Add asADash entry point into SkPathEffect to allow extracting Dash info from PathEffects

tests/AsADashTest.cpp

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "Test.h"
+
+#include "SkPathEffect.h"
+#include "SkDashPathEffect.h"
+#include "SkCornerPathEffect.h"
+
+DEF_TEST(AsADashTest_noneDash, reporter) {
+    SkAutoTUnref<SkCornerPathEffect> pe(SkCornerPathEffect::Create(1.0));
+    SkPathEffect::DashInfo info;
+     
+    SkPathEffect::DashType dashType = pe->asADash(&info);
+    REPORTER_ASSERT(reporter, SkPathEffect::kNone_DashType == dashType);
+}
+
+DEF_TEST(AsADashTest_nullInfo, reporter) {
+    SkScalar inIntervals[] = { 4.0, 2.0, 1.0, 3.0 };
+    const SkScalar phase = 2.0;
+    SkAutoTUnref<SkDashPathEffect> pe(SkDashPathEffect::Create(inIntervals, 4, phase, true));
+    
+    SkPathEffect::DashType dashType = pe->asADash(NULL);
+    REPORTER_ASSERT(reporter, SkPathEffect::kDash_DashType == dashType);
+}
+
+DEF_TEST(AsADashTest_usingDash, reporter) {
+    SkScalar inIntervals[] = { 4.0, 2.0, 1.0, 3.0 };
+    SkScalar totalIntSum = 10.0;
+    const SkScalar phase = 2.0;
+
+    SkAutoTUnref<SkDashPathEffect> pe(SkDashPathEffect::Create(inIntervals, 4, phase, true));
+
+    SkPathEffect::DashInfo info;

[reed1, 2014/03/28 14:52:53]

since we "read" fIntervals, and only that field, perhaps we can have the
constructor for info set that to zero?

+    info.fCount = 0;
+    info.fIntervals = NULL;
+    
+    SkPathEffect::DashType dashType = pe->asADash(&info);
+    REPORTER_ASSERT(reporter, SkPathEffect::kDash_DashType == dashType);
+    REPORTER_ASSERT(reporter, 4 == info.fCount);
+    REPORTER_ASSERT(reporter, SkScalarMod(phase, totalIntSum) == info.fPhase);
+    REPORTER_ASSERT(reporter, true == info.fScaleToFit);
+
+    // Since it is a kDash_DashType, allocate space for the intervals and recall asADash
+    SkAutoTArray<SkScalar> intervals(info.fCount);
+    info.fIntervals = intervals.get();
+    pe->asADash(&info);
+    REPORTER_ASSERT(reporter, inIntervals[0] == info.fIntervals[0]);
+    REPORTER_ASSERT(reporter, inIntervals[1] == info.fIntervals[1]);
+    REPORTER_ASSERT(reporter, inIntervals[2] == info.fIntervals[2]);
+    REPORTER_ASSERT(reporter, inIntervals[3] == info.fIntervals[3]);
+
+    // Make sure nothing else has changed on us
+    REPORTER_ASSERT(reporter, 4 == info.fCount);
+    REPORTER_ASSERT(reporter, SkScalarMod(phase, totalIntSum) == info.fPhase);
+    REPORTER_ASSERT(reporter, true == info.fScaleToFit);
+}