Fixed cosmetic line drawing where begin and end points are equal.

This case has typically required specific work-arounds in other
rendering paths as well.

(cherry picked from commit dfb55f8a6c8d3ec4da840191c331ace3c2aa2bf3)

Task-number: QTBUG-25153
Change-Id: I217e710a30222792ebca3bf297e438d944c32992
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

2 files changed, 26 insertions, 0 deletions

diff --git a/src/gui/painting/qcosmeticstroker.cpp b/src/gui/painting/qcosmeticstroker.cpp
index 6c1be87..f99edc6 100644
--- a/src/gui/painting/qcosmeticstroker.cpp
+++ b/src/gui/painting/qcosmeticstroker.cpp
@@ -356,6 +356,11 @@ bool QCosmeticStroker::clipLine(qreal &x1, qreal &y1, qreal &x2, qreal &y2)
 
 void QCosmeticStroker::drawLine(const QPointF &p1, const QPointF &p2)
 {
+    if (p1 == p2) {
+        drawPoints(&p1, 1);
+        return;
+    }
+
     QPointF start = p1 * state->matrix;
     QPointF end = p2 * state->matrix;
 
diff --git a/tests/auto/qpainter/tst_qpainter.cpp b/tests/auto/qpainter/tst_qpainter.cpp
index c21f3b5..fc2d045 100644
--- a/tests/auto/qpainter/tst_qpainter.cpp
+++ b/tests/auto/qpainter/tst_qpainter.cpp
@@ -270,6 +270,7 @@ private slots:
     void drawTextOutsideGuiThread();
 
     void QTBUG26013_squareCapStroke();
+    void QTBUG25153_drawLine();
 
 private:
     void fillData();
@@ -4810,6 +4811,26 @@ void tst_QPainter::QTBUG26013_squareCapStroke()
     }
 }
 
+void tst_QPainter::QTBUG25153_drawLine()
+{
+    QImage image(2, 2, QImage::Format_RGB32);
+
+    QVector<Qt::PenCapStyle> styles;
+    styles << Qt::FlatCap << Qt::SquareCap << Qt::RoundCap;
+
+    foreach (Qt::PenCapStyle style, styles) {
+        image.fill(0xffffffff);
+        QPainter p(&image);
+        p.setPen(QPen(Qt::black, 0, Qt::SolidLine, style));
+        p.drawLine(QLineF(0, 0, 0, 0));
+        p.end();
+
+        QCOMPARE(image.pixel(0, 0), 0xff000000);
+        QCOMPARE(image.pixel(0, 1), 0xffffffff);
+        QCOMPARE(image.pixel(1, 0), 0xffffffff);
+    }
+}
+
 QTEST_MAIN(tst_QPainter)
 
 #include "tst_qpainter.moc"