tdf#160430: Fix glyph bounds calculation, and use basegfx::B2DRectangle

... instead of tools::Rectangle.

Several problems were there:
1. First, a horizontal bounding rectangle was calculated, with due
rounding; and then the result was rotated, and after that, rounded
again. That made the resulting rotated rectangle coordinates very
imprecise.
2. Also, ceil/floor was applied without normalization; and in case
of rotated font, that meant, that sometimes the range could be not
expanded to cover partially covered pixels, but instead collapsed.
3. The rotation to angles other than 90 degree multiples was done
incorrectly, resulting in cut off parts of characters.
4. For 90 degrees, the imprecise result of sin/cos converted 0.0
into values like 3e-16, which then could be ceil'ed up to 1.

Using B2DRectangle and its transform allows to simplify and fix
the calculations easily, and avoids premature rounding. Render of
rotated text of small size is more stable with this change.

Change-Id: Idffd74b9937feb2418ab76a8d325fdaf4ff841b7
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/165553
Tested-by: Jenkins
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/vcl/source/outdev/font.cxx b/vcl/source/outdev/font.cxx
index 0b87c8ef8418..9416963b93b6 100644
--- a/vcl/source/outdev/font.cxx
+++ b/vcl/source/outdev/font.cxx
@@ -948,7 +948,7 @@ void OutputDevice::ImplDrawEmphasisMarks( SalLayout& rSalLayout )
     aOffset += Point( nEmphasisWidth2, nEmphasisHeight2 );
 
     basegfx::B2DPoint aOutPoint;
-    tools::Rectangle aRectangle;
+    basegfx::B2DRectangle aRectangle;
     const GlyphItem* pGlyph;
     const LogicalFontInstance* pGlyphFont;
     int nStart = 0;
@@ -968,7 +968,7 @@ void OutputDevice::ImplDrawEmphasisMarks( SalLayout& rSalLayout )
             else
             {
                 aAdjPoint = aOffset;
-                aAdjPoint.AdjustX(aRectangle.Left() + (aRectangle.GetWidth() - aEmphasisMark.GetWidth()) / 2 );
+                aAdjPoint.AdjustX(aRectangle.getMinX() + (aRectangle.getWidth() - aEmphasisMark.GetWidth()) / 2 );
             }
 
             if ( mpFontInstance->mnOrientation )