Define accelerated steps time function.

ui/gfx/geometry/steps.cc

+// Copyright 2014 Samsung. All rights reserved.

[ajuma, 2014/02/24 21:11:16]

"The Chromium Authors"

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ui/gfx/geometry/steps.h"
+
+#include <cmath>
+
+#include "base/logging.h"
+
+namespace gfx {
+
+Steps::Steps(int steps, bool steps_at_start)
+    : steps_(steps),
+      steps_at_start_(steps_at_start) {
+}
+
+Steps::~Steps() {
+}
+
+double Steps::Solve(double x) const {

[ajuma, 2014/02/24 21:11:16]

x should be clamped to [0, 1] (so that, e.g., Solve(-4.0) is equivalent to
Solve(0.0)).

+  return std::min(1.0, (floor(steps_ * x) + steps_at_start_) / steps_);
+}
+
+void Steps::Range(double* min, double* max) const {
+  *min = static_cast<float>(steps_at_start_) / static_cast<float>(steps_);

[ajuma, 2014/02/24 21:11:16]

Use doubles instead of floats here (since *min is a double).

+  *max = 1.0;
+}
+
+}  // namespace gfx