Fixed QPrintPreview text drawing (visible in Assistant).

WebKit (which Assistant uses) uses QFont::setPixelSize() to specify
the font sizes. Those are treated differently in Qt than fonts specified
with setPointSize(). Fonts specified with setPixelSize() should *not*
be scaled to compensate for DPI changes between devices, unlike fonts
with a pointSize() set.

Task-number: QTBUG-9282
Reviewed-by: Eskil

1 files changed, 7 insertions, 2 deletions

diff --git a/src/gui/image/qpicture.cpp b/src/gui/image/qpicture.cpp
index 3220a67..45b3ed0 100644
--- a/src/gui/image/qpicture.cpp
+++ b/src/gui/image/qpicture.cpp
@@ -651,7 +651,12 @@ bool QPicture::exec(QPainter *painter, QDataStream &s, int nrecords)
                 s >> dbl;
                 QFont fnt(font, painter->device());
 
-                qreal scale = painter->device()->logicalDpiY() / (dbl*qt_defaultDpiY());
+                // Fonts that specify a pixel size should not be scaled - QPicture already
+                // have a matrix set to compensate for the DPI differences between the
+                // default Qt DPI and the actual target device DPI, and we have to take that
+                // into consideration in the case where the font has a pixel size set.
+
+                qreal scale = fnt.pointSize() == -1 ? 1 : painter->device()->logicalDpiY() / (dbl*qt_defaultDpiY());
                 painter->save();
                 painter->scale(1/scale, 1/scale);
 
@@ -660,7 +665,7 @@ bool QPicture::exec(QPainter *painter, QDataStream &s, int nrecords)
 
                 int flags = Qt::TextSingleLine | Qt::TextDontClip | Qt::TextForceLeftToRight;
 
-                QSizeF size(scale, scale);
+                QSizeF size(1, 1);
                 if (justificationWidth > 0) {
                     size.setWidth(justificationWidth*scale);
                     flags |= Qt::TextJustificationForced;