private Rect GetBounds(StylusPoint stylusPoint,
Point position,
IInputElement relativeTo,
GeneralTransform elementToRoot,
GeneralTransform rootToElement)
{
// Get width and heith in pixel value
double width = GetStylusPointWidthOrHeight(stylusPoint, /*isWidth*/ true);
double height = GetStylusPointWidthOrHeight(stylusPoint, /*isWidth*/ false);
// Get the position with respect to root
Point rootPoint;
if (elementToRoot == null ||
!elementToRoot.TryTransform(position, out rootPoint))
{
rootPoint = position;
}
// Create a Rect with respect to root and transform it to element coordinate space
Rect rectBounds = new Rect(rootPoint.X - width * 0.5, rootPoint.Y - height * 0.5, width, height);
if (rootToElement != null)
{
rectBounds = rootToElement.TransformBounds(rectBounds);
}
return rectBounds;
}
// Creates an axis-aligned caret for possibly rotated glyphs
private Rect _GetTransformedCaretRect(GeneralTransform transform, Point origin, double height)
{
Point bottom = origin;
bottom.Y += height;
transform.TryTransform(origin, out origin);
transform.TryTransform(bottom, out bottom);
Rect caretRect = new Rect(origin, bottom);
if (caretRect.Width > 0)
{
// only vertical carets are supported by TextEditor
// What to do if height == 0?
caretRect.X += caretRect.Width / 2;
caretRect.Width = 0;
}
if (caretRect.Height < 1)
{
caretRect.Height = 1;
}
return caretRect;
}
// Clips a Point to the ActualWidth/Height of a containing FrameworkElement.
private static void ClipToElement(FrameworkElement element, GeneralTransform transform,
ref double horizontalOffset, ref double verticalOffset)
{
Point minPoint;
Point maxPoint;
Geometry clip = VisualTreeHelper.GetClip(element);
if (clip != null)
{
Rect bounds = clip.Bounds;
minPoint = new Point(bounds.X, bounds.Y);
maxPoint = new Point(bounds.X + bounds.Width, bounds.Y + bounds.Height);
}
else
{
if (element.ActualWidth == 0 && element.ActualHeight == 0)
{
// Some elements, noteably Canvas, have a (0, 0) desired size
// and should be ignored.
return;
}
minPoint = new Point(0, 0);
maxPoint = new Point(element.ActualWidth, element.ActualHeight);
}
transform.TryTransform(minPoint, out minPoint);
transform.TryTransform(maxPoint, out maxPoint);
// NB: ClipToBounds will handle the case where transform flips a coordinate
// axis. In that case, minPoint.X will be > maxPoint.X.
horizontalOffset = ClipToBounds(minPoint.X, horizontalOffset, maxPoint.X);
verticalOffset = ClipToBounds(minPoint.Y, verticalOffset, maxPoint.Y);
}