Integrated new triangulating stroker into Qt

1 files changed, 258 insertions, 0 deletions

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