use pathops utils to improve precision of cubic chopping in scan converter
BUG=skia:
Review URL: https://codereview.chromium.org/1113963002
diff --git a/src/core/SkEdgeClipper.cpp b/src/core/SkEdgeClipper.cpp
index 32277bc..87bfbb9 100644
--- a/src/core/SkEdgeClipper.cpp
+++ b/src/core/SkEdgeClipper.cpp
@@ -225,6 +225,7 @@
///////////////////////////////////////////////////////////////////////////////
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
static SkScalar eval_cubic_coeff(SkScalar A, SkScalar B, SkScalar C,
SkScalar D, SkScalar t) {
return SkScalarMulAdd(SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C), t, D);
@@ -274,23 +275,29 @@
static bool chopMonoCubicAtX(SkPoint pts[4], SkScalar x, SkScalar* t) {
return chopMonoCubicAt(pts[0].fX, pts[1].fX, pts[2].fX, pts[3].fX, x, t);
}
+#endif
// Modify pts[] in place so that it is clipped in Y to the clip rect
static void chop_cubic_in_Y(SkPoint pts[4], const SkRect& clip) {
// are we partially above
if (pts[0].fY < clip.fTop) {
+ SkPoint tmp[7];
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
SkScalar t;
if (chopMonoCubicAtY(pts, clip.fTop, &t)) {
- SkPoint tmp[7];
SkChopCubicAt(pts, tmp, t);
-
- // tmp[3, 4, 5].fY should all be to the below clip.fTop.
+#else
+ if (SkChopMonoCubicAtY(pts, clip.fTop, tmp)) {
+#endif
+ // tmp[3, 4].fY should all be to the below clip.fTop.
// Since we can't trust the numerics of
// the chopper, we force those conditions now
tmp[3].fY = clip.fTop;
clamp_ge(tmp[4].fY, clip.fTop);
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
clamp_ge(tmp[5].fY, clip.fTop);
+#endif
pts[0] = tmp[3];
pts[1] = tmp[4];
@@ -306,10 +313,14 @@
// are we partially below
if (pts[3].fY > clip.fBottom) {
+ SkPoint tmp[7];
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
SkScalar t;
if (chopMonoCubicAtY(pts, clip.fBottom, &t)) {
- SkPoint tmp[7];
SkChopCubicAt(pts, tmp, t);
+#else
+ if (SkChopMonoCubicAtY(pts, clip.fBottom, tmp)) {
+#endif
tmp[3].fY = clip.fBottom;
clamp_le(tmp[2].fY, clip.fBottom);
@@ -360,18 +371,24 @@
// are we partially to the left
if (pts[0].fX < clip.fLeft) {
+ SkPoint tmp[7];
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
SkScalar t;
if (chopMonoCubicAtX(pts, clip.fLeft, &t)) {
- SkPoint tmp[7];
SkChopCubicAt(pts, tmp, t);
+#else
+ if (SkChopMonoCubicAtX(pts, clip.fLeft, tmp)) {
+#endif
this->appendVLine(clip.fLeft, tmp[0].fY, tmp[3].fY, reverse);
- // tmp[3, 4, 5].fX should all be to the right of clip.fLeft.
+ // tmp[3, 4].fX should all be to the right of clip.fLeft.
// Since we can't trust the numerics of
// the chopper, we force those conditions now
tmp[3].fX = clip.fLeft;
clamp_ge(tmp[4].fX, clip.fLeft);
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
clamp_ge(tmp[5].fX, clip.fLeft);
+#endif
pts[0] = tmp[3];
pts[1] = tmp[4];
@@ -386,13 +403,19 @@
// are we partially to the right
if (pts[3].fX > clip.fRight) {
+ SkPoint tmp[7];
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
SkScalar t;
if (chopMonoCubicAtX(pts, clip.fRight, &t)) {
- SkPoint tmp[7];
SkChopCubicAt(pts, tmp, t);
+#else
+ if (SkChopMonoCubicAtX(pts, clip.fRight, tmp)) {
+#endif
tmp[3].fX = clip.fRight;
clamp_le(tmp[2].fX, clip.fRight);
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
clamp_le(tmp[1].fX, clip.fRight);
+#endif
this->appendCubic(tmp, reverse);
this->appendVLine(clip.fRight, tmp[3].fY, tmp[6].fY, reverse);
diff --git a/src/core/SkGeometry.cpp b/src/core/SkGeometry.cpp
index b9366f3..671a1ea 100644
--- a/src/core/SkGeometry.cpp
+++ b/src/core/SkGeometry.cpp
@@ -916,6 +916,33 @@
return count + 1;
}
+#include "../pathops/SkPathOpsCubic.h"
+
+typedef int (SkDCubic::*InterceptProc)(double intercept, double roots[3]) const;
+
+static bool cubic_dchop_at_intercept(const SkPoint src[4], SkScalar intercept, SkPoint dst[7],
+ InterceptProc method) {
+ SkDCubic cubic;
+ double roots[3];
+ int count = (cubic.set(src).*method)(intercept, roots);
+ if (count > 0) {
+ SkDCubicPair pair = cubic.chopAt(roots[0]);
+ for (int i = 0; i < 7; ++i) {
+ dst[i] = pair.pts[i].asSkPoint();
+ }
+ return true;
+ }
+ return false;
+}
+
+bool SkChopMonoCubicAtY(SkPoint src[4], SkScalar y, SkPoint dst[7]) {
+ return cubic_dchop_at_intercept(src, y, dst, &SkDCubic::horizontalIntersect);
+}
+
+bool SkChopMonoCubicAtX(SkPoint src[4], SkScalar x, SkPoint dst[7]) {
+ return cubic_dchop_at_intercept(src, x, dst, &SkDCubic::verticalIntersect);
+}
+
///////////////////////////////////////////////////////////////////////////////
/* Find t value for quadratic [a, b, c] = d.
diff --git a/src/core/SkGeometry.h b/src/core/SkGeometry.h
index 811678e..a0c13d6 100644
--- a/src/core/SkGeometry.h
+++ b/src/core/SkGeometry.h
@@ -166,6 +166,9 @@
int SkChopCubicAtMaxCurvature(const SkPoint src[4], SkPoint dst[13],
SkScalar tValues[3] = NULL);
+bool SkChopMonoCubicAtX(SkPoint src[4], SkScalar y, SkPoint dst[7]);
+bool SkChopMonoCubicAtY(SkPoint src[4], SkScalar x, SkPoint dst[7]);
+
enum SkCubicType {
kSerpentine_SkCubicType,
kCusp_SkCubicType,
diff --git a/src/pathops/SkDCubicLineIntersection.cpp b/src/pathops/SkDCubicLineIntersection.cpp
index f658b09..ee1e3d3 100644
--- a/src/pathops/SkDCubicLineIntersection.cpp
+++ b/src/pathops/SkDCubicLineIntersection.cpp
@@ -425,3 +425,13 @@
}
return fUsed;
}
+
+// SkDCubic accessors to Intersection utilities
+
+int SkDCubic::horizontalIntersect(double yIntercept, double roots[3]) const {
+ return LineCubicIntersections::HorizontalIntersect(*this, yIntercept, roots);
+}
+
+int SkDCubic::verticalIntersect(double xIntercept, double roots[3]) const {
+ return LineCubicIntersections::VerticalIntersect(*this, xIntercept, roots);
+}
diff --git a/src/pathops/SkPathOpsCubic.h b/src/pathops/SkPathOpsCubic.h
index f9d2910..3d68151 100644
--- a/src/pathops/SkPathOpsCubic.h
+++ b/src/pathops/SkPathOpsCubic.h
@@ -97,6 +97,17 @@
int searchRoots(double extremes[6], int extrema, double axisIntercept,
SearchAxis xAxis, double* validRoots) const;
+ /**
+ * Return the number of valid roots (0 < root < 1) for this cubic intersecting the
+ * specified horizontal line.
+ */
+ int horizontalIntersect(double yIntercept, double roots[3]) const;
+ /**
+ * Return the number of valid roots (0 < root < 1) for this cubic intersecting the
+ * specified vertical line.
+ */
+ int verticalIntersect(double xIntercept, double roots[3]) const;
+
const SkDCubic& set(const SkPoint pts[kPointCount]) {
fPts[0] = pts[0];
fPts[1] = pts[1];