/// <summary>
/// Hit-testing for stroke erase scenario.
/// </summary>
/// <param name="iterator">the stroke nodes to iterate</param>
/// <returns>true if the strokes intersect, false otherwise</returns>
internal bool HitTest(StrokeNodeIterator iterator)
{
System.Diagnostics.Debug.Assert(iterator != null);
if ((_erasingStrokeNodes == null) || (_erasingStrokeNodes.Count == 0))
{
return(false);
}
Rect inkSegmentBounds = Rect.Empty;
for (int i = 0; i < iterator.Count; i++)
{
StrokeNode inkStrokeNode = iterator[i];
Rect inkNodeBounds = inkStrokeNode.GetBounds();
inkSegmentBounds.Union(inkNodeBounds);
if (inkSegmentBounds.IntersectsWith(_bounds))
{
//
foreach (StrokeNode erasingStrokeNode in _erasingStrokeNodes)
{
if (inkSegmentBounds.IntersectsWith(erasingStrokeNode.GetBoundsConnected()) &&
erasingStrokeNode.HitTest(inkStrokeNode))
{
return(true);
}
}
}
}
return(false);
}
/// <summary>
/// Hit-testing for stroke erase scenario.
/// </summary>
/// <param name="iterator">the stroke nodes to iterate</param>
/// <returns>true if the strokes intersect, false otherwise</returns>
internal bool HitTest(StrokeNodeIterator iterator)
{
System.Diagnostics.Debug.Assert(iterator != null);
if ((_erasingStrokeNodes == null) || (_erasingStrokeNodes.Count == 0))
{
return(false);
}
Rect inkSegmentBounds = Rect.Empty;
for (int i = 0; i < iterator.Count; i++)
{
StrokeNode inkStrokeNode = iterator[i];
Rect inkNodeBounds = inkStrokeNode.GetBounds();
inkSegmentBounds.Union(inkNodeBounds);
if (inkSegmentBounds.IntersectsWith(_bounds))
{
for (var index = 0; index < _erasingStrokeNodes.Count; index++)
{
var erasingStrokeNodeBound = _erasingStrokeNodeBounds[index];
if (inkSegmentBounds.IntersectsWith(erasingStrokeNodeBound))
{
StrokeNode erasingStrokeNode = _erasingStrokeNodes[index];
if (erasingStrokeNode.HitTest(inkStrokeNode))
{
return(true);
}
}
}
}
}
return(false);
}
internal static void CalcGeometryAndBounds(StrokeNodeIterator iterator,
DrawingAttributes drawingAttributes,
#if DEBUG_RENDERING_FEEDBACK
DrawingContext debugDC,
double feedbackSize,
bool showFeedback,
#endif
bool calculateBounds,
out Geometry geometry,
out Rect bounds)
{
Debug.Assert(iterator != null && drawingAttributes != null);
//we can use our new algorithm for identity only.
Matrix stylusTipTransform = drawingAttributes.StylusTipTransform;
if (stylusTipTransform != Matrix.Identity && stylusTipTransform._type != MatrixTypes.TRANSFORM_IS_SCALING)
{
//second best optimization
CalcGeometryAndBoundsWithTransform(iterator, drawingAttributes, stylusTipTransform._type, calculateBounds, out geometry, out bounds);
}
else
{
StreamGeometry streamGeometry = new StreamGeometry();
streamGeometry.FillRule = FillRule.Nonzero;
StreamGeometryContext context = streamGeometry.Open();
geometry = streamGeometry;
Rect empty = Rect.Empty;
bounds = empty;
try
{
//
// We keep track of three StrokeNodes as we iterate across
// the Stroke. Since these are structs, the default ctor will
// be called and .IsValid will be false until we initialize them
//
StrokeNode emptyStrokeNode = new StrokeNode();
StrokeNode prevPrevStrokeNode = new StrokeNode();
StrokeNode prevStrokeNode = new StrokeNode();
StrokeNode strokeNode = new StrokeNode();
Rect prevPrevStrokeNodeBounds = empty;
Rect prevStrokeNodeBounds = empty;
Rect strokeNodeBounds = empty;
//percentIntersect is a function of drawingAttributes height / width
double percentIntersect = 95d;
double maxExtent = Math.Max(drawingAttributes.Height, drawingAttributes.Width);
percentIntersect += Math.Min(4.99999d, ((maxExtent / 20d) * 5d));
double prevAngle = double.MinValue;
bool isStartOfSegment = true;
bool isEllipse = drawingAttributes.StylusTip == StylusTip.Ellipse;
bool ignorePressure = drawingAttributes.IgnorePressure;
//
// Two List<Point>'s that get reused for adding figures
// to the streamgeometry.
//
List<Point> pathFigureABSide = new List<Point>();//don't prealloc. It causes Gen2 collections to rise and doesn't help execution time
List<Point> pathFigureDCSide = new List<Point>();
List<Point> polyLinePoints = new List<Point>(4);
int iteratorCount = iterator.Count;
for (int index = 0, previousIndex = -1; index < iteratorCount; )
{
if (!prevPrevStrokeNode.IsValid)
{
if (prevStrokeNode.IsValid)
{
//we're sliding our pointers forward
prevPrevStrokeNode = prevStrokeNode;
prevPrevStrokeNodeBounds = prevStrokeNodeBounds;
prevStrokeNode = emptyStrokeNode;
}
else
{
prevPrevStrokeNode = iterator[index++, previousIndex++];
prevPrevStrokeNodeBounds = prevPrevStrokeNode.GetBounds();
continue; //so we always check if index < iterator.Count
}
}
//we know prevPrevStrokeNode is valid
if (!prevStrokeNode.IsValid)
{
if (strokeNode.IsValid)
{
//we're sliding our pointers forward
prevStrokeNode = strokeNode;
prevStrokeNodeBounds = strokeNodeBounds;
strokeNode = emptyStrokeNode;
}
else
{
//get the next strokeNode, but don't automatically update previousIndex
prevStrokeNode = iterator[index++, previousIndex];
prevStrokeNodeBounds = prevStrokeNode.GetBounds();
RectCompareResult result =
FuzzyContains( prevStrokeNodeBounds,
prevPrevStrokeNodeBounds,
isStartOfSegment ? 99.99999d : percentIntersect);
if (result == RectCompareResult.Rect1ContainsRect2)
{
// this node already contains the prevPrevStrokeNodeBounds (PP):
//
// |------------|
// | |----| |
// | | PP | P |
// | |----| |
// |------------|
//
prevPrevStrokeNode = iterator[index - 1, prevPrevStrokeNode.Index - 1]; ;
prevPrevStrokeNodeBounds = Rect.Union(prevStrokeNodeBounds, prevPrevStrokeNodeBounds);
// at this point prevPrevStrokeNodeBounds already contains this node
// we can just ignore this node
prevStrokeNode = emptyStrokeNode;
// update previousIndex to point to this node
previousIndex = index - 1;
// go back to our main loop
continue;
}
else if (result == RectCompareResult.Rect2ContainsRect1)
{
// this prevPrevStrokeNodeBounds (PP) already contains this node:
//
// |------------|
// | |----||
// | PP | P ||
// | |----||
// |------------|
//
//prevPrevStrokeNodeBounds already contains this node
//we can just ignore this node
prevStrokeNode = emptyStrokeNode;
// go back to our main loop, but do not update previousIndex
// because it should continue to point to previousPrevious
continue;
}
Debug.Assert(!prevStrokeNode.GetConnectingQuad().IsEmpty, "prevStrokeNode.GetConnectingQuad() is Empty!");
// if neither was true, we now have two of our three nodes required to
// start our computation, we need to update previousIndex to point
// to our current, valid prevStrokeNode
previousIndex = index - 1;
continue; //so we always check if index < iterator.Count
}
}
//we know prevPrevStrokeNode and prevStrokeNode are both valid
if (!strokeNode.IsValid)
{
strokeNode = iterator[index++, previousIndex];
strokeNodeBounds = strokeNode.GetBounds();
RectCompareResult result =
FuzzyContains( strokeNodeBounds,
prevStrokeNodeBounds,
isStartOfSegment ? 99.99999 : percentIntersect);
RectCompareResult result2 =
FuzzyContains( strokeNodeBounds,
prevPrevStrokeNodeBounds,
isStartOfSegment ? 99.99999 : percentIntersect);
if ( isStartOfSegment &&
result == RectCompareResult.Rect1ContainsRect2 &&
result2 == RectCompareResult.Rect1ContainsRect2)
{
if (pathFigureABSide.Count > 0)
{
//we've started a stroke, we need to end it before resetting
//prevPrev
#if DEBUG_RENDERING_FEEDBACK
prevStrokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide, debugDC, feedbackSize, showFeedback);
#else
prevStrokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide);
#endif
//render
ReverseDCPointsRenderAndClear(context, pathFigureABSide, pathFigureDCSide, polyLinePoints, isEllipse, true/*clear the point collections*/);
}
//we're resetting
//prevPrevStrokeNode. We need to gen one
//without a connecting quad
prevPrevStrokeNode = iterator[index - 1, prevPrevStrokeNode.Index - 1];
prevPrevStrokeNodeBounds = prevPrevStrokeNode.GetBounds();
prevStrokeNode = emptyStrokeNode;
strokeNode = emptyStrokeNode;
// increment previousIndex to to point to this node
previousIndex = index - 1;
continue;
}
else if (result == RectCompareResult.Rect1ContainsRect2)
{
// this node (C) already contains the prevStrokeNodeBounds (P):
//
// |------------|
// |----| | |----| |
// | PP | | | P | C |
// |----| | |----| |
// |------------|
//
//we have to generate a new stroke node that points
//to pp since the connecting quad from C to P could be empty
//if they have the same point
strokeNode = iterator[index - 1, prevStrokeNode.Index - 1];
if (!strokeNode.GetConnectingQuad().IsEmpty)
{
//only update prevStrokeNode if we have a valid connecting quad
prevStrokeNode = strokeNode;
prevStrokeNodeBounds = Rect.Union(strokeNodeBounds, prevStrokeNodeBounds);
// update previousIndex, since it should point to this node now
previousIndex = index - 1;
}
// at this point we can just ignore this node
strokeNode = emptyStrokeNode;
//strokeNodeBounds = empty;
prevAngle = double.MinValue; //invalidate
// go back to our main loop
continue;
}
else if (result == RectCompareResult.Rect2ContainsRect1)
{
// this prevStrokeNodeBounds (P) already contains this node (C):
//
// |------------|
// |----| | |----||
// | PP | | P | C ||
// |----| | |----||
// |------------|
//
//prevStrokeNodeBounds already contains this node
//we can just ignore this node
strokeNode = emptyStrokeNode;
// go back to our main loop, but do not update previousIndex
// because it should continue to point to previous
continue;
}
Debug.Assert(!strokeNode.GetConnectingQuad().IsEmpty, "strokeNode.GetConnectingQuad was empty, this is unexpected");
//
// NOTE: we do not check if C contains PP, or PP contains C because
// that indicates a change in direction, which we handle below
//
// if neither was true P and C are separate,
// we now have all three nodes required to
// start our computation, we need to update previousIndex to point
// to our current, valid prevStrokeNode
previousIndex = index - 1;
}
// see if we have an overlap between the first and third node
bool overlap = prevPrevStrokeNodeBounds.IntersectsWith(strokeNodeBounds);
// prevPrevStrokeNode, prevStrokeNode and strokeNode are all
// valid nodes now. Now we need to figure out what do add to our
// PathFigure. First calc bounds on the strokeNode we know we need to render
if (calculateBounds)
{
bounds.Union(prevStrokeNodeBounds);
}
// determine what points to add to pathFigureABSide and pathFigureDCSide
// from prevPrevStrokeNode
if (pathFigureABSide.Count == 0)
{
Debug.Assert(pathFigureDCSide.Count == 0);
if (calculateBounds)
{
bounds.Union(prevPrevStrokeNodeBounds);
}
if (isStartOfSegment && overlap)
{
//render a complete first stroke node or we can get artifacts
prevPrevStrokeNode.GetContourPoints(polyLinePoints);
AddFigureToStreamGeometryContext(context, polyLinePoints, prevPrevStrokeNode.IsEllipse/*isBezierFigure*/);
polyLinePoints.Clear();
}
// we're starting a new pathfigure
// we need to add parts of the prevPrevStrokeNode contour
// to pathFigureABSide and pathFigureDCSide
#if DEBUG_RENDERING_FEEDBACK
prevStrokeNode.GetPointsAtStartOfSegment(pathFigureABSide, pathFigureDCSide, debugDC, feedbackSize, showFeedback);
#else
prevStrokeNode.GetPointsAtStartOfSegment(pathFigureABSide, pathFigureDCSide);
#endif
//set our marker, we're no longer at the start of the stroke
isStartOfSegment = false;
}
if (prevAngle == double.MinValue)
{
//prevAngle is no longer valid
prevAngle = GetAngleBetween(prevPrevStrokeNode.Position, prevStrokeNode.Position);
}
double delta = GetAngleDeltaFromLast(prevStrokeNode.Position, strokeNode.Position, ref prevAngle);
bool directionChangedOverAbsoluteThreshold = Math.Abs(delta) > 90d && Math.Abs(delta) < (360d - 90d);
bool directionChangedOverOverlapThreshold = overlap && !(ignorePressure || strokeNode.PressureFactor == 1f) && Math.Abs(delta) > 30d && Math.Abs(delta) < (360d - 30d);
double prevArea = prevStrokeNodeBounds.Height * prevStrokeNodeBounds.Width;
double currArea = strokeNodeBounds.Height * strokeNodeBounds.Width;
bool areaChanged = !(prevArea == currArea && prevArea == (prevPrevStrokeNodeBounds.Height * prevPrevStrokeNodeBounds.Width));
bool areaChangeOverThreshold = false;
if (overlap && areaChanged)
{
if ((Math.Min(prevArea, currArea) / Math.Max(prevArea, currArea)) <= 0.90d)
{
//the min area is < 70% of the max area
areaChangeOverThreshold = true;
}
}
if (areaChanged || delta != 0.0d || index >= iteratorCount)
{
//the area changed between the three nodes OR there was an angle delta OR we're at the end
//of the stroke... either way, this is a significant node. If not, we're going to drop it.
if ((overlap && (directionChangedOverOverlapThreshold || areaChangeOverThreshold)) ||
directionChangedOverAbsoluteThreshold)
{
//
// we need to stop the pathfigure at P
// and render the pathfigure
//
// |--| |--| |--||--| |------|
// |PP|------|P | |PP||P | |PP P C|
// |--| |--| |--||--| |------|
// / |C |
// |--| |--|
// |C |
// |--|
#if DEBUG_RENDERING_FEEDBACK
prevStrokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide, debugDC, feedbackSize, showFeedback);
#else
//end the figure
prevStrokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide);
#endif
//render
ReverseDCPointsRenderAndClear(context, pathFigureABSide, pathFigureDCSide, polyLinePoints, isEllipse, true/*clear the point collections*/);
if (areaChangeOverThreshold)
{
//render a complete stroke node or we can get artifacts
prevStrokeNode.GetContourPoints(polyLinePoints);
AddFigureToStreamGeometryContext(context, polyLinePoints, prevStrokeNode.IsEllipse/*isBezierFigure*/);
polyLinePoints.Clear();
}
}
else
{
//
// direction didn't change over the threshold, add the midpoint data
// |--| |--|
// |PP|------|P |
// |--| |--|
// \
// |--|
// |C |
// |--|
bool endSegment; //flag that tell us if we missed an intersection
#if DEBUG_RENDERING_FEEDBACK
strokeNode.GetPointsAtMiddleSegment(prevStrokeNode, delta, pathFigureABSide, pathFigureDCSide, out endSegment, debugDC, feedbackSize, showFeedback);
#else
strokeNode.GetPointsAtMiddleSegment(prevStrokeNode, delta, pathFigureABSide, pathFigureDCSide, out endSegment);
#endif
if (endSegment)
{
//we have a missing intersection, we need to end the
//segment at P
#if DEBUG_RENDERING_FEEDBACK
prevStrokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide, debugDC, feedbackSize, showFeedback);
#else
//end the figure
prevStrokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide);
#endif
//render
ReverseDCPointsRenderAndClear(context, pathFigureABSide, pathFigureDCSide, polyLinePoints, isEllipse, true/*clear the point collections*/);
}
}
}
//
// either way... slide our pointers forward, to do this, we simply mark
// our first pointer as 'empty'
//
prevPrevStrokeNode = emptyStrokeNode;
prevPrevStrokeNodeBounds = empty;
}
//
// anything left to render?
//
if (prevPrevStrokeNode.IsValid)
{
if (prevStrokeNode.IsValid)
{
if (calculateBounds)
{
bounds.Union(prevPrevStrokeNodeBounds);
bounds.Union(prevStrokeNodeBounds);
}
Debug.Assert(!strokeNode.IsValid);
//
// we never made it to strokeNode, render two points, OR
// strokeNode was a dupe
//
if (pathFigureABSide.Count > 0)
{
#if DEBUG_RENDERING_FEEDBACK
prevStrokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide, debugDC, feedbackSize, showFeedback);
#else
//
// strokeNode was a dupe, we just need to render the end of the stroke
// which is at prevStrokeNode
//
prevStrokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide);
#endif
//render
ReverseDCPointsRenderAndClear(context, pathFigureABSide, pathFigureDCSide, polyLinePoints, isEllipse, false/*clear the point collections*/);
}
else
{
// we've only seen two points to render
Debug.Assert(pathFigureDCSide.Count == 0);
//contains all the logic to render two stroke nodes
RenderTwoStrokeNodes( context,
prevPrevStrokeNode,
prevPrevStrokeNodeBounds,
prevStrokeNode,
prevStrokeNodeBounds,
pathFigureABSide,
pathFigureDCSide,
polyLinePoints
#if DEBUG_RENDERING_FEEDBACK
,debugDC,
feedbackSize,
showFeedback
#endif
);
}
}
else
{
if (calculateBounds)
{
bounds.Union(prevPrevStrokeNodeBounds);
}
// we only have a single point to render
Debug.Assert(pathFigureABSide.Count == 0);
prevPrevStrokeNode.GetContourPoints(pathFigureABSide);
AddFigureToStreamGeometryContext(context, pathFigureABSide, prevPrevStrokeNode.IsEllipse/*isBezierFigure*/);
}
}
else if (prevStrokeNode.IsValid && strokeNode.IsValid)
{
if (calculateBounds)
{
bounds.Union(prevStrokeNodeBounds);
bounds.Union(strokeNodeBounds);
}
// typical case, we hit the end of the stroke
// see if we need to start a stroke, or just end one
if (pathFigureABSide.Count > 0)
{
#if DEBUG_RENDERING_FEEDBACK
strokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide, debugDC, feedbackSize, showFeedback);
#else
strokeNode.GetPointsAtEndOfSegment(pathFigureABSide, pathFigureDCSide);
#endif
//render
ReverseDCPointsRenderAndClear(context, pathFigureABSide, pathFigureDCSide, polyLinePoints, isEllipse, false/*clear the point collections*/);
if (FuzzyContains(strokeNodeBounds, prevStrokeNodeBounds, 70d) != RectCompareResult.NoItersection)
{
//render a complete stroke node or we can get artifacts
strokeNode.GetContourPoints(polyLinePoints);
AddFigureToStreamGeometryContext(context, polyLinePoints, strokeNode.IsEllipse/*isBezierFigure*/);
}
}
else
{
Debug.Assert(pathFigureDCSide.Count == 0);
//contains all the logic to render two stroke nodes
RenderTwoStrokeNodes( context,
prevStrokeNode,
prevStrokeNodeBounds,
strokeNode,
strokeNodeBounds,
pathFigureABSide,
pathFigureDCSide,
polyLinePoints
#if DEBUG_RENDERING_FEEDBACK
,debugDC,
feedbackSize,
showFeedback
#endif
);
}
}
}
finally
{
context.Close();
geometry.Freeze();
}
}
}
/// <summary>
/// Hit-testing for point erase.
/// </summary>
/// <param name="iterator"></param>
/// <param name="intersections"></param>
/// <returns></returns>
internal bool EraseTest(StrokeNodeIterator iterator, List <StrokeIntersection> intersections)
{
System.Diagnostics.Debug.Assert(iterator != null);
System.Diagnostics.Debug.Assert(intersections != null);
intersections.Clear();
List <StrokeFIndices> eraseAt = new List <StrokeFIndices>();
if ((_erasingStrokeNodes == null) || (_erasingStrokeNodes.Count == 0))
{
return(false);
}
Rect inkSegmentBounds = Rect.Empty;
for (int x = 0; x < iterator.Count; x++)
{
StrokeNode inkStrokeNode = iterator[x];
Rect inkNodeBounds = inkStrokeNode.GetBounds();
inkSegmentBounds.Union(inkNodeBounds);
if (inkSegmentBounds.IntersectsWith(_bounds))
{
//
int index = eraseAt.Count;
foreach (StrokeNode erasingStrokeNode in _erasingStrokeNodes)
{
if (false == inkSegmentBounds.IntersectsWith(erasingStrokeNode.GetBoundsConnected()))
{
continue;
}
StrokeFIndices fragment = inkStrokeNode.CutTest(erasingStrokeNode);
if (fragment.IsEmpty)
{
continue;
}
// Merge it with the other results for this ink segment
bool inserted = false;
for (int i = index; i < eraseAt.Count; i++)
{
StrokeFIndices lastFragment = eraseAt[i];
if (fragment.BeginFIndex < lastFragment.EndFIndex)
{
// If the fragments overlap, merge them
if (fragment.EndFIndex > lastFragment.BeginFIndex)
{
fragment = new StrokeFIndices(
Math.Min(lastFragment.BeginFIndex, fragment.BeginFIndex),
Math.Max(lastFragment.EndFIndex, fragment.EndFIndex));
// If the fragment doesn't go beyond lastFragment, break
if ((fragment.EndFIndex <= lastFragment.EndFIndex) || ((i + 1) == eraseAt.Count))
{
inserted = true;
eraseAt[i] = fragment;
break;
}
else
{
eraseAt.RemoveAt(i);
i--;
}
}
// insert otherwise
else
{
eraseAt.Insert(i, fragment);
inserted = true;
break;
}
}
}
// If not merged nor inserted, add it to the end of the list
if (false == inserted)
{
eraseAt.Add(fragment);
}
// Break out if the entire ink segment is hit - {BeforeFirst, AfterLast}
if (eraseAt[eraseAt.Count - 1].IsFull)
{
break;
}
}
// Merge inter-segment overlapping fragments
if ((index > 0) && (index < eraseAt.Count))
{
StrokeFIndices lastFragment = eraseAt[index - 1];
if (DoubleUtil.AreClose(lastFragment.EndFIndex, StrokeFIndices.AfterLast))
{
if (DoubleUtil.AreClose(eraseAt[index].BeginFIndex, StrokeFIndices.BeforeFirst))
{
lastFragment.EndFIndex = eraseAt[index].EndFIndex;
eraseAt[index - 1] = lastFragment;
eraseAt.RemoveAt(index);
}
else
{
lastFragment.EndFIndex = inkStrokeNode.Index;
eraseAt[index - 1] = lastFragment;
}
}
}
}
// Start next ink segment
inkSegmentBounds = inkNodeBounds;
}
if (eraseAt.Count != 0)
{
foreach (StrokeFIndices segment in eraseAt)
{
intersections.Add(new StrokeIntersection(segment.BeginFIndex, StrokeFIndices.AfterLast,
StrokeFIndices.BeforeFirst, segment.EndFIndex));
}
}
return(eraseAt.Count != 0);
}
internal StrokeIntersection[] HitTest(StrokeNodeIterator iterator)
{
System.Diagnostics.Debug.Assert(_points != null);
System.Diagnostics.Debug.Assert(iterator != null);
if (_points.Count < 3)
{
//
// it takes at least 3 points to create a lasso
//
return(Array.Empty <StrokeIntersection>());
}
//
// We're about to perform hit testing with a lasso.
// To do so we need to iterate through each StrokeNode.
// As we do, we calculate the bounding rect between it
// and the previous StrokeNode and store this in 'currentStrokeSegmentBounds'
//
// Next, we check to see if that StrokeNode pair's bounding box intersects
// with the bounding box of the Lasso points. If not, we continue iterating through
// StrokeNode pairs.
//
// If it does, we do a more granular hit test by pairing points in the Lasso, getting
// their bounding box and seeing if that bounding box intersects our current StrokeNode
// pair
//
Point lastNodePosition = new Point();
Point lassoLastPoint = _points[_points.Count - 1];
Rect currentStrokeSegmentBounds = Rect.Empty;
// Initilize the current crossing to be an empty one
LassoCrossing currentCrossing = LassoCrossing.EmptyCrossing;
// Creat a list to hold all the crossings
List <LassoCrossing> crossingList = new List <LassoCrossing>();
for (int i = 0; i < iterator.Count; i++)
{
StrokeNode strokeNode = iterator[i];
Rect nodeBounds = strokeNode.GetBounds();
currentStrokeSegmentBounds.Union(nodeBounds);
// Skip the node if it's outside of the lasso's bounds
if (currentStrokeSegmentBounds.IntersectsWith(_bounds) == true)
{
// currentStrokeSegmentBounds, made up of the bounding box of
// this StrokeNode unioned with the last StrokeNode,
// intersects the lasso bounding box.
//
// Now we need to iterate through the lasso points and find out where they cross
//
Point lastPoint = lassoLastPoint;
foreach (Point point in _points)
{
//
// calculate a segment of the lasso from the last point
// to the current point
//
Rect lassoSegmentBounds = new Rect(lastPoint, point);
//
// see if this lasso segment intersects with the current stroke segment
//
if (!currentStrokeSegmentBounds.IntersectsWith(lassoSegmentBounds))
{
lastPoint = point;
continue;
}
//
// the lasso segment DOES intersect with the current stroke segment
// find out precisely where
//
StrokeFIndices strokeFIndices = strokeNode.CutTest(lastPoint, point);
lastPoint = point;
if (strokeFIndices.IsEmpty)
{
// current lasso segment does not hit the stroke segment, continue with the next lasso point
continue;
}
// Create a potentially new crossing for the current hit testing result.
LassoCrossing potentialNewCrossing = new LassoCrossing(strokeFIndices, strokeNode);
// Try to merge with the current crossing. If the merge is succussful (return true), the new crossing is actually
// continueing the current crossing, so do not start a new crossing. Otherwise, start a new one and add the existing
// one to the list.
if (!currentCrossing.Merge(potentialNewCrossing))
{
// start a new crossing and add the existing on to the list
crossingList.Add(currentCrossing);
currentCrossing = potentialNewCrossing;
}
}
}
// Continue with the next node
currentStrokeSegmentBounds = nodeBounds;
lastNodePosition = strokeNode.Position;
}
// Adding the last crossing to the list, if valid
if (!currentCrossing.IsEmpty)
{
crossingList.Add(currentCrossing);
}
// Handle the special case of no intersection at all
if (crossingList.Count == 0)
{
// the stroke was either completely inside the lasso
// or outside the lasso
if (this.Contains(lastNodePosition))
{
StrokeIntersection[] strokeIntersections = new StrokeIntersection[1];
strokeIntersections[0] = StrokeIntersection.Full;
return(strokeIntersections);
}
else
{
return(Array.Empty <StrokeIntersection>());
}
}
// It is still possible that the current crossing list is not sorted or overlapping.
// Sort the list and merge the overlapping ones.
SortAndMerge(ref crossingList);
// Produce the hit test results and store them in a list
List <StrokeIntersection> strokeIntersectionList = new List <StrokeIntersection>();
ProduceHitTestResults(crossingList, strokeIntersectionList);
return(strokeIntersectionList.ToArray());
}