qpaintengine_opengl.cpp

奇趣公司比较新的qt/emd版本

        return;

    const qreal xpadding = 1.0;
    const qreal ypadding = 1.0;

    qreal topDist = offscreenHeight - trap.top;
    qreal bottomDist = offscreenHeight - trap.bottom;

    qreal reciprocal = bottomDist / (bottomDist - topDist);

    qreal leftB = trap.bottomLeftX + (trap.topLeftX - trap.bottomLeftX) * reciprocal;
    qreal rightB = trap.bottomRightX + (trap.topRightX - trap.bottomRightX) * reciprocal;

    const bool topZero = qFuzzyCompare(topDist, 0);

    reciprocal = topZero ? 1.0 / bottomDist : 1.0 / topDist;

    qreal leftA = topZero ? (trap.bottomLeftX - leftB) * reciprocal : (trap.topLeftX - leftB) * reciprocal;
    qreal rightA = topZero ? (trap.bottomRightX - rightB) * reciprocal : (trap.topRightX - rightB) * reciprocal;

    qreal invLeftA = qFuzzyCompare(leftA, qreal(0.0)) ? 0.0 : 1.0 / leftA;
    qreal invRightA = qFuzzyCompare(rightA, qreal(0.0)) ? 0.0 : 1.0 / rightA;

    // fragment program needs the negative of invRightA as it mirrors the line
    glTexCoord4f(topDist, bottomDist, invLeftA, -invRightA);
    glMultiTexCoord4f(GL_TEXTURE1, leftA, leftB, rightA, rightB);

    qreal topY = trap.top - ypadding;
    qreal bottomY = trap.bottom + ypadding;

    qreal bounds_bottomLeftX = leftA * (offscreenHeight - bottomY) + leftB;
    qreal bounds_bottomRightX = rightA * (offscreenHeight - bottomY) + rightB;
    qreal bounds_topLeftX = leftA * (offscreenHeight - topY) + leftB;
    qreal bounds_topRightX = rightA * (offscreenHeight - topY) + rightB;

    QPointF leftNormal(1, -leftA);
    leftNormal /= sqrt(leftNormal.x() * leftNormal.x() + leftNormal.y() * leftNormal.y());
    QPointF rightNormal(1, -rightA);
    rightNormal /= sqrt(rightNormal.x() * rightNormal.x() + rightNormal.y() * rightNormal.y());

    qreal left_padding = xpadding / qAbs(leftNormal.x());
    qreal right_padding = xpadding / qAbs(rightNormal.x());

    glVertex2d(bounds_topLeftX - left_padding, topY);
    glVertex2d(bounds_topRightX + right_padding, topY);
    glVertex2d(bounds_bottomRightX + right_padding, bottomY);
    glVertex2d(bounds_bottomLeftX - left_padding, bottomY);

    glTexCoord4f(0.0f, 0.0f, 0.0f, 1.0f);
}
#endif // !Q_WS_QWS

class QOpenGLTrapezoidToArrayTessellator : public QOpenGLTessellator
{
public:
    QOpenGLTrapezoidToArrayTessellator() : vertices(0), allocated(0), size(0) {}
    ~QOpenGLTrapezoidToArrayTessellator() { free(vertices); }
    float *vertices;
    int allocated;
    int size;
    QRectF bounds;
    void addTrap(const Trapezoid &trap);
    void tessellate(const QPointF *points, int nPoints, bool winding) {
        size = 0;
        setWinding(winding);
        bounds = QTessellator::tessellate(points, nPoints);
    }
};

void QOpenGLTrapezoidToArrayTessellator::addTrap(const Trapezoid &trap)
{
#ifndef Q_WS_QWS
    if (size > allocated - 8) {
#else
    if (size > allocated - 12) {
#endif
        allocated = qMax(2*allocated, 512);
        vertices = (float *)realloc(vertices, allocated * sizeof(float));
    }

    QGLTrapezoid t = toGLTrapezoid(trap);

#ifndef Q_WS_QWS
    vertices[size++] = t.topLeftX;
    vertices[size++] = t.top;
    vertices[size++] = t.topRightX;
    vertices[size++] = t.top;
    vertices[size++] = t.bottomRightX;
    vertices[size++] = t.bottom;
    vertices[size++] = t.bottomLeftX;
    vertices[size++] = t.bottom;
#else
    vertices[size++] = t.topLeftX;
    vertices[size++] = t.top;
    vertices[size++] = t.topRightX;
    vertices[size++] = t.top;
    vertices[size++] = t.bottomRightX;
    vertices[size++] = t.bottom;

    vertices[size++] = t.bottomLeftX;
    vertices[size++] = t.bottom;
    vertices[size++] = t.topLeftX;
    vertices[size++] = t.top;
    vertices[size++] = t.bottomRightX;
    vertices[size++] = t.bottom;
#endif
}


void QOpenGLPaintEnginePrivate::fillPolygon_dev(const QPointF *polygonPoints, int pointCount,
                                                Qt::FillRule fill)
{
    QOpenGLTrapezoidToArrayTessellator tessellator;
    tessellator.tessellate(polygonPoints, pointCount, fill == Qt::WindingFill);

    DEBUG_ONCE qDebug() << "QOpenGLPaintEnginePrivate: Drawing polygon with" << pointCount << "points using fillPolygon_dev";

    setGradientOps(cbrush, tessellator.bounds);

    bool fast_style = current_style == Qt::LinearGradientPattern
                      || current_style == Qt::SolidPattern;

#ifndef Q_WS_QWS
    GLenum geometry_mode = GL_QUADS;
#else
    GLenum geometry_mode = GL_TRIANGLES;
#endif

    if (use_fragment_programs && !(fast_style && has_fast_composition_mode)) {
        composite(geometry_mode, tessellator.vertices, tessellator.size / 2);
    } else {
        glVertexPointer(2, GL_FLOAT, 0, tessellator.vertices);
        glEnableClientState(GL_VERTEX_ARRAY);
        glDrawArrays(geometry_mode, 0, tessellator.size/2);
        glDisableClientState(GL_VERTEX_ARRAY);
    }
}


inline void QOpenGLPaintEnginePrivate::lineToStencil(qreal x, qreal y)
{
    tess_points.add(QPointF(x, y));

    if (x > max_x)
        max_x = x;
    else if (x < min_x)
        min_x = x;
    if (y > max_y)
        max_y = y;
    else if (y < min_y)
        min_y = y;
}

inline void QOpenGLPaintEnginePrivate::curveToStencil(const QPointF &cp1, const QPointF &cp2, const QPointF &ep)
{
    qreal inverseScaleHalf = inverseScale / 2;

    QBezier beziers[32];
    beziers[0] = QBezier::fromPoints(tess_points.last(), cp1, cp2, ep);
    QBezier *b = beziers;
    while (b >= beziers) {
        // check if we can pop the top bezier curve from the stack
        qreal l = qAbs(b->x4 - b->x1) + qAbs(b->y4 - b->y1);
        qreal d;
        if (l > inverseScale) {
            d = qAbs( (b->x4 - b->x1)*(b->y1 - b->y2) - (b->y4 - b->y1)*(b->x1 - b->x2) )
                + qAbs( (b->x4 - b->x1)*(b->y1 - b->y3) - (b->y4 - b->y1)*(b->x1 - b->x3) );
            d /= l;
        } else {
            d = qAbs(b->x1 - b->x2) + qAbs(b->y1 - b->y2) +
                qAbs(b->x1 - b->x3) + qAbs(b->y1 - b->y3);
        }
        if (d < inverseScaleHalf || b == beziers + 31) {
            // good enough, we pop it off and add the endpoint
            lineToStencil(b->x4, b->y4);
            --b;
        } else {
            // split, second half of the polygon goes lower into the stack
            b->split(b+1, b);
           ++b;
        }
    }
}


void QOpenGLPaintEnginePrivate::pathToVertexArrays(const QPainterPath &path)
{
    const QPainterPath::Element &first = path.elementAt(0);
    min_x = max_x = first.x;
    min_y = max_y = first.y;

    tess_points.reset();
    tess_points_stops.clear();
    lineToStencil(first.x, first.y);

    for (int i=1; i<path.elementCount(); ++i) {
        const QPainterPath::Element &e = path.elementAt(i);
        switch (e.type) {
        case QPainterPath::MoveToElement:
            tess_points_stops.append(tess_points.size());
            lineToStencil(e.x, e.y);
            break;
        case QPainterPath::LineToElement:
            lineToStencil(e.x, e.y);
            break;
        case QPainterPath::CurveToElement:
            curveToStencil(e, path.elementAt(i+1), path.elementAt(i+2));
            i+=2;
            break;
        default:
            break;
        }
    }
    lineToStencil(first.x, first.y);
    tess_points_stops.append(tess_points.size());
}


void QOpenGLPaintEnginePrivate::drawVertexArrays()
{
    glEnableClientState(GL_VERTEX_ARRAY);
    glVertexPointer(2, GL_DOUBLE, 0, tess_points.data());
    int previous_stop = 0;
    foreach(int stop, tess_points_stops) {
        glDrawArrays(GL_TRIANGLE_FAN, previous_stop, stop-previous_stop);
        previous_stop = stop;
    }
    glDisableClientState(GL_VERTEX_ARRAY);
}

void QOpenGLPaintEnginePrivate::fillVertexArray(Qt::FillRule fillRule)
{
    glStencilMask(~0);

    // Enable stencil.
    glEnable(GL_STENCIL_TEST);

    // Disable color writes.
    glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);

    GLuint stencilMask = 0;

    if (fillRule == Qt::OddEvenFill) {
        stencilMask = 1;

        // Enable stencil writes.
        glStencilMask(stencilMask);

        // Set stencil xor mode.
        glStencilOp(GL_KEEP, GL_KEEP, GL_INVERT);

        // Disable stencil func.
        glStencilFunc(GL_ALWAYS, 0, ~0);

        drawVertexArrays();
    } else if (fillRule == Qt::WindingFill) {
        stencilMask = ~0;

        if (has_stencil_face_ext) {
            QGL_FUNC_CONTEXT;
            glEnable(GL_STENCIL_TEST_TWO_SIDE_EXT);

            glActiveStencilFaceEXT(GL_BACK);
            glStencilOp(GL_KEEP, GL_KEEP, GL_DECR_WRAP_EXT);
            glStencilFunc(GL_ALWAYS, 0, ~0);

            glActiveStencilFaceEXT(GL_FRONT);
            glStencilOp(GL_KEEP, GL_KEEP, GL_INCR_WRAP_EXT);
            glStencilFunc(GL_ALWAYS, 0, ~0);

            drawVertexArrays();

            glDisable(GL_STENCIL_TEST_TWO_SIDE_EXT);
        } else {
            glStencilFunc(GL_ALWAYS, 0, ~0);
            glEnable(GL_CULL_FACE);

            glCullFace(GL_BACK);
            glStencilOp(GL_KEEP, GL_KEEP, GL_INCR_WRAP_EXT);
            drawVertexArrays();

            glCullFace(GL_FRONT);
            glStencilOp(GL_KEEP, GL_KEEP, GL_DECR_WRAP_EXT);
            drawVertexArrays();

            glDisable(GL_CULL_FACE);
        }
    }

    // Enable color writes.
    glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
    glStencilMask(0);

    setGradientOps(cbrush, QRectF(QPointF(min_x, min_y), QSizeF(max_x - min_x, max_y - min_y)));

    bool fast_fill = has_fast_composition_mode && (current_style == Qt::LinearGradientPattern || current_style == Qt::SolidPattern);

    if (use_fragment_programs && !fast_fill) {
        DEBUG_ONCE qDebug() << "QOpenGLPaintEnginePrivate: Drawing polygon using stencil method (fragment programs)";
        QRectF rect(QPointF(min_x, min_y), QSizeF(max_x - min_x, max_y - min_y));

        // Enable stencil func.
        glStencilFunc(GL_NOTEQUAL, 0, stencilMask);
        composite(rect);
    } else {
        DEBUG_ONCE qDebug() << "QOpenGLPaintEnginePrivate: Drawing polygon using stencil method (no fragment programs)";

        // Enable stencil func.
        glStencilFunc(GL_NOTEQUAL, 0, stencilMask);
#ifndef Q_WS_QWS
        glBegin(GL_QUADS);
        glVertex2f(min_x, min_y);
        glVertex2f(max_x, min_y);
        glVertex2f(max_x, max_y);
        glVertex2f(min_x, max_y);
        glEnd();
#endif
    }

    glStencilMask(~0);
    glStencilFunc(GL_ALWAYS, 0, 0);
    glStencilOp(GL_ZERO, GL_ZERO, GL_ZERO);

    // clear all stencil values to 0
    glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);

#ifndef Q_WS_QWS
    glBegin(GL_QUADS);
    glVertex2f(min_x, min_y);
    glVertex2f(max_x, min_y);
    glVertex2f(max_x, max_y);
    glVertex2f(min_x, max_y);
    glEnd();
#endif

    glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);

    // Disable stencil writes.
    glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);
    glStencilMask(0);
    glDisable(GL_STENCIL_TEST);
}

void QOpenGLPaintEnginePrivate::fillPath(const QPainterPath &path)
{
    if (path.isEmpty())
        return;

    if (use_stencil_method && !high_quality_antialiasing) {
        pathToVertexArrays(path);
        fillVertexArray(path.fillRule());
        return;
    }

    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity();

    if (high_quality_antialiasing)
        drawOffscreenPath(path);
    else {
        QPolygonF poly = path.toFillPolygon(matrix);
        fillPolygon_dev(poly.data(), poly.count(),
                        path.fillRule());
    }

    glMatrixMode(GL_MODELVIEW);

#ifndef Q_WS_QWS
    GLdouble mat[4][4];
#else
    GLfloat mat[4][4];
#endif
    QTransform mtx = matrix;
    mat[0][0] = mtx.m11();
    mat[0][1] = mtx.m12();
    mat[0][2] = 0;
    mat[0][3] = mtx.m13();

    mat[1][0] = mtx.m21();
    mat[1][1] = mtx.m22();
    mat[1][2] = 0;
    mat[1][3] = mtx.m23();

    mat[2][0] = 0;
    mat[2][1] = 0;
    mat[2][2] = 1;
    mat[2][3] = 0;

    mat[3][0] = mtx.dx();
    mat[3][1] = mtx.dy();
    mat[3][2] = 0;
    mat[3][3] = 1;

#ifndef Q_WS_QWS
    glLoadMatrixd(&mat[0][0]);
#else
    glLoadMatrixf(&mat[0][0]);
#endif
}

void QOpenGLPaintEngine::updatePen(const QPen &pen)
{
    Q_D(QOpenGLPaintEngine);
    Qt::PenStyle pen_style = pen.style();
    d->pen_brush_style = pen.brush().style();
    d->cpen = pen;
    d->has_pen = (pen_style != Qt::NoPen);

    if (pen.isCosmetic()) {
        GLfloat width = pen.widthF() == 0.0f ? 1.0f : pen.widthF();
        glLineWidth(width);
        glPointSize(width);
    }

    if (d->pen_brush_style >= Qt::LinearGradientPattern
        && d->pen_brush_style <= Qt::ConicalGradientPattern)
    {
        d->setGLPen(Qt::white);
    } else {