssociatedViewer.ManipulationDelta -= h);
var manipulationCompleted = Observable.FromEvent<ManipulationCompletedEventHandler, ManipulationCompletedRoutedEventArgs>(
h => (sender, e) => h(e),
h => AssociatedViewer.ManipulationCompleted += h,
h => AssociatedViewer.ManipulationCompleted -= h);
disposer.Add(manipulationDelta
.SkipUntil(manipulationStarted.Do(e => OnManipulationStarted(e)))
.TakeUntil(manipulationCompleted.Do(e => OnManipulationCompleted(e)))
.Throttle(TimeSpan.FromMilliseconds(10)) // 10 msec throttling
.ObserveOn(SynchronizationContext.Current)
.Repeat()
.Subscribe(e => OnManipulationDelta(e)));
}
private Point startPosition;
private double startHorizontalOffset;
private double startVerticalOffset;
private float startZoomFactor;
private void OnManipulationStarted(ManipulationStartedRoutedEventArgs e)
{
Debug.WriteLine("Manipulation Started!");
e.Handled = true;
try
{
startPosition = e.Position;
startHorizontalOffset = AssociatedViewer.HorizontalOffset;
startVerticalOffset = AssociatedViewer.VerticalOffset;
startZoomFactor = AssociatedViewer.ZoomFactor;
}
catch (Exception ex)
{
Debug.WriteLine($"Failed to handle manipulation started event.\r\n{ex}");
}
}
private void OnManipulationCompleted(ManipulationCompletedRoutedEventArgs e)
{
Debug.WriteLine("Manipulation Completed!");
e.Handled = true;
}
private void OnManipulationDelta(ManipulationDeltaRoutedEventArgs e)
{
e.Handled = true;
try
{
float? factor = null;
var offsetX = startHorizontalOffset - e.Cumulative.Translation.X;
var offsetY = startVerticalOffset - e.Cumulative.Translation.Y;
var currentScale = e.Cumulative.Scale;
if (currentScale != 1F)
{
factor = startZoomFactor * currentScale;
offsetX = offsetX * currentScale + startPosition.X * (currentScale - 1F);
offsetY = offsetY * currentScale + startPosition.Y * (currentScale - 1F);
}
AssociatedViewer.ChangeView(offsetX, offsetY, factor);
}
catch (Exception ex)
{
Debug.WriteLine($"Failed to reflect changes of ManipulationDalta.\r\n{ex}");
}
}
#endregion
#region Move(Pointer)
private void StartListenPointer()
{
var pointerPressed = Observable.FromEvent<PointerEventHandler, PointerRoutedEventArgs>(
h => (sender, e) => h(e),
h => AssociatedSelector.PointerPressed += h,
h => AssociatedSelector.PointerPressed -= h)
.Where(e => e.Pointer.PointerDeviceType == PointerDeviceType.Mouse);
var pointerMoved = Observable.FromEvent<PointerEventHandler, PointerRoutedEventArgs>(
h => (sender, e) => h(e),
h => AssociatedSelector.PointerMoved += h,
h => AssociatedSelector.PointerMoved -= h);
// PointerReleased and other events seems not to fire from ScrollViewer if its content is ItemsControl.
var pointerUnpressed = Observable.Merge(
Observable.FromEvent<PointerEventHandler, PointerRoutedEventArgs>(
h => (sender, e) => h(e),
h => AssociatedSelector.PointerReleased += h,
h => AssociatedSelector.PointerReleased -= h),
Observable.FromEvent<PointerEventHandler, PointerRoutedEventArgs>(
h => (sender, e) => h(e),
h => AssociatedSelector.PointerCanceled += h,
h => AssociatedSelector.PointerCanceled -= h),
Observable.FromEvent<PointerEventHandler, PointerRoutedEventArgs>(
h => (sender, e) => h(e),
h => AssociatedSelector.PointerCaptureLost += h,
h => AssociatedSelector.PointerCaptureLost -= h));
disposer.Add(pointerMoved
.SkipUntil(pointerPressed.Do(e => OnPointerPressed(e)))
.TakeUntil(pointerUnpressed.Do(e => OnPointerUnpressed(e)))
.Throttle(TimeSpan.FromMilliseconds(10)) // 10 msec throttling
.ObserveOn(SynchronizationContext.Current)
.Repeat()
.Subscribe(e => OnPointerMoved(e)));
}
private double startHorizontalOffsetPosition;
private double startVerticalOffsetPosition;
private void OnPointerPressed(PointerRoutedEventArgs e)
{
Debug.WriteLine("Pointer pressed.");
e.Handled = true;
var startPosition = e.GetCurrentPoint(AssociatedViewer).Position;
startHorizontalOffsetPosition = AssociatedViewer.HorizontalOffset + startPosition.X;
startVerticalOffsetPosition = AssociatedViewer.VerticalOffset + startPosition.Y;
}
private void OnPointerUnpressed(PointerRoutedEventArgs e)
{
Debug.WriteLine("Pointer unpressed.");
e.Handled = true;
}
private void OnPointerMoved(PointerRoutedEventArgs e)
{
e.Handled = true;
var position = e.GetCurrentPoint(AssociatedViewer).Position;
var offsetX = startHorizontalOffsetPosition - position.X;
var offsetY = startVerticalOffsetPosition - position.Y;
AssociatedViewer.ChangeView(offsetX, offsetY, null);
}
#endregion
}
}