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Fix bug where SkPath will convert an arc to an oval and change the starting point.

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Adds unit tests to test the behavior of addArc to oval conversions.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2017743002

Review-Url: https://codereview.chromium.org/2017743002
This commit is contained in:
bsalomon 2016-05-31 10:42:16 -07:00 committed by Commit bot
parent 18c4943e90
commit 1978ce22eb
2 changed files with 83 additions and 5 deletions
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18
src/core/SkPath.cpp
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@ -5,6 +5,7 @@
* found in the LICENSE file.
*/
#include <cmath>
#include "SkBuffer.h"
#include "SkCubicClipper.h"
#include "SkErrorInternals.h"
@ -1421,10 +1422,21 @@ void SkPath::addArc(const SkRect& oval, SkScalar startAngle, SkScalar sweepAngle
const SkScalar kFullCircleAngle = SkIntToScalar(360);
if (sweepAngle >= kFullCircleAngle || sweepAngle <= -kFullCircleAngle) {
this->addOval(oval, sweepAngle > 0 ? kCW_Direction : kCCW_Direction);
} else {
this->arcTo(oval, startAngle, sweepAngle, true);
// We can treat the arc as an oval if it begins at one of our legal starting positions.
// See SkPath::addOval() docs.
SkScalar startOver90 = startAngle / 90.f;
SkScalar startOver90I = SkScalarRoundToScalar(startOver90);
SkScalar error = startOver90 - startOver90I;
if (SkScalarNearlyEqual(error, 0)) {
// Index 1 is at startAngle == 0.
SkScalar startIndex = std::fmod(startOver90I + 1.f, 4.f);
startIndex = startIndex < 0 ? startIndex + 4.f : startIndex;
this->addOval(oval, sweepAngle > 0 ? kCW_Direction : kCCW_Direction,
(unsigned) startIndex);
return;
}
}
this->arcTo(oval, startAngle, sweepAngle, true);
}
/*

70
tests/PathTest.cpp
View File

@ -5,6 +5,7 @@
* found in the LICENSE file.
*/
#include <cmath>
#include "SkCanvas.h"
#include "SkGeometry.h"
#include "SkPaint.h"
@ -3306,12 +3307,12 @@ static void test_arc(skiatest::Reporter* reporter) {
p.reset();
SkPath cwOval;
cwOval.addOval(oval);
p.addArc(oval, 1, 360);
p.addArc(oval, 0, 360);
REPORTER_ASSERT(reporter, p == cwOval);
p.reset();
SkPath ccwOval;
ccwOval.addOval(oval, SkPath::kCCW_Direction);
p.addArc(oval, 1, -360);
p.addArc(oval, 0, -360);
REPORTER_ASSERT(reporter, p == ccwOval);
p.reset();
p.addArc(oval, 1, 180);
@ -3321,6 +3322,70 @@ static void test_arc(skiatest::Reporter* reporter) {
REPORTER_ASSERT(reporter, p.isConvex());
}
static inline SkScalar oval_start_index_to_angle(unsigned start) {
switch (start) {
case 0:
return 270.f;
case 1:
return 0.f;
case 2:
return 90.f;
case 3:
return 180.f;
default:
return -1.f;
}
}
static inline SkScalar canonical_start_angle(float angle) {
while (angle < 0.f) {
angle += 360.f;
}
while (angle >= 360.f) {
angle -= 360.f;
}
return angle;
}
static void check_oval_arc(skiatest::Reporter* reporter, SkScalar start, SkScalar sweep,
const SkPath& path) {
SkRect r = SkRect::MakeEmpty();
SkPath::Direction d = SkPath::kCCW_Direction;
unsigned s = ~0U;
bool isOval = path.isOval(&r, &d, &s);
REPORTER_ASSERT(reporter, isOval);
SkPath recreatedPath;
recreatedPath.addOval(r, d, s);
REPORTER_ASSERT(reporter, path == recreatedPath);
REPORTER_ASSERT(reporter, oval_start_index_to_angle(s) == canonical_start_angle(start));
REPORTER_ASSERT(reporter, (SkPath::kCW_Direction == d) == (sweep > 0.f));
}
static void test_arc_ovals(skiatest::Reporter* reporter) {
SkRect oval = SkRect::MakeWH(10, 20);
for (SkScalar sweep : {-720.f, -540.f, -360.f, 360.f, 432.f, 720.f}) {
for (SkScalar start = -360.f; start <= 360.f; start += 1.f) {
SkPath path;
path.addArc(oval, start, sweep);
// SkPath's interfaces for inserting and extracting ovals only allow contours
// to start at multiples of 90 degrees.
if (std::fmod(start, 90.f) == 0) {
check_oval_arc(reporter, start, sweep, path);
} else {
REPORTER_ASSERT(reporter, !path.isOval(nullptr));
}
}
// Test start angles that are nearly at valid oval start angles.
for (float start : {-180.f, -90.f, 90.f, 180.f}) {
for (float delta : {-SK_ScalarNearlyZero, SK_ScalarNearlyZero}) {
SkPath path;
path.addArc(oval, start + delta, sweep);
check_oval_arc(reporter, start, sweep, path);
}
}
}
}
static void check_move(skiatest::Reporter* reporter, SkPath::RawIter* iter,
SkScalar x0, SkScalar y0) {
SkPoint pts[4];
@ -4121,6 +4186,7 @@ DEF_TEST(Paths, reporter) {
test_path_to_region(reporter);
test_rrect(reporter);
test_arc(reporter);
test_arc_ovals(reporter);
test_arcTo(reporter);
test_addPath(reporter);
test_addPathMode(reporter, false, false);