C++ SkTSwap函数代码示例

// Only handles lines for now. If returns true, dstPath is the new (smaller)
// path. If returns false, then dstPath parameter is ignored.
static bool cull_path(const SkPath& srcPath, const SkStrokeRec& rec,
                      const SkRect* cullRect, SkScalar intervalLength,
                      SkPath* dstPath) {
    if (NULL == cullRect) {
        return false;
    }

    SkPoint pts[2];
    if (!srcPath.isLine(pts)) {
        return false;
    }

    SkRect bounds = *cullRect;
    outset_for_stroke(&bounds, rec);

    SkScalar dx = pts[1].x() - pts[0].x();
    SkScalar dy = pts[1].y() - pts[0].y();

    // just do horizontal lines for now (lazy)
    if (dy) {
        return false;
    }

    SkScalar minX = pts[0].fX;
    SkScalar maxX = pts[1].fX;

    if (maxX < bounds.fLeft || minX > bounds.fRight) {
        return false;
    }

    if (dx < 0) {
        SkTSwap(minX, maxX);
    }

    // Now we actually perform the chop, removing the excess to the left and
    // right of the bounds (keeping our new line "in phase" with the dash,
    // hence the (mod intervalLength).

    if (minX < bounds.fLeft) {
        minX = bounds.fLeft - SkScalarMod(bounds.fLeft - minX,
                                          intervalLength);
    }
    if (maxX > bounds.fRight) {
        maxX = bounds.fRight + SkScalarMod(maxX - bounds.fRight,
                                           intervalLength);
    }

    SkASSERT(maxX >= minX);
    if (dx < 0) {
        SkTSwap(minX, maxX);
    }
    pts[0].fX = minX;
    pts[1].fX = maxX;

    dstPath->moveTo(pts[0]);
    dstPath->lineTo(pts[1]);
    return true;
}

// first pass, add missing T values
// second pass, determine winding values of overlaps
void SkOpContour::addCoincidentPoints() {
    int count = fCoincidences.count();
    for (int index = 0; index < count; ++index) {
        SkCoincidence& coincidence = fCoincidences[index];
        int thisIndex = coincidence.fSegments[0];
        SkOpSegment& thisOne = fSegments[thisIndex];
        SkOpContour* otherContour = coincidence.fOther;
        int otherIndex = coincidence.fSegments[1];
        SkOpSegment& other = otherContour->fSegments[otherIndex];
        if ((thisOne.done() || other.done()) && thisOne.complete() && other.complete()) {
            // OPTIMIZATION: remove from array
            continue;
        }
    #if DEBUG_CONCIDENT
        thisOne.debugShowTs();
        other.debugShowTs();
    #endif
        double startT = coincidence.fTs[0][0];
        double endT = coincidence.fTs[0][1];
        bool startSwapped, oStartSwapped, cancelers;
        if ((cancelers = startSwapped = startT > endT)) {
            SkTSwap(startT, endT);
        }
        SkASSERT(!approximately_negative(endT - startT));
        double oStartT = coincidence.fTs[1][0];
        double oEndT = coincidence.fTs[1][1];
        if ((oStartSwapped = oStartT > oEndT)) {
            SkTSwap(oStartT, oEndT);
            cancelers ^= true;
        }
        SkASSERT(!approximately_negative(oEndT - oStartT));
        if (cancelers) {
            // make sure startT and endT have t entries
            if (startT > 0 || oEndT < 1
                    || thisOne.isMissing(startT) || other.isMissing(oEndT)) {
                thisOne.addTPair(startT, &other, oEndT, true, coincidence.fPts[startSwapped]);
            }
            if (oStartT > 0 || endT < 1
                    || thisOne.isMissing(endT) || other.isMissing(oStartT)) {
                other.addTPair(oStartT, &thisOne, endT, true, coincidence.fPts[oStartSwapped]);
            }
        } else {
            if (startT > 0 || oStartT > 0
                    || thisOne.isMissing(startT) || other.isMissing(oStartT)) {
                thisOne.addTPair(startT, &other, oStartT, true, coincidence.fPts[startSwapped]);
            }
            if (endT < 1 || oEndT < 1
                    || thisOne.isMissing(endT) || other.isMissing(oEndT)) {
                other.addTPair(oEndT, &thisOne, endT, true, coincidence.fPts[!oStartSwapped]);
            }
        }
    #if DEBUG_CONCIDENT
        thisOne.debugShowTs();
        other.debugShowTs();
    #endif
    }
}

int SkEdge::setLine(const SkPoint& p0, const SkPoint& p1, const SkIRect* clip,
                    int shift) {
    SkFDot6 x0, y0, x1, y1;

    {
#ifdef SK_RASTERIZE_EVEN_ROUNDING
        x0 = SkScalarRoundToFDot6(p0.fX, shift);
        y0 = SkScalarRoundToFDot6(p0.fY, shift);
        x1 = SkScalarRoundToFDot6(p1.fX, shift);
        y1 = SkScalarRoundToFDot6(p1.fY, shift);
#else
        float scale = float(1 << (shift + 6));
        x0 = int(p0.fX * scale);
        y0 = int(p0.fY * scale);
        x1 = int(p1.fX * scale);
        y1 = int(p1.fY * scale);
#endif
    }

    int winding = 1;

    if (y0 > y1) {
        SkTSwap(x0, x1);
        SkTSwap(y0, y1);
        winding = -1;
    }

    int top = SkFDot6Round(y0);
    int bot = SkFDot6Round(y1);

    // are we a zero-height line?
    if (top == bot) {
        return 0;
    }
    // are we completely above or below the clip?
    if (clip && (top >= clip->fBottom || bot <= clip->fTop)) {
        return 0;
    }

    SkFixed slope = SkFDot6Div(x1 - x0, y1 - y0);
    const SkFDot6 dy  = SkEdge_Compute_DY(top, y0);

    fX          = SkFDot6ToFixed(x0 + SkFixedMul(slope, dy));   // + SK_Fixed1/2
    fDX         = slope;
    fFirstY     = top;
    fLastY      = bot - 1;
    fCurveCount = 0;
    fWinding    = SkToS8(winding);
    fCurveShift = 0;

    if (clip) {
        this->chopLineWithClip(*clip);
    }
    return 1;
}

int SkEdge::setLine(const SkPoint& p0, const SkPoint& p1, const SkIRect* clip,
                    int shift) {
    SkFDot6 x0, y0, x1, y1;

    {
#ifdef SK_SCALAR_IS_FLOAT
        float scale = float(1 << (shift + 6));
        x0 = int(p0.fX * scale);
        y0 = int(p0.fY * scale);
        x1 = int(p1.fX * scale);
        y1 = int(p1.fY * scale);
#else
        shift = 10 - shift;
        x0 = p0.fX >> shift;
        y0 = p0.fY >> shift;
        x1 = p1.fX >> shift;
        y1 = p1.fY >> shift;
#endif
    }

    int winding = 1;

    if (y0 > y1) {
        SkTSwap(x0, x1);
        SkTSwap(y0, y1);
        winding = -1;
    }

    int top = SkFDot6Round(y0);
    int bot = SkFDot6Round(y1);

    // are we a zero-height line?
    if (top == bot) {
        return 0;
    }
    // are we completely above or below the clip?
    if (NULL != clip && (top >= clip->fBottom || bot <= clip->fTop)) {
        return 0;
    }

    SkFixed slope = SkFDot6Div(x1 - x0, y1 - y0);

    fX          = SkFDot6ToFixed(x0 + SkFixedMul(slope, (32 - y0) & 63));   // + SK_Fixed1/2
    fDX         = slope;
    fFirstY     = top;
    fLastY      = bot - 1;
    fCurveCount = 0;
    fWinding    = SkToS8(winding);
    fCurveShift = 0;

    if (clip) {
        this->chopLineWithClip(*clip);
    }
    return 1;
}

int SkPDFCatalog::assignObjNum(SkPDFObject* obj) {
    int pos = findObjectIndex(obj);
    // If this assert fails, it means you probably forgot to add an object
    // to the resource list.
    SkASSERT(pos >= 0);
    uint32_t currentIndex = pos;
    if (fCatalog[currentIndex].fObjNumAssigned) {
        return currentIndex + 1;
    }

    // First assignment.
    if (fNextFirstPageObjNum == 0) {
        fNextFirstPageObjNum = fCatalog.count() - fFirstPageCount + 1;
    }

    uint32_t objNum;
    if (fCatalog[currentIndex].fOnFirstPage) {
        objNum = fNextFirstPageObjNum;
        fNextFirstPageObjNum++;
    } else {
        objNum = fNextObjNum;
        fNextObjNum++;
    }

    // When we assign an object an object number, we put it in that array
    // offset (minus 1 because object number 0 is reserved).
    SkASSERT(!fCatalog[objNum - 1].fObjNumAssigned);
    if (objNum - 1 != currentIndex) {
        SkTSwap(fCatalog[objNum - 1], fCatalog[currentIndex]);
    }
    fCatalog[objNum - 1].fObjNumAssigned = true;
    return objNum;
}

static int winding_line(const SkPoint pts[], SkScalar x, SkScalar y) {
    SkScalar x0 = pts[0].fX;
    SkScalar y0 = pts[0].fY;
    SkScalar x1 = pts[1].fX;
    SkScalar y1 = pts[1].fY;

    SkScalar dy = y1 - y0;

    int dir = 1;
    if (y0 > y1) {
        SkTSwap(y0, y1);
        dir = -1;
    }
    if (y < y0 || y >= y1) {
        return 0;
    }

    SkScalar cross = SkScalarMul(x1 - x0, y - pts[0].fY) -
                     SkScalarMul(dy, x - pts[0].fX);

    if (SkScalarSignAsInt(cross) == dir) {
        dir = 0;
    }
    return dir;
}

void GrGpuGLShaders::flushTextureDomain(int s) {
    const GrGLint& uni = fProgramData->fUniLocations.fStages[s].fTexDomUni;
    const GrDrawState& drawState = this->getDrawState();
    if (GrGLProgram::kUnusedUniform != uni) {
        const GrRect &texDom = drawState.getSampler(s).getTextureDomain();

        if (((1 << s) & fDirtyFlags.fTextureChangedMask) ||
            fProgramData->fTextureDomain[s] != texDom) {

            fProgramData->fTextureDomain[s] = texDom;

            float values[4] = {
                GrScalarToFloat(texDom.left()),
                GrScalarToFloat(texDom.top()),
                GrScalarToFloat(texDom.right()),
                GrScalarToFloat(texDom.bottom())
            };

            const GrGLTexture* texture =
                static_cast<const GrGLTexture*>(drawState.getTexture(s));
            GrGLTexture::Orientation orientation = texture->orientation();

            // vertical flip if necessary
            if (GrGLTexture::kBottomUp_Orientation == orientation) {
                values[1] = 1.0f - values[1];
                values[3] = 1.0f - values[3];
                // The top and bottom were just flipped, so correct the ordering
                // of elements so that values = (l, t, r, b).
                SkTSwap(values[1], values[3]);
            }

            GL_CALL(Uniform4fv(uni, 1, values));
        }
    }
}

// Returns true if a ray from (0,0) to (x1,y1) is coincident with a ray (0,0) to (x2,y2)
// OPTIMIZE: a specialty routine could speed this up -- may not be called very often though
bool SkDLine::NearRay(double x1, double y1, double x2, double y2) {
    double denom1 = x1 * x1 + y1 * y1;
    double denom2 = x2 * x2 + y2 * y2;
    SkDLine line = {{{0, 0}, {x1, y1}}};
    SkDPoint pt = {x2, y2};
    if (denom2 > denom1) {
        SkTSwap(line[1], pt);
    }
    return line.nearRay(pt);
}

static int vertical_coincident(const SkDLine& line, double x) {
    double min = line[0].fX;
    double max = line[1].fX;
    if (min > max) {
        SkTSwap(min, max);
    }
    if (!precisely_between(min, x, max)) {
        return 0;
    }
    if (AlmostEqualUlps(min, max)) {
        return 2;
    }
    return 1;
}

static int horizontal_coincident(const SkDLine& line, double y) {
    double min = line[0].fY;
    double max = line[1].fY;
    if (min > max) {
        SkTSwap(min, max);
    }
    if (min > y || max < y) {
        return 0;
    }
    if (AlmostEqualUlps(min, max) && max - min < fabs(line[0].fX - line[1].fX)) {
        return 2;
    }
    return 1;
}

template <typename T> T pin_unsorted(T value, T limit0, T limit1) {
    if (limit1 < limit0) {
        SkTSwap(limit0, limit1);
    }
    // now the limits are sorted
    SkASSERT(limit0 <= limit1);

    if (value < limit0) {
        value = limit0;
    } else if (value > limit1) {
        value = limit1;
    }
    return value;
}

int intersect(const Cubic& c, Intersections& i) {
    // check to see if x or y end points are the extrema. Are other quick rejects possible?
    if (ends_are_extrema_in_x_or_y(c)) {
        return false;
    }
    (void) intersect3(c, c, i);
    if (i.used() > 0) {
        SkASSERT(i.used() == 1);
        if (i.fT[0][0] > i.fT[1][0]) {
            SkTSwap(i.fT[0][0], i.fT[1][0]);
        }
    }
    return i.used();
}

void SkLinearGradient::
LinearGradient4fContext::shadeSpanInternal(int x, int y, dstType dst[], int count,
                                           float bias0, float bias1) const {
    SkPoint pt;
    fDstToPosProc(fDstToPos,
                  x + SK_ScalarHalf,
                  y + SK_ScalarHalf,
                  &pt);
    const SkScalar fx = pinFx<tileMode>(pt.x());
    const SkScalar dx = fDstToPos.getScaleX();
    LinearIntervalProcessor<dstType, premul, tileMode> proc(fIntervals->begin(),
                                                            fIntervals->end() - 1,
                                                            this->findInterval(fx),
                                                            fx,
                                                            dx,
                                                            SkScalarNearlyZero(dx * count));
    Sk4f bias4f0(bias0),
         bias4f1(bias1);

    while (count > 0) {
        // What we really want here is SkTPin(advance, 1, count)
        // but that's a significant perf hit for >> stops; investigate.
        const int n = SkScalarTruncToInt(
            SkTMin<SkScalar>(proc.currentAdvance() + 1, SkIntToScalar(count)));

        // The current interval advance can be +inf (e.g. when reaching
        // the clamp mode end intervals) - when that happens, we expect to
        //   a) consume all remaining count in one swoop
        //   b) return a zero color gradient
        SkASSERT(SkScalarIsFinite(proc.currentAdvance())
            || (n == count && proc.currentRampIsZero()));

        if (proc.currentRampIsZero()) {
            DstTraits<dstType, premul>::store(proc.currentColor(), dst, n);
        } else {
            ramp<dstType, premul>(proc.currentColor(), proc.currentColorGrad(), dst, n,
                                  bias4f0, bias4f1);
        }

        proc.advance(SkIntToScalar(n));
        count -= n;
        dst   += n;

        if (n & 1) {
            SkTSwap(bias4f0, bias4f1);
        }
    }
}

static void intersectWithOrder(const Quadratic& simple1, int order1, const Quadratic& simple2,
        int order2, Intersections& i) {
    if (order1 == 3 && order2 == 3) {
        intersect2(simple1, simple2, i);
    } else if (order1 <= 2 && order2 <= 2) {
        intersect((const _Line&) simple1, (const _Line&) simple2, i);
    } else if (order1 == 3 && order2 <= 2) {
        intersect(simple1, (const _Line&) simple2, i);
    } else {
        SkASSERT(order1 <= 2 && order2 == 3);
        intersect(simple2, (const _Line&) simple1, i);
        for (int s = 0; s < i.fUsed; ++s) {
            SkTSwap(i.fT[0][s], i.fT[1][s]);
        }
    }
}

void CubicPathToSimple(const SkPath& cubicPath, SkPath* simplePath) {
    simplePath->reset();
    SkDCubic cubic;
    SkPath::RawIter iter(cubicPath);
    uint8_t verb;
    SkPoint pts[4];
    while ((verb = iter.next(pts)) != SkPath::kDone_Verb) {
        switch (verb) {
            case SkPath::kMove_Verb:
                simplePath->moveTo(pts[0].fX, pts[0].fY);
                continue;
            case SkPath::kLine_Verb:
                simplePath->lineTo(pts[1].fX, pts[1].fY);
                break;
            case SkPath::kQuad_Verb:
                simplePath->quadTo(pts[1].fX, pts[1].fY, pts[2].fX, pts[2].fY);
                break;
            case SkPath::kCubic_Verb: {
                cubic.set(pts);
                double tInflects[2];
                int inflections = cubic.findInflections(tInflects);
                if (inflections > 1 && tInflects[0] > tInflects[1]) {
                    SkTSwap(tInflects[0], tInflects[1]);
                }
                double lo = 0;
                for (int index = 0; index <= inflections; ++index) {
                    double hi = index < inflections ? tInflects[index] : 1;
                    SkDCubic part = cubic.subDivide(lo, hi);
                    SkPoint cPts[3];
                    cPts[0] = part[1].asSkPoint();
                    cPts[1] = part[2].asSkPoint();
                    cPts[2] = part[3].asSkPoint();
                    simplePath->cubicTo(cPts[0].fX, cPts[0].fY, cPts[1].fX, cPts[1].fY,
                            cPts[2].fX, cPts[2].fY);
                    lo = hi;
                }
                break;
            } 
            case SkPath::kClose_Verb:
                 simplePath->close();
                break;
            default:
                SkDEBUGFAIL("bad verb");
                return;
        }
    }
}