using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Input;
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namespace Bro.Common.ImageCanvas
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{
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public partial class ZoomAndPanControl
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{
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private readonly Stack<UndoRedoStackItem> _undoStack = new Stack<UndoRedoStackItem>();
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private readonly Stack<UndoRedoStackItem> _redoStack = new Stack<UndoRedoStackItem>();
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private UndoRedoStackItem _viewportZoomCache;
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/// <summary>
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/// Record the previous zoom level, so that we can return to it.
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/// </summary>
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public void SaveZoom()
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{
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_viewportZoomCache = CreateUndoRedoStackItem();
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if (_undoStack.Any() && _viewportZoomCache.Equals(_undoStack.Peek())) return;
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_undoStack.Push(_viewportZoomCache);
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_redoStack.Clear();
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_undoZoomCommand?.RaiseCanExecuteChanged();
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_redoZoomCommand?.RaiseCanExecuteChanged();
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}
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/// <summary>
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/// Record the last saved zoom level, so that we can return to it if no activity for 750 milliseconds
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/// </summary>
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public void DelayedSaveZoom750Miliseconds()
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{
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if (_timer750Miliseconds?.Running != true) _viewportZoomCache = CreateUndoRedoStackItem();
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(_timer750Miliseconds ?? (_timer750Miliseconds = new KeepAliveTimer(TimeSpan.FromMilliseconds(740), () =>
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{
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if (_undoStack.Any() && _viewportZoomCache.Equals(_undoStack.Peek())) return;
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_undoStack.Push(_viewportZoomCache);
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_redoStack.Clear();
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_undoZoomCommand?.RaiseCanExecuteChanged();
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_redoZoomCommand?.RaiseCanExecuteChanged();
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}))).Nudge();
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}
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private KeepAliveTimer _timer750Miliseconds;
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/// <summary>
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/// Record the last saved zoom level, so that we can return to it if no activity for 1550 milliseconds
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/// </summary>
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public void DelayedSaveZoom1500Miliseconds()
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{
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if (!_timer1500Miliseconds?.Running != true) _viewportZoomCache = CreateUndoRedoStackItem();
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(_timer1500Miliseconds ?? (_timer1500Miliseconds = new KeepAliveTimer(TimeSpan.FromMilliseconds(1500), () =>
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{
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if (_undoStack.Any() && _viewportZoomCache.Equals(_undoStack.Peek())) return;
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_undoStack.Push(_viewportZoomCache);
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_redoStack.Clear();
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_undoZoomCommand?.RaiseCanExecuteChanged();
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_redoZoomCommand?.RaiseCanExecuteChanged();
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}))).Nudge();
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}
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private KeepAliveTimer _timer1500Miliseconds;
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private UndoRedoStackItem CreateUndoRedoStackItem()
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{
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return new UndoRedoStackItem(ContentOffsetX, ContentOffsetY,
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ContentViewportWidth, ContentViewportHeight, InternalViewportZoom);
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}
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/// <summary>
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/// Jump back to the previous zoom level, saving current zoom to Redo Stack.
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/// </summary>
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private void UndoZoom()
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{
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_viewportZoomCache = CreateUndoRedoStackItem();
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if (!_undoStack.Any() || !_viewportZoomCache.Equals(_undoStack.Peek()))
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_redoStack.Push(_viewportZoomCache);
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_viewportZoomCache = _undoStack.Pop();
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AnimatedZoomTo(_viewportZoomCache.Zoom, _viewportZoomCache.Rect);
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SetScrollViewerFocus();
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_undoZoomCommand?.RaiseCanExecuteChanged();
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_redoZoomCommand?.RaiseCanExecuteChanged();
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}
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/// <summary>
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/// Jump back to the most recent zoom level saved on redo stack.
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/// </summary>
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private void RedoZoom()
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{
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_viewportZoomCache = CreateUndoRedoStackItem();
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if (!_redoStack.Any() || !_viewportZoomCache.Equals(_redoStack.Peek()))
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_undoStack.Push(_viewportZoomCache);
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_viewportZoomCache = _redoStack.Pop();
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AnimatedZoomTo(_viewportZoomCache.Zoom, _viewportZoomCache.Rect);
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SetScrollViewerFocus();
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_undoZoomCommand?.RaiseCanExecuteChanged();
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_redoZoomCommand?.RaiseCanExecuteChanged();
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}
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private bool CanUndoZoom => _undoStack.Any();
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private bool CanRedoZoom => _redoStack.Any();
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/// <summary>
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/// Command to implement Undo
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/// </summary>
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public ICommand UndoZoomCommand => _undoZoomCommand ?? (_undoZoomCommand =
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new RelayCommand(UndoZoom, () => CanUndoZoom));
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private RelayCommand _undoZoomCommand;
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/// <summary>
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/// Command to implement Redo
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/// </summary>
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public ICommand RedoZoomCommand => _redoZoomCommand ?? (_redoZoomCommand =
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new RelayCommand(RedoZoom, () => CanRedoZoom));
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private RelayCommand _redoZoomCommand;
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private class UndoRedoStackItem
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{
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public UndoRedoStackItem(Rect rect, double zoom)
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{
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Rect = rect;
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Zoom = zoom;
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}
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public UndoRedoStackItem(double offsetX, double offsetY, double width, double height, double zoom)
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{
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Rect = new Rect(offsetX, offsetY, width, height);
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Zoom = zoom;
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}
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public Rect Rect { get; }
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public double Zoom { get; }
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public override string ToString()
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{
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return $"Rectangle {{{Rect.X},{Rect.X}}}, Zoom {Zoom}";
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}
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public bool Equals(UndoRedoStackItem obj)
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{
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return Zoom.IsWithinOnePercent(obj.Zoom) && Rect.Equals(obj.Rect);
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}
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}
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private void SetScrollViewerFocus()
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{
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var scrollViewer = _content.FindParentControl<ScrollViewer>();
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if (scrollViewer != null)
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{
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Keyboard.Focus(scrollViewer);
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scrollViewer.Focus();
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}
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}
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}
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}
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