Add SkDashMeasure.h (name up for bikeshedding) which takes a dashinfo

src/core/SkDashMeasure.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkCurveMeasure.h"
+#include "SkGeometry.h"
+#include "SkPath.h"
+#include "SkPathEffect.h"
+#include "SkPathMeasurePriv.h"
+
+static inline void getDashedPath(const SkPath& path,
+                            const struct SkPathEffect::DashInfo& dashInfo,
+                            SkPath* dst) {
+    const SkScalar* intervals = dashInfo.fIntervals;
+
+    SkScalar interval_accum = 0.0f;

[caryclark, 2016/08/11 12:35:12]

remove this

[Harry Stern, 2016/08/11 15:21:09]

Done.

+    int32_t interval_index = 0;
+
+    interval_accum = intervals[interval_index];

[caryclark, 2016/08/11 12:35:12]

SkScalar internal_accum ...

[Harry Stern, 2016/08/11 15:21:09]

Done.

+
+    SkPath::Iter iter(path, false);
+    SkPath::Verb current;
+    SkPoint pts[4];
+
+    while ((current = iter.next(pts)) != SkPath::kDone_Verb) {
+        SkSegType segtype;
+        SkPoint end;
+        switch (current) {
+            case (SkPath::kMove_Verb):

[caryclark, 2016/08/11 12:35:12]

no need for parens

[Harry Stern, 2016/08/11 15:21:09]

Done.

+                dst->moveTo(pts[0]);
+                continue;
+            case (SkPath::kLine_Verb):
+                segtype = kLine_SegType;
+                end = pts[1];
+                break;
+            case (SkPath::kQuad_Verb):
+                segtype = kQuad_SegType;
+                end = pts[2];
+                break;
+            case (SkPath::kConic_Verb):
+                segtype = kConic_SegType;
+                end = pts[3];

[caryclark, 2016/08/11 12:35:12]

pts[2]

[Harry Stern, 2016/08/11 15:21:09]

Done.

+                break;
+            case (SkPath::kCubic_Verb):
+                segtype = kCubic_SegType;
+                end = pts[3];
+                break;
+            case (SkPath::kClose_Verb):
+                // should not appear in the iter since we're not using RawIter
+                SkASSERT(false);
+                break;
+            default:  // unreachable
+                SkASSERT(false);
+                break;
+        }
+
+        // TODO(hstern): Do heuristic check to see whether we should do
+        // pathmeasure or curvemeasure. probably do it before the outer loop
+        // by giving CurveMeasure a reset() and reusing the object inside.
+        SkCurveMeasure meas(pts, segtype);
+
+        SkScalar prevT = 0.0f;

[caryclark, 2016/08/11 12:35:12]

0 is fine here

[Harry Stern, 2016/08/11 15:21:09]

Done.

+
+        SkScalar current_length = meas.getLength();
+        while (interval_accum < current_length) {
+            SkScalar time;
+            SkPoint pos;
+            meas.getPosTanTime(interval_accum, &pos, nullptr, &time);
+            if (!(interval_index%2)) {

[caryclark, 2016/08/11 12:35:12]

spaces on both sides of %

[Harry Stern, 2016/08/11 15:21:09]

Done. I'm actually going to put this in a tiny helper function since it's not
clear just from reading it what/why I'm doing.

+                SkPathMeasure_segTo(pts, segtype, prevT, time, dst);
+            }
+            else {
+                dst->moveTo(pos);

[caryclark, 2016/08/11 12:35:12]

put else on same line as close brace

[Harry Stern, 2016/08/11 15:21:09]

Done, but I have written my elses on separate lines pretty much everywhere else.
Should I go through SkCurveMeasure and open a CL to fix those?

+            }
+            prevT = time;
+
+            interval_accum += intervals[interval_index];
+            interval_index = (interval_index+1)%dashInfo.fCount;

[caryclark, 2016/08/11 12:35:12]

spaces on both sides of %

[Harry Stern, 2016/08/11 15:21:09]

Done.

+        }
+        if (!(interval_index%2)) {

[caryclark, 2016/08/11 12:35:12]

spaces on either side of %

[Harry Stern, 2016/08/11 15:21:09]

Done.

+            SkPathMeasure_segTo(pts, segtype, prevT, 1.0f, dst);

[caryclark, 2016/08/11 12:35:12]

1 is fine here

[Harry Stern, 2016/08/11 15:21:09]

Done.

+        }
+        else {

[caryclark, 2016/08/11 12:35:12]

put else on same line as close brace

[Harry Stern, 2016/08/11 15:21:09]

Done.

+            dst->moveTo(end);
+        }
+
+        interval_accum = interval_accum - current_length;
+    }
+}