Revert of allow one zero length dash (patchset #8 id:140001 of https://codereview.chromium.org/1805963002/ )

Reason for revert:
Causes the dash bench to crash.

Example crash:
https://build.chromium.org/p/client.skia/builders/Perf-Ubuntu-GCC-GCE-CPU-AVX2-x86_64-Release/builds/5581/steps/nanobench/logs/stdio

Original issue's description:
> allow one zero length dash
>
> If the constructed stroke that represents a dash has a
> single dash of length zero, and the end cap is square or
> round, draw the cap.
>
> The old code initialized the initial dash length to zero,
> making it ambiguous whether the first length is zero or
> not.
>
> R=robertphillips@google.com
> BUG=583299
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1805963002
>
> Committed: https://skia.googlesource.com/skia/+/5e1a24808415df2748822e8082e21a361362cdfe

TBR=robertphillips@google.com,reed@google.com,caryclark@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=583299

Review URL: https://codereview.chromium.org/1808303004

1 files changed, 10 insertions, 4 deletions

diff --git a/src/effects/SkDashPathEffect.cpp b/src/effects/SkDashPathEffect.cpp
index 3816499915..ced0aab69a 100644
--- a/src/effects/SkDashPathEffect.cpp
+++ b/src/effects/SkDashPathEffect.cpp
@@ -14,7 +14,7 @@
 
 SkDashPathEffect::SkDashPathEffect(const SkScalar intervals[], int count, SkScalar phase)
         : fPhase(0)
-        , fInitialDashLength(-1)
+        , fInitialDashLength(0)
         , fInitialDashIndex(0)
         , fIntervalLength(0) {
     SkASSERT(intervals);
@@ -23,6 +23,7 @@ SkDashPathEffect::SkDashPathEffect(const SkScalar intervals[], int count, SkScal
     fIntervals = (SkScalar*)sk_malloc_throw(sizeof(SkScalar) * count);
     fCount = count;
     for (int i = 0; i < count; i++) {
+        SkASSERT(intervals[i] >= 0);
         fIntervals[i] = intervals[i];
     }
 
@@ -37,7 +38,7 @@ SkDashPathEffect::~SkDashPathEffect() {
 
 bool SkDashPathEffect::filterPath(SkPath* dst, const SkPath& src,
                               SkStrokeRec* rec, const SkRect* cullRect) const {
-    return SkDashPath::InternalFilter(dst, src, rec, cullRect, fIntervals, fCount,
+    return SkDashPath::FilterDashPath(dst, src, rec, cullRect, fIntervals, fCount,
                                       fInitialDashLength, fInitialDashIndex, fIntervalLength);
 }
 
@@ -161,7 +162,7 @@ bool SkDashPathEffect::asPoints(PointData* results,
                                 const SkMatrix& matrix,
                                 const SkRect* cullRect) const {
     // width < 0 -> fill && width == 0 -> hairline so requiring width > 0 rules both out
-    if (0 >= rec.getWidth()) {
+    if (fInitialDashLength < 0 || 0 >= rec.getWidth()) {
         return false;
     }
 
@@ -387,8 +388,13 @@ void SkDashPathEffect::toString(SkString* str) const {
 //////////////////////////////////////////////////////////////////////////////////////////////////
 
 SkPathEffect* SkDashPathEffect::Create(const SkScalar intervals[], int count, SkScalar phase) {
-    if (!SkDashPath::ValidDashPath(phase, intervals, count)) {
+    if ((count < 2) || !SkIsAlign2(count)) {
         return nullptr;
     }
+    for (int i = 0; i < count; i++) {
+        if (intervals[i] < 0) {
+            return nullptr;
+        }
+    }
     return new SkDashPathEffect(intervals, count, phase);
 }