qdrawhelper.cpp

奇趣公司比较新的qt/emd版本

            if (ipos < 0) ipos = 0;
            else if (ipos >= GRADIENT_STOPTABLE_SIZE) ipos = GRADIENT_STOPTABLE_SIZE-1;
        }
    }

    Q_ASSERT(ipos >= 0);
    Q_ASSERT(ipos < GRADIENT_STOPTABLE_SIZE);

    return data->colorTable[ipos];
}
#endif

static void QT_FASTCALL getLinearGradientValues(LinearGradientValues *v, const QSpanData *data)
{
    v->dx = data->gradient.linear.end.x - data->gradient.linear.origin.x;
    v->dy = data->gradient.linear.end.y - data->gradient.linear.origin.y;
    v->l = v->dx * v->dx + v->dy * v->dy;
    v->off = 0;
    if (v->l != 0) {
        v->dx /= v->l;
        v->dy /= v->l;
        v->off = -v->dx * data->gradient.linear.origin.x - v->dy * data->gradient.linear.origin.y;
    }
}

#ifdef Q_WS_QWS
static const uint * QT_FASTCALL fetchLinearGradient(uint *buffer, const Operator *op, const QSpanData *data,
                                                    int y, int x, int length)
{
    const uint *b = buffer;
    qreal t, inc;

    bool affine = true;
    qreal rx=0, ry=0;
    if (op->linear.l == 0) {
        t = inc = 0;
    } else {
        rx = data->m21 * y + data->m11 * x + data->dx;
        ry = data->m22 * y + data->m12 * x + data->dy;
        t = op->linear.dx*rx + op->linear.dy*ry + op->linear.off;
        inc = op->linear.dx * data->m11 + op->linear.dy * data->m12;
        affine = !data->m13 && !data->m23;

        if (affine) {
            t *= GRADIENT_STOPTABLE_SIZE;
            inc *= GRADIENT_STOPTABLE_SIZE;
        }
    }

    const uint *end = buffer + length;
    if (affine) {
        if (inc > -1e-5 && inc < 1e-5) {
            QT_MEMFILL_UINT(buffer, length, qt_gradient_pixel_fixed(&data->gradient, int(t * FIXPT_SIZE)));
        } else {
            if (t+inc*length < qreal(INT_MAX >> (FIXPT_BITS + 1)) &&
                t+inc*length > qreal(INT_MIN >> (FIXPT_BITS + 1))) {
                // we can use fixed point math
                int t_fixed = int(t * FIXPT_SIZE);
                int inc_fixed = int(inc * FIXPT_SIZE);
                while (buffer < end) {
                    *buffer = qt_gradient_pixel_fixed(&data->gradient, t_fixed);
                    t_fixed += inc_fixed;
                    ++buffer;
                }
            } else {
                // we have to fall back to float math
                while (buffer < end) {
                    *buffer = qt_gradient_pixel(&data->gradient, t/GRADIENT_STOPTABLE_SIZE);
                    t += inc;
                    ++buffer;
                }
            }
        }
    } else { // fall back to float math here as well
        qreal rw = data->m23 * y + data->m13 * x + 1.;
        while (buffer < end) {
            qreal x = rx/rw;
            qreal y = ry/rw;
            t = (op->linear.dx*x + op->linear.dy *y) + op->linear.off;

            *buffer = qt_gradient_pixel(&data->gradient, t);
            rx += data->m11;
            ry += data->m12;
            rw += data->m13;
            if (!rw) {
                rw += data->m13;
            }
            ++buffer;
        }
    }

    return b;
}
#else
static const uint * QT_FASTCALL fetchLinearGradient(uint *buffer, const Operator *op, const QSpanData *data,
                                                    int y, int x, int length)
{
    const uint *b = buffer;
    qreal t, inc;

    bool affine = true;
    qreal rx=0, ry=0;
    if (op->linear.l == 0) {
        t = inc = 0;
    } else {
        rx = data->m21 * y + data->m11 * x + data->dx;
        ry = data->m22 * y + data->m12 * x + data->dy;
        t = op->linear.dx*rx + op->linear.dy*ry + op->linear.off;
        inc = op->linear.dx * data->m11 + op->linear.dy * data->m12;
        affine = !data->m13 && !data->m23;
    }

    const uint *end = buffer + length;
    if (affine) {
        if (inc > -1e-6 && inc < 1e-6) {
            QT_MEMFILL_UINT(buffer, length, qt_gradient_pixel(&data->gradient, t));
        } else {
            while (buffer < end) {
                *buffer = qt_gradient_pixel(&data->gradient, t);

                t += inc;
                ++buffer;
            }
        }
    } else {
        qreal rw = data->m23 * y + data->m13 * x + 1.;
        while (buffer < end) {
            qreal x = rx/rw;
            qreal y = ry/rw;
            t = (op->linear.dx*x + op->linear.dy *y) + op->linear.off;

            *buffer = qt_gradient_pixel(&data->gradient, t);
            rx += data->m11;
            ry += data->m12;
            rw += data->m13;
            if (!rw) {
                rw += data->m13;
            }
            ++buffer;
        }
    }

    return b;
}
#endif

static inline qreal determinant(qreal a, qreal b, qreal c)
{
    return (b * b) - (4 * a * c);
}

// function to evaluate real roots
static inline qreal realRoots(qreal a, qreal b, qreal detSqrt)
{
    return (-b + detSqrt)/(2 * a);
}

static void QT_FASTCALL getRadialGradientValues(RadialGradientValues *v, const QSpanData *data)
{
    v->dx = data->gradient.radial.center.x - data->gradient.radial.focal.x;
    v->dy = data->gradient.radial.center.y - data->gradient.radial.focal.y;
    v->a = data->gradient.radial.radius*data->gradient.radial.radius - v->dx*v->dx - v->dy*v->dy;
}

static const uint * QT_FASTCALL fetchRadialGradient(uint *buffer, const Operator *op, const QSpanData *data,
                                                    int y, int x, int length)
{
    const uint *b = buffer;
    qreal rx = data->m21 * (y + 0.5)
               + data->dx + data->m11 * (x + 0.5);
    qreal ry = data->m22 * (y + 0.5)
               + data->dy + data->m12 * (x + 0.5);
    bool affine = !data->m13 && !data->m23;
    //qreal r  = data->gradient.radial.radius;

    const uint *end = buffer + length;
    if (affine) {
        rx -= data->gradient.radial.focal.x;
        ry -= data->gradient.radial.focal.y;
        while (buffer < end) {
            qreal b  = 2*(rx*op->radial.dx + ry*op->radial.dy);
            qreal det = determinant(op->radial.a, b , -(rx*rx + ry*ry));
            qreal s = realRoots(op->radial.a, b, qSqrt(det));

            *buffer = qt_gradient_pixel(&data->gradient,  s);

            rx += data->m11;
            ry += data->m12;
            ++buffer;
        }
    } else {
        qreal rw = data->m23 * (y + 0.5)
                   + 1. + data->m13 * (x + 0.5);
        if (!rw)
            rw = 1;
        while (buffer < end) {
            qreal gx = rx/rw - data->gradient.radial.focal.x;
            qreal gy = ry/rw - data->gradient.radial.focal.y;
            qreal b  = 2*(gx*op->radial.dx + gy*op->radial.dy);
            qreal det = determinant(op->radial.a, b , -(gx*gx + gy*gy));
            qreal s = realRoots(op->radial.a, b, qSqrt(det));

        *buffer = qt_gradient_pixel(&data->gradient, s);

            rx += data->m11;
            ry += data->m12;
            rw += data->m13;
            if (!rw) {
                rw += data->m13;
            }
            ++buffer;
        }
    }

    return b;
}

static const uint * QT_FASTCALL fetchConicalGradient(uint *buffer, const Operator *, const QSpanData *data,
                                                     int y, int x, int length)
{
    const uint *b = buffer;
    qreal rx = data->m21 * (y + 0.5)
               + data->dx + data->m11 * (x + 0.5);
    qreal ry = data->m22 * (y + 0.5)
               + data->dy + data->m12 * (x + 0.5);
    bool affine = !data->m13 && !data->m23;

    const uint *end = buffer + length;
    if (affine) {
        rx -= data->gradient.conical.center.x;
        ry -= data->gradient.conical.center.y;
        while (buffer < end) {
            qreal angle = atan2(ry, rx) + data->gradient.conical.angle;

            *buffer = qt_gradient_pixel(&data->gradient, 1. - angle / (2*Q_PI));

            rx += data->m11;
            ry += data->m12;
            ++buffer;
        }
    } else {
        qreal rw = data->m23 * (y + 0.5)
                   + 1. + data->m13 * (x + 0.5);
        if (!rw)
            rw = 1;
        while (buffer < end) {
            qreal angle = atan2(ry/rw - data->gradient.conical.center.x,
                                rx/rw - data->gradient.conical.center.y)
                          + data->gradient.conical.angle;

            *buffer = qt_gradient_pixel(&data->gradient, 1. - angle / (2*Q_PI));

            rx += data->m11;
            ry += data->m12;
            rw += data->m13;
            if (!rw) {
                rw += data->m13;
            }
            ++buffer;
        }
    }
    return b;
}



/* The constant alpha factor describes an alpha factor that gets applied
   to the result of the composition operation combining it with the destination.

   The intent is that if const_alpha == 0. we get back dest, and if const_alpha == 1.
   we get the unmodified operation

   result = src op dest
   dest = result * const_alpha + dest * (1. - const_alpha)

   This means that in the comments below, the first line is the const_alpha==255 case, the
   second line the general one.

   In the lines below:
   s == src, sa == alpha(src), sia = 1 - alpha(src)
   d == dest, da == alpha(dest), dia = 1 - alpha(dest)
   ca = const_alpha, cia = 1 - const_alpha

   The methods exist in two variants. One where we have a constant source, the other
   where the source is an array of pixels.
*/

/*
  result = 0
  d = d * cia
*/
static void QT_FASTCALL comp_func_solid_Clear(uint *dest, int length, uint, uint const_alpha)
{
    if (const_alpha == 255) {
        QT_MEMFILL_UINT(dest, length, 0);
    } else {
        int ialpha = 255 - const_alpha;
        for (int i = 0; i < length; ++i)
            dest[i] = BYTE_MUL(dest[i], ialpha);
    }
}

static void QT_FASTCALL comp_func_Clear(uint *dest, const uint *, int length, uint const_alpha)
{
    if (const_alpha == 255) {
        QT_MEMFILL_UINT(dest, length, 0);
    } else {
        int ialpha = 255 - const_alpha;
        for (int i = 0; i < length; ++i)
            dest[i] = BYTE_MUL(dest[i], ialpha);
    }
}

/*
  result = s
  dest = s * ca + d * cia
*/
static void QT_FASTCALL comp_func_solid_Source(uint *dest, int length, uint color, uint const_alpha)
{
    if (const_alpha == 255) {
        QT_MEMFILL_UINT(dest, length, color);
    } else {
        int ialpha = 255 - const_alpha;
        color = BYTE_MUL(color, const_alpha);
        for (int i = 0; i < length; ++i)
            dest[i] = color + BYTE_MUL(dest[i], ialpha);
    }
}

static void QT_FASTCALL comp_func_Source(uint *dest, const uint *src, int length, uint const_alpha)
{
    if (const_alpha == 255) {
        ::memcpy(dest, src, length * sizeof(uint));
    } else {
        int ialpha = 255 - const_alpha;
        for (int i = 0; i < length; ++i)
            dest[i] = INTERPOLATE_PIXEL_255(src[i], const_alpha, dest[i], ialpha);
    }
}

/*
  result = s + d * sia
  dest = (s + d * sia) * ca + d * cia
       = s * ca + d * (sia * ca + cia)
       = s * ca + d * (1 - sa*ca)
*/
static void QT_FASTCALL comp_func_solid_SourceOver(uint *dest, int length, uint color, uint const_alpha)
{
    if ((const_alpha & qAlpha(color)) == 255) {
        QT_MEMFILL_UINT(dest, length, color);
    } else {
        if (const_alpha != 255)
            color = BYTE_MUL(color, const_alpha);
        for (int i = 0; i < length; ++i)
            dest[i] = color + BYTE_MUL(dest[i], qAlpha(~color));
    }
}

static void QT_FASTCALL comp_func_SourceOver(uint *dest, const uint *src, int length, uint const_alpha)
{
    if (const_alpha == 255) {
        for (int i = 0; i < length; ++i) {
            uint s = src[i];
            dest[i] = s + BYTE_MUL(dest[i], qAlpha(~s));
        }
    } else {
        for (int i = 0; i < length; ++i) {
            uint s = BYTE_MUL(src[i], const_alpha);
            dest[i] = s + BYTE_MUL(dest[i], qAlpha(~s));
        }
    }
}

/*
  result = d + s * dia
  dest = (d + s * dia) * ca + d * cia
       = d + s * dia * ca
*/
static void QT_FASTCALL comp_func_solid_DestinationOver(uint *dest, int length, uint color, uint const_alpha)
{
    if (const_alpha != 255)
        color = BYTE_MUL(color, const_alpha);
    for (int i = 0; i < length; ++i) {
        uint d = dest[i];
        dest[i] = d + BYTE_MUL(color, qAlpha(~d));
    }
}

static void QT_FASTCALL comp_func_DestinationOver(uint *dest, const uint *src, int length, uint const_alpha)
{
    if (const_alpha == 255) {
        for (int i = 0; i < length; ++i) {
            uint d = dest[i];
            dest[i] = d + BYTE_MUL(src[i], qAlpha(~d));
        }
    } else {
        for (int i = 0; i < length; ++i) {
            uint d = dest[i];
            uint s = BYTE_MUL(src[i], const_alpha);
            dest[i] = d + BYTE_MUL(s, qAlpha(~d));
        }
    }
}

/*
  result = s * da
  dest = s * da * ca + d * cia
*/
static void QT_FASTCALL comp_func_solid_SourceIn(uint *dest, int length, uint color, uint const_alpha)
{
    if (const_alpha == 255) {
        for (int i = 0; i < length; ++i)
            dest[i] = BYTE_MUL(color, qAlpha(dest[i]));
    } else {
        color = BYTE_MUL(color, const_alpha);
        uint cia = 255 - const_alpha;
        for (int i = 0; i < length; ++i) {
            uint d = dest[i];
            dest[i] = INTERPOLATE_PIXEL_255(color, qAlpha(d), d, cia);
        }
    }
}