/// <summary> Inserts the given content into this instance. </summary>
/// <param name="caret"> The caret which represents the point at which the content should be
/// inserted. </param>
/// <param name="text"> The text that should be inserted into the text fragment </param>
public TextCaret Insert(TextCaret caret, string text)
{
if (caret.Content != this)
{
throw new ArgumentException("Caret does not refer to this Content instance", nameof(caret));
}
if (text == null)
{
throw new ArgumentNullException(nameof(text));
}
// easy, it's empty
if (text == "")
{
return(caret);
}
var originalNumGraphemes = _buffer.GraphemeLength;
_buffer.InsertText(caret.Offset.CharOffset, text);
var nowNumGraphemes = _buffer.GraphemeLength;
NotifyChanged();
return(TextCaret.FromOffset(this, caret.Offset.GraphemeOffset + nowNumGraphemes - originalNumGraphemes));
}
/// <summary> Retrieves a cursor that points at the given character. </summary>
/// <exception cref="Exception"> Thrown when an exception error condition occurs. </exception>
/// <param name="graphemeIndex"> The index of the grapheme to point at. </param>
/// <returns> A TextBlockValueCursor that is pointing at the given grapheme. </returns>
public TextCaret CursorFromGraphemeIndex(int graphemeIndex)
{
if (graphemeIndex < 0 || graphemeIndex > _buffer.GraphemeLength)
{
throw new ArgumentException($"Invalid index for cursor; index={graphemeIndex}; maximum={_buffer.GraphemeLength}", nameof(graphemeIndex));
}
return(TextCaret.FromOffset(this, graphemeIndex));
}
/// <summary> Deletes text at the given position. </summary>
public static TextCaret DeleteText(this TextCaret caret, int numberOfGraphemes)
{
var endCaret = caret;
while (numberOfGraphemes > 0)
{
var next = endCaret.GetNextPosition();
if (!next.IsValid)
{
break;
}
endCaret = next;
numberOfGraphemes--;
}
// TODO special case when we're deleting the entire fragment
caret.Content.DeleteText(caret.Offset, endCaret.Offset);
return(TextCaret.FromOffset(caret.Content, caret.Offset.GraphemeOffset));
}
