Merge remote-tracking branch 'origin/release' into stable

Change-Id: If29ca1b27da4592d40a7678837c359f75dac1209

3 files changed, 72 insertions, 33 deletions

diff --git a/src/gui/painting/qcosmeticstroker.cpp b/src/gui/painting/qcosmeticstroker.cpp
index 0f3cde3efd..39f64224f0 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;
 
     const int half = stroker->legacyRounding ? 31 : 0;
     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 05c8a2b0cf..5fc3559da4 100644
--- a/src/gui/painting/qcosmeticstroker_p.h
+++ b/src/gui/painting/qcosmeticstroker_p.h
@@ -53,7 +53,7 @@ QT_BEGIN_NAMESPACE
 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
 {
diff --git a/src/gui/painting/qrasterizer.cpp b/src/gui/painting/qrasterizer.cpp
index a6be7c6c78..197d49369e 100644
--- a/src/gui/painting/qrasterizer.cpp
+++ b/src/gui/painting/qrasterizer.cpp
@@ -734,6 +734,35 @@ static inline QPointF snapTo26Dot6Grid(const QPointF &p)
                    qFloorF(p.y() * 64) * (1 / qreal(64)));
 }
 
+/*
+   The rasterize line function relies on some div by zero which should
+   result in +/-inf values. However, when floating point exceptions are
+   enabled, this will cause crashes, so we return high numbers instead.
+   As the returned value is used in further arithmetic, returning
+   FLT_MAX/DBL_MAX will also cause values, so instead return a value
+   that is well outside the int-range.
+ */
+static inline qreal qSafeDivide(qreal x, qreal y)
+{
+    if (y == 0)
+        return x > 0 ? 1e20 : -1e20;
+    return x / y;
+}
+
+/* Conversion to int fails if the value is too large to fit into INT_MAX or
+   too small to fit into INT_MIN, so we need this slightly safer conversion
+   when floating point exceptions are enabled
+ */
+static inline int qSafeFloatToQ16Dot16(qreal x)
+{
+    qreal tmp = x * 65536.;
+    if (tmp > qreal(INT_MAX))
+        return INT_MAX;
+    else if (tmp < qreal(INT_MIN))
+        return -INT_MAX;
+    return int(tmp);
+}
+
 void QRasterizer::rasterizeLine(const QPointF &a, const QPointF &b, qreal width, bool squareCap)
 {
     if (a == b || width == 0 || d->clipRect.isEmpty())
@@ -946,23 +975,23 @@ void QRasterizer::rasterizeLine(const QPointF &a, const QPointF &b, qreal width,
         const QPointF bottomLeftEdge = bottom - left;
         const QPointF bottomRightEdge = bottom - right;
 
-        const qreal topLeftSlope = topLeftEdge.x() / topLeftEdge.y();
-        const qreal bottomLeftSlope = bottomLeftEdge.x() / bottomLeftEdge.y();
+        const qreal topLeftSlope = qSafeDivide(topLeftEdge.x(), topLeftEdge.y());
+        const qreal bottomLeftSlope = qSafeDivide(bottomLeftEdge.x(), bottomLeftEdge.y());
 
-        const qreal topRightSlope = topRightEdge.x() / topRightEdge.y();
-        const qreal bottomRightSlope = bottomRightEdge.x() / bottomRightEdge.y();
+        const qreal topRightSlope = qSafeDivide(topRightEdge.x(), topRightEdge.y());
+        const qreal bottomRightSlope = qSafeDivide(bottomRightEdge.x(), bottomRightEdge.y());
 
-        const Q16Dot16 topLeftSlopeFP = FloatToQ16Dot16(topLeftSlope);
-        const Q16Dot16 topRightSlopeFP = FloatToQ16Dot16(topRightSlope);
+        const Q16Dot16 topLeftSlopeFP = qSafeFloatToQ16Dot16(topLeftSlope);
+        const Q16Dot16 topRightSlopeFP = qSafeFloatToQ16Dot16(topRightSlope);
 
-        const Q16Dot16 bottomLeftSlopeFP = FloatToQ16Dot16(bottomLeftSlope);
-        const Q16Dot16 bottomRightSlopeFP = FloatToQ16Dot16(bottomRightSlope);
+        const Q16Dot16 bottomLeftSlopeFP = qSafeFloatToQ16Dot16(bottomLeftSlope);
+        const Q16Dot16 bottomRightSlopeFP = qSafeFloatToQ16Dot16(bottomRightSlope);
 
-        const Q16Dot16 invTopLeftSlopeFP = FloatToQ16Dot16(1 / topLeftSlope);
-        const Q16Dot16 invTopRightSlopeFP = FloatToQ16Dot16(1 / topRightSlope);
+        const Q16Dot16 invTopLeftSlopeFP = qSafeFloatToQ16Dot16(qSafeDivide(1, topLeftSlope));
+        const Q16Dot16 invTopRightSlopeFP = qSafeFloatToQ16Dot16(qSafeDivide(1, topRightSlope));
 
-        const Q16Dot16 invBottomLeftSlopeFP = FloatToQ16Dot16(1 / bottomLeftSlope);
-        const Q16Dot16 invBottomRightSlopeFP = FloatToQ16Dot16(1 / bottomRightSlope);
+        const Q16Dot16 invBottomLeftSlopeFP = qSafeFloatToQ16Dot16(qSafeDivide(1, bottomLeftSlope));
+        const Q16Dot16 invBottomRightSlopeFP = qSafeFloatToQ16Dot16(qSafeDivide(1, bottomRightSlope));
 
         if (d->antialiased) {
             const Q16Dot16 iTopFP = IntToQ16Dot16(int(topBound));
@@ -1137,10 +1166,10 @@ void QRasterizer::rasterizeLine(const QPointF &a, const QPointF &b, qreal width,
             int iBottom = bottom.y() < 0.5f? -1 : int(bottom.y() - 0.5f);
             int iMiddle = qMin(iLeft, iRight);
 
-            Q16Dot16 leftIntersectAf = FloatToQ16Dot16(top.x() + 0.5f + (iTop + 0.5f - top.y()) * topLeftSlope);
-            Q16Dot16 leftIntersectBf = FloatToQ16Dot16(left.x() + 0.5f + (iLeft + 1.5f - left.y()) * bottomLeftSlope);
-            Q16Dot16 rightIntersectAf = FloatToQ16Dot16(top.x() - 0.5f + (iTop + 0.5f - top.y()) * topRightSlope);
-            Q16Dot16 rightIntersectBf = FloatToQ16Dot16(right.x() - 0.5f + (iRight + 1.5f - right.y()) * bottomRightSlope);
+            Q16Dot16 leftIntersectAf = qSafeFloatToQ16Dot16(top.x() + 0.5f + (iTop + 0.5f - top.y()) * topLeftSlope);
+            Q16Dot16 leftIntersectBf = qSafeFloatToQ16Dot16(left.x() + 0.5f + (iLeft + 1.5f - left.y()) * bottomLeftSlope);
+            Q16Dot16 rightIntersectAf = qSafeFloatToQ16Dot16(top.x() - 0.5f + (iTop + 0.5f - top.y()) * topRightSlope);
+            Q16Dot16 rightIntersectBf = qSafeFloatToQ16Dot16(right.x() - 0.5f + (iRight + 1.5f - right.y()) * bottomRightSlope);
 
             int ny;
             int y = iTop;