[patch] getRowNearY (was: anchor_row_)

[Alfredo Braunstein]

On Friday 15 August 2003 17:19, André wrote:

> > > Ok. What about paragraph count from beginning  plus position within?
> >
> > Fine... and you can even drop the position I guess.
> >
> > I wonder if this anchor_par_ shouldn't be stored on the bufferview
> > instead of the lyxtext.
>
> Good idea actually. The insets don't use 'their' anchor anyway.
>
> > Another thing: the anchor_row_ was also used to speed up getRowNearY and
> > friends (yes, *after* real profiling) so I guess we should pay attention
> > to preformance if we do the change.
>
> This code is currently broken. I don't understand the  '- 1 row magic'
> needed to make it work -- which in turn mean that we never reach the
> last row of a par with 'setCursorFromCoordinate' - which is bad.
>
> I wouldn't mind if you had a look ;-)

The -1 row is right because it seems that the convention for getRowNearY(y)
is to return 'the last row with y coordinate less or equal than y'
In this case, the absolute last row would be reached if y is big enough,
i.e. something like this should do:

Index: text.C
===================================================================
RCS file: /usr/local/lyx/cvsroot/lyx-devel/src/text.C,v
retrieving revision 1.421
diff -u -p -u -r1.421 text.C
--- text.C      15 Aug 2003 15:20:50 -0000      1.421
+++ text.C      15 Aug 2003 21:24:22 -0000
@@ -2150,7 +2150,7 @@ RowList::iterator LyXText::cursorIRow() 
 
 
 RowList::iterator LyXText::getRowNearY(int & y,
-       ParagraphList::iterator & pit) const
+                                      ParagraphList::iterator & pit) const
 {
        ParagraphList::iterator const end = ownerParagraphs().end();
        //lyxerr << "getRowNearY: y " << y << endl;
@@ -2170,15 +2170,16 @@ RowList::iterator LyXText::getRowNearY(i
                }
        }
 
-#if 1
+#if 0
        pit = ownerParagraphs().begin();
        y = 0;
        lyxerr << "row not found near " << y << "  pit: " << &*pit << endl;
        return firstRow();
 #else
+       RowList::iterator rit = lastRow();
+       y = rit->y();
        pit = boost::prior(ownerParagraphs().end());
-       lyxerr << "row not found near " << y << "  pit: " << &*pit << endl;
-       return lastRow();
+       return rit;
 #endif
 }

Of course the whole thing could be written in a more natural way with
nextRow (slightly slower maybe):

RowList::iterator LyXText::getRowNearY(int & y,
                                       ParagraphList::iterator & pit) const
{
        //lyxerr << "getRowNearY: y " << y << endl;
        pit = ownerParagraphs().begin();
        RowList::iterator rit = firstRow();
        RowList::iterator rend = endRow();

        for (; rit != rend; nextRow(pit, rit))
                if (rit->y() > y)
                        break;
        previousRow(pit, rit);
        y = rit->y();
        return rit;
}

(note that for this to work correctly, the following fix is needed for
nextRow):

@@ -2208,25 +2209,22 @@ RowList::iterator LyXText::endRow() cons
 
 
 void LyXText::nextRow(ParagraphList::iterator & pit,
        RowList::iterator & rit) const
 {
        if (boost::next(rit) != pit->rows.end()) {
                rit = boost::next(rit);
        } else {
                ++pit;
-               if (pit == ownerParagraphs().end())
+               if (pit == ownerParagraphs().end()) {
                        rit = boost::next(rit);
+                       --pit;
-               else
+               } else
                        rit = pit->rows.begin();
        }
 }
 
Regards, Alfredo