remove prototype pathops code

experimental/Intersection/CubicBezierClip.cpp

-/*
- * Copyright 2012 Google Inc.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-#include "CurveIntersection.h"
-#include "CurveUtilities.h"
-#include "LineParameters.h"
-
-// return false if unable to clip (e.g., unable to create implicit line)
-// caller should subdivide, or create degenerate if the values are too small
-bool bezier_clip(const Cubic& cubic1, const Cubic& cubic2, double& minT, double& maxT) {
-    minT = 1;
-    maxT = 0;
-    // determine normalized implicit line equation for pt[0] to pt[3]
-    //   of the form ax + by + c = 0, where a*a + b*b == 1
-
-    // find the implicit line equation parameters
-    LineParameters endLine;
-    endLine.cubicEndPoints(cubic1);
-    if (!endLine.normalize()) {
-        printf("line cannot be normalized: need more code here\n");
-        return false;
-    }
-
-    double distance[2];
-    distance[0] = endLine.controlPtDistance(cubic1, 1);
-    distance[1] = endLine.controlPtDistance(cubic1, 2);
-
-    // find fat line
-    double top = distance[0];
-    double bottom = distance[1];
-    if (top > bottom) {
-        SkTSwap(top, bottom);
-    }
-    if (top * bottom >= 0) {
-        const double scale = 3/4.0; // http://cagd.cs.byu.edu/~tom/papers/bezclip.pdf (13)
-        if (top < 0) {
-            top *= scale;
-            bottom = 0;
-        } else {
-            top = 0;
-            bottom *= scale;
-        }
-    } else {
-        const double scale = 4/9.0; // http://cagd.cs.byu.edu/~tom/papers/bezclip.pdf (15)
-        top *= scale;
-        bottom *= scale;
-    }
-
-    // compute intersecting candidate distance
-    Cubic distance2y; // points with X of (0, 1/3, 2/3, 1)
-    endLine.cubicDistanceY(cubic2, distance2y);
-
-    int flags = 0;
-    if (approximately_lesser_or_equal(distance2y[0].y, top)) {
-        flags |= kFindTopMin;
-    } else if (approximately_greater_or_equal(distance2y[0].y, bottom)) {
-        flags |= kFindBottomMin;
-    } else {
-        minT = 0;
-    }
-
-    if (approximately_lesser_or_equal(distance2y[3].y, top)) {
-        flags |= kFindTopMax;
-    } else if (approximately_greater_or_equal(distance2y[3].y, bottom)) {
-        flags |= kFindBottomMax;
-    } else {
-        maxT = 1;
-    }
-    // Find the intersection of distance convex hull and fat line.
-    char to_0[2];
-    char to_3[2];
-    bool do_1_2_edge = convex_x_hull(distance2y, to_0, to_3);
-    x_at(distance2y[0], distance2y[to_0[0]], top, bottom, flags, minT, maxT);
-    if (to_0[0] != to_0[1]) {
-        x_at(distance2y[0], distance2y[to_0[1]], top, bottom, flags, minT, maxT);
-    }
-    x_at(distance2y[to_3[0]], distance2y[3], top, bottom, flags, minT, maxT);
-    if (to_3[0] != to_3[1]) {
-        x_at(distance2y[to_3[1]], distance2y[3], top, bottom, flags, minT, maxT);
-    }
-    if (do_1_2_edge) {
-        x_at(distance2y[1], distance2y[2], top, bottom, flags, minT, maxT);
-    }
-
-    return minT < maxT; // returns false if distance shows no intersection
-}