Re: [PATCH 1/2] riched20: Implement ITextRange::MoveStart() and ITextRange::MoveEnd() for tomCharacter

[Damjan Jovanovic]

On Mon, Aug 17, 2020 at 12:02 PM Huw Davies  wrote:
> On Mon, Aug 17, 2020 at 05:22:57AM +0200, Damjan Jovanovic wrote:
> > Signed-off-by: Damjan Jovanovic
> >
> > dlls/riched20/richole.c       | 77 +++++++++++++++++++++++++--
> >  dlls/riched20/tests/richole.c | 98 ++++++++++++++++++++++++++++++++++-
> >  2 files changed, 169 insertions(+), 6 deletions(-)
> > diff --git a/dlls/riched20/richole.c b/dlls/riched20/richole.c
> > index 7c281ab364..1fd307eb92 100644
> > --- a/dlls/riched20/richole.c
> > +++ b/dlls/riched20/richole.c
> > @@ -2191,17 +2191,63 @@ static HRESULT WINAPI
>
> ITextRange_fnMove(ITextRange *me, LONG unit, LONG count, L
> >  return E_NOTIMPL;
> >
> > }
> >
> > +static HRESULT textrange_movestart(ITextRange *range, LONG unit, LONG
>
> count, LONG *delta)
> > +{
> > - LONG old_start, old_end, new_start, new_end;
> > - HRESULT hr = S_OK;
> > -
> > - if (!count)
> > - {
> > -
> >    if (delta)
> > -
> >        *delta = 0;
> > -
> >    return S_FALSE;
> > - }
> > -
> > - ITextRange_GetStart(range, &old_start);
> > - ITextRange_GetEnd(range, &old_end);
> > - switch (unit)
> > - {
> > - case tomCharacter:
> > - {
> > -
> >    ME_TextEditor *editor;
> > -
> >    ME_Cursor cursor;
> > -
> >    LONG moved;
> > -
> >    ITextRangeImpl *This = impl_from_ITextRange(range);
> > -
> >    editor = This->child.reole->editor;
> > -
> > -
> >    ME_CursorFromCharOfs(editor, old_start, &cursor);
> > -
> >    moved = ME_MoveCursorChars(editor, &cursor, count, FALSE);
> > -
> >    new_start = old_start + moved;
> > -
> >    new_end = old_end;
> > -
> >    if (new_end < new_start)
> > -
> >        new_end = new_start;
> > -
> >    if (delta)
> > -
> >        *delta = moved;
> > -
> >    break;
> > - }
> > - default:
> > -
> >    FIXME("unit %d is not supported\n", unit);
> > -
> >    return E_NOTIMPL;
> > - }
> > - if (new_start == old_start)
> > -
> >    hr = S_FALSE;
> > - ITextRange_SetStart(range, new_start);
> > - ITextRange_SetEnd(range, new_end);
> > -
> > - return hr;
> >
> > +}
> > -
> >
> > static HRESULT WINAPI ITextRange_fnMoveStart(ITextRange *me, LONG unit,
>
> LONG count,
> >                                           LONG *delta)
> >
> > {
> >      ITextRangeImpl *This = impl_from_ITextRange(me);
> > - FIXME("(%p)->(%d %d %p): stub\n", This, unit, count, delta);
> > -
> >
> > TRACE("(%p)->(%d %d %p)\n", This, unit, count, delta);
> >
> > if (!This->child.reole)
> >     return CO_E_RELEASED;
> > - return E_NOTIMPL;
> > - return textrange_movestart(me, unit, count, delta);
> >
> > }
>
> I know textrange_moveend() is a thing, but it's not clear why.
> I think all of the implementation of MoveStart should go in
> ITextRange_fnMoveStart, then ITextSelection_fnMoveStart would call
> ITextRage_MoveStart().

I tried that. Unfortunately ITextSelection_fnQueryInterface() implements
IID_ITextRange by returning itself, resulting in ITextSelection_fnMoveEnd()
calling itself until the stack overflows.

ITextRange and ITextSelection are on separate objects, we can't QI from the
one to the other. Using a common textrange_moveend() style function
independent of the objects, seems like the only way. Sadly even those
functions are wrong in my patches, because they cannot call
impl_from_ITextRange() on an ITextSelection. I think the calling functions
could pass them whatever they need from their impl, such as ME_TextEditor*.

New patches will take a while.