Fix misaligned selection region with text when centered

If the text is centered, the x/y position in the selection QRectF may
be a multiple of 0.5 which is rounded up. This rounding causes
misalignment of the selection region with the text.

The alignment is fixed by using qFloor on the x and y components.

Task-number: QTBUG-34218
Task-number: QTBUG-34234
Change-Id: I4f2fadeb38602f62a93773c6e5faecf03b28069f
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>
(cherry picked from qtbase/5d8a882c11201a29475c5ea71cfb76c9de6573f5)

1 files changed, 14 insertions, 5 deletions

diff --git a/src/gui/text/qtextlayout.cpp b/src/gui/text/qtextlayout.cpp
index 3d340cb..8d652ea 100644
--- a/src/gui/text/qtextlayout.cpp
+++ b/src/gui/text/qtextlayout.cpp
@@ -44,6 +44,7 @@
 
 #include <qfont.h>
 #include <qapplication.h>
+#include <qmath.h>
 #include <qpainter.h>
 #include <qvarlengtharray.h>
 #include <qtextformat.h>
@@ -979,15 +980,23 @@ static void addSelectedRegionsToPath(QTextEngine *eng, int lineNumber, const QPo
                 continue;
             }
 
-            if (lastSelectionWidth > 0)
-                region->addRect(boundingRect & QRectF(lastSelectionX.toReal(), selectionY, lastSelectionWidth.toReal(), lineHeight));
+            if (lastSelectionWidth > 0) {
+                QRectF rect = boundingRect & QRectF(lastSelectionX.toReal(), selectionY, lastSelectionWidth.toReal(), lineHeight);
+                rect.moveLeft(qFloor(rect.left()));
+                rect.moveTop(qFloor(rect.top()));
+                region->addRect(rect);
+            }
 
             lastSelectionX = selectionX;
             lastSelectionWidth = selectionWidth;
         }
     }
-    if (lastSelectionWidth > 0)
-        region->addRect(boundingRect & QRectF(lastSelectionX.toReal(), selectionY, lastSelectionWidth.toReal(), lineHeight));
+    if (lastSelectionWidth > 0) {
+        QRectF rect = boundingRect & QRectF(lastSelectionX.toReal(), selectionY, lastSelectionWidth.toReal(), lineHeight);
+        rect.moveLeft(qFloor(rect.left()));
+        rect.moveTop(qFloor(rect.top()));
+        region->addRect(rect);
+    }
 }
 
 static inline QRectF clipIfValid(const QRectF &rect, const QRectF &clip)
@@ -2081,7 +2090,7 @@ static void setPenAndDrawBackground(QPainter *p, const QPen &defaultPen, const Q
 
     QBrush bg = chf.background();
     if (bg.style() != Qt::NoBrush && !chf.property(SuppressBackground).toBool())
-        p->fillRect(r, bg);
+        p->fillRect(QRectF(qFloor(r.x()), qFloor(r.y()), r.width(), r.height()), bg);
     if (c.style() != Qt::NoBrush) {
         p->setPen(QPen(c, 0));
     }