Fix SkPathStroker::lineTo() for line with length SK_ScalarNearlyZero
Review URL: https://codereview.appspot.com/5992077
git-svn-id: http://skia.googlecode.com/svn/trunk@3650 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/core/SkPoint.cpp b/src/core/SkPoint.cpp
index 5747504..a347b86 100644
--- a/src/core/SkPoint.cpp
+++ b/src/core/SkPoint.cpp
@@ -87,31 +87,49 @@
return this->setLength(fX, fY, length);
}
+#ifdef SK_SCALAR_IS_FLOAT
+
+// Returns the square of the Euclidian distance to (dx,dy).
+static inline float getLengthSquared(float dx, float dy) {
+ return dx * dx + dy * dy;
+}
+
+// Calculates the square of the Euclidian distance to (dx,dy) and stores it in
+// *lengthSquared. Returns true if the distance is judged to be "nearly zero".
+//
+// This logic is encapsulated in a helper method to make it explicit that we
+// always perform this check in the same manner, to avoid inconsistencies
+// (see http://code.google.com/p/skia/issues/detail?id=560 ).
+static inline bool isLengthNearlyZero(float dx, float dy,
+ float *lengthSquared) {
+ *lengthSquared = getLengthSquared(dx, dy);
+ return *lengthSquared <= (SK_ScalarNearlyZero * SK_ScalarNearlyZero);
+}
+
SkScalar SkPoint::Normalize(SkPoint* pt) {
- SkScalar mag = SkPoint::Length(pt->fX, pt->fY);
- if (mag > SK_ScalarNearlyZero) {
- SkScalar scale = SkScalarInvert(mag);
- pt->fX = SkScalarMul(pt->fX, scale);
- pt->fY = SkScalarMul(pt->fY, scale);
+ float mag2;
+ if (!isLengthNearlyZero(pt->fX, pt->fY, &mag2)) {
+ float mag = sk_float_sqrt(mag2);
+ float scale = 1.0 / mag;
+ pt->fX = pt->fX * scale;
+ pt->fY = pt->fY * scale;
return mag;
}
return 0;
}
-#ifdef SK_SCALAR_IS_FLOAT
-
bool SkPoint::CanNormalize(SkScalar dx, SkScalar dy) {
- float mag2 = dx * dx + dy * dy;
- return mag2 > SK_ScalarNearlyZero * SK_ScalarNearlyZero;
+ float mag2_unused;
+ return !isLengthNearlyZero(dx, dy, &mag2_unused);
}
SkScalar SkPoint::Length(SkScalar dx, SkScalar dy) {
- return sk_float_sqrt(dx * dx + dy * dy);
+ return sk_float_sqrt(getLengthSquared(dx, dy));
}
bool SkPoint::setLength(float x, float y, float length) {
- float mag2 = x * x + y * y;
- if (mag2 > SK_ScalarNearlyZero * SK_ScalarNearlyZero) {
+ float mag2;
+ if (!isLengthNearlyZero(x, y, &mag2)) {
float scale = length / sk_float_sqrt(mag2);
fX = x * scale;
fY = y * scale;
@@ -124,12 +142,25 @@
#include "Sk64.h"
-bool SkPoint::CanNormalize(SkScalar dx, SkScalar dy) {
- Sk64 tmp1, tmp2, tolSqr;
-
- tmp1.setMul(dx, dx);
- tmp2.setMul(dy, dy);
- tmp1.add(tmp2);
+// Returns the square of the Euclidian distance to (dx,dy) in *result.
+static inline void getLengthSquared(SkScalar dx, SkScalar dy, Sk64 *result) {
+ Sk64 dySqr;
+
+ result->setMul(dx, dx);
+ dySqr.setMul(dy, dy);
+ result->add(dySqr);
+}
+
+// Calculates the square of the Euclidian distance to (dx,dy) and stores it in
+// *lengthSquared. Returns true if the distance is judged to be "nearly zero".
+//
+// This logic is encapsulated in a helper method to make it explicit that we
+// always perform this check in the same manner, to avoid inconsistencies
+// (see http://code.google.com/p/skia/issues/detail?id=560 ).
+static inline bool isLengthNearlyZero(SkScalar dx, SkScalar dy,
+ Sk64 *lengthSquared) {
+ Sk64 tolSqr;
+ getLengthSquared(dx, dy, lengthSquared);
// we want nearlyzero^2, but to compute it fast we want to just do a
// 32bit multiply, so we require that it not exceed 31bits. That is true
@@ -138,17 +169,30 @@
SkASSERT(SK_ScalarNearlyZero <= 0xB504);
tolSqr.set(0, SK_ScalarNearlyZero * SK_ScalarNearlyZero);
- return tmp1 > tolSqr;
+ return *lengthSquared <= tolSqr;
+}
+
+SkScalar SkPoint::Normalize(SkPoint* pt) {
+ Sk64 mag2;
+ if (!isLengthNearlyZero(pt->fX, pt->fY, &mag2)) {
+ SkScalar mag = mag2.getSqrt();
+ SkScalar scale = SkScalarInvert(mag);
+ pt->fX = SkScalarMul(pt->fX, scale);
+ pt->fY = SkScalarMul(pt->fY, scale);
+ return mag;
+ }
+ return 0;
+}
+
+bool SkPoint::CanNormalize(SkScalar dx, SkScalar dy) {
+ Sk64 mag2_unused;
+ return !isLengthNearlyZero(dx, dy, &mag2_unused);
}
SkScalar SkPoint::Length(SkScalar dx, SkScalar dy) {
- Sk64 tmp1, tmp2;
-
- tmp1.setMul(dx, dx);
- tmp2.setMul(dy, dy);
- tmp1.add(tmp2);
-
- return tmp1.getSqrt();
+ Sk64 tmp;
+ getLengthSquared(dx, dy, &tmp);
+ return tmp.getSqrt();
}
#ifdef SK_DEBUGx