/// <summary>
/// Gets the caret column position when moving caret vertically.
/// If the Caret is already on first or last line the caret is set
/// to the start of file or to the end of the file, respectively.
/// If the Caret is positioned left off the stored column position
/// the caret is set to the stored column position or the end of line.
/// </summary>
/// <param name="caretPosition"></param>
/// <param name="snapshot"></param>
/// <returns></returns>
internal int GetCaretColumnPosition(int caretPosition, ITextSnapshot snapshot)
{
var previousLineNumber = snapshot.GetLineNumberFromPosition(Caret.GetPosition(snapshot));
var caretLine = snapshot.GetLineFromPosition(caretPosition);
if (caretLine.LineNumber == previousLineNumber && caretLine.LineNumber == 0)
{
return(0);
}
else if (caretLine.LineNumber == previousLineNumber &&
caretLine.LineNumber == snapshot.LineCount - 1)
{
return(snapshot.Length);
}
else if (ColumnPosition > (caretPosition - caretLine.Start.Position))
{
var correctColumnPosition = (ColumnPosition > caretLine.Length) ?
caretLine.Length
: ColumnPosition;
return(caretLine.Start.Position + correctColumnPosition);
}
else
{
return(caretPosition);
}
}
internal void UpdateSelection(int previousCaretPosition, ITextSnapshot snapshot)
{
var caretPosition = Caret.GetPosition(snapshot);
if (IsSelection())
{
var startPosition = Start.GetPosition(snapshot);
var endPosition = End.GetPosition(snapshot);
if (caretPosition < startPosition && startPosition < previousCaretPosition)
{
End = Start;
Start = Caret;
}
else if (previousCaretPosition < endPosition && endPosition < caretPosition)
{
Start = End;
End = Caret;
}
else if (caretPosition >= startPosition && startPosition != previousCaretPosition)
{
End = Caret;
}
else
{
Start = Caret;
}
}
else
{
Start = caretPosition > previousCaretPosition?
snapshot.CreateTrackingPoint(previousCaretPosition)
: Caret;
End = caretPosition > previousCaretPosition ?
Caret
: snapshot.CreateTrackingPoint(previousCaretPosition);
}
if (Start.GetPosition(snapshot) == End.GetPosition(snapshot))
{
Start = null;
End = null;
}
}
internal bool IsReversed(ITextSnapshot snapshot)
{
return(Caret.GetPosition(snapshot) == Start?.GetPosition(snapshot));
}
internal bool Reversing(ITextSnapshot snapshot)
{
return(Caret.GetPosition(snapshot) < End?.GetPosition(snapshot));
}