Ugly round corners when no border is drawn

When specifying round corners with QStyleSheetStyle and no border-width
specified, the round corners were not rendered with antialiasing. Furthermore,
if border-width was set to 0, part of the border was rendered in discordance
with CSS3.

The background in now rendered directly instead of drawing a clipped
rectangle. The actual border width is checked before rendering.

A test has been added at tests/auto/uiloader/baseline/css_borderradius_allwidgets.ui

Task-number: 230362
Reviewed-by: olivier

2 files changed, 14 insertions, 7 deletions

diff --git a/src/gui/painting/qcssutil.cpp b/src/gui/painting/qcssutil.cpp
index ac0ea08..ae8afed 100644
--- a/src/gui/painting/qcssutil.cpp
+++ b/src/gui/painting/qcssutil.cpp
@@ -353,7 +353,7 @@ void qDrawBorder(QPainter *p, const QRect &rect, const QCss::BorderStyle *styles
     qNormalizeRadii(rect, radii, &tlr, &trr, &blr, &brr);
 
     // Drawn in increasing order of precendence
-    if (styles[BottomEdge] != BorderStyle_None) {
+    if (styles[BottomEdge] != BorderStyle_None && borders[BottomEdge] > 0) {
         qreal dw1 = (blr.width() || paintsOver(styles, colors, BottomEdge, LeftEdge)) ? 0 : borders[LeftEdge];
         qreal dw2 = (brr.width() || paintsOver(styles, colors, BottomEdge, RightEdge)) ? 0 : borders[RightEdge];
         qreal x1 = br.x() + blr.width();
@@ -365,7 +365,7 @@ void qDrawBorder(QPainter *p, const QRect &rect, const QCss::BorderStyle *styles
         if (blr.width() || brr.width())
             qDrawRoundedCorners(p, x1, y1, x2, y2, blr, brr, BottomEdge, styles[BottomEdge], colors[BottomEdge]);
     }
-    if (styles[RightEdge] != BorderStyle_None) {
+    if (styles[RightEdge] != BorderStyle_None && borders[RightEdge] > 0) {
         qreal dw1 = (trr.height() || paintsOver(styles, colors, RightEdge, TopEdge)) ? 0 : borders[TopEdge];
         qreal dw2 = (brr.height() || paintsOver(styles, colors, RightEdge, BottomEdge)) ? 0 : borders[BottomEdge];
         qreal x1 = br.x() + br.width() - borders[RightEdge];
@@ -377,7 +377,7 @@ void qDrawBorder(QPainter *p, const QRect &rect, const QCss::BorderStyle *styles
         if (trr.height() || brr.height())
             qDrawRoundedCorners(p, x1, y1, x2, y2, trr, brr, RightEdge, styles[RightEdge], colors[RightEdge]);
     }
-    if (styles[LeftEdge] != BorderStyle_None) {
+    if (styles[LeftEdge] != BorderStyle_None && borders[LeftEdge] > 0) {
         qreal dw1 = (tlr.height() || paintsOver(styles, colors, LeftEdge, TopEdge)) ? 0 : borders[TopEdge];
         qreal dw2 = (blr.height() || paintsOver(styles, colors, LeftEdge, BottomEdge)) ? 0 : borders[BottomEdge];
         qreal x1 = br.x();
@@ -389,7 +389,7 @@ void qDrawBorder(QPainter *p, const QRect &rect, const QCss::BorderStyle *styles
         if (tlr.height() || blr.height())
             qDrawRoundedCorners(p, x1, y1, x2, y2, tlr, blr, LeftEdge, styles[LeftEdge], colors[LeftEdge]);
     }
-    if (styles[TopEdge] != BorderStyle_None) {
+    if (styles[TopEdge] != BorderStyle_None && borders[TopEdge] > 0) {
         qreal dw1 = (tlr.width() || paintsOver(styles, colors, TopEdge, LeftEdge)) ? 0 : borders[LeftEdge];
         qreal dw2 = (trr.width() || paintsOver(styles, colors, TopEdge, RightEdge)) ? 0 : borders[RightEdge];
         qreal x1 = br.x() + tlr.width();
diff --git a/src/gui/styles/qstylesheetstyle.cpp b/src/gui/styles/qstylesheetstyle.cpp
index 370290f..8ac811c 100644
--- a/src/gui/styles/qstylesheetstyle.cpp
+++ b/src/gui/styles/qstylesheetstyle.cpp
@@ -1298,7 +1298,6 @@ void QRenderRule::unsetClip(QPainter *p)
 
 void QRenderRule::drawBackground(QPainter *p, const QRect& rect, const QPoint& off)
 {
-    setClip(p, borderRect(rect));
     QBrush brush = hasBackground() ? background()->brush : QBrush();
     if (brush.style() == Qt::NoBrush)
         brush = defaultBackground;
@@ -1306,11 +1305,19 @@ void QRenderRule::drawBackground(QPainter *p, const QRect& rect, const QPoint& o
     if (brush.style() != Qt::NoBrush) {
         Origin origin = hasBackground() ? background()->clip : Origin_Border;
         // ### fix for  gradients
-        p->fillRect(originRect(rect, origin), brush);
+        const QPainterPath &borderPath = borderClip(originRect(rect, origin));
+        if (!borderPath.isEmpty()) {
+            // Drawn intead of being used as clipping path for better visual quality
+            bool wasAntialiased = p->renderHints() & QPainter::Antialiasing;
+            p->setRenderHint(QPainter::Antialiasing);
+            p->fillPath(borderPath, brush);
+            p->setRenderHint(QPainter::Antialiasing, wasAntialiased);
+        } else {
+            p->fillRect(originRect(rect, origin), brush);
+        }
     }
 
     drawBackgroundImage(p, rect, off);
-    unsetClip(p);
 }
 
 void QRenderRule::drawFrame(QPainter *p, const QRect& rect)