pathops version two

tests/PathOpsTestCommon.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 "PathOpsTestCommon.h"
 #include "SkPathOpsBounds.h"
 #include "SkPathOpsCubic.h"
 #include "SkPathOpsLine.h"
 #include "SkPathOpsQuad.h"
-#include "SkPathOpsTriangle.h"
+#include "SkReduceOrder.h"
+#include "SkTSort.h"
+
+static double calc_t_div(const SkDCubic& cubic, double precision, double start) {
+    const double adjust = sqrt(3.) / 36;
+    SkDCubic sub;
+    const SkDCubic* cPtr;
+    if (start == 0) {
+        cPtr = &cubic;
+    } else {
+        // OPTIMIZE: special-case half-split ?
+        sub = cubic.subDivide(start, 1);
+        cPtr = ⊂
+    }
+    const SkDCubic& c = *cPtr;
+    double dx = c[3].fX - 3 * (c[2].fX - c[1].fX) - c[0].fX;
+    double dy = c[3].fY - 3 * (c[2].fY - c[1].fY) - c[0].fY;
+    double dist = sqrt(dx * dx + dy * dy);
+    double tDiv3 = precision / (adjust * dist);
+    double t = SkDCubeRoot(tDiv3);
+    if (start > 0) {
+        t = start + (1 - start) * t;
+    }
+    return t;
+}
+
+static bool add_simple_ts(const SkDCubic& cubic, double precision, SkTArray<double, true>* ts) {
+    double tDiv = calc_t_div(cubic, precision, 0);
+    if (tDiv >= 1) {
+        return true;
+    }
+    if (tDiv >= 0.5) {
+        ts->push_back(0.5);
+        return true;
+    }
+    return false;
+}
+
+static void addTs(const SkDCubic& cubic, double precision, double start, double end,
+        SkTArray<double, true>* ts) {
+    double tDiv = calc_t_div(cubic, precision, 0);
+    double parts = ceil(1.0 / tDiv);
+    for (double index = 0; index < parts; ++index) {
+        double newT = start + (index / parts) * (end - start);
+        if (newT > 0 && newT < 1) {
+            ts->push_back(newT);
+        }
+    }
+}
+
+static void toQuadraticTs(const SkDCubic* cubic, double precision, SkTArray<double, true>* ts) {
+    SkReduceOrder reducer;
+    int order = reducer.reduce(*cubic, SkReduceOrder::kAllow_Quadratics);
+    if (order < 3) {
+        return;
+    }
+    double inflectT[5];
+    int inflections = cubic->findInflections(inflectT);
+    SkASSERT(inflections <= 2);
+    if (!cubic->endsAreExtremaInXOrY()) {
+        inflections += cubic->findMaxCurvature(&inflectT[inflections]);
+        SkASSERT(inflections <= 5);
+    }
+    SkTQSort<double>(inflectT, &inflectT[inflections - 1]);
+    // OPTIMIZATION: is this filtering common enough that it needs to be pulled out into its
+    // own subroutine?
+    while (inflections && approximately_less_than_zero(inflectT[0])) {
+        memmove(inflectT, &inflectT[1], sizeof(inflectT[0]) * --inflections);
+    }
+    int start = 0;
+    int next = 1;
+    while (next < inflections) {
+        if (!approximately_equal(inflectT[start], inflectT[next])) {
+            ++start;
+        ++next;
+            continue;
+        }
+        memmove(&inflectT[start], &inflectT[next], sizeof(inflectT[0]) * (--inflections - start));
+    }
+
+    while (inflections && approximately_greater_than_one(inflectT[inflections - 1])) {
+        --inflections;
+    }
+    SkDCubicPair pair;
+    if (inflections == 1) {
+        pair = cubic->chopAt(inflectT[0]);
+        int orderP1 = reducer.reduce(pair.first(), SkReduceOrder::kNo_Quadratics);
+        if (orderP1 < 2) {
+            --inflections;
+        } else {
+            int orderP2 = reducer.reduce(pair.second(), SkReduceOrder::kNo_Quadratics);
+            if (orderP2 < 2) {
+                --inflections;
+            }
+        }
+    }
+    if (inflections == 0 && add_simple_ts(*cubic, precision, ts)) {
+        return;
+    }
+    if (inflections == 1) {
+        pair = cubic->chopAt(inflectT[0]);
+        addTs(pair.first(), precision, 0, inflectT[0], ts);
+        addTs(pair.second(), precision, inflectT[0], 1, ts);
+        return;
+    }
+    if (inflections > 1) {
+        SkDCubic part = cubic->subDivide(0, inflectT[0]);
+        addTs(part, precision, 0, inflectT[0], ts);
+        int last = inflections - 1;
+        for (int idx = 0; idx < last; ++idx) {
+            part = cubic->subDivide(inflectT[idx], inflectT[idx + 1]);
+            addTs(part, precision, inflectT[idx], inflectT[idx + 1], ts);
+        }
+        part = cubic->subDivide(inflectT[last], 1);
+        addTs(part, precision, inflectT[last], 1, ts);
+        return;
+    }
+    addTs(*cubic, precision, 0, 1, ts);
+}
 
 void CubicToQuads(const SkDCubic& cubic, double precision, SkTArray<SkDQuad, true>& quads) {
     SkTArray<double, true> ts;
-    cubic.toQuadraticTs(precision, &ts);
+    toQuadraticTs(&cubic, precision, &ts);
     if (ts.count() <= 0) {
         SkDQuad quad = cubic.toQuad();
         quads.push_back(quad);
         return;
     }
     double tStart = 0;
     for (int i1 = 0; i1 <= ts.count(); ++i1) {
         const double tEnd = i1 < ts.count() ? ts[i1] : 1;
         SkDCubic part = cubic.subDivide(tStart, tEnd);
         SkDQuad quad = part.toQuad();
@@ skipping 146 matching lines @@
 
 bool ValidQuad(const SkDQuad& quad) {
     for (int index = 0; index < 3; ++index) {
         if (!ValidPoint(quad[index])) {
             return false;
         }
     }
     return true;
 }
 
-bool ValidTriangle(const SkDTriangle& triangle) {
-    for (int index = 0; index < 3; ++index) {
-        if (!ValidPoint(triangle.fPts[index])) {
-            return false;
-        }
-    }
-    return true;
-}
-
 bool ValidVector(const SkDVector& v) {
     if (SkDoubleIsNaN(v.fX)) {
         return false;
     }
     return !SkDoubleIsNaN(v.fY);
 }