/// <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);
//
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 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
//
}