src/pathops/SkPathOpsCurve.h

/*
 * Copyright 2012 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
#ifndef SkPathOpsCurve_DEFINE
#define SkPathOpsCurve_DEFINE

#include "SkPathOpsCubic.h"
#include "SkPathOpsLine.h"
#include "SkPathOpsQuad.h"

static SkDPoint dline_xy_at_t(const SkPoint a[2], double t) {
    SkDLine line;
    line.set(a);
    return line.ptAtT(t);
}

static SkDPoint dquad_xy_at_t(const SkPoint a[3], double t) {
    SkDQuad quad;
    quad.set(a);
    return quad.ptAtT(t);
}

static SkDPoint dcubic_xy_at_t(const SkPoint a[4], double t) {
    SkDCubic cubic;
    cubic.set(a);
    return cubic.ptAtT(t);
}

static SkDPoint (* const CurveDPointAtT[])(const SkPoint[], double ) = {
    NULL,
    dline_xy_at_t,
    dquad_xy_at_t,
    dcubic_xy_at_t
};

static SkPoint fline_xy_at_t(const SkPoint a[2], double t) {
    return dline_xy_at_t(a, t).asSkPoint();
}

static SkPoint fquad_xy_at_t(const SkPoint a[3], double t) {
    return dquad_xy_at_t(a, t).asSkPoint();
}

static SkPoint fcubic_xy_at_t(const SkPoint a[4], double t) {
    return dcubic_xy_at_t(a, t).asSkPoint();
}

static SkPoint (* const CurvePointAtT[])(const SkPoint[], double ) = {
    NULL,
    fline_xy_at_t,
    fquad_xy_at_t,
    fcubic_xy_at_t
};

static SkDVector dline_dxdy_at_t(const SkPoint a[2], double ) {
    SkDLine line;
    line.set(a);
    return line[1] - line[0];
}

static SkDVector dquad_dxdy_at_t(const SkPoint a[3], double t) {
    SkDQuad quad;
    quad.set(a);
    return quad.dxdyAtT(t);
}

static SkDVector dcubic_dxdy_at_t(const SkPoint a[4], double t) {
    SkDCubic cubic;
    cubic.set(a);
    return cubic.dxdyAtT(t);
}

static SkDVector (* const CurveDSlopeAtT[])(const SkPoint[], double ) = {
    NULL,
    dline_dxdy_at_t,
    dquad_dxdy_at_t,
    dcubic_dxdy_at_t
};

static SkVector fline_dxdy_at_t(const SkPoint a[2], double ) {
    return a[1] - a[0];
}

static SkVector fquad_dxdy_at_t(const SkPoint a[3], double t) {
    return dquad_dxdy_at_t(a, t).asSkVector();
}

static SkVector fcubic_dxdy_at_t(const SkPoint a[4], double t) {
    return dcubic_dxdy_at_t(a, t).asSkVector();
}

static SkVector (* const CurveSlopeAtT[])(const SkPoint[], double ) = {
    NULL,
    fline_dxdy_at_t,
    fquad_dxdy_at_t,
    fcubic_dxdy_at_t
};

static SkPoint quad_top(const SkPoint a[3], double startT, double endT) {
    SkDQuad quad;
    quad.set(a);
    SkDPoint topPt = quad.top(startT, endT);
    return topPt.asSkPoint();
}

static SkPoint cubic_top(const SkPoint a[4], double startT, double endT) {
    SkDCubic cubic;
    cubic.set(a);
    SkDPoint topPt = cubic.top(startT, endT);
    return topPt.asSkPoint();
}

static SkPoint (* const CurveTop[])(const SkPoint[], double , double ) = {
    NULL,
    NULL,
    quad_top,
    cubic_top
};

static bool line_is_vertical(const SkPoint a[2], double startT, double endT) {
    SkDLine line;
    line.set(a);
    SkDPoint dst[2] = { line.ptAtT(startT), line.ptAtT(endT) };
    return AlmostEqualUlps(dst[0].fX, dst[1].fX);
}

static bool quad_is_vertical(const SkPoint a[3], double startT, double endT) {
    SkDQuad quad;
    quad.set(a);
    SkDQuad dst = quad.subDivide(startT, endT);
    return AlmostEqualUlps(dst[0].fX, dst[1].fX) && AlmostEqualUlps(dst[1].fX, dst[2].fX);
}

static bool cubic_is_vertical(const SkPoint a[4], double startT, double endT) {
    SkDCubic cubic;
    cubic.set(a);
    SkDCubic dst = cubic.subDivide(startT, endT);
    return AlmostEqualUlps(dst[0].fX, dst[1].fX) && AlmostEqualUlps(dst[1].fX, dst[2].fX)
            && AlmostEqualUlps(dst[2].fX, dst[3].fX);
}

static bool (* const CurveIsVertical[])(const SkPoint[], double , double) = {
    NULL,
    line_is_vertical,
    quad_is_vertical,
    cubic_is_vertical
};

#endif