C++ SkVector::scale方法代码示例

static void pts_to_unit_matrix(const SkPoint pts[2], SkMatrix* matrix) {
    SkVector    vec = pts[1] - pts[0];
    SkScalar    mag = vec.length();
    SkScalar    inv = mag ? SkScalarInvert(mag) : 0;

    vec.scale(inv);
    matrix->setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
    matrix->postTranslate(-pts[0].fX, -pts[0].fY);
    matrix->postScale(inv, inv);
}

static void unitToPointsMatrix(const SkPoint pts[2], SkMatrix* matrix) {
    SkVector    vec = pts[1] - pts[0];
    SkScalar    mag = vec.length();
    SkScalar    inv = mag ? SkScalarInvert(mag) : 0;

    vec.scale(inv);
    matrix->setSinCos(vec.fY, vec.fX);
    matrix->preTranslate(pts[0].fX, pts[0].fY);
    matrix->preScale(mag, mag);
}

static void toUnitMatrix(const SkPoint pts[2], SkMatrix* matrix) {
    SkVector vec = pts[1] - pts[0];
    const float mag = vec.length();
    const float inv = mag ? 1.0f / mag : 0;

    vec.scale(inv);
    matrix->setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
    matrix->postTranslate(-pts[0].fX, -pts[0].fY);
    matrix->postScale(inv, inv);
}

static SkMatrix pts_to_unit_matrix(const SkPoint pts[2]) {
    SkVector    vec = pts[1] - pts[0];
    SkScalar    mag = vec.length();
    SkScalar    inv = mag ? SkScalarInvert(mag) : 0;

    vec.scale(inv);
    SkMatrix matrix;
    matrix.setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
    matrix.postTranslate(-pts[0].fX, -pts[0].fY);
    matrix.postScale(inv, inv);
    return matrix;
}

// calculates the rotation needed to aligned pts to the x axis with pts[0] < pts[1]
// Stores the rotation matrix in rotMatrix, and the mapped points in ptsRot
static void align_to_x_axis(const SkPoint pts[2], SkMatrix* rotMatrix, SkPoint ptsRot[2] = NULL) {
    SkVector vec = pts[1] - pts[0];
    SkScalar mag = vec.length();
    SkScalar inv = mag ? SkScalarInvert(mag) : 0;

    vec.scale(inv);
    rotMatrix->setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
    if (ptsRot) {
        rotMatrix->mapPoints(ptsRot, pts, 2);
        // correction for numerical issues if map doesn't make ptsRot exactly horizontal
        ptsRot[1].fY = pts[0].fY;
    }
}

static void BluntJoiner(SkPath* outer, SkPath* inner, const SkVector& beforeUnitNormal,
                        const SkPoint& pivot, const SkVector& afterUnitNormal,
                        SkScalar radius, SkScalar invMiterLimit, bool, bool)
{
    SkVector    after;
    afterUnitNormal.scale(radius, &after);

    if (!is_clockwise(beforeUnitNormal, afterUnitNormal))
    {
        SkTSwap<SkPath*>(outer, inner);
        after.negate();
    }

    outer->lineTo(pivot.fX + after.fX, pivot.fY + after.fY);
    HandleInnerJoin(inner, pivot, after);
}

static void calc_dash_scaling(SkScalar* parallelScale, SkScalar* perpScale,
                            const SkMatrix& viewMatrix, const SkPoint pts[2]) {
    SkVector vecSrc = pts[1] - pts[0];
    SkScalar magSrc = vecSrc.length();
    SkScalar invSrc = magSrc ? SkScalarInvert(magSrc) : 0;
    vecSrc.scale(invSrc);

    SkVector vecSrcPerp;
    vecSrc.rotateCW(&vecSrcPerp);
    viewMatrix.mapVectors(&vecSrc, 1);
    viewMatrix.mapVectors(&vecSrcPerp, 1);

    // parallelScale tells how much to scale along the line parallel to the dash line
    // perpScale tells how much to scale in the direction perpendicular to the dash line
    *parallelScale = vecSrc.length();
    *perpScale = vecSrcPerp.length();
}

static void RoundJoiner(SkPath* outer, SkPath* inner, const SkVector& beforeUnitNormal,
                        const SkPoint& pivot, const SkVector& afterUnitNormal,
                        SkScalar radius, SkScalar invMiterLimit, bool, bool)
{
    SkScalar    dotProd = SkPoint::DotProduct(beforeUnitNormal, afterUnitNormal);
    AngleType   angleType = Dot2AngleType(dotProd);

    if (angleType == kNearlyLine_AngleType)
        return;

    SkVector            before = beforeUnitNormal;
    SkVector            after = afterUnitNormal;
    SkRotationDirection dir = kCW_SkRotationDirection;

    if (!is_clockwise(before, after))
    {
        SkTSwap<SkPath*>(outer, inner);
        before.negate();
        after.negate();
        dir = kCCW_SkRotationDirection;
    }

    SkPoint     pts[kSkBuildQuadArcStorage];
    SkMatrix    matrix;
    matrix.setScale(radius, radius);
    matrix.postTranslate(pivot.fX, pivot.fY);
    int count = SkBuildQuadArc(before, after, dir, &matrix, pts);
    SkASSERT((count & 1) == 1);

    if (count > 1)
    {
        for (int i = 1; i < count; i += 2)
            outer->quadTo(pts[i].fX, pts[i].fY, pts[i+1].fX, pts[i+1].fY);

        after.scale(radius);
        HandleInnerJoin(inner, pivot, after);
    }
}

// Currently asPoints is more restrictive then it needs to be. In the future
// we need to:
//      allow kRound_Cap capping (could allow rotations in the matrix with this)
//      allow paths to be returned
bool SkDashPathEffect::asPoints(PointData* results,
                                const SkPath& src,
                                const SkStrokeRec& rec,
                                const SkMatrix& matrix,
                                const SkRect* cullRect) const {
    // width < 0 -> fill && width == 0 -> hairline so requiring width > 0 rules both out
    if (fInitialDashLength < 0 || 0 >= rec.getWidth()) {
        return false;
    }

    // TODO: this next test could be eased up. We could allow any number of
    // intervals as long as all the ons match and all the offs match.
    // Additionally, they do not necessarily need to be integers.
    // We cannot allow arbitrary intervals since we want the returned points
    // to be uniformly sized.
    if (fCount != 2 ||
        !SkScalarNearlyEqual(fIntervals[0], fIntervals[1]) ||
        !SkScalarIsInt(fIntervals[0]) ||
        !SkScalarIsInt(fIntervals[1])) {
        return false;
    }

    SkPoint pts[2];

    if (!src.isLine(pts)) {
        return false;
    }

    // TODO: this test could be eased up to allow circles
    if (SkPaint::kButt_Cap != rec.getCap()) {
        return false;
    }

    // TODO: this test could be eased up for circles. Rotations could be allowed.
    if (!matrix.rectStaysRect()) {
        return false;
    }

    // See if the line can be limited to something plausible.
    if (!cull_line(pts, rec, matrix, cullRect, fIntervalLength)) {
        return false;
    }

    SkScalar length = SkPoint::Distance(pts[1], pts[0]);

    SkVector tangent = pts[1] - pts[0];
    if (tangent.isZero()) {
        return false;
    }

    tangent.scale(SkScalarInvert(length));

    // TODO: make this test for horizontal & vertical lines more robust
    bool isXAxis = true;
    if (SkScalarNearlyEqual(SK_Scalar1, tangent.fX) ||
        SkScalarNearlyEqual(-SK_Scalar1, tangent.fX)) {
        results->fSize.set(SkScalarHalf(fIntervals[0]), SkScalarHalf(rec.getWidth()));
    } else if (SkScalarNearlyEqual(SK_Scalar1, tangent.fY) ||
               SkScalarNearlyEqual(-SK_Scalar1, tangent.fY)) {
        results->fSize.set(SkScalarHalf(rec.getWidth()), SkScalarHalf(fIntervals[0]));
        isXAxis = false;
    } else if (SkPaint::kRound_Cap != rec.getCap()) {
        // Angled lines don't have axis-aligned boxes.
        return false;
    }

    if (results) {
        results->fFlags = 0;
        SkScalar clampedInitialDashLength = SkMinScalar(length, fInitialDashLength);

        if (SkPaint::kRound_Cap == rec.getCap()) {
            results->fFlags |= PointData::kCircles_PointFlag;
        }

        results->fNumPoints = 0;
        SkScalar len2 = length;
        if (clampedInitialDashLength > 0 || 0 == fInitialDashIndex) {
            SkASSERT(len2 >= clampedInitialDashLength);
            if (0 == fInitialDashIndex) {
                if (clampedInitialDashLength > 0) {
                    if (clampedInitialDashLength >= fIntervals[0]) {
                        ++results->fNumPoints;  // partial first dash
                    }
                    len2 -= clampedInitialDashLength;
                }
                len2 -= fIntervals[1];  // also skip first space
                if (len2 < 0) {
                    len2 = 0;
                }
            } else {
                len2 -= clampedInitialDashLength; // skip initial partial empty
            }
        }
        int numMidPoints = SkScalarFloorToInt(len2 / fIntervalLength);
        results->fNumPoints += numMidPoints;
        len2 -= numMidPoints * fIntervalLength;
//.........这里部分代码省略.........

static void MiterJoiner(SkPath* outer, SkPath* inner, const SkVector& beforeUnitNormal,
                        const SkPoint& pivot, const SkVector& afterUnitNormal,
                        SkScalar radius, SkScalar invMiterLimit,
                        bool prevIsLine, bool currIsLine)
{
    // negate the dot since we're using normals instead of tangents
    SkScalar    dotProd = SkPoint::DotProduct(beforeUnitNormal, afterUnitNormal);
    AngleType   angleType = Dot2AngleType(dotProd);
    SkVector    before = beforeUnitNormal;
    SkVector    after = afterUnitNormal;
    SkVector    mid;
    SkScalar    sinHalfAngle;
    bool        ccw;

    if (angleType == kNearlyLine_AngleType)
        return;
    if (angleType == kNearly180_AngleType)
    {
        currIsLine = false;
        goto DO_BLUNT;
    }

    ccw = !is_clockwise(before, after);
    if (ccw)
    {
        SkTSwap<SkPath*>(outer, inner);
        before.negate();
        after.negate();
    }

    /*  Before we enter the world of square-roots and divides,
        check if we're trying to join an upright right angle
        (common case for stroking rectangles). If so, special case
        that (for speed an accuracy).
        Note: we only need to check one normal if dot==0
    */
    if (0 == dotProd && invMiterLimit <= kOneOverSqrt2)
    {
        mid.set(SkScalarMul(before.fX + after.fX, radius),
                SkScalarMul(before.fY + after.fY, radius));
        goto DO_MITER;
    }

    /*  midLength = radius / sinHalfAngle
        if (midLength > miterLimit * radius) abort
        if (radius / sinHalf > miterLimit * radius) abort
        if (1 / sinHalf > miterLimit) abort
        if (1 / miterLimit > sinHalf) abort
        My dotProd is opposite sign, since it is built from normals and not tangents
        hence 1 + dot instead of 1 - dot in the formula
    */
    sinHalfAngle = SkScalarSqrt(SkScalarHalf(SK_Scalar1 + dotProd));
    if (sinHalfAngle < invMiterLimit)
    {
        currIsLine = false;
        goto DO_BLUNT;
    }

    // choose the most accurate way to form the initial mid-vector
    if (angleType == kSharp_AngleType)
    {
        mid.set(after.fY - before.fY, before.fX - after.fX);
        if (ccw)
            mid.negate();
    }
    else
        mid.set(before.fX + after.fX, before.fY + after.fY);

    mid.setLength(SkScalarDiv(radius, sinHalfAngle));
DO_MITER:
    if (prevIsLine)
        outer->setLastPt(pivot.fX + mid.fX, pivot.fY + mid.fY);
    else
        outer->lineTo(pivot.fX + mid.fX, pivot.fY + mid.fY);

DO_BLUNT:
    after.scale(radius);
    if (!currIsLine)
        outer->lineTo(pivot.fX + after.fX, pivot.fY + after.fY);
    HandleInnerJoin(inner, pivot, after);
}