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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//#define DEBUG_LASSO_FEEDBACK // DO NOT LEAVE ENABLED IN CHECKED IN CODE
//
// Description:
// LassoSelectionBehavior
//
using MS.Internal.Controls;
using System.Collections;
using System.Windows.Input;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Ink;
using System.Windows.Media;
namespace MS.Internal.Ink
{
/// <summary>
/// Eraser Behavior
/// </summary>
internal sealed class LassoSelectionBehavior : StylusEditingBehavior
{
//-------------------------------------------------------------------------------
//
// Constructors
//
//-------------------------------------------------------------------------------
#region Constructors
internal LassoSelectionBehavior(EditingCoordinator editingCoordinator, InkCanvas inkCanvas)
: base(editingCoordinator, inkCanvas)
{
}
#endregion Constructors
//-------------------------------------------------------------------------------
//
// Protected Methods
//
//-------------------------------------------------------------------------------
#region Protected Methods
/// <summary>
/// Overrides SwitchToMode as the following expectations
/// 31. From Select To InkAndGesture
/// Lasso is discarded. After mode change ink is being collected, gesture event fires. If its not a gesture, StrokeCollected event fires.
/// 32. From Select To GestureOnly
/// Lasso is discarded. After mode change ink is being collected. On StylusUp gesture event fires. Stroke gets removed on StylusUp even if its not a gesture.
/// 33. From Select To EraseByPoint
/// Lasso is discarded. PointErasing is performed after changing the mode.
/// 34. From Select To EraseByStroke
/// Lasso is discarded. StrokeErasing is performed after changing the mode.
/// 35. From Select To Ink
/// Ink collection starts when changing the mode.
/// 36. From Select To None
/// Nothing gets selected.
/// </summary>
/// <param name="mode"></param>
protected override void OnSwitchToMode(InkCanvasEditingMode mode)
{
Debug.Assert(EditingCoordinator.IsInMidStroke, "SwitchToMode should only be called in a mid-stroke");
switch ( mode )
{
case InkCanvasEditingMode.Ink:
case InkCanvasEditingMode.InkAndGesture:
case InkCanvasEditingMode.GestureOnly:
{
// Discard the lasso
Commit(false);
// Change the mode. The dynamic renderer will be reset automatically.
EditingCoordinator.ChangeStylusEditingMode(this, mode);
break;
}
case InkCanvasEditingMode.EraseByPoint:
case InkCanvasEditingMode.EraseByStroke:
{
// Discard the lasso
Commit(false);
// Change the mode
EditingCoordinator.ChangeStylusEditingMode(this, mode);
break;
}
case InkCanvasEditingMode.Select:
{
Debug.Assert(false, "Cannot switch from Select to Select in mid-stroke");
break;
}
case InkCanvasEditingMode.None:
{
// Discard the lasso.
Commit(false);
// Change to the None mode
EditingCoordinator.ChangeStylusEditingMode(this, mode);
break;
}
default:
Debug.Assert(false, "Unknown InkCanvasEditingMode!");
break;
}
}
/// <summary>
/// StylusInputBegin
/// </summary>
/// <param name="stylusPoints">stylusPoints</param>
/// <param name="userInitiated">true if the source eventArgs.UserInitiated flag was set to true</param>
protected override void StylusInputBegin(StylusPointCollection stylusPoints, bool userInitiated)
{
Debug.Assert(stylusPoints.Count != 0, "An empty stylusPoints has been passed in.");
_disableLasso = false;
bool startLasso = false;
List<Point> points = new List<Point>();
for ( int x = 0; x < stylusPoints.Count; x++ )
{
Point point = (Point)( stylusPoints[x] );
if ( x == 0 )
{
_startPoint = point;
points.Add(point);
continue;
}
if ( !startLasso )
{
// If startLasso hasn't be flagged, we should check if the distance between two points is greater than
// our tolerance. If so, we should flag startLasso.
Vector vector = point - _startPoint;
double distanceSquared = vector.LengthSquared;
if ( DoubleUtil.GreaterThan(distanceSquared, LassoHelper.MinDistanceSquared) )
{
points.Add(point);
startLasso = true;
}
}
else
{
// The flag is set. We just add the point.
points.Add(point);
}
}
// Start Lasso if it isn't a tap selection.
if ( startLasso )
{
StartLasso(points);
}
}
/// <summary>
/// StylusInputContinue
/// </summary>
/// <param name="stylusPoints">stylusPoints</param>
/// <param name="userInitiated">true if the source eventArgs.UserInitiated flag was set to true</param>
protected override void StylusInputContinue(StylusPointCollection stylusPoints, bool userInitiated)
{
// Check whether Lasso has started.
if ( _lassoHelper != null )
{
//
// pump packets to the LassoHelper, it will convert them into an array of equidistant
// lasso points, render those lasso point and return them to hit test against.
//
List<Point> points = new List<Point>();
for ( int x = 0; x < stylusPoints.Count; x++ )
{
points.Add((Point)stylusPoints[x]);
}
Point[] lassoPoints = _lassoHelper.AddPoints(points);
if ( 0 != lassoPoints.Length )
{
_incrementalLassoHitTester.AddPoints(lassoPoints);
}
}
else if ( !_disableLasso )
{
// If Lasso hasn't start and been disabled, we should try to start it when it is needed.
bool startLasso = false;
List<Point> points = new List<Point>();
for ( int x = 0; x < stylusPoints.Count; x++ )
{
Point point = (Point)( stylusPoints[x] );
if ( !startLasso )
{
// If startLasso hasn't be flagged, we should check if the distance between two points is greater than
// our tolerance. If so, we should flag startLasso.
Vector vector = point - _startPoint;
double distanceSquared = vector.LengthSquared;
if ( DoubleUtil.GreaterThan(distanceSquared, LassoHelper.MinDistanceSquared) )
{
points.Add(point);
startLasso = true;
}
}
else
{
// The flag is set. We just add the point.
points.Add(point);
}
}
// Start Lasso if it isn't a tap selection.
if ( startLasso )
{
StartLasso(points);
}
}
}
/// <summary>
/// StylusInputEnd
/// </summary>
/// <param name="commit">commit</param>
protected override void StylusInputEnd(bool commit)
{
// Initialize with empty selection
StrokeCollection selectedStrokes = new StrokeCollection();
List<UIElement> elementsToSelect = new List<UIElement>();
if ( _lassoHelper != null )
{
// This is a lasso selection.
//
// end dynamic rendering
//
selectedStrokes = InkCanvas.EndDynamicSelection(_lassoHelper.Visual);
//
// hit test for elements
//
// NOTE: HitTestForElements uses the _lassoHelper so it must be alive at this point
elementsToSelect = HitTestForElements();
_incrementalLassoHitTester.SelectionChanged -= new LassoSelectionChangedEventHandler(OnSelectionChanged);
_incrementalLassoHitTester.EndHitTesting();
_incrementalLassoHitTester = null;
_lassoHelper = null;
}
else
{
// This is a tap selection.
// Now try the tap selection
Stroke tappedStroke;
UIElement tappedElement;
TapSelectObject(_startPoint, out tappedStroke, out tappedElement);
// If we have a pre-selected object, we should select it now.
if ( tappedStroke != null )
{
Debug.Assert(tappedElement == null);
selectedStrokes = new StrokeCollection();
selectedStrokes.Add(tappedStroke);
}
else if ( tappedElement != null )
{
Debug.Assert(tappedStroke == null);
elementsToSelect.Add(tappedElement);
}
}
SelfDeactivate();
if ( commit )
{
InkCanvas.ChangeInkCanvasSelection(selectedStrokes, elementsToSelect.ToArray());
}
}
/// <summary>
/// OnCommitWithoutStylusInput
/// </summary>
/// <param name="commit"></param>
protected override void OnCommitWithoutStylusInput(bool commit)
{
// We only deactivate LSB in this case.
SelfDeactivate();
}
/// <summary>
/// Get the current cursor for this editing mode
/// </summary>
/// <returns></returns>
protected override Cursor GetCurrentCursor()
{
// By default return cross cursor.
return Cursors.Cross;
}
#endregion Protected Methods
//-------------------------------------------------------------------------------
//
// Private Methods
//
//-------------------------------------------------------------------------------
#region Private Methods
/// <summary>
/// Private event handler that updates which strokes are actually selected
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void OnSelectionChanged(object sender, LassoSelectionChangedEventArgs e)
{
this.InkCanvas.UpdateDynamicSelection(e.SelectedStrokes, e.DeselectedStrokes);
}
/// <summary>
/// Private helper that will hit test for elements
/// </summary>
private List<UIElement> HitTestForElements()
{
List<UIElement> elementsToSelect = new List<UIElement>();
if ( this.InkCanvas.Children.Count == 0 )
{
return elementsToSelect;
}
for (int x = 0; x < this.InkCanvas.Children.Count; x++)
{
UIElement uiElement = this.InkCanvas.Children[x];
HitTestElement(InkCanvas.InnerCanvas, uiElement, elementsToSelect);
}
return elementsToSelect;
}
/// <summary>
/// Private helper that will turn an element in any nesting level into a stroke
/// in the InkCanvas's coordinate space. This method calls itself recursively
/// </summary>
private void HitTestElement(InkCanvasInnerCanvas parent, UIElement uiElement, List<UIElement> elementsToSelect)
{
ElementCornerPoints elementPoints = LassoSelectionBehavior.GetTransformedElementCornerPoints(parent, uiElement);
if (elementPoints.Set != false)
{
Point[] points = GeneratePointGrid(elementPoints);
//
// perform hit testing against our lasso
//
System.Diagnostics.Debug.Assert(null != _lassoHelper);
if (_lassoHelper.ArePointsInLasso(points, _percentIntersectForElements))
{
elementsToSelect.Add(uiElement);
}
}
//
// we used to recurse into the childrens children. That is no longer necessary
//
}
/// <summary>
/// Private helper that takes an element and transforms it's 4 points
/// into the InkCanvas's space
/// </summary>
private static ElementCornerPoints GetTransformedElementCornerPoints(InkCanvasInnerCanvas canvas, UIElement childElement)
{
Debug.Assert(canvas != null);
Debug.Assert(childElement != null);
Debug.Assert(canvas.CheckAccess());
ElementCornerPoints elementPoints = new ElementCornerPoints();
elementPoints.Set = false;
if (childElement.Visibility != Visibility.Visible)
{
//
// this little one's not worth it...
//
return elementPoints;
}
//
// get the transform from us to our parent InkCavas
//
GeneralTransform parentTransform = childElement.TransformToAncestor(canvas);
// REVIEW: any of the methods below may not actually perform the transformation
// Do we need to do anything special in that scenario?
parentTransform.TryTransform(new Point(0, 0), out elementPoints.UpperLeft);
parentTransform.TryTransform(new Point(childElement.RenderSize.Width, 0), out elementPoints.UpperRight);
parentTransform.TryTransform(new Point(0, childElement.RenderSize.Height), out elementPoints.LowerLeft);
parentTransform.TryTransform(new Point(childElement.RenderSize.Width, childElement.RenderSize.Height), out elementPoints.LowerRight);
elementPoints.Set = true;
return elementPoints;
}
/// <summary>
/// Private helper that will generate a grid of points 5 px apart given the elements bounding points
/// this works with any affline transformed points
/// </summary>
private Point[] GeneratePointGrid(ElementCornerPoints elementPoints)
{
if (!elementPoints.Set)
{
return new Point[]{};
}
ArrayList pointArray = new ArrayList();
UpdatePointDistances(elementPoints);
//
// add our original points
//
pointArray.Add(elementPoints.UpperLeft);
pointArray.Add(elementPoints.UpperRight);
FillInPoints(pointArray, elementPoints.UpperLeft, elementPoints.UpperRight);
pointArray.Add(elementPoints.LowerLeft);
pointArray.Add(elementPoints.LowerRight);
FillInPoints(pointArray, elementPoints.LowerLeft, elementPoints.LowerRight);
FillInGrid( pointArray,
elementPoints.UpperLeft,
elementPoints.UpperRight,
elementPoints.LowerRight,
elementPoints.LowerLeft);
Point[] retPointArray = new Point[pointArray.Count];
pointArray.CopyTo(retPointArray);
return retPointArray;
}
/// <summary>
/// Private helper that fills in the points between two points by calling itself
/// recursively in a divide and conquer fashion
/// </summary>
private void FillInPoints(ArrayList pointArray, Point point1, Point point2)
{
// this algorithm improves perf by 20%
if(!PointsAreCloseEnough(point1, point2))
{
Point midPoint = LassoSelectionBehavior.GeneratePointBetweenPoints(point1, point2);
pointArray.Add(midPoint);
if(!PointsAreCloseEnough(point1, midPoint))
{
FillInPoints(pointArray, point1, midPoint);
}
//sort the right
if(!PointsAreCloseEnough(midPoint, point2))
{
FillInPoints(pointArray, midPoint, point2);
}
}
}
/// <summary>
/// Private helper that fills in the points between four points by calling itself
/// recursively in a divide and conquer fashion
/// </summary>
private void FillInGrid(ArrayList pointArray,
Point upperLeft,
Point upperRight,
Point lowerRight,
Point lowerLeft)
{
// this algorithm improves perf by 20%
if(!PointsAreCloseEnough(upperLeft, lowerLeft))
{
Point midPointLeft = LassoSelectionBehavior.GeneratePointBetweenPoints(upperLeft, lowerLeft);
Point midPointRight = LassoSelectionBehavior.GeneratePointBetweenPoints(upperRight, lowerRight);
pointArray.Add(midPointLeft);
pointArray.Add(midPointRight);
FillInPoints(pointArray, midPointLeft, midPointRight);
if(!PointsAreCloseEnough(upperLeft, midPointLeft))
{
FillInGrid(pointArray, upperLeft, upperRight, midPointRight, midPointLeft);
}
//sort the right
if(!PointsAreCloseEnough(midPointLeft, lowerLeft))
{
FillInGrid(pointArray, midPointLeft, midPointRight, lowerRight, lowerLeft);
}
}
}
/// <summary>
/// Private helper that will generate a new point between two points
/// </summary>
private static Point GeneratePointBetweenPoints(Point point1, Point point2)
{
//
// compute the new point in the middle of the previous two
//
double maxX = point1.X > point2.X ? point1.X : point2.X;
double minX = point1.X < point2.X ? point1.X : point2.X;
double maxY = point1.Y > point2.Y ? point1.Y : point2.Y;
double minY = point1.Y < point2.Y ? point1.Y : point2.Y;
return new Point( (minX + ((maxX - minX) * 0.5f)),
(minY + ((maxY - minY) * 0.5f)));
}
/// <summary>
/// Private helper used to determine if we're close enough between two points
/// </summary>
private bool PointsAreCloseEnough(Point point1, Point point2)
{
double x = point1.X - point2.X;
double y = point1.Y - point2.Y;
if ((x < _xDiff && x > -_xDiff) && (y < _yDiff && y > -_yDiff))
{
return true;
}
return false;
}
/// <summary>
/// Used to calc the diff between points on the x and y axis
/// </summary>
private void UpdatePointDistances(ElementCornerPoints elementPoints)
{
//
// calc the x and y diffs
//
double width = elementPoints.UpperLeft.X - elementPoints.UpperRight.X;
if (width < 0)
{
width = -width;
}
double height = elementPoints.UpperLeft.Y - elementPoints.LowerLeft.Y;
if (height < 0)
{
height = -height;
}
_xDiff = width * 0.25f;
if (_xDiff > _maxThreshold)
{
_xDiff = _maxThreshold;
}
else if (_xDiff < _minThreshold)
{
_xDiff = _minThreshold;
}
_yDiff = height * 0.25f;
if (_yDiff > _maxThreshold)
{
_yDiff = _maxThreshold;
}
else if (_yDiff < _minThreshold)
{
_yDiff = _minThreshold;
}
}
/// <summary>
/// StartLasso
/// </summary>
/// <param name="points"></param>
private void StartLasso(List<Point> points)
{
Debug.Assert(!_disableLasso && _lassoHelper == null, "StartLasso is called unexpectedly.");
if ( InkCanvas.ClearSelectionRaiseSelectionChanging() // If user cancels clearing the selection, we shouldn't initiate Lasso.
//
// If the active editng mode is no longer as Select, we shouldn't activate LassoSelectionBehavior.
// Note the order really matters here. This checking has to be done
// after ClearSelectionRaiseSelectionChanging is invoked.
&& EditingCoordinator.ActiveEditingMode == InkCanvasEditingMode.Select )
{
//
// obtain a dynamic hit-tester for selecting with lasso
//
_incrementalLassoHitTester =
this.InkCanvas.Strokes.GetIncrementalLassoHitTester(_percentIntersectForInk);
//
// add event handler
//
_incrementalLassoHitTester.SelectionChanged += new LassoSelectionChangedEventHandler(OnSelectionChanged);
//
// start dynamic rendering
//
_lassoHelper = new LassoHelper();
InkCanvas.BeginDynamicSelection(_lassoHelper.Visual);
Point[] lassoPoints = _lassoHelper.AddPoints(points);
if ( 0 != lassoPoints.Length )
{
_incrementalLassoHitTester.AddPoints(lassoPoints);
}
}
else
{
// If we fail on clearing the selection or switching to Select mode, we should just disable lasso.
_disableLasso = true;
}
}
/// <summary>
/// Pre-Select the object which user taps on.
/// </summary>
/// <param name="point"></param>
/// <param name="tappedStroke"></param>
/// <param name="tappedElement"></param>
private void TapSelectObject(Point point, out Stroke tappedStroke, out UIElement tappedElement)
{
tappedStroke = null;
tappedElement = null;
StrokeCollection hitTestStrokes = InkCanvas.Strokes.HitTest(point, 5.0d);
if ( hitTestStrokes.Count > 0 )
{
tappedStroke = hitTestStrokes[hitTestStrokes.Count - 1];
}
else
{
GeneralTransform transformToInnerCanvas = InkCanvas.TransformToVisual(InkCanvas.InnerCanvas);
Point pointOnInnerCanvas = transformToInnerCanvas.Transform(point);
// Try to find out whether we have a pre-select object.
tappedElement = InkCanvas.InnerCanvas.HitTestOnElements(pointOnInnerCanvas);
}
}
#endregion Private Methods
//-------------------------------------------------------------------------------
//
// Private Fields
//
//-------------------------------------------------------------------------------
#region Private Fields
private Point _startPoint;
private bool _disableLasso;
private LassoHelper _lassoHelper = null;
private IncrementalLassoHitTester _incrementalLassoHitTester;
private double _xDiff;
private double _yDiff;
private const double _maxThreshold = 50f;
private const double _minThreshold = 15f;
private const int _percentIntersectForInk = 80;
private const int _percentIntersectForElements = 60;
#if DEBUG_LASSO_FEEDBACK
private ContainerVisual _tempVisual;
#endif
/// <summary>
/// Private struct
/// </summary>
private struct ElementCornerPoints
{
internal Point UpperLeft;
internal Point UpperRight;
internal Point LowerRight;
internal Point LowerLeft;
internal bool Set;
}
#endregion Private Fields
}
}
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