move some headers out of public

include/core/SkGeometry.h

-
-/*
- * Copyright 2006 The Android Open Source Project
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-
-#ifndef SkGeometry_DEFINED
-#define SkGeometry_DEFINED
-
-#include "SkMatrix.h"
-
-/** An XRay is a half-line that runs from the specific point/origin to
-    +infinity in the X direction. e.g. XRay(3,5) is the half-line
-    (3,5)....(infinity, 5)
- */
-typedef SkPoint SkXRay;
-
-/** Given a line segment from pts[0] to pts[1], and an xray, return true if
-    they intersect. Optional outgoing "ambiguous" argument indicates
-    whether the answer is ambiguous because the query occurred exactly at
-    one of the endpoints' y coordinates, indicating that another query y
-    coordinate is preferred for robustness.
-*/
-bool SkXRayCrossesLine(const SkXRay& pt, const SkPoint pts[2],
-                       bool* ambiguous = NULL);
-
-/** Given a quadratic equation Ax^2 + Bx + C = 0, return 0, 1, 2 roots for the
-    equation.
-*/
-int SkFindUnitQuadRoots(SkScalar A, SkScalar B, SkScalar C, SkScalar roots[2]);
-
-///////////////////////////////////////////////////////////////////////////////
-
-/** Set pt to the point on the src quadratic specified by t. t must be
-    0 <= t <= 1.0
-*/
-void SkEvalQuadAt(const SkPoint src[3], SkScalar t, SkPoint* pt,
-                  SkVector* tangent = NULL);
-void SkEvalQuadAtHalf(const SkPoint src[3], SkPoint* pt,
-                      SkVector* tangent = NULL);
-
-/** Given a src quadratic bezier, chop it at the specified t value,
-    where 0 < t < 1, and return the two new quadratics in dst:
-    dst[0..2] and dst[2..4]
-*/
-void SkChopQuadAt(const SkPoint src[3], SkPoint dst[5], SkScalar t);
-
-/** Given a src quadratic bezier, chop it at the specified t == 1/2,
-    The new quads are returned in dst[0..2] and dst[2..4]
-*/
-void SkChopQuadAtHalf(const SkPoint src[3], SkPoint dst[5]);
-
-/** Given the 3 coefficients for a quadratic bezier (either X or Y values), look
-    for extrema, and return the number of t-values that are found that represent
-    these extrema. If the quadratic has no extrema betwee (0..1) exclusive, the
-    function returns 0.
-    Returned count      tValues[]
-    0                   ignored
-    1                   0 < tValues[0] < 1
-*/
-int SkFindQuadExtrema(SkScalar a, SkScalar b, SkScalar c, SkScalar tValues[1]);
-
-/** Given 3 points on a quadratic bezier, chop it into 1, 2 beziers such that
-    the resulting beziers are monotonic in Y. This is called by the scan converter.
-    Depending on what is returned, dst[] is treated as follows
-    0   dst[0..2] is the original quad
-    1   dst[0..2] and dst[2..4] are the two new quads
-*/
-int SkChopQuadAtYExtrema(const SkPoint src[3], SkPoint dst[5]);
-int SkChopQuadAtXExtrema(const SkPoint src[3], SkPoint dst[5]);
-
-/** Given 3 points on a quadratic bezier, if the point of maximum
-    curvature exists on the segment, returns the t value for this
-    point along the curve. Otherwise it will return a value of 0.
-*/
-float SkFindQuadMaxCurvature(const SkPoint src[3]);
-
-/** Given 3 points on a quadratic bezier, divide it into 2 quadratics
-    if the point of maximum curvature exists on the quad segment.
-    Depending on what is returned, dst[] is treated as follows
-    1   dst[0..2] is the original quad
-    2   dst[0..2] and dst[2..4] are the two new quads
-    If dst == null, it is ignored and only the count is returned.
-*/
-int SkChopQuadAtMaxCurvature(const SkPoint src[3], SkPoint dst[5]);
-
-/** Given 3 points on a quadratic bezier, use degree elevation to
-    convert it into the cubic fitting the same curve. The new cubic
-    curve is returned in dst[0..3].
-*/
-SK_API void SkConvertQuadToCubic(const SkPoint src[3], SkPoint dst[4]);
-
-///////////////////////////////////////////////////////////////////////////////
-
-/** Convert from parametric from (pts) to polynomial coefficients
-    coeff[0]*T^3 + coeff[1]*T^2 + coeff[2]*T + coeff[3]
-*/
-void SkGetCubicCoeff(const SkPoint pts[4], SkScalar cx[4], SkScalar cy[4]);
-
-/** Set pt to the point on the src cubic specified by t. t must be
-    0 <= t <= 1.0
-*/
-void SkEvalCubicAt(const SkPoint src[4], SkScalar t, SkPoint* locOrNull,
-                   SkVector* tangentOrNull, SkVector* curvatureOrNull);
-
-/** Given a src cubic bezier, chop it at the specified t value,
-    where 0 < t < 1, and return the two new cubics in dst:
-    dst[0..3] and dst[3..6]
-*/
-void SkChopCubicAt(const SkPoint src[4], SkPoint dst[7], SkScalar t);
-/** Given a src cubic bezier, chop it at the specified t values,
-    where 0 < t < 1, and return the new cubics in dst:
-    dst[0..3],dst[3..6],...,dst[3*t_count..3*(t_count+1)]
-*/
-void SkChopCubicAt(const SkPoint src[4], SkPoint dst[], const SkScalar t[],
-                   int t_count);
-
-/** Given a src cubic bezier, chop it at the specified t == 1/2,
-    The new cubics are returned in dst[0..3] and dst[3..6]
-*/
-void SkChopCubicAtHalf(const SkPoint src[4], SkPoint dst[7]);
-
-/** Given the 4 coefficients for a cubic bezier (either X or Y values), look
-    for extrema, and return the number of t-values that are found that represent
-    these extrema. If the cubic has no extrema betwee (0..1) exclusive, the
-    function returns 0.
-    Returned count      tValues[]
-    0                   ignored
-    1                   0 < tValues[0] < 1
-    2                   0 < tValues[0] < tValues[1] < 1
-*/
-int SkFindCubicExtrema(SkScalar a, SkScalar b, SkScalar c, SkScalar d,
-                       SkScalar tValues[2]);
-
-/** Given 4 points on a cubic bezier, chop it into 1, 2, 3 beziers such that
-    the resulting beziers are monotonic in Y. This is called by the scan converter.
-    Depending on what is returned, dst[] is treated as follows
-    0   dst[0..3] is the original cubic
-    1   dst[0..3] and dst[3..6] are the two new cubics
-    2   dst[0..3], dst[3..6], dst[6..9] are the three new cubics
-    If dst == null, it is ignored and only the count is returned.
-*/
-int SkChopCubicAtYExtrema(const SkPoint src[4], SkPoint dst[10]);
-int SkChopCubicAtXExtrema(const SkPoint src[4], SkPoint dst[10]);
-
-/** Given a cubic bezier, return 0, 1, or 2 t-values that represent the
-    inflection points.
-*/
-int SkFindCubicInflections(const SkPoint src[4], SkScalar tValues[2]);
-
-/** Return 1 for no chop, 2 for having chopped the cubic at a single
-    inflection point, 3 for having chopped at 2 inflection points.
-    dst will hold the resulting 1, 2, or 3 cubics.
-*/
-int SkChopCubicAtInflections(const SkPoint src[4], SkPoint dst[10]);
-
-int SkFindCubicMaxCurvature(const SkPoint src[4], SkScalar tValues[3]);
-int SkChopCubicAtMaxCurvature(const SkPoint src[4], SkPoint dst[13],
-                              SkScalar tValues[3] = NULL);
-
-/** Given a monotonic cubic bezier, determine whether an xray intersects the
-    cubic.
-    By definition the cubic is open at the starting point; in other
-    words, if pt.fY is equivalent to cubic[0].fY, and pt.fX is to the
-    left of the curve, the line is not considered to cross the curve,
-    but if it is equal to cubic[3].fY then it is considered to
-    cross.
-    Optional outgoing "ambiguous" argument indicates whether the answer is
-    ambiguous because the query occurred exactly at one of the endpoints' y
-    coordinates, indicating that another query y coordinate is preferred
-    for robustness.
- */
-bool SkXRayCrossesMonotonicCubic(const SkXRay& pt, const SkPoint cubic[4],
-                                 bool* ambiguous = NULL);
-
-/** Given an arbitrary cubic bezier, return the number of times an xray crosses
-    the cubic. Valid return values are [0..3]
-    By definition the cubic is open at the starting point; in other
-    words, if pt.fY is equivalent to cubic[0].fY, and pt.fX is to the
-    left of the curve, the line is not considered to cross the curve,
-    but if it is equal to cubic[3].fY then it is considered to
-    cross.
-    Optional outgoing "ambiguous" argument indicates whether the answer is
-    ambiguous because the query occurred exactly at one of the endpoints' y
-    coordinates or at a tangent point, indicating that another query y
-    coordinate is preferred for robustness.
- */
-int SkNumXRayCrossingsForCubic(const SkXRay& pt, const SkPoint cubic[4],
-                               bool* ambiguous = NULL);
-
-///////////////////////////////////////////////////////////////////////////////
-
-enum SkRotationDirection {
-    kCW_SkRotationDirection,
-    kCCW_SkRotationDirection
-};
-
-/** Maximum number of points needed in the quadPoints[] parameter for
-    SkBuildQuadArc()
-*/
-#define kSkBuildQuadArcStorage  17
-
-/** Given 2 unit vectors and a rotation direction, fill out the specified
-    array of points with quadratic segments. Return is the number of points
-    written to, which will be { 0, 3, 5, 7, ... kSkBuildQuadArcStorage }
-
-    matrix, if not null, is appled to the points before they are returned.
-*/
-int SkBuildQuadArc(const SkVector& unitStart, const SkVector& unitStop,
-                   SkRotationDirection, const SkMatrix*, SkPoint quadPoints[]);
-
-// experimental
-struct SkConic {
-    SkPoint  fPts[3];
-    SkScalar fW;
-
-    void set(const SkPoint pts[3], SkScalar w) {
-        memcpy(fPts, pts, 3 * sizeof(SkPoint));
-        fW = w;
-    }
-
-    /**
-     *  Given a t-value [0...1] return its position and/or tangent.
-     *  If pos is not null, return its position at the t-value.
-     *  If tangent is not null, return its tangent at the t-value. NOTE the
-     *  tangent value's length is arbitrary, and only its direction should
-     *  be used.
-     */
-    void evalAt(SkScalar t, SkPoint* pos, SkVector* tangent = NULL) const;
-    void chopAt(SkScalar t, SkConic dst[2]) const;
-    void chop(SkConic dst[2]) const;
-
-    void computeAsQuadError(SkVector* err) const;
-    bool asQuadTol(SkScalar tol) const;
-
-    /**
-     *  return the power-of-2 number of quads needed to approximate this conic
-     *  with a sequence of quads. Will be >= 0.
-     */
-    int computeQuadPOW2(SkScalar tol) const;
-
-    /**
-     *  Chop this conic into N quads, stored continguously in pts[], where
-     *  N = 1 << pow2. The amount of storage needed is (1 + 2 * N)
-     */
-    int chopIntoQuadsPOW2(SkPoint pts[], int pow2) const;
-
-    bool findXExtrema(SkScalar* t) const;
-    bool findYExtrema(SkScalar* t) const;
-    bool chopAtXExtrema(SkConic dst[2]) const;
-    bool chopAtYExtrema(SkConic dst[2]) const;
-
-    void computeTightBounds(SkRect* bounds) const;
-    void computeFastBounds(SkRect* bounds) const;
-
-    /** Find the parameter value where the conic takes on its maximum curvature.
-     *
-     *  @param t   output scalar for max curvature.  Will be unchanged if
-     *             max curvature outside 0..1 range.
-     *
-     *  @return  true if max curvature found inside 0..1 range, false otherwise
-     */
-    bool findMaxCurvature(SkScalar* t) const;
-};
-
-#include "SkTemplates.h"
-
-/**
- *  Help class to allocate storage for approximating a conic with N quads.
- */
-class SkAutoConicToQuads {
-public:
-    SkAutoConicToQuads() : fQuadCount(0) {}
-
-    /**
-     *  Given a conic and a tolerance, return the array of points for the
-     *  approximating quad(s). Call countQuads() to know the number of quads
-     *  represented in these points.
-     *
-     *  The quads are allocated to share end-points. e.g. if there are 4 quads,
-     *  there will be 9 points allocated as follows
-     *      quad[0] == pts[0..2]
-     *      quad[1] == pts[2..4]
-     *      quad[2] == pts[4..6]
-     *      quad[3] == pts[6..8]
-     */
-    const SkPoint* computeQuads(const SkConic& conic, SkScalar tol) {
-        int pow2 = conic.computeQuadPOW2(tol);
-        fQuadCount = 1 << pow2;
-        SkPoint* pts = fStorage.reset(1 + 2 * fQuadCount);
-        conic.chopIntoQuadsPOW2(pts, pow2);
-        return pts;
-    }
-
-    const SkPoint* computeQuads(const SkPoint pts[3], SkScalar weight,
-                                SkScalar tol) {
-        SkConic conic;
-        conic.set(pts, weight);
-        return computeQuads(conic, tol);
-    }
-
-    int countQuads() const { return fQuadCount; }
-
-private:
-    enum {
-        kQuadCount = 8, // should handle most conics
-        kPointCount = 1 + 2 * kQuadCount,
-    };
-    SkAutoSTMalloc<kPointCount, SkPoint> fStorage;
-    int fQuadCount; // #quads for current usage
-};
-
-#endif