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Unified Diff: src/utils/SkCurveMeasure.cpp

Issue 2233983003: Add better bounds checks for getTime to fix perf debug assert below (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Created 4 years, 4 months ago
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Index: src/utils/SkCurveMeasure.cpp
diff --git a/src/utils/SkCurveMeasure.cpp b/src/utils/SkCurveMeasure.cpp
index fc2aa84faa119558d5dce1c30f6bdd826c3eb890..60fbf34ff24be9d78085f7333e4a74db0ae2b07b 100644
--- a/src/utils/SkCurveMeasure.cpp
+++ b/src/utils/SkCurveMeasure.cpp
@@ -6,10 +6,66 @@
*/
#include "SkCurveMeasure.h"
+#include "SkGeometry.h"
// for abs
#include <cmath>
+#define UNIMPLEMENTED SkDEBUGF(("%s:%d unimplemented\n", __FILE__, __LINE__))
+
+/// Used inside SkCurveMeasure::getTime's Newton's iteration
+static inline SkPoint evaluate(const SkPoint pts[4], SkSegType segType,
+ SkScalar t) {
+ SkPoint pos;
+ switch (segType) {
+ case kQuad_SegType:
+ pos = SkEvalQuadAt(pts, t);
+ break;
+ case kLine_SegType:
+ pos = SkPoint::Make(SkScalarInterp(pts[0].x(), pts[1].x(), t),
+ SkScalarInterp(pts[0].y(), pts[1].y(), t));
+ break;
+ case kCubic_SegType:
+ SkEvalCubicAt(pts, t, &pos, nullptr, nullptr);
+ break;
+ case kConic_SegType: {
+ SkConic conic(pts, pts[3].x());
+ conic.evalAt(t, &pos);
+ }
+ break;
+ default:
+ UNIMPLEMENTED;
+ }
+
+ return pos;
+}
+
+/// Used inside SkCurveMeasure::getTime's Newton's iteration
+static inline SkVector evaluateDerivative(const SkPoint pts[4],
+ SkSegType segType, SkScalar t) {
+ SkVector tan;
+ switch (segType) {
+ case kQuad_SegType:
+ tan = SkEvalQuadTangentAt(pts, t);
+ break;
+ case kLine_SegType:
+ tan = pts[1] - pts[0];
+ break;
+ case kCubic_SegType:
+ SkEvalCubicAt(pts, t, nullptr, &tan, nullptr);
+ break;
+ case kConic_SegType: {
+ SkConic conic(pts, pts[3].x());
+ conic.evalAt(t, nullptr, &tan);
+ }
+ break;
+ default:
+ UNIMPLEMENTED;
+ }
+
+ return tan;
+}
+/// Used in ArcLengthIntegrator::computeLength
static inline Sk8f evaluateDerivativeLength(const Sk8f& ts,
const Sk8f (&xCoeff)[3],
const Sk8f (&yCoeff)[3],
@@ -21,18 +77,15 @@ static inline Sk8f evaluateDerivativeLength(const Sk8f& ts,
x = xCoeff[0]*ts + xCoeff[1];
y = yCoeff[0]*ts + yCoeff[1];
break;
- case kLine_SegType:
- SkDebugf("Unimplemented");
- break;
case kCubic_SegType:
x = (xCoeff[0]*ts + xCoeff[1])*ts + xCoeff[2];
y = (yCoeff[0]*ts + yCoeff[1])*ts + yCoeff[2];
break;
case kConic_SegType:
- SkDebugf("Unimplemented");
+ UNIMPLEMENTED;
break;
default:
- SkDebugf("Unimplemented");
+ UNIMPLEMENTED;
}
x = x * x;
@@ -40,6 +93,7 @@ static inline Sk8f evaluateDerivativeLength(const Sk8f& ts,
return (x + y).sqrt();
}
+
ArcLengthIntegrator::ArcLengthIntegrator(const SkPoint* pts, SkSegType segType)
: fSegType(segType) {
switch (fSegType) {
@@ -59,9 +113,6 @@ ArcLengthIntegrator::ArcLengthIntegrator(const SkPoint* pts, SkSegType segType)
yCoeff[1] = Sk8f(2.0f*(By - Ay));
}
break;
- case kLine_SegType:
- SkDEBUGF(("Unimplemented"));
- break;
case kCubic_SegType:
{
float Ax = pts[0].x();
@@ -73,6 +124,7 @@ ArcLengthIntegrator::ArcLengthIntegrator(const SkPoint* pts, SkSegType segType)
float Cy = pts[2].y();
float Dy = pts[3].y();
+ // precompute coefficients for derivative
xCoeff[0] = Sk8f(3.0f*(-Ax + 3.0f*(Bx - Cx) + Dx));
xCoeff[1] = Sk8f(3.0f*(2.0f*(Ax - 2.0f*Bx + Cx)));
xCoeff[2] = Sk8f(3.0f*(-Ax + Bx));
@@ -83,10 +135,10 @@ ArcLengthIntegrator::ArcLengthIntegrator(const SkPoint* pts, SkSegType segType)
}
break;
case kConic_SegType:
- SkDEBUGF(("Unimplemented"));
+ UNIMPLEMENTED;
break;
default:
- SkDEBUGF(("Unimplemented"));
+ UNIMPLEMENTED;
}
}
@@ -117,7 +169,9 @@ SkCurveMeasure::SkCurveMeasure(const SkPoint* pts, SkSegType segType)
}
break;
case SkSegType::kLine_SegType:
- SkDebugf("Unimplemented");
+ fPts[0] = pts[0];
+ fPts[1] = pts[1];
+ fLength = (fPts[1] - fPts[0]).length();
break;
case SkSegType::kCubic_SegType:
for (size_t i = 0; i < 4; i++) {
@@ -125,13 +179,17 @@ SkCurveMeasure::SkCurveMeasure(const SkPoint* pts, SkSegType segType)
}
break;
case SkSegType::kConic_SegType:
- SkDebugf("Unimplemented");
+ for (size_t i = 0; i < 4; i++) {
+ fPts[i] = pts[i];
+ }
break;
default:
- SkDEBUGF(("Unimplemented"));
+ UNIMPLEMENTED;
break;
}
- fIntegrator = ArcLengthIntegrator(fPts, fSegType);
+ if (kLine_SegType != segType) {
+ fIntegrator = ArcLengthIntegrator(fPts, fSegType);
+ }
}
SkScalar SkCurveMeasure::getLength() {
@@ -151,15 +209,18 @@ SkScalar SkCurveMeasure::getLength() {
// which is equal to the length of the tangent (so we have to do a sqrt).
SkScalar SkCurveMeasure::getTime(SkScalar targetLength) {
- if (targetLength == 0.0f) {
+ if (targetLength <= 0.0f) {
return 0.0f;
}
SkScalar currentLength = getLength();
- if (SkScalarNearlyEqual(targetLength, currentLength)) {
+ if (targetLength > currentLength || (SkScalarNearlyEqual(targetLength, currentLength))) {
return 1.0f;
}
+ if (kLine_SegType == fSegType) {
+ return targetLength / currentLength;
+ }
// initial estimate of t is percentage of total length
SkScalar currentT = targetLength / currentLength;
@@ -199,9 +260,8 @@ SkScalar SkCurveMeasure::getTime(SkScalar targetLength) {
prevT = currentT;
if (iterations < kNewtonIters) {
- // TODO(hstern) switch here on curve type.
// This is just newton's formula.
- SkScalar dt = evaluateQuadDerivative(currentT).length();
+ SkScalar dt = evaluateDerivative(fPts, fSegType, currentT).length();
newT = currentT - (lengthDiff / dt);
// If newT is out of bounds, bisect inside newton.
@@ -218,7 +278,7 @@ SkScalar SkCurveMeasure::getTime(SkScalar targetLength) {
newT = (minT + maxT) * 0.5f;
} else {
SkDEBUGF(("%.7f %.7f didn't get close enough after bisection.\n",
- currentT, currentLength));
+ currentT, currentLength));
break;
}
currentT = newT;
@@ -235,52 +295,16 @@ SkScalar SkCurveMeasure::getTime(SkScalar targetLength) {
}
void SkCurveMeasure::getPosTanTime(SkScalar targetLength, SkPoint* pos,
- SkVector* tan, SkScalar* time) {
+ SkVector* tan, SkScalar* time) {
SkScalar t = getTime(targetLength);
if (time) {
*time = t;
}
if (pos) {
- // TODO(hstern) switch here on curve type.
- *pos = evaluateQuad(t);
+ *pos = evaluate(fPts, fSegType, t);
}
if (tan) {
- // TODO(hstern) switch here on curve type.
- *tan = evaluateQuadDerivative(t);
+ *tan = evaluateDerivative(fPts, fSegType, t);
}
}
-
-// this is why I feel that the ArcLengthIntegrator should be combined
-// with some sort of evaluator that caches the constants computed from the
-// control points. this is basically the same code in ArcLengthIntegrator
-SkPoint SkCurveMeasure::evaluateQuad(SkScalar t) {
- SkScalar ti = 1.0f - t;
-
- SkScalar Ax = fPts[0].x();
- SkScalar Bx = fPts[1].x();
- SkScalar Cx = fPts[2].x();
- SkScalar Ay = fPts[0].y();
- SkScalar By = fPts[1].y();
- SkScalar Cy = fPts[2].y();
-
- SkScalar x = Ax*ti*ti + 2.0f*Bx*t*ti + Cx*t*t;
- SkScalar y = Ay*ti*ti + 2.0f*By*t*ti + Cy*t*t;
- return SkPoint::Make(x, y);
-}
-
-SkVector SkCurveMeasure::evaluateQuadDerivative(SkScalar t) {
- SkScalar Ax = fPts[0].x();
- SkScalar Bx = fPts[1].x();
- SkScalar Cx = fPts[2].x();
- SkScalar Ay = fPts[0].y();
- SkScalar By = fPts[1].y();
- SkScalar Cy = fPts[2].y();
-
- SkScalar A2BCx = 2.0f*(Ax - 2*Bx + Cx);
- SkScalar A2BCy = 2.0f*(Ay - 2*By + Cy);
- SkScalar ABx = 2.0f*(Bx - Ax);
- SkScalar ABy = 2.0f*(By - Ay);
-
- return SkPoint::Make(A2BCx*t + ABx, A2BCy*t + ABy);
-}
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