diff options
author | Eirik Aavitsland <eirik.aavitsland@theqtcompany.com> | 2015-03-19 08:46:56 +0100 |
---|---|---|
committer | aavit <eirik.aavitsland@theqtcompany.com> | 2015-03-19 09:01:08 +0000 |
commit | d5c6335ff3f86616b49a8ca0cb6f4991ff5dfef9 (patch) | |
tree | 85be6266bc646d5271fac4c8f926550bd613cc87 | |
parent | 90461979bcf0bf89027053eec37047ff7b88752f (diff) |
Fix rasterization errors in aliased cosmetic drawPolyLine
If a cosmetic polyline contained a 1-pixel segment, the next segment
would be drawn with wrong starting point.
The original fix for QTBUG-26156 had some unwanted side effects
(QTBUG-31579 and now QTBUG-42398). It tried to skip start-point update
if stroke() did not actually draw anything (because the segment was
too small). However, to determine that, it tested for a change in
lastPixel. But that was not failsafe; in some cases (1-pixel segment),
lastPixel could be unchanged even though the segment had been
drawn. With this change, we instead test directly whether stroke()
skipped the segment or not.
Task-number: QTBUG-42398
Change-Id: Id751db69a18cd1af4f45070db9d5698aa532d22a
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>
-rw-r--r-- | src/gui/painting/qcosmeticstroker.cpp | 20 | ||||
-rw-r--r-- | tests/auto/gui/painting/qpainter/tst_qpainter.cpp | 37 |
2 files changed, 45 insertions, 12 deletions
diff --git a/src/gui/painting/qcosmeticstroker.cpp b/src/gui/painting/qcosmeticstroker.cpp index d179002127..c416b9e044 100644 --- a/src/gui/painting/qcosmeticstroker.cpp +++ b/src/gui/painting/qcosmeticstroker.cpp @@ -601,8 +601,7 @@ void QCosmeticStroker::drawPath(const QVectorPath &path) if (!closed && drawCaps && points == end - 2) caps |= CapEnd; - QCosmeticStroker::Point last = this->lastPixel; - bool unclipped = stroke(this, p.x(), p.y(), p2.x(), p2.y(), caps); + bool moveNextStart = stroke(this, p.x(), p.y(), p2.x(), p2.y(), caps); /* fix for gaps in polylines with fastpen and aliased in a sequence of points with small distances: if current point p2 has been dropped @@ -612,14 +611,8 @@ void QCosmeticStroker::drawPath(const QVectorPath &path) still need to update p to avoid drawing the line after this one from a bad starting position. */ - if (fastPenAliased && unclipped) { - if (last.x != lastPixel.x || last.y != lastPixel.y - || points == begin + 2 || points == end - 2) { - p = p2; - } - } else { + if (!fastPenAliased || moveNextStart || points == begin + 2 || points == end - 2) p = p2; - } points += 2; caps = NoCaps; } @@ -726,8 +719,9 @@ template<DrawPixel drawPixel, class Dasher> static bool drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps) { if (stroker->clipLine(rx1, ry1, rx2, ry2)) - return false; + return true; + bool didDraw = false; const int half = stroker->legacyRounding ? 31 : 0; int x1 = toF26Dot6(rx1) + half; int y1 = toF26Dot6(ry1) + half; @@ -812,6 +806,7 @@ static bool drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, dasher.adjust(); x += xinc; } while (++y < ys); + didDraw = true; } } else { // horizontal @@ -886,10 +881,11 @@ static bool drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, dasher.adjust(); y += yinc; } while (++x < xs); + didDraw = true; } } stroker->lastPixel = last; - return true; + return didDraw; } @@ -897,7 +893,7 @@ template<DrawPixel drawPixel, class Dasher> static bool drawLineAA(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps) { if (stroker->clipLine(rx1, ry1, rx2, ry2)) - return false; + return true; int x1 = toF26Dot6(rx1); int y1 = toF26Dot6(ry1); diff --git a/tests/auto/gui/painting/qpainter/tst_qpainter.cpp b/tests/auto/gui/painting/qpainter/tst_qpainter.cpp index 8a0705630d..bf19a04203 100644 --- a/tests/auto/gui/painting/qpainter/tst_qpainter.cpp +++ b/tests/auto/gui/painting/qpainter/tst_qpainter.cpp @@ -290,6 +290,10 @@ private slots: void RasterOp_NotDestination(); void drawTextNoHinting(); + + void drawPolyline_data(); + void drawPolyline(); + private: void fillData(); void setPenColor(QPainter& p); @@ -4828,6 +4832,39 @@ void tst_QPainter::drawTextNoHinting() QVERIFY(true); } +void tst_QPainter::drawPolyline_data() +{ + QTest::addColumn< QVector<QPointF> >("points"); + + QTest::newRow("basic") << (QVector<QPointF>() << QPointF(10, 10) << QPointF(20, 10) << QPointF(20, 20) << QPointF(10, 20)); + QTest::newRow("clipped") << (QVector<QPointF>() << QPoint(-10, 100) << QPoint(-1, 100) << QPoint(-1, -2) << QPoint(100, -2) << QPoint(100, 40)); // QTBUG-31579 + QTest::newRow("shortsegment") << (QVector<QPointF>() << QPoint(20, 100) << QPoint(20, 99) << QPoint(21, 99) << QPoint(21, 104)); // QTBUG-42398 +} + +void tst_QPainter::drawPolyline() +{ + QFETCH(QVector<QPointF>, points); + QImage images[2]; + + for (int r = 0; r < 2; r++) { + images[r] = QImage(150, 150, QImage::Format_ARGB32); + images[r].fill(Qt::transparent); + QPainter p(images + r); + QPen pen(Qt::red, 0, Qt::SolidLine, Qt::FlatCap); + p.setPen(pen); + QVERIFY(p.pen().isCosmetic()); + if (r) { + for (int i = 0; i < points.count()-1; i++) { + p.drawLine(points.at(i), points.at(i+1)); + } + } else { + p.drawPolyline(points); + } + } + + QCOMPARE(images[0], images[1]); +} + QTEST_MAIN(tst_QPainter) #include "tst_qpainter.moc" |