sw/source/core/bastyp/swregion.cxx | 92 +++++++++++++++++++++----------------
1 file changed, 54 insertions(+), 38 deletions(-)
New commits:
commit d13b63a9859d653d1aba688a56590aa0ef24b89c
Author: Luboš Luňák <l.lu...@collabora.com>
AuthorDate: Wed Sep 15 13:49:11 2021 +0200
Commit: Luboš Luňák <l.lu...@collabora.com>
CommitDate: Thu Sep 16 11:29:19 2021 +0200
optimize SwRegionRects::Compress()
This function gets called on modifying documents, and it shows up
noticeably e.g. when profiling editing in Online.
The code repeatedly restarts the whole process on most changes,
but in practice this seems to only lead to repeated checks with
the same outcome. So finish the whole compression and try again
only at the end, if deemed needed. And even there I'm not sure
if it's actually ever needed, since I couldn't trigger such a case
in practice.
Change-Id: I15b0a83c6865bad21fe60a7e9ca0b87ceea5b489
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/122156
Tested-by: Luboš Luňák <l.lu...@collabora.com>
Reviewed-by: Luboš Luňák <l.lu...@collabora.com>
diff --git a/sw/source/core/bastyp/swregion.cxx
b/sw/source/core/bastyp/swregion.cxx
index ea59d25d532e..54b237c3756d 100644
--- a/sw/source/core/bastyp/swregion.cxx
+++ b/sw/source/core/bastyp/swregion.cxx
@@ -135,7 +135,7 @@ void SwRegionRects::Invert()
swap( aInvRegion );
}
-static SwTwips CalcArea( const SwRect &rRect )
+static inline SwTwips CalcArea( const SwRect &rRect )
{
return rRect.Width() * rRect.Height();
}
@@ -143,51 +143,67 @@ static SwTwips CalcArea( const SwRect &rRect )
// combine all adjacent rectangles
void SwRegionRects::Compress()
{
- for (size_type i = 0; i < size(); )
+ bool bAgain;
+ do
{
- bool bRestart(false);
- for ( size_type j = i+1; j < size(); ++j )
+ bAgain = false;
+ for (size_type i = 0; i < size(); ++i )
{
- // If one rectangle contains a second completely than the latter
- // does not need to be stored and can be deleted
- if ( (*this)[i].IsInside( (*this)[j] ) )
+ for ( size_type j = i+1; j < size(); ++j )
{
- erase( begin() + j );
- --j;
- }
- else if ( (*this)[j].IsInside( (*this)[i] ) )
- {
- (*this)[i] = (*this)[j];
- erase( begin() + j );
- bRestart = true;
- break;
- }
- else
- {
- // If two rectangles have the same area of their union minus
the
- // intersection then one of them can be deleted.
- // For combining as much as possible (and for having less
single
- // paints), the area of the union can be a little bit larger:
- // ( 9622 * 141.5 = 1361513 ~= a quarter (1/4) centimeter wider
- // than the width of an A4 page
- const tools::Long nFuzzy = 1361513;
- SwRect aUnion( (*this)[i] );
- aUnion.Union( (*this)[j] );
- SwRect aInter( (*this)[i] );
- aInter.Intersection( (*this)[j] );
- if ( (::CalcArea( (*this)[i] ) +
- ::CalcArea( (*this)[j] ) + nFuzzy) >=
- (::CalcArea( aUnion ) - CalcArea( aInter )) )
+ // If one rectangle contains a second completely than the
latter
+ // does not need to be stored and can be deleted
+ if ( (*this)[i].IsInside( (*this)[j] ) )
+ {
+ erase( begin() + j );
+ --j;
+ }
+ else if ( (*this)[j].IsInside( (*this)[i] ) )
{
- (*this)[i] = aUnion;
+ (*this)[i] = (*this)[j];
erase( begin() + j );
- bRestart = true;
- break;
+ --j;
+ bAgain = true;
+ }
+ else
+ {
+ // TODO: I think the comment below and the code are
partially incorrect.
+ // An obvious mistake is the comment saying that one
rectangle can be deleted,
+ // while it's the union that gets used instead of the two
rectangles.
+ // I think this code is supposed to merge adjacent
rectangles (possibly
+ // overlapping), and such rectangles can be detected by
their merged areas
+ // being equal to the area of the union (which is
obviously the case if they
+ // share one side, and using the nFuzzy extra allow
merging also rectangles
+ // that do not quite cover the entire union but it's close
enough).
+ // So another mistake seems to be using '- CalcArea(
aInter )',
+ // it should be on the other side of the comparison to
subtract shared area
+ // counted twice. In practice it seems rectangles here do
not share areas,
+ // so the error is irrelevant.
+
+ // If two rectangles have the same area of their union
minus the
+ // intersection then one of them can be deleted.
+ // For combining as much as possible (and for having less
single
+ // paints), the area of the union can be a little bit
larger:
+ // ( 9622 * 141.5 = 1361513 ~= a quarter (1/4) centimeter
wider
+ // than the width of an A4 page
+ const tools::Long nFuzzy = 1361513;
+ SwRect aUnion( (*this)[i] );
+ aUnion.Union( (*this)[j] );
+ SwRect aInter( (*this)[i] );
+ aInter.Intersection( (*this)[j] );
+ if ( (::CalcArea( (*this)[i] ) +
+ ::CalcArea( (*this)[j] ) + nFuzzy) >=
+ (::CalcArea( aUnion ) - CalcArea( aInter )) )
+ {
+ (*this)[i] = aUnion;
+ erase( begin() + j );
+ --j;
+ bAgain = true;
+ }
}
}
}
- i = bRestart ? 0 : i+1;
- }
+ } while(bAgain);
}
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