Add base types for path ops

Paths contain lines, quads, and cubics, which are
collectively curves.

To work with path intersections, intermediary curves
are constructed. For now, those intermediates use
doubles to guarantee sufficient precision.

The DVector, DPoint, DLine, DQuad, and DCubic
structs encapsulate these intermediate curves.

The DRect and DTriangle structs are created to
describe intersectable areas of interest.

The Bounds struct inherits from SkRect to create
a SkScalar-based rectangle that intersects shared
edges.

This also includes common math equalities and
debugging that the remainder of path ops builds on,
as well as a temporary top-level interface in
include/pathops/SkPathOps.h.
Review URL: https://codereview.chromium.org/12827020

git-svn-id: http://skia.googlecode.com/svn/trunk@8551 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 243 insertions, 0 deletions

diff --git a/src/pathops/SkIntersections.h b/src/pathops/SkIntersections.h
new file mode 100644
index 0000000000..c2f05fe936
--- /dev/null
+++ b/src/pathops/SkIntersections.h
@@ -0,0 +1,243 @@
+/*
+ * 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 SkIntersections_DEFINE
+#define SkIntersections_DEFINE
+
+#include "SkPathOpsCubic.h"
+#include "SkPathOpsLine.h"
+#include "SkPathOpsPoint.h"
+#include "SkPathOpsQuad.h"
+
+class SkIntersections {
+public:
+    SkIntersections()
+        : fSwap(0)
+#ifdef SK_DEBUG
+        , fDepth(0)
+#endif
+    {
+        sk_bzero(fPt, sizeof(fPt));
+        sk_bzero(fT, sizeof(fT));
+        sk_bzero(fIsCoincident, sizeof(fIsCoincident));
+        reset();
+    }
+
+    class TArray {
+    public:
+        explicit TArray(const double ts[9]) : fTArray(ts) {}
+        double operator[](int n) const {
+            return fTArray[n];
+        }
+        const double* fTArray;
+    };
+    TArray operator[](int n) const { return TArray(fT[n]); }
+
+    int cubic(const SkPoint a[4]) {
+        SkDCubic cubic;
+        cubic.set(a);
+        return intersect(cubic);
+    }
+
+    int cubicCubic(const SkPoint a[4], const SkPoint b[4]) {
+        SkDCubic aCubic;
+        aCubic.set(a);
+        SkDCubic bCubic;
+        bCubic.set(b);
+        return intersect(aCubic, bCubic);
+    }
+
+    int cubicHorizontal(const SkPoint a[4], SkScalar left, SkScalar right, SkScalar y,
+                        bool flipped) {
+        SkDCubic cubic;
+        cubic.set(a);
+        return horizontal(cubic, left, right, y, flipped);
+    }
+
+    int cubicVertical(const SkPoint a[4], SkScalar top, SkScalar bottom, SkScalar x, bool flipped) {
+        SkDCubic cubic;
+        cubic.set(a);
+        return vertical(cubic, top, bottom, x, flipped);
+    }
+
+    int cubicLine(const SkPoint a[4], const SkPoint b[2]) {
+        SkDCubic cubic;
+        cubic.set(a);
+        SkDLine line;
+        line.set(b);
+        return intersect(cubic, line);
+    }
+
+    int cubicQuad(const SkPoint a[4], const SkPoint b[3]) {
+        SkDCubic cubic;
+        cubic.set(a);
+        SkDQuad quad;
+        quad.set(b);
+        return intersect(cubic, quad);
+    }
+
+    int insertSwap(double one, double two, const SkDPoint& pt) {
+        if (fSwap) {
+            return insert(two, one, pt);
+        } else {
+            return insert(one, two, pt);
+        }
+    }
+
+    bool isCoincident(int index) {
+        return (fIsCoincident[0] & 1 << index) != 0;
+    }
+
+    int lineHorizontal(const SkPoint a[2], SkScalar left, SkScalar right, SkScalar y,
+                       bool flipped) {
+        SkDLine line;
+        line.set(a);
+        return horizontal(line, left, right, y, flipped);
+    }
+
+    int lineVertical(const SkPoint a[2], SkScalar top, SkScalar bottom, SkScalar x, bool flipped) {
+        SkDLine line;
+        line.set(a);
+        return vertical(line, top, bottom, x, flipped);
+    }
+
+    int lineLine(const SkPoint a[2], const SkPoint b[2]) {
+        SkDLine aLine, bLine;
+        aLine.set(a);
+        bLine.set(b);
+        return intersect(aLine, bLine);
+    }
+
+    const SkDPoint& pt(int index) const {
+        return fPt[index];
+    }
+
+    int quadHorizontal(const SkPoint a[3], SkScalar left, SkScalar right, SkScalar y,
+                       bool flipped) {
+        SkDQuad quad;
+        quad.set(a);
+        return horizontal(quad, left, right, y, flipped);
+    }
+
+    int quadVertical(const SkPoint a[3], SkScalar top, SkScalar bottom, SkScalar x, bool flipped) {
+        SkDQuad quad;
+        quad.set(a);
+        return vertical(quad, top, bottom, x, flipped);
+    }
+
+    int quadLine(const SkPoint a[3], const SkPoint b[2]) {
+        SkDQuad quad;
+        quad.set(a);
+        SkDLine line;
+        line.set(b);
+        return intersect(quad, line);
+    }
+
+    int quadQuad(const SkPoint a[3], const SkPoint b[3]) {
+        SkDQuad aQuad;
+        aQuad.set(a);
+        SkDQuad bQuad;
+        bQuad.set(b);
+        return intersect(aQuad, bQuad);
+    }
+
+    int quadRay(const SkPoint pts[3], const SkDLine& line);
+    void removeOne(int index);
+
+    // leaves flip, swap alone
+    void reset() {
+        fUsed = 0;
+    }
+
+    void swap() {
+        fSwap ^= true;
+    }
+
+    void swapPts();
+
+    bool swapped() const {
+        return fSwap;
+    }
+
+    int used() const {
+        return fUsed;
+    }
+
+    void downDepth() {
+        SkASSERT(--fDepth >= 0);
+    }
+
+    void upDepth() {
+        SkASSERT(++fDepth < 16);
+    }
+
+    static double Axial(const SkDQuad& , const SkDPoint& , bool vertical);
+    int coincidentUsed() const;
+    int cubicRay(const SkPoint pts[4], const SkDLine& line);
+    void flip();
+    int horizontal(const SkDLine&, double y);
+    int horizontal(const SkDLine&, double left, double right, double y);
+    int horizontal(const SkDLine&, double left, double right, double y, bool flipped);
+    int horizontal(const SkDQuad&, double left, double right, double y, bool flipped);
+    int horizontal(const SkDQuad&, double left, double right, double y, double tRange[2]);
+    int horizontal(const SkDCubic&, double y, double tRange[3]);
+    int horizontal(const SkDCubic&, double left, double right, double y, bool flipped);
+    int horizontal(const SkDCubic&, double left, double right, double y, double tRange[3]);
+    // FIXME : does not respect swap
+    int insert(double one, double two, const SkDPoint& pt);
+    // start if index == 0 : end if index == 1
+    void insertCoincident(double one, double two, const SkDPoint& pt);
+    void insertCoincidentPair(double s1, double e1, double s2, double e2,
+            const SkDPoint& startPt, const SkDPoint& endPt);
+    int intersect(const SkDLine&, const SkDLine&);
+    int intersect(const SkDQuad&, const SkDLine&);
+    int intersect(const SkDQuad&, const SkDQuad&);
+    int intersect(const SkDCubic&);  // return true if cubic self-intersects
+    int intersect(const SkDCubic&, const SkDLine&);
+    int intersect(const SkDCubic&, const SkDQuad&);
+    int intersect(const SkDCubic&, const SkDCubic&);
+    int intersectRay(const SkDCubic& , const SkDLine&);
+    int intersectRay(const SkDQuad& , const SkDLine&);
+    static SkDPoint Line(const SkDLine& , const SkDLine&);
+    void offset(int base, double start, double end);
+    void quickRemoveOne(int index, int replace);
+    static bool Test(const SkDLine& , const SkDLine&);
+    int vertical(const SkDLine&, double x);
+    int vertical(const SkDLine&, double top, double bottom, double x, bool flipped);
+    int vertical(const SkDQuad&, double top, double bottom, double x, bool flipped);
+    int vertical(const SkDCubic&, double top, double bottom, double x, bool flipped);
+    int verticalCubic(const SkPoint a[4], SkScalar top, SkScalar bottom, SkScalar x, bool flipped);
+    int verticalLine(const SkPoint a[2], SkScalar top, SkScalar bottom, SkScalar x, bool flipped);
+    int verticalQuad(const SkPoint a[3], SkScalar top, SkScalar bottom, SkScalar x, bool flipped);
+
+    int depth() const {
+#ifdef SK_DEBUG
+        return fDepth;
+#else
+        return 0;
+#endif
+    }
+
+private:
+    int computePoints(const SkDLine& line, int used);
+    // used by addCoincident to remove ordinary intersections in range
+    void remove(double one, double two, const SkDPoint& startPt, const SkDPoint& endPt);
+
+    SkDPoint fPt[9];
+    double fT[2][9];
+    uint16_t fIsCoincident[2];  // bit arrays, one bit set for each coincident T
+    unsigned char fUsed;
+    bool fSwap;
+#ifdef SK_DEBUG
+    int fDepth;
+#endif
+};
+
+extern int (SkIntersections::*CurveRay[])(const SkPoint[], const SkDLine& );
+extern int (SkIntersections::*CurveVertical[])(const SkPoint[], SkScalar top, SkScalar bottom,
+            SkScalar x, bool flipped);
+
+#endif