fix selection rendering issues if rounding leads to left-out pixels

instead of manual qFloor, use the toAlignedRect() function to get the minimal enclosing rectangle
this will in some cases over-paint one-pixel, which is preferable to under-paint which
leaves gaps inside painting text lines that can not be fixed by the user of the painting routines

Task-number: QTBUG-66036
Change-Id: I8d6c2f7370e55bd544e1ff93d5c07b554b20ffeb
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>
Reviewed-by: Dominik Haumann <dhaumann@kde.org>
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

1 files changed, 5 insertions, 9 deletions

diff --git a/src/gui/text/qtextlayout.cpp b/src/gui/text/qtextlayout.cpp
index 87f73e1e83..71d7157032 100644
--- a/src/gui/text/qtextlayout.cpp
+++ b/src/gui/text/qtextlayout.cpp
@@ -1006,10 +1006,8 @@ static void addSelectedRegionsToPath(QTextEngine *eng, int lineNumber, const QPo
             }
 
             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);
+                const QRectF rect = boundingRect & QRectF(lastSelectionX.toReal(), selectionY, lastSelectionWidth.toReal(), lineHeight);
+                region->addRect(rect.toAlignedRect());
             }
 
             lastSelectionX = selectionX;
@@ -1017,10 +1015,8 @@ static void addSelectedRegionsToPath(QTextEngine *eng, int lineNumber, const QPo
         }
     }
     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);
+        const QRectF rect = boundingRect & QRectF(lastSelectionX.toReal(), selectionY, lastSelectionWidth.toReal(), lineHeight);
+        region->addRect(rect.toAlignedRect());
     }
 }
 
@@ -2135,7 +2131,7 @@ 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(QRectF(qFloor(r.x()), qFloor(r.y()), r.width(), r.height()), bg);
+        p->fillRect(r.toAlignedRect(), bg);
     if (c.style() != Qt::NoBrush) {
         p->setPen(QPen(c, 0));
     }