pagelayout: Fix inaccuracy in marginsPixels and paintRectPixels

Do not use rounded value for conversion, which gives inaccurate result.

Example case: typical margin for A4 paper size is 8.4 pt. At 600 dpi,
the old code was using rounded point value of 8, which produces an
incorrect result:

8 / (72.0 / 600) = 67 pixels

The correct margin is of course:

8.4 / (72.0 / 600) = 70 pixels

Pick-to: 6.6
Change-Id: I44b2eeabb82fd3bf8e2dcfcba66ae96cde763875
Reviewed-by: David Faure <david.faure@kdab.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

2 files changed, 78 insertions, 6 deletions

diff --git a/src/gui/painting/qpagelayout.cpp b/src/gui/painting/qpagelayout.cpp
index 4c57d33d5a..ec505f2cce 100644
--- a/src/gui/painting/qpagelayout.cpp
+++ b/src/gui/painting/qpagelayout.cpp
@@ -82,7 +82,7 @@ public:
     void clampMargins(const QMarginsF &margins);
 
     QMarginsF margins(QPageLayout::Unit units) const;
-    QMargins marginsPoints() const;
+    QMarginsF marginsPoints() const;
     QMargins marginsPixels(int resolution) const;
 
     void setDefaultMargins(const QMarginsF &minMargins);
@@ -164,14 +164,14 @@ QMarginsF QPageLayoutPrivate::margins(QPageLayout::Unit units) const
     return qt_convertMargins(m_margins, m_units, units);
 }
 
-QMargins QPageLayoutPrivate::marginsPoints() const
+QMarginsF QPageLayoutPrivate::marginsPoints() const
 {
-    return qt_convertMargins(m_margins, m_units, QPageLayout::Point).toMargins();
+    return qt_convertMargins(m_margins, m_units, QPageLayout::Point);
 }
 
 QMargins QPageLayoutPrivate::marginsPixels(int resolution) const
 {
-    return marginsPoints() / qt_pixelMultiplier(resolution);
+    return QMarginsF(marginsPoints() / qt_pixelMultiplier(resolution)).toMargins();
 }
 
 void QPageLayoutPrivate::setDefaultMargins(const QMarginsF &minMargins)
@@ -699,7 +699,7 @@ QMarginsF QPageLayout::margins(Unit units) const
 
 QMargins QPageLayout::marginsPoints() const
 {
-    return d->marginsPoints();
+    return d->marginsPoints().toMargins();
 }
 
 /*!
@@ -866,7 +866,7 @@ QRect QPageLayout::paintRectPoints() const
     if (!isValid())
         return QRect();
     return d->m_mode == FullPageMode ? d->fullRectPoints()
-                                                  : d->fullRectPoints() - d->marginsPoints();
+                                                  : d->fullRectPoints() - d->marginsPoints().toMargins();
 }
 
 /*!
diff --git a/tests/auto/gui/painting/qpagelayout/tst_qpagelayout.cpp b/tests/auto/gui/painting/qpagelayout/tst_qpagelayout.cpp
index dbfdab2ac4..0967a12e42 100644
--- a/tests/auto/gui/painting/qpagelayout/tst_qpagelayout.cpp
+++ b/tests/auto/gui/painting/qpagelayout/tst_qpagelayout.cpp
@@ -90,12 +90,14 @@ void tst_QPageLayout::basics()
     QCOMPARE(tenpoint.margins(QPageLayout::Millimeter), QMarginsF(3.53, 3.53, 3.53, 3.53));
     QCOMPARE(tenpoint.marginsPoints(), QMargins(10, 10, 10, 10));
     QCOMPARE(tenpoint.marginsPixels(72), QMargins(10, 10, 10, 10));
+    QCOMPARE(tenpoint.marginsPixels(600), QMargins(83, 83, 83, 83));
     QCOMPARE(tenpoint.minimumMargins(), QMarginsF(0, 0, 0, 0));
     QCOMPARE(tenpoint.maximumMargins(), QMarginsF(595, 842, 595, 842));
     QCOMPARE(tenpoint.fullRect(), QRectF(0, 0, 595, 842));
     QCOMPARE(tenpoint.fullRect(QPageLayout::Millimeter), QRectF(0, 0, 210, 297));
     QCOMPARE(tenpoint.fullRectPoints(), QRect(0, 0, 595, 842));
     QCOMPARE(tenpoint.fullRectPixels(72), QRect(0, 0, 595, 842));
+    QCOMPARE(tenpoint.fullRectPixels(600), QRect(0, 0, 4958, 7016));
     QCOMPARE(tenpoint.paintRect(), QRectF(10, 10, 575, 822));
     QCOMPARE(tenpoint.paintRect(QPageLayout::Millimeter), QRectF(3.53, 3.53, 202.94, 289.94));
     QCOMPARE(tenpoint.paintRect(QPageLayout::Millimeter).x(), 3.53);
@@ -108,6 +110,7 @@ void tst_QPageLayout::basics()
     QCOMPARE(tenpoint.paintRect(QPageLayout::Millimeter).bottom(), 293.47);
     QCOMPARE(tenpoint.paintRectPoints(), QRect(10, 10, 575, 822));
     QCOMPARE(tenpoint.paintRectPixels(72), QRect(10, 10, 575, 822));
+    QCOMPARE(tenpoint.paintRectPixels(600), QRect(83, 83, 4792, 6850));
 
     // Change orientation
     tenpoint.setOrientation(QPageLayout::Landscape);
@@ -119,10 +122,12 @@ void tst_QPageLayout::basics()
     QCOMPARE(tenpoint.fullRect(QPageLayout::Millimeter), QRectF(0, 0, 297, 210));
     QCOMPARE(tenpoint.fullRectPoints(), QRect(0, 0, 842, 595));
     QCOMPARE(tenpoint.fullRectPixels(72), QRect(0, 0, 842, 595));
+    QCOMPARE(tenpoint.fullRectPixels(600), QRect(0, 0, 7016, 4958));
     QCOMPARE(tenpoint.paintRect(), QRectF(10, 10, 822, 575));
     QCOMPARE(tenpoint.paintRect(QPageLayout::Millimeter), QRectF(3.53, 3.53, 289.94, 202.94));
     QCOMPARE(tenpoint.paintRectPoints(), QRect(10, 10, 822, 575));
     QCOMPARE(tenpoint.paintRectPixels(72), QRect(10, 10, 822, 575));
+    QCOMPARE(tenpoint.paintRectPixels(600), QRect(83, 83, 6850, 4792));
 
     // Change mode
     QCOMPARE(tenpoint.mode(), QPageLayout::StandardMode);
@@ -136,10 +141,77 @@ void tst_QPageLayout::basics()
     QCOMPARE(tenpoint.fullRect(QPageLayout::Millimeter), QRectF(0, 0, 297, 210));
     QCOMPARE(tenpoint.fullRectPoints(), QRect(0, 0, 842, 595));
     QCOMPARE(tenpoint.fullRectPixels(72), QRect(0, 0, 842, 595));
+    QCOMPARE(tenpoint.fullRectPixels(600), QRect(0, 0, 7016, 4958));
     QCOMPARE(tenpoint.paintRect(), QRectF(0, 0, 842, 595));
     QCOMPARE(tenpoint.paintRect(QPageLayout::Millimeter), QRectF(0, 0, 297, 210));
     QCOMPARE(tenpoint.paintRectPoints(), QRect(0, 0, 842, 595));
     QCOMPARE(tenpoint.paintRectPixels(72), QRect(0, 0, 842, 595));
+    QCOMPARE(tenpoint.paintRectPixels(600), QRect(0, 0, 7016, 4958));
+
+    // A4, 8.4pt margins
+    QPageLayout fraction = QPageLayout(QPageSize(QPageSize::A4), QPageLayout::Portrait, QMarginsF(8.4, 8.4, 8.4, 8.4));
+    QCOMPARE(fraction.isValid(), true);
+    QCOMPARE(fraction.margins(), QMarginsF(8.4, 8.4, 8.4, 8.4));
+    QCOMPARE(fraction.margins(QPageLayout::Millimeter), QMarginsF(2.96, 2.96, 2.96, 2.96));
+    QCOMPARE(fraction.marginsPoints(), QMarginsF(8, 8, 8, 8));
+    QCOMPARE(fraction.marginsPixels(72), QMargins(8, 8, 8, 8));
+    QCOMPARE(fraction.marginsPixels(600), QMargins(70, 70, 70, 70));
+    QCOMPARE(fraction.minimumMargins(), QMarginsF(0, 0, 0, 0));
+    QCOMPARE(fraction.maximumMargins(), QMarginsF(595, 842, 595, 842));
+    QCOMPARE(fraction.fullRect(), QRectF(0, 0, 595, 842));
+    QCOMPARE(fraction.fullRect(QPageLayout::Millimeter), QRectF(0, 0, 210, 297));
+    QCOMPARE(fraction.fullRectPoints(), QRect(0, 0, 595, 842));
+    QCOMPARE(fraction.fullRectPixels(72), QRect(0, 0, 595, 842));
+    QCOMPARE(fraction.fullRectPixels(600), QRect(0, 0, 4958, 7016));
+    QCOMPARE(fraction.paintRect(), QRectF(8.4, 8.4, 578.2, 825.2));
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter), QRectF(2.96, 2.96, 204.08, 291.08));
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter).x(), 2.96);
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter).y(), 2.96);
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter).width(), 204.08);
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter).height(), 291.08);
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter).left(), 2.96);
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter).right(), 207.04);
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter).top(), 2.96);
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter).bottom(), 294.04);
+    QCOMPARE(fraction.paintRectPoints(), QRect(8, 8, 579, 826));
+    QCOMPARE(fraction.paintRectPixels(72), QRect(8, 8, 579, 826));
+    QCOMPARE(fraction.paintRectPixels(600), QRect(70, 70, 4818, 6876));
+
+    // Change orientation
+    fraction.setOrientation(QPageLayout::Landscape);
+    QCOMPARE(fraction.orientation(), QPageLayout::Landscape);
+    QCOMPARE(fraction.margins(), QMarginsF(8.4, 8.4, 8.4, 8.4));
+    QCOMPARE(fraction.minimumMargins(), QMarginsF(0, 0, 0, 0));
+    QCOMPARE(fraction.maximumMargins(), QMarginsF(842, 595, 842, 595));
+    QCOMPARE(fraction.fullRect(), QRectF(0, 0, 842, 595));
+    QCOMPARE(fraction.fullRect(QPageLayout::Millimeter), QRectF(0, 0, 297, 210));
+    QCOMPARE(fraction.fullRectPoints(), QRect(0, 0, 842, 595));
+    QCOMPARE(fraction.fullRectPixels(72), QRect(0, 0, 842, 595));
+    QCOMPARE(fraction.fullRectPixels(600), QRect(0, 0, 7016, 4958));
+    QCOMPARE(fraction.paintRect(), QRectF(8.4, 8.4, 825.2, 578.2));
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter), QRectF(2.96, 2.96, 291.08, 204.08));
+    QCOMPARE(fraction.paintRectPoints(), QRect(8, 8, 826, 579));
+    QCOMPARE(fraction.paintRectPixels(72), QRect(8, 8, 826, 579));
+    QCOMPARE(fraction.paintRectPixels(600), QRect(70, 70, 6876, 4818));
+
+    // Change mode
+    QCOMPARE(fraction.mode(), QPageLayout::StandardMode);
+    fraction.setMode(QPageLayout::FullPageMode);
+    QCOMPARE(fraction.mode(), QPageLayout::FullPageMode);
+    QCOMPARE(fraction.orientation(), QPageLayout::Landscape);
+    QCOMPARE(fraction.margins(), QMarginsF(8.4, 8.4, 8.4, 8.4));
+    QCOMPARE(fraction.minimumMargins(), QMarginsF(0, 0, 0, 0));
+    QCOMPARE(fraction.maximumMargins(), QMarginsF(842, 595, 842, 595));
+    QCOMPARE(fraction.fullRect(), QRectF(0, 0, 842, 595));
+    QCOMPARE(fraction.fullRect(QPageLayout::Millimeter), QRectF(0, 0, 297, 210));
+    QCOMPARE(fraction.fullRectPoints(), QRect(0, 0, 842, 595));
+    QCOMPARE(fraction.fullRectPixels(72), QRect(0, 0, 842, 595));
+    QCOMPARE(fraction.fullRectPixels(600), QRect(0, 0, 7016, 4958));
+    QCOMPARE(fraction.paintRect(), QRectF(0, 0, 842, 595));
+    QCOMPARE(fraction.paintRect(QPageLayout::Millimeter), QRectF(0, 0, 297, 210));
+    QCOMPARE(fraction.paintRectPoints(), QRect(0, 0, 842, 595));
+    QCOMPARE(fraction.paintRectPixels(72), QRect(0, 0, 842, 595));
+    QCOMPARE(fraction.paintRectPixels(600), QRect(0, 0, 7016, 4958));
 }
 
 void tst_QPageLayout::setGetMargins()