// Helper for UpdateCaretState -- calculates caret rectangle from text selection.
// regular (non-interim) case of caret positioning
private static Rect CalculateCaretRectangle(ITextSelection currentTextSelection, ITextPointer caretPosition)
{
Transform caretTransform;
Rect caretRectangle = currentTextSelection.TextView.GetRawRectangleFromTextPosition(caretPosition, out caretTransform);
if (caretRectangle.IsEmpty)
{
// Caret is not at an insertion position, it has no geometry
// and will not be displayed.
return Rect.Empty;
}
// Convert to local coordiantes.
caretRectangle = caretTransform.TransformBounds(caretRectangle);
// We will use the system defined caret width later.
caretRectangle.Width = 0;
if (currentTextSelection.IsEmpty)
{
// Calculate caret height - from current font size (ignoring a rect returned by TextView,
// as it can be a rect of embedded object, which should not affect caret height)
double fontSize = (double)currentTextSelection.GetPropertyValue(TextElement.FontSizeProperty);
FontFamily fontFamily = (FontFamily)currentTextSelection.GetPropertyValue(TextElement.FontFamilyProperty);
double caretHeight = fontFamily.LineSpacing * fontSize;
if (caretHeight < caretRectangle.Height)
{
// Decrease the height of caret to the font height and lower the caret to keep its bottom
// staying on the baseline.
caretRectangle.Y += caretRectangle.Height - caretHeight;
caretRectangle.Height = caretHeight;
}
if (!caretTransform.IsIdentity)
{
Point top = new Point(caretRectangle.X, caretRectangle.Y);
Point bottom = new Point(caretRectangle.X, caretRectangle.Y + caretRectangle.Height);
caretTransform.TryTransform(top, out top);
caretTransform.TryTransform(bottom, out bottom);
caretRectangle.Y += caretRectangle.Height - Math.Abs(bottom.Y - top.Y);
caretRectangle.Height = Math.Abs(bottom.Y - top.Y);
}
}
return caretRectangle;
}