/// <summary>
/// Return true if Delete() will delete something. Default is that it will not.
/// </summary>
public override bool CanDelete()
{
var sel = new InsertionPoint(Hookup, StringPosition, AssociatePrevious);
sel = sel.MoveByKey(new KeyEventArgs(Keys.Right)) as InsertionPoint;
return(Hookup.CanDelete(this, sel));
}
/// <summary>
/// Delete the selected material, or whatever else is appropriate when the Delete key is pressed.
/// (Insertion Point deletes the following character.)
/// </summary>
public override void Delete()
{
Invalidate(); // while we still know the old position.
if (Hookup == null)
{
return;
}
if (StringPosition == Hookup.Text.Length)
{
if (Hookup.ClientRunIndex == Para.Source.ClientRuns.Count - 1)
{
DeleteLineBreak();
return;
}
if (Para.Source.ClientRuns[Hookup.ClientRunIndex + 1] is TextClientRun)
{
// Delete at end of previous run.
var nextClientRun = Para.Source.NonEmptyStringClientRunBeginningAfter(Hookup.ClientRunIndex);
if (nextClientRun == null)
{
return;
}
// Enhance JohnT: maybe some kind of hookup can merge with previous para or delete an embedded object?
CopyFrom(nextClientRun.SelectAtStart(Para));
//Debug.Assert(StringPosition != Hookup.Text.Length - 1, "should have selected at the START of a non-empty run");
}
}
var insertionPointEnd = new InsertionPoint(Hookup, StringPosition + 1, AssociatePrevious);
if (!Hookup.CanDelete(this, insertionPointEnd))
{
return;
}
Hookup.Delete(this, insertionPointEnd);
}
/// <summary>
/// Implement the backspace key function (delete one character, or merge two paragraphs).
/// </summary>
public void Backspace()
{
Invalidate(); // while we still know the old position.
if (Hookup == null)
{
return;
}
if (StringPosition == 0)
{
if (Hookup.ClientRunIndex == 0)
{
BackspaceDeleteLineBreak();
return;
}
if (Para.Source.ClientRuns[Hookup.ClientRunIndex - 1] is TextClientRun)
{
// Delete at end of previous run.
var prevClientRun = Para.Source.NonEmptyStringClientRunEndingBefore(Hookup.ClientRunIndex);
if (prevClientRun == null)
{
return;
}
// Enhance JohnT: maybe some kind of hookup can merge with previous para or delete an embedded object?
CopyFrom(prevClientRun.SelectAtEnd(Para));
Debug.Assert(StringPosition != 0, "should have selected at the END of a non-empty run");
}
}
string oldValue = Hookup.Text;
int newPos = Surrogates.PrevChar(oldValue, StringPosition); // Enhance JohnT: should we delete back to a base?
var start = new InsertionPoint(Hookup, newPos, false);
if (!Hookup.CanDelete(start, this))
{
return;
}
Hookup.Delete(start, this);
StringPosition = newPos;
}
