From 88e56d0932a3615231adf40d5ae033e742d72c33 Mon Sep 17 00:00:00 2001
From: Allan Sandfeld Jensen <allan.jensen@qt.io>
Date: Wed, 21 Jun 2017 10:05:07 +0200
Subject: [PATCH] Improve rounding of QRect::toRect

Avoid the dimensions of the rounded QRect being off by more than one
pixel. This ensures the aligned containing rect also contains the
rounded rect.

Task-number: QTBUG-56420
Change-Id: Ib79110e51ab80de2dc83d01ea83fc5fbf3852e75
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/tools/qrect.h                    |  2 +-
 tests/auto/corelib/tools/qrect/tst_qrect.cpp | 32 ++++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/src/corelib/tools/qrect.h b/src/corelib/tools/qrect.h
index 19ff87b420..3b40055b5a 100644
--- a/src/corelib/tools/qrect.h
+++ b/src/corelib/tools/qrect.h
@@ -870,7 +870,7 @@ Q_DECL_CONSTEXPR inline bool operator!=(const QRectF &r1, const QRectF &r2) Q_DE
 
 Q_DECL_CONSTEXPR inline QRect QRectF::toRect() const Q_DECL_NOTHROW
 {
-    return QRect(qRound(xp), qRound(yp), qRound(w), qRound(h));
+    return QRect(QPoint(qRound(xp), qRound(yp)), QPoint(qRound(xp + w) - 1, qRound(yp + h) - 1));
 }
 
 Q_DECL_CONSTEXPR inline QRectF operator+(const QRectF &lhs, const QMarginsF &rhs) Q_DECL_NOTHROW
diff --git a/tests/auto/corelib/tools/qrect/tst_qrect.cpp b/tests/auto/corelib/tools/qrect/tst_qrect.cpp
index d3c6412b0d..1c2221ec29 100644
--- a/tests/auto/corelib/tools/qrect/tst_qrect.cpp
+++ b/tests/auto/corelib/tools/qrect/tst_qrect.cpp
@@ -171,6 +171,7 @@ private slots:
     void containsPointF_data();
     void containsPointF();
     void smallRects() const;
+    void toRect();
 };
 
 // Used to work around some floating point precision problems.
@@ -4331,5 +4332,36 @@ void tst_QRect::smallRects() const
     QVERIFY(r1 != r2);
 }
 
+void tst_QRect::toRect()
+{
+    for (qreal x = 1.0; x < 2.0; x += 0.25) {
+        for (qreal y = 1.0; y < 2.0; y += 0.25) {
+            for (qreal w = 1.0; w < 2.0; w += 0.25) {
+                for (qreal h = 1.0; h < 2.0; h += 0.25) {
+                    const QRectF rectf(x, y, w, h);
+                    const QRectF rect = rectf.toRect();
+                    QVERIFY(qAbs(rect.x() - rectf.x()) < 1.0);
+                    QVERIFY(qAbs(rect.y() - rectf.y()) < 1.0);
+                    QVERIFY(qAbs(rect.width() - rectf.width()) < 1.0);
+                    QVERIFY(qAbs(rect.height() - rectf.height()) < 1.0);
+                    QVERIFY(qAbs(rect.right() - rectf.right()) < 1.0);
+                    QVERIFY(qAbs(rect.bottom() - rectf.bottom()) < 1.0);
+
+                    const QRectF arect = rectf.toAlignedRect();
+                    QVERIFY(qAbs(arect.x() - rectf.x()) < 1.0);
+                    QVERIFY(qAbs(arect.y() - rectf.y()) < 1.0);
+                    QVERIFY(qAbs(arect.width() - rectf.width()) < 2.0);
+                    QVERIFY(qAbs(arect.height() - rectf.height()) < 2.0);
+                    QVERIFY(qAbs(arect.right() - rectf.right()) < 1.0);
+                    QVERIFY(qAbs(arect.bottom() - rectf.bottom()) < 1.0);
+
+                    QVERIFY(arect.contains(rectf));
+                    QVERIFY(arect.contains(rect));
+                }
+            }
+        }
+    }
+}
+
 QTEST_MAIN(tst_QRect)
 #include "tst_qrect.moc"