qt: add patch for QTBUG-31579 to fix polyline drawing

Upstream bug: https://bugreports.qt-project.org/browse/QTBUG-31579

Signed-off-by: Jonathan Liu <net147@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

1 files changed, 145 insertions, 0 deletions

diff --git a/package/qt/qt-fix-polyline-drawing.patch b/package/qt/qt-fix-polyline-drawing.patch
new file mode 100644
index 000000000..d0c3d0737
--- /dev/null
+++ b/package/qt/qt-fix-polyline-drawing.patch
@@ -0,0 +1,145 @@
+From b7029fbd12c32e851ed7d81b692197176eb71d9e Mon Sep 17 00:00:00 2001
+From: Gunnar Sletta <gunnar.sletta@digia.com>
+Date: Thu, 4 Jul 2013 16:20:40 +1000
+Subject: [PATCH] Fix drawing of 0-width polylines from outside the devicerect.
+
+This was broken by a previous fix which aimed to fix gaps in
+polylines with tiny line segments. The result was that we
+skipped updating the origin point when stroke() didn't produce
+pixels which accidentally included the case of the line
+being completely outside the deviceRect. I fixed this
+by returning the value of clipLine in drawLine to the caller
+so we could still update the origin for this case.
+
+Task-number: QTBUG-31579
+Change-Id: Iac29436f042da7658bbeaf9370351dc6f2c95065
+(cherry picked from qtbase/900cccfd459fcbdbc4aa3d313afe12cfbf68fd87)
+---
+ src/gui/painting/qcosmeticstroker.cpp | 42 ++++++++++++++++++++++-------------
+ src/gui/painting/qcosmeticstroker_p.h |  2 +-
+ 2 files changed, 27 insertions(+), 17 deletions(-)
+
+diff --git a/src/gui/painting/qcosmeticstroker.cpp b/src/gui/painting/qcosmeticstroker.cpp
+index 0061ecb..4413170 100644
+--- a/src/gui/painting/qcosmeticstroker.cpp
++++ b/src/gui/painting/qcosmeticstroker.cpp
+@@ -133,10 +133,15 @@ struct NoDasher {
+ 
+ };
+ 
++/*
++ * The return value is the result of the clipLine() call performed at the start
++ * of each of the two functions, aka "false" means completely outside the devices
++ * rect.
++ */
+ template<DrawPixel drawPixel, class Dasher>
+-static void drawLine(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
++static bool drawLine(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
+ template<DrawPixel drawPixel, class Dasher>
+-static void drawLineAA(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
++static bool drawLineAA(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
+ 
+ inline void drawPixel(QCosmeticStroker *stroker, int x, int y, int coverage)
+ {
+@@ -602,17 +607,20 @@ void QCosmeticStroker::drawPath(const QVectorPath &path)
+                 caps |= CapEnd;
+ 
+             QCosmeticStroker::Point last = this->lastPixel;
+-            stroke(this, p.x(), p.y(), p2.x(), p2.y(), caps);
++            bool unclipped = 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
+-               out, keep last non dropped point p. */
+-            if (fastPenAliased) {
+-                if (last.x != lastPixel.x || last.y != lastPixel.y ||
+-                    points == begin + 2 || points == end - 2 ) {
+-                    {
+-                        p = p2;
+-                    }
++               out, keep last non dropped point p.
++
++               However, if the line was completely outside the devicerect, we
++               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 {
+                 p = p2;
+@@ -720,10 +728,10 @@ static inline void capAdjust(int caps, int &x1, int &x2, int &y, int yinc)
+   the drawing shifts from horizontal to vertical or back.
+   */
+ template<DrawPixel drawPixel, class Dasher>
+-static void drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps)
++static bool drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps)
+ {
+     if (stroker->clipLine(rx1, ry1, rx2, ry2))
+-        return;
++        return false;
+ 
+     static const int half = 31;
+     int x1 = toF26Dot6(rx1) + half;
+@@ -813,7 +821,7 @@ static void drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2,
+     } else {
+         // horizontal
+         if (!dx)
+-            return;
++            return true;
+ 
+         QCosmeticStroker::Direction dir = QCosmeticStroker::LeftToRight;
+ 
+@@ -886,14 +894,15 @@ static void drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2,
+         }
+     }
+     stroker->lastPixel = last;
++    return true;
+ }
+ 
+ 
+ template<DrawPixel drawPixel, class Dasher>
+-static void drawLineAA(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps)
++static bool drawLineAA(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps)
+ {
+     if (stroker->clipLine(rx1, ry1, rx2, ry2))
+-        return;
++        return false;
+ 
+     int x1 = toF26Dot6(rx1);
+     int y1 = toF26Dot6(ry1);
+@@ -967,7 +976,7 @@ static void drawLineAA(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx
+     } else {
+         // horizontal
+         if (!dx)
+-            return;
++            return true;
+ 
+         int yinc = F16Dot16FixedDiv(dy, dx);
+ 
+@@ -1029,6 +1038,7 @@ static void drawLineAA(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx
+             drawPixel(stroker, x, (y>>16) + 1, alpha * alphaEnd >> 6);
+         }
+     }
++    return true;
+ }
+ 
+ QT_END_NAMESPACE
+diff --git a/src/gui/painting/qcosmeticstroker_p.h b/src/gui/painting/qcosmeticstroker_p.h
+index 870738b..3216856 100644
+--- a/src/gui/painting/qcosmeticstroker_p.h
++++ b/src/gui/painting/qcosmeticstroker_p.h
+@@ -56,7 +56,7 @@ QT_MODULE(Gui)
+ class QCosmeticStroker;
+ 
+ 
+-typedef void (*StrokeLine)(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
++typedef bool (*StrokeLine)(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
+ 
+ class QCosmeticStroker
+ {
+-- 
+1.8.3.2
+