Web Animations API: Implement step-middle and steps(x, middle) timing functions.

Source/platform/animation/TimingFunction.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "platform/animation/TimingFunction.h"
 
 namespace WebCore {
 
 String LinearTimingFunction::toString() const
@@ skipping 29 matching lines @@
 }
 
 double CubicBezierTimingFunction::evaluate(double fraction, double accuracy) const
 {
     ASSERT_WITH_MESSAGE(fraction >= 0 && fraction <= 1, "Web Animations not yet implemented: Timing function behavior outside the range [0, 1] is not yet specified");
     if (!m_bezier)
         m_bezier = adoptPtr(new UnitBezier(m_x1, m_y1, m_x2, m_y2));
     return m_bezier->solve(fraction, accuracy);
 }
 
+// FIXME: Unit test this thoroughly

[dstockwell, 2014/02/24 04:58:40]

Not a good fixme.

[rjwright, 2014/02/24 11:17:46]

Done.

 String StepsTimingFunction::toString() const
 {
     StringBuilder builder;
     switch (this->subType()) {
     case StepsTimingFunction::Start:
         return "step-start";
+    case StepsTimingFunction::Middle:
+        return "step-middle";
     case StepsTimingFunction::End:
         return "step-end";
     case StepsTimingFunction::Custom:
         builder.append("steps(" + String::numberToStringECMAScript(this->numberOfSteps()) + ", ");
-        builder.append(this->stepAtStart() ? "start" : "end");
+
+        if (this->stepAtPosition() == StepsTimingFunction::StepAtStart)
+            builder.append("start");
+        else if (this->stepAtPosition() == StepsTimingFunction::StepAtMiddle)
+            builder.append("middle");
+        else if (this->stepAtPosition() == StepsTimingFunction::StepAtEnd)
+            builder.append("end");
+        else
+            ASSERT_NOT_REACHED();
+
         builder.append(")");
         break;
     default:
         ASSERT_NOT_REACHED();
     }
     return builder.toString();
 }
 
 double StepsTimingFunction::evaluate(double fraction, double) const
 {
     ASSERT_WITH_MESSAGE(fraction >= 0 && fraction <= 1, "Web Animations not yet implemented: Timing function behavior outside the range [0, 1] is not yet specified");
-    return std::min(1.0, (floor(m_steps * fraction) + m_stepAtStart) / m_steps);
+    double startOffset = 0;
+    switch (m_stepAtPosition) {
+    case StepAtStart:
+        startOffset = 1;
+        break;
+    case StepAtMiddle:
+        startOffset = 0.5;
+        break;
+    case StepAtEnd:
+        startOffset = 0;
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+        break;
+    }
+    return std::min(1.0, floor((m_steps * fraction) + startOffset) / m_steps);
 }
 
 String ChainedTimingFunction::toString() const
 {
     StringBuilder builder;
     builder.append("chained(");
     for (size_t i = 0; i < this->m_segments.size(); i++) {
         ChainedTimingFunction::Segment segment = this->m_segments[i];
         builder.append(segment.m_timingFunction->toString());
         builder.append("[" + String::numberToStringECMAScript(segment.m_min) + " -> " + String::numberToStringECMAScript(segment.m_max) + "]");
@@ skipping 12 matching lines @@
     ASSERT(m_segments.last().max() == 1);
     size_t i = 0;
     const Segment* segment = &m_segments[i++];
     while (fraction >= segment->max() && i < m_segments.size()) {
         segment = &m_segments[i++];
     }
     return segment->evaluate(fraction, accuracy);
 }
 
 } // namespace WebCore