Integrated new triangulating stroker into Qt

5 files changed, 730 insertions, 54 deletions

diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
index 13efbda..bcc6bdb 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
@@ -81,6 +81,8 @@
 #include "qglengineshadermanager_p.h"
 #include "qgl2pexvertexarray_p.h"
 
+#include "qtriangulatingstroker_p.h"
+
 #include <QDebug>
 
 QT_BEGIN_NAMESPACE
@@ -572,7 +574,6 @@ void QGL2PaintEngineExPrivate::updateMatrix()
     //
     // We expand out the multiplication to save the cost of a full 4x4
     // matrix multiplication as most of the components are trivial.
-
     const QTransform& transform = q->state()->matrix;
 
     if (mode == TextDrawingMode) {
@@ -628,6 +629,9 @@ void QGL2PaintEngineExPrivate::updateMatrix()
     // The actual data has been updated so both shader program's uniforms need updating
     simpleShaderMatrixUniformDirty = true;
     shaderMatrixUniformDirty = true;
+
+    dasher.setInvScale(inverseScale);
+    stroker.setInvScale(inverseScale);
 }
 
 
@@ -838,28 +842,6 @@ void QGL2PaintEngineExPrivate::transferMode(EngineMode newMode)
     mode = newMode;
 }
 
-void QGL2PaintEngineExPrivate::drawOutline(const QVectorPath& path)
-{
-    transferMode(BrushDrawingMode);
-
-    // Might need to call updateMatrix to re-calculate inverseScale
-    if (matrixDirty)
-        updateMatrix();
-
-    vertexCoordinateArray.clear();
-    vertexCoordinateArray.addPath(path, inverseScale);
-
-    if (path.hasImplicitClose()) {
-        // Close the path's outline
-        vertexCoordinateArray.lineToArray(path.points()[0], path.points()[1]);
-        vertexCoordinateArray.stops().last() += 1;
-    }
-
-    prepareForDraw(currentBrush->isOpaque());
-    drawVertexArrays(vertexCoordinateArray, GL_LINE_STRIP);
-}
-
-
 // Assumes everything is configured for the brush you want to use
 void QGL2PaintEngineExPrivate::fill(const QVectorPath& path)
 {
@@ -922,8 +904,14 @@ void QGL2PaintEngineExPrivate::fill(const QVectorPath& path)
 }
 
 
-void QGL2PaintEngineExPrivate::fillStencilWithVertexArray(QGL2PEXVertexArray& vertexArray, bool useWindingFill)
+void QGL2PaintEngineExPrivate::fillStencilWithVertexArray(const float *data,
+                                                          int count,
+                                                          const QVector<int> *stops,
+                                                          const QGLRect &bounds,
+                                                          StencilFillMode mode)
 {
+    Q_ASSERT(count || stops);
+
 //     qDebug("QGL2PaintEngineExPrivate::fillStencilWithVertexArray()");
     glStencilMask(0xff); // Enable stencil writes
 
@@ -955,19 +943,20 @@ void QGL2PaintEngineExPrivate::fillStencilWithVertexArray(QGL2PEXVertexArray& ve
     }
 #endif
 
-    if (useWindingFill) {
+    if (mode == WindingFillMode) {
+        Q_ASSERT(stops && !count);
         if (q->state()->clipTestEnabled) {
             // Flatten clip values higher than current clip, and set high bit to match current clip
             glStencilFunc(GL_LEQUAL, GL_STENCIL_HIGH_BIT | q->state()->currentClip, ~GL_STENCIL_HIGH_BIT);
             glStencilOp(GL_KEEP, GL_REPLACE, GL_REPLACE);
-            composite(vertexArray.boundingRect());
+            composite(bounds);
 
             glStencilFunc(GL_EQUAL, GL_STENCIL_HIGH_BIT, GL_STENCIL_HIGH_BIT);
         } else if (!stencilClean) {
             // Clear stencil buffer within bounding rect
             glStencilFunc(GL_ALWAYS, 0, 0xff);
             glStencilOp(GL_ZERO, GL_ZERO, GL_ZERO);
-            composite(vertexArray.boundingRect());
+            composite(bounds);
         }
 
         // Inc. for front-facing triangle
@@ -975,19 +964,43 @@ void QGL2PaintEngineExPrivate::fillStencilWithVertexArray(QGL2PEXVertexArray& ve
         // Dec. for back-facing "holes"
         glStencilOpSeparate(GL_BACK, GL_KEEP, GL_DECR_WRAP, GL_DECR_WRAP);
         glStencilMask(~GL_STENCIL_HIGH_BIT);
-        drawVertexArrays(vertexArray, GL_TRIANGLE_FAN);
+        drawVertexArrays(data, stops, GL_TRIANGLE_FAN);
 
         if (q->state()->clipTestEnabled) {
             // Clear high bit of stencil outside of path
             glStencilFunc(GL_EQUAL, q->state()->currentClip, ~GL_STENCIL_HIGH_BIT);
             glStencilOp(GL_KEEP, GL_REPLACE, GL_REPLACE);
             glStencilMask(GL_STENCIL_HIGH_BIT);
-            composite(vertexArray.boundingRect());
+            composite(bounds);
         }
-    } else {
+    } else if (mode == OddEvenFillMode) {
+        glStencilMask(GL_STENCIL_HIGH_BIT);
+        glStencilOp(GL_KEEP, GL_KEEP, GL_INVERT); // Simply invert the stencil bit
+        drawVertexArrays(data, stops, GL_TRIANGLE_FAN);
+
+    } else { // TriStripStrokeFillMode
+        Q_ASSERT(count && !stops); // tristrips generated directly, so no vertexArray or stops
         glStencilMask(GL_STENCIL_HIGH_BIT);
+#if 0
         glStencilOp(GL_KEEP, GL_KEEP, GL_INVERT); // Simply invert the stencil bit
-        drawVertexArrays(vertexArray, GL_TRIANGLE_FAN);
+        glEnableVertexAttribArray(QT_VERTEX_COORDS_ATTR);
+        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, data);
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, count);
+        glDisableVertexAttribArray(QT_VERTEX_COORDS_ATTR);
+#else
+
+        glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);
+        if (q->state()->clipTestEnabled) {
+            glStencilFunc(GL_LEQUAL, q->state()->currentClip | GL_STENCIL_HIGH_BIT,
+                          ~GL_STENCIL_HIGH_BIT);
+        } else {
+            glStencilFunc(GL_ALWAYS, GL_STENCIL_HIGH_BIT, 0xff);
+        }
+        glEnableVertexAttribArray(QT_VERTEX_COORDS_ATTR);
+        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, data);
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, count);
+        glDisableVertexAttribArray(QT_VERTEX_COORDS_ATTR);
+#endif
     }
 
     // Enable color writes & disable stencil writes
@@ -1122,14 +1135,15 @@ void QGL2PaintEngineExPrivate::composite(const QGLRect& boundingRect)
 }
 
 // Draws the vertex array as a set of <vertexArrayStops.size()> triangle fans.
-void QGL2PaintEngineExPrivate::drawVertexArrays(QGL2PEXVertexArray& vertexArray, GLenum primitive)
+void QGL2PaintEngineExPrivate::drawVertexArrays(const float *data, const QVector<int> *stops,
+                                                GLenum primitive)
 {
     // Now setup the pointer to the vertex array:
     glEnableVertexAttribArray(QT_VERTEX_COORDS_ATTR);
-    glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, vertexArray.data());
+    glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, GL_FALSE, 0, data);
 
     int previousStop = 0;
-    foreach(int stop, vertexArray.stops()) {
+    foreach(int stop, *stops) {
 /*
         qDebug("Drawing triangle fan for vertecies %d -> %d:", previousStop, stop-1);
         for (int i=previousStop; i<stop; ++i)
@@ -1180,12 +1194,29 @@ void QGL2PaintEngineEx::fill(const QVectorPath &path, const QBrush &brush)
 {
     Q_D(QGL2PaintEngineEx);
 
-    if (qbrush_style(brush) == Qt::NoBrush)
+    Qt::BrushStyle style = qbrush_style(brush);
+    if (style == Qt::NoBrush)
         return;
     if (!d->inRenderText)
         ensureActive();
+
+    QOpenGL2PaintEngineState *s = state();
+    bool doOffset = !(s->renderHints & QPainter::Antialiasing) && style == Qt::SolidPattern;
+
+    if (doOffset) {
+        d->temporaryTransform = s->matrix;
+        QTransform tx = QTransform::fromTranslate(.49, .49);
+        s->matrix = s->matrix * tx;
+        d->matrixDirty = true;
+    }
+
     d->setBrush(&brush);
     d->fill(path);
+
+    if (doOffset) {
+        s->matrix = d->temporaryTransform;
+        d->matrixDirty = true;
+    }
 }
 
 void QGL2PaintEngineEx::stroke(const QVectorPath &path, const QPen &pen)
@@ -1197,23 +1228,89 @@ void QGL2PaintEngineEx::stroke(const QVectorPath &path, const QPen &pen)
     if (penStyle == Qt::NoPen || qbrush_style(penBrush) == Qt::NoBrush)
         return;
 
+    QOpenGL2PaintEngineState *s = state();
+
     ensureActive();
 
-    qreal penWidth = qpen_widthf(pen);
-    if ( (pen.isCosmetic() && (penStyle == Qt::SolidLine)) && (penWidth < 2.5f) )
-    {
-        // We only handle solid, cosmetic pens with a width of 1 pixel
-        const QBrush& brush = pen.brush();
-        d->setBrush(&brush);
+    bool doOffset = !(s->renderHints & QPainter::Antialiasing);
+    if (doOffset) {
+        d->temporaryTransform = s->matrix;
+        QTransform tx = QTransform::fromTranslate(0.49, .49);
+        s->matrix = s->matrix * tx;
+        d->matrixDirty = true;
+    }
 
-        if (penWidth < 0.01f)
-            glLineWidth(1.0);
-        else
-            glLineWidth(penWidth);
+    bool opaque = penBrush.isOpaque() && s->opacity > 0.99;
+    d->setBrush(&penBrush);
+    d->transferMode(BrushDrawingMode);
+
+    // updateMatrix() is responsible for setting the inverse scale on
+    // the strokers, so we need to call it here and not wait for
+    // prepareForDraw() down below.
+    d->updateMatrix();
+
+    if (penStyle == Qt::SolidLine) {
+        d->stroker.process(path, pen);
+
+    } else { // Some sort of dash
+        d->dasher.process(path, pen);
+
+        QVectorPath dashStroke(d->dasher.points(),
+                               d->dasher.elementCount(),
+                               d->dasher.elementTypes());
+        d->stroker.process(dashStroke, pen);
+    }
+
+
+    QGLContext *ctx = d->ctx;
+
+    if (opaque) {
+        d->prepareForDraw(opaque);
+        glEnableVertexAttribArray(QT_VERTEX_COORDS_ATTR);
+        glVertexAttribPointer(QT_VERTEX_COORDS_ATTR, 2, GL_FLOAT, false, 0, d->stroker.vertices());
+        glDrawArrays(GL_TRIANGLE_STRIP, 0, d->stroker.vertexCount() / 2);
+
+//         QBrush b(Qt::green);
+//         d->setBrush(&b);
+//         d->prepareForDraw(true);
+//         glDrawArrays(GL_LINE_STRIP, 0, d->stroker.vertexCount() / 2);
 
-        d->drawOutline(path);
-    } else
-        return QPaintEngineEx::stroke(path, pen);
+        glDisableVertexAttribArray(QT_VERTEX_COORDS_ATTR);
+
+    } else {
+        qreal width = qpen_widthf(pen) / 2;
+        if (width == 0)
+            width = 0.5;
+        qreal extra = pen.joinStyle() == Qt::MiterJoin
+                      ? qMax(pen.miterLimit() * width, width)
+                      : width;
+
+        if (pen.isCosmetic())
+            extra = extra * d->inverseScale;
+
+        QRectF bounds = path.controlPointRect().adjusted(-extra, -extra, extra, extra);
+
+        d->fillStencilWithVertexArray(d->stroker.vertices(), d->stroker.vertexCount() / 2,
+                                      0, bounds, QGL2PaintEngineExPrivate::TriStripStrokeFillMode);
+
+        glStencilOp(GL_KEEP, GL_REPLACE, GL_REPLACE);
+
+        // Pass when any bit is set, replace stencil value with 0
+        glStencilFunc(GL_NOTEQUAL, 0, GL_STENCIL_HIGH_BIT);
+        d->prepareForDraw(false);
+
+        // Stencil the brush onto the dest buffer
+        d->composite(bounds);
+
+        glStencilMask(0);
+
+        d->updateClipScissorTest();
+    }
+
+    if (doOffset) {
+        s->matrix = d->temporaryTransform;
+        d->matrixDirty = true;
+    }
 }
 
 void QGL2PaintEngineEx::penChanged() { }
@@ -1542,7 +1639,7 @@ void QGL2PaintEngineEx::drawPixmaps(const QDrawPixmaps::Data *drawingData, int d
             s = qFastSin(drawingData[i].rotation * Q_PI / 180);
             c = qFastCos(drawingData[i].rotation * Q_PI / 180);
         }
-        
+
         qreal right = 0.5 * drawingData[i].scaleX * drawingData[i].source.width();
         qreal bottom = 0.5 * drawingData[i].scaleY * drawingData[i].source.height();
         QGLPoint bottomRight(right * c - bottom * s, right * s + bottom * c);
diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
index 5704a04..209cd36 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2_p.h
@@ -62,6 +62,7 @@
 #include <private/qglpixmapfilter_p.h>
 #include <private/qfontengine_p.h>
 #include <private/qdatabuffer_p.h>
+#include <private/qtriangulatingstroker_p.h>
 
 enum EngineMode {
     ImageDrawingMode,
@@ -160,6 +161,12 @@ class QGL2PaintEngineExPrivate : public QPaintEngineExPrivate
 {
     Q_DECLARE_PUBLIC(QGL2PaintEngineEx)
 public:
+    enum StencilFillMode {
+        OddEvenFillMode,
+        WindingFillMode,
+        TriStripStrokeFillMode
+    };
+
     QGL2PaintEngineExPrivate(QGL2PaintEngineEx *q_ptr) :
             q(q_ptr),
             width(0), height(0),
@@ -185,15 +192,24 @@ public:
 
     // fill, drawOutline, drawTexture & drawCachedGlyphs are the rendering entry points:
     void fill(const QVectorPath &path);
-    void drawOutline(const QVectorPath& path);
     void drawTexture(const QGLRect& dest, const QGLRect& src, const QSize &textureSize, bool opaque, bool pattern = false);
     void drawCachedGlyphs(const QPointF &p, QFontEngineGlyphCache::Type glyphType, const QTextItemInt &ti);
 
-    void drawVertexArrays(QGL2PEXVertexArray& vertexArray, GLenum primitive);
+    void drawVertexArrays(const float *data, const QVector<int> *stops, GLenum primitive);
+    void drawVertexArrays(QGL2PEXVertexArray &vertexArray, GLenum primitive) {
+        drawVertexArrays((const float *) vertexArray.data(), &vertexArray.stops(), primitive);
+    }
+
         // ^ draws whatever is in the vertex array
     void composite(const QGLRect& boundingRect);
         // ^ Composites the bounding rect onto dest buffer
-    void fillStencilWithVertexArray(QGL2PEXVertexArray& vertexArray, bool useWindingFill);
+
+    void fillStencilWithVertexArray(const float *data, int count, const QVector<int> *stops, const QGLRect &bounds, StencilFillMode mode);
+    void fillStencilWithVertexArray(QGL2PEXVertexArray& vertexArray, bool useWindingFill) {
+        fillStencilWithVertexArray((const float *) vertexArray.data(), 0, &vertexArray.stops(),
+                                   vertexArray.boundingRect(),
+                                   useWindingFill ? WindingFillMode : OddEvenFillMode);
+    }
         // ^ Calls drawVertexArrays to render into stencil buffer
 
     bool prepareForDraw(bool srcPixelsAreOpaque);
@@ -266,6 +282,10 @@ public:
 
     float textureInvertedY;
 
+    QTriangulatingStroker stroker;
+    QDashedStrokeProcessor dasher;
+    QTransform temporaryTransform;
+
     QScopedPointer<QPixmapFilter> convolutionFilter;
     QScopedPointer<QPixmapFilter> colorizeFilter;
     QScopedPointer<QPixmapFilter> blurFilter;
diff --git a/src/opengl/gl2paintengineex/qtriangulatingstroker.cpp b/src/opengl/gl2paintengineex/qtriangulatingstroker.cpp
new file mode 100644
index 0000000..250dab6
--- /dev/null
+++ b/src/opengl/gl2paintengineex/qtriangulatingstroker.cpp
@@ -0,0 +1,299 @@
+#include "qtriangulatingstroker_p.h"
+#include <qmath.h>
+
+
+#define CURVE_FLATNESS Q_PI / 8
+
+
+
+
+void QTriangulatingStroker::endCapOrJoinClosed(const qreal *start, const qreal *cur,
+                                               bool implicitClose, bool endsAtStart)
+{
+    if (endsAtStart) {
+        join(start + 2);
+    } else if (implicitClose) {
+        join(start);
+        lineTo(start);
+        join(start+2);
+    } else {
+        endCap(cur);
+    }
+}
+
+
+void QTriangulatingStroker::process(const QVectorPath &path, const QPen &pen)
+{
+    const qreal *pts = path.points();
+    const QPainterPath::ElementType *types = path.elements();
+    int count = path.elementCount();
+    if (count < 2)
+        return;
+
+    float realWidth = qpen_widthf(pen);
+    if (realWidth == 0)
+        realWidth = 1;
+
+    m_width = realWidth / 2;
+
+    bool cosmetic = pen.isCosmetic();
+    if (cosmetic) {
+        m_width = m_width * m_inv_scale;
+    }
+
+    m_join_style = qpen_joinStyle(pen);
+    m_cap_style = qpen_capStyle(pen);
+    m_vertices.reset();
+    m_miter_limit = pen.miterLimit() * qpen_widthf(pen);
+
+    // The curvyness is based on the notion that I originally wanted
+    // roughly one line segment pr 4 pixels. This may seem little, but
+    // because we sample at constantly incrementing B(t) E [0<t<1], we
+    // will get longer segments where the curvature is small and smaller
+    // segments when the curvature is high.
+    //
+    // To get a rough idea of the length of each curve, I pretend that
+    // the curve is a 90 degree arc, whose radius is
+    // qMax(curveBounds.width, curveBounds.height). Based on this
+    // logic we can estimate the length of the outline edges based on
+    // the radius + a pen width and adjusting for scale factors
+    // depending on if the pen is cosmetic or not.
+    //
+    // The curvyness value of PI/14 was based on,
+    // arcLength=2*PI*r/4=PI/2 and splitting length into somewhere
+    // between 3 and 8 where 5 seemed to be give pretty good results
+    // hence: Q_PI/14. Lower divisors will give more detail at the
+    // direct cost of performance.
+
+    // simplfy pens that are thin in device size (2px wide or less)
+    if (realWidth < 2.5 && (cosmetic || m_inv_scale == 1)) {
+        if (m_cap_style == Qt::RoundCap)
+            m_cap_style = Qt::SquareCap;
+        if (m_join_style == Qt::RoundJoin)
+            m_join_style = Qt::MiterJoin;
+        m_curvyness_add = 0.5;
+        m_curvyness_mul = CURVE_FLATNESS;
+        m_roundness = 1;
+    } else if (cosmetic) {
+        m_curvyness_add = realWidth / 2;
+        m_curvyness_mul = CURVE_FLATNESS;
+        m_roundness = qMax<int>(4, realWidth * CURVE_FLATNESS);
+    } else {
+        m_curvyness_add = m_width;
+        m_curvyness_mul = CURVE_FLATNESS / m_inv_scale;
+        m_roundness = qMax<int>(4, realWidth * m_curvyness_mul);
+    }
+
+    // Over this level of segmentation, there doesn't seem to be any
+    // benefit, even for huge penWidth
+    if (m_roundness > 24)
+        m_roundness = 24;
+
+    m_sin_theta = qSin(Q_PI / m_roundness); // ### Use qFastSin
+    m_cos_theta = qCos(Q_PI / m_roundness);
+
+    const qreal *endPts = pts + (count<<1);
+    const qreal *startPts;
+
+    Qt::PenCapStyle cap = m_cap_style;
+
+    if (!types) {
+        startPts = pts;
+
+        bool endsAtStart = startPts[0] == *(endPts-2) && startPts[1] == *(endPts-1);
+
+        Qt::PenCapStyle cap = m_cap_style;
+        if (endsAtStart || path.hasImplicitClose())
+            m_cap_style = Qt::FlatCap;
+        moveTo(pts);
+        m_cap_style = cap;
+        pts += 2;
+        lineTo(pts);
+        pts += 2;
+        while (pts < endPts) {
+            join(pts);
+            lineTo(pts);
+            pts += 2;
+        }
+
+        endCapOrJoinClosed(startPts, pts-2, path.hasImplicitClose(), endsAtStart);
+
+    } else {
+        bool endsAtStart;
+        while (pts < endPts) {
+            switch (*types) {
+            case QPainterPath::MoveToElement: {
+                if (pts != path.points())
+                    endCapOrJoinClosed(startPts, pts, path.hasImplicitClose(), endsAtStart);
+
+                startPts = pts;
+                int end = (endPts - pts) / 2;
+                int i = 2; // Start looking to ahead since we never have two moveto's in a row
+                while (i<end && types[i] != QPainterPath::MoveToElement) {
+                    ++i;
+                }
+                endsAtStart = startPts[0] == pts[i*2 - 2] && startPts[1] == pts[i*2 - 1];
+                if (endsAtStart || path.hasImplicitClose())
+                    m_cap_style = Qt::FlatCap;
+
+                moveTo(pts);
+                m_cap_style = cap;
+                pts+=2;
+                ++types;
+                break; }
+            case QPainterPath::LineToElement:
+                if (*(types - 1) != QPainterPath::MoveToElement)
+                    join(pts);
+                lineTo(pts);
+                pts+=2;
+                ++types;
+                break;
+            case QPainterPath::CurveToElement:
+                if (*(types - 1) != QPainterPath::MoveToElement)
+                    join(pts);
+                cubicTo(pts);
+                pts+=6;
+                types+=3;
+                break;
+            default:
+                Q_ASSERT(false);
+                break;
+            }
+        }
+
+        endCapOrJoinClosed(startPts, pts-2, path.hasImplicitClose(), endsAtStart);
+    }
+}
+
+void QTriangulatingStroker::cubicTo(const qreal *pts)
+{
+    const QPointF *p = (const QPointF *) pts;
+    QBezier bezier = QBezier::fromPoints(*(p - 1), p[0], p[1], p[2]);
+
+    QRectF bounds = bezier.bounds();
+    float rad = qMax(bounds.width(), bounds.height());
+    int threshold = qMin<float>(64, (rad + m_curvyness_add) * m_curvyness_mul);
+    if (threshold < 4)
+        threshold = 4;
+    qreal threshold_minus_1 = threshold - 1;
+    float vx, vy;
+
+    float cx = m_cx, cy = m_cy;
+    float x, y;
+
+    for (int i=1; i<threshold; ++i) {
+        qreal t = qreal(i) / threshold_minus_1;
+        QPointF p = bezier.pointAt(t);
+        x = p.x();
+        y = p.y();
+
+        normalVector(cx, cy, x, y, &vx, &vy);
+
+        emitLineSegment(x, y, vx, vy);
+
+        cx = x;
+        cy = y;
+    }
+
+    m_cx = cx;
+    m_cy = cy;
+
+    m_nvx = vx;
+    m_nvy = vy;
+}
+
+
+
+static void qdashprocessor_moveTo(qreal x, qreal y, void *data)
+{
+    ((QDashedStrokeProcessor *) data)->addElement(QPainterPath::MoveToElement, x, y);
+}
+
+static void qdashprocessor_lineTo(qreal x, qreal y, void *data)
+{
+    ((QDashedStrokeProcessor *) data)->addElement(QPainterPath::LineToElement, x, y);
+}
+
+static void qdashprocessor_cubicTo(qreal, qreal, qreal, qreal, qreal, qreal, void *)
+{
+    Q_ASSERT(0); // The dasher should not produce curves...
+}
+
+QDashedStrokeProcessor::QDashedStrokeProcessor()
+    : m_dash_stroker(0), m_inv_scale(1)
+{
+    m_dash_stroker.setMoveToHook(qdashprocessor_moveTo);
+    m_dash_stroker.setLineToHook(qdashprocessor_lineTo);
+    m_dash_stroker.setCubicToHook(qdashprocessor_cubicTo);
+}
+
+void QDashedStrokeProcessor::process(const QVectorPath &path, const QPen &pen)
+{
+
+    const qreal *pts = path.points();
+    const QPainterPath::ElementType *types = path.elements();
+    int count = path.elementCount();
+
+    m_points.reset();
+    m_types.reset();
+
+    qreal width = pen.width();
+    if (width == 0)
+        width = 1;
+
+    m_dash_stroker.setDashPattern(pen.dashPattern());
+    m_dash_stroker.setStrokeWidth(width);
+    m_dash_stroker.setMiterLimit(pen.miterLimit());
+    qreal curvyness = sqrt(width) * m_inv_scale / 8;
+
+    if (count < 2)
+        return;
+
+    const qreal *endPts = pts + (count<<1);
+
+    m_dash_stroker.begin(this);
+
+    if (!types) {
+        m_dash_stroker.moveTo(pts[0], pts[1]);
+        pts += 2;
+        while (pts < endPts) {
+            m_dash_stroker.lineTo(pts[0], pts[1]);
+            pts += 2;
+        }
+    } else {
+        while (pts < endPts) {
+            switch (*types) {
+            case QPainterPath::MoveToElement:
+                m_dash_stroker.moveTo(pts[0], pts[1]);
+                pts += 2;
+                ++types;
+                break;
+            case QPainterPath::LineToElement:
+                m_dash_stroker.lineTo(pts[0], pts[1]);
+                pts += 2;
+                ++types;
+                break;
+            case QPainterPath::CurveToElement: {
+                QBezier b = QBezier::fromPoints(*(((const QPointF *) pts) - 1),
+                                                *(((const QPointF *) pts)),
+                                                *(((const QPointF *) pts) + 1),
+                                                *(((const QPointF *) pts) + 2));
+                QRectF bounds = b.bounds();
+                int threshold = qMin<float>(64, qMax(bounds.width(), bounds.height()) * curvyness);
+                if (threshold < 4)
+                    threshold = 4;
+                qreal threshold_minus_1 = threshold - 1;
+                for (int i=0; i<threshold; ++i) {
+                    QPointF pt = b.pointAt(i / threshold_minus_1);
+                    m_dash_stroker.lineTo(pt.x(), pt.y());
+                }
+                pts += 6;
+                types += 3;
+                break; }
+            default: break;
+            }
+        }
+    }
+
+    m_dash_stroker.end();
+}
diff --git a/src/opengl/gl2paintengineex/qtriangulatingstroker_p.h b/src/opengl/gl2paintengineex/qtriangulatingstroker_p.h
new file mode 100644
index 0000000..a28fc45
--- /dev/null
+++ b/src/opengl/gl2paintengineex/qtriangulatingstroker_p.h
@@ -0,0 +1,258 @@
+#ifndef QTRIANGULATINGSTROKER_P_H
+#define QTRIANGULATINGSTROKER_P_H
+
+#include <private/qdatabuffer_p.h>
+#include <private/qvectorpath_p.h>
+#include <private/qbezier_p.h>
+#include <private/qnumeric_p.h>
+#include <private/qmath_p.h>
+
+
+class QTriangulatingStroker
+{
+public:
+    void process(const QVectorPath &path, const QPen &pen);
+
+    inline int vertexCount() const { return m_vertices.size(); }
+    inline const float *vertices() const { return m_vertices.data(); }
+
+    inline void setInvScale(qreal invScale) { m_inv_scale = invScale; }
+
+private:
+    inline void emitLineSegment(float x, float y, float nx, float ny);
+    inline void moveTo(const qreal *pts);
+    inline void lineTo(const qreal *pts);
+    void cubicTo(const qreal *pts);
+    inline void join(const qreal *pts);
+    inline void normalVector(float x1, float y1, float x2, float y2, float *nx, float *ny);
+    inline void endCap(const qreal *pts);
+    inline void arc(float x, float y);
+    void endCapOrJoinClosed(const qreal *start, const qreal *cur, bool implicitClose, bool endsAtStart);
+
+
+    QDataBuffer<float> m_vertices;
+
+    float m_cx, m_cy;           // current points
+    float m_nvx, m_nvy;         // normal vector...
+    float m_width;
+    qreal m_miter_limit;
+
+    int m_roundness;            // Number of line segments in a round join
+    qreal m_sin_theta;          // sin(m_roundness / 360);
+    qreal m_cos_theta;          // cos(m_roundness / 360);
+    qreal m_inv_scale;
+    float m_curvyness_mul;
+    float m_curvyness_add;
+
+    Qt::PenJoinStyle m_join_style;
+    Qt::PenCapStyle m_cap_style;
+};
+
+class QDashedStrokeProcessor
+{
+public:
+    QDashedStrokeProcessor();
+
+    void process(const QVectorPath &path, const QPen &pen);
+
+    inline void addElement(QPainterPath::ElementType type, qreal x, qreal y) {
+        m_points.add(x);
+        m_points.add(y);
+        m_types.add(type);
+    }
+
+    inline int elementCount() const { return m_types.size(); }
+    inline qreal *points() const { return m_points.data(); }
+    inline QPainterPath::ElementType *elementTypes() const { return m_types.data(); }
+
+    inline void setInvScale(qreal invScale) { m_inv_scale = invScale; }
+
+private:
+    QDataBuffer<qreal> m_points;
+    QDataBuffer<QPainterPath::ElementType> m_types;
+    QDashStroker m_dash_stroker;
+    qreal m_inv_scale;
+};
+
+
+
+
+
+inline void QTriangulatingStroker::normalVector(float x1, float y1, float x2, float y2,
+                                                float *nx, float *ny)
+{
+    float dx = x2 - x1;
+    float dy = y2 - y1;
+    float pw = m_width / sqrt(dx*dx + dy*dy);
+    *nx = -dy * pw;
+    *ny = dx * pw;
+}
+
+
+
+inline void QTriangulatingStroker::emitLineSegment(float x, float y, float vx, float vy)
+{
+    m_vertices.add(x + vx);
+    m_vertices.add(y + vy);
+    m_vertices.add(x - vx);
+    m_vertices.add(y - vy);
+}
+
+
+
+// We draw a full circle for any round join or round cap which is a
+// bit of overkill...
+inline void QTriangulatingStroker::arc(float x, float y)
+{
+    float dx = m_width;
+    float dy = 0;
+    for (int i=0; i<=m_roundness; ++i) {
+        float tmpx = dx * m_cos_theta - dy * m_sin_theta;
+        float tmpy = dx * m_sin_theta + dy * m_cos_theta;
+        dx = tmpx;
+        dy = tmpy;
+        emitLineSegment(x, y, dx, dy);
+    }
+}
+
+
+
+inline void QTriangulatingStroker::endCap(const qreal *pts)
+{
+    switch (m_cap_style) {
+    case Qt::FlatCap:
+        break;
+    case Qt::SquareCap: {
+        float dx = m_cx - *(pts - 2);
+        float dy = m_cy - *(pts - 1);
+
+        float len = m_width / sqrt(dx * dx + dy * dy);
+        dx = dx * len;
+        dy = dy * len;
+
+        emitLineSegment(m_cx + dx, m_cy + dy, m_nvx, m_nvy);
+        break; }
+    case Qt::RoundCap:
+        arc(m_cx, m_cy);
+        break;
+    default: break; // to shut gcc up...
+    }
+
+    int count = m_vertices.size();
+    m_vertices.add(m_vertices.at(count-2));
+    m_vertices.add(m_vertices.at(count-1));
+}
+
+
+void QTriangulatingStroker::moveTo(const qreal *pts)
+{
+    m_cx = pts[0];
+    m_cy = pts[1];
+
+    float x2 = pts[2];
+    float y2 = pts[3];
+    normalVector(m_cx, m_cy, x2, y2, &m_nvx, &m_nvy);
+
+
+    // To acheive jumps we insert zero-area tringles. This is done by
+    // adding two identical points in both the end of previous strip
+    // and beginning of next strip
+    bool invisibleJump = m_vertices.size();
+
+    switch (m_cap_style) {
+    case Qt::FlatCap:
+        if (invisibleJump) {
+            m_vertices.add(m_cx + m_nvx);
+            m_vertices.add(m_cy + m_nvy);
+        }
+        break;
+    case Qt::SquareCap: {
+        float dx = x2 - m_cx;
+        float dy = y2 - m_cy;
+        float len = m_width / sqrt(dx * dx + dy * dy);
+        dx = dx * len;
+        dy = dy * len;
+        float sx = m_cx - dx;
+        float sy = m_cy - dy;
+        if (invisibleJump) {
+            m_vertices.add(sx + m_nvx);
+            m_vertices.add(sy + m_nvy);
+        }
+        emitLineSegment(sx, sy, m_nvx, m_nvy);
+        break; }
+    case Qt::RoundCap:
+        if (invisibleJump) {
+            m_vertices.add(m_cx + m_nvx);
+            m_vertices.add(m_cy + m_nvy);
+        }
+
+        // This emitLineSegment is not needed for the arc, but we need
+        // to start where we put the invisibleJump vertex, otherwise
+        // we'll have visible triangles between subpaths.
+        emitLineSegment(m_cx, m_cy, m_nvx, m_nvy);
+        arc(m_cx, m_cy);
+        break;
+    default: break; // ssssh gcc...
+    }
+    emitLineSegment(m_cx, m_cy, m_nvx, m_nvy);
+}
+
+
+
+void QTriangulatingStroker::lineTo(const qreal *pts)
+{
+    emitLineSegment(pts[0], pts[1], m_nvx, m_nvy);
+    m_cx = pts[0];
+    m_cy = pts[1];
+}
+
+
+
+
+
+void QTriangulatingStroker::join(const qreal *pts)
+{
+    // Creates a join to the next segment (m_cx, m_cy) -> (pts[0], pts[1])
+    normalVector(m_cx, m_cy, pts[0], pts[1], &m_nvx, &m_nvy);
+
+    switch (m_join_style) {
+    case Qt::BevelJoin:
+        break;
+    case Qt::MiterJoin: {
+        int p1 = m_vertices.size() - 6;
+        int p2 = m_vertices.size() - 2;
+        QLineF line(m_vertices.at(p1), m_vertices.at(p1+1),
+                    m_vertices.at(p2), m_vertices.at(p2+1));
+        QLineF nextLine(m_cx - m_nvx, m_cy - m_nvy,
+                        pts[0] - m_nvx, pts[1] - m_nvy);
+
+        QPointF isect;
+        if (line.intersect(nextLine, &isect) != QLineF::NoIntersection
+            && QLineF(line.p2(), isect).length() <= m_miter_limit) {
+            // The intersection point mirrored over the m_cx, m_cy point
+            m_vertices.add(m_cx - (isect.x() - m_cx));
+            m_vertices.add(m_cy - (isect.y() - m_cy));
+
+            // The intersection point
+            m_vertices.add(isect.x());
+            m_vertices.add(isect.y());
+        }
+        // else
+        // Do a plain bevel join if the miter limit is exceeded or if
+        // the lines are parallel. This is not what the raster
+        // engine's stroker does, but it is both faster and similar to
+        // what some other graphics API's do.
+
+        break; }
+    case Qt::RoundJoin:
+        arc(m_cx, m_cy);
+        break;
+
+    default: break; // gcc warn--
+    }
+
+    emitLineSegment(m_cx, m_cy, m_nvx, m_nvy);
+}
+
+
+#endif
diff --git a/src/opengl/opengl.pro b/src/opengl/opengl.pro
index e561932..058016e 100644
--- a/src/opengl/opengl.pro
+++ b/src/opengl/opengl.pro
@@ -60,7 +60,8 @@ SOURCES	+= qgl.cpp \
                 gl2paintengineex/qgl2pexvertexarray_p.h \
                 gl2paintengineex/qpaintengineex_opengl2_p.h \
                 gl2paintengineex/qglengineshadersource_p.h \
-                gl2paintengineex/qglcustomshaderstage_p.h
+                gl2paintengineex/qglcustomshaderstage_p.h \
+                gl2paintengineex/qtriangulatingstroker_p.h 
 
     SOURCES +=  qglshaderprogram.cpp \
                 qglpixmapfilter.cpp \
@@ -72,7 +73,8 @@ SOURCES	+= qgl.cpp \
                 gl2paintengineex/qglengineshadermanager.cpp \
                 gl2paintengineex/qgl2pexvertexarray.cpp \
                 gl2paintengineex/qpaintengineex_opengl2.cpp \
-                gl2paintengineex/qglcustomshaderstage.cpp
+                gl2paintengineex/qglcustomshaderstage.cpp \
+                gl2paintengineex/qtriangulatingstroker.cpp
 
 }