allow one zero length dash

src/effects/SkDashPathEffect.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkDashPathEffect.h"
 
 #include "SkDashPathPriv.h"
 #include "SkReadBuffer.h"
 #include "SkWriteBuffer.h"
 #include "SkStrokeRec.h"
 
 SkDashPathEffect::SkDashPathEffect(const SkScalar intervals[], int count, SkScalar phase)
         : fPhase(0)

[robertphillips, 2016/03/16 18:01:39]

Don't we use a -1 initial dash length as a signal for bad data (e.g., in
CalcDashParameters) ?

[caryclark, 2016/03/16 18:45:54]

Switched to explict flag. Please let me know if you like this better.

-        , fInitialDashLength(0)
+        , fInitialDashLength(-1)
         , fInitialDashIndex(0)
         , fIntervalLength(0) {
     SkASSERT(intervals);
     SkASSERT(count > 1 && SkAlign2(count) == count);
 
     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];
@@ skipping 363 matching lines @@
     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);
 }