CC::Animations should use TimeTicks & TimeDelta to represent time

cc/input/page_scale_animation.cc

 // Copyright 2012 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 "cc/input/page_scale_animation.h"
 
 #include <math.h>
 
 #include "base/logging.h"
 #include "cc/animation/timing_function.h"
@@ skipping 22 matching lines @@
 gfx::Vector2dF InterpolateBetween(const gfx::Vector2dF& start,
                                   const gfx::Vector2dF& end,
                                   float interp) {
   return start + gfx::ScaleVector2d(end - start, interp);
 }
 
 }  // namespace
 
 namespace cc {
 
+using base::TimeTicks;
+using base::TimeDelta;
+
 scoped_ptr<PageScaleAnimation> PageScaleAnimation::Create(
     const gfx::Vector2dF& start_scroll_offset,
     float start_page_scale_factor,
     const gfx::SizeF& viewport_size,
     const gfx::SizeF& root_layer_size,
     scoped_ptr<TimingFunction> timing_function) {
   return make_scoped_ptr(new PageScaleAnimation(start_scroll_offset,
                                                 start_page_scale_factor,
                                                 viewport_size,
                                                 root_layer_size,
                                                 timing_function.Pass()));
 }
 
 PageScaleAnimation::PageScaleAnimation(
     const gfx::Vector2dF& start_scroll_offset,
     float start_page_scale_factor,
     const gfx::SizeF& viewport_size,
     const gfx::SizeF& root_layer_size,
     scoped_ptr<TimingFunction> timing_function)
     : start_page_scale_factor_(start_page_scale_factor),
       target_page_scale_factor_(0.f),
       start_scroll_offset_(start_scroll_offset),
       start_anchor_(),
       target_anchor_(),
       viewport_size_(viewport_size),
       root_layer_size_(root_layer_size),
-      start_time_(-1.0),
-      duration_(0.0),
-      timing_function_(timing_function.Pass()) {}
+      start_time_(TimeTicks::FromInternalValue(
+          -1.0 * base::Time::kMicrosecondsPerSecond)),

[aelias_OOO_until_Jul13, 2014/05/13 06:00:07]

This default value is a bad idea here, particularly as TimeTicks holds an
unsigned internally.  Please switch to the normal null value of
base::TimeTicks() and change the DCHECKs below to use > instead of >=.

[ajuma, 2014/05/13 13:44:48]

Fwiw, TimeTicks uses a (signed) int64 internally. That said, changing this to
the normal null value of base::TimeTicks() still seems like a good idea. Note
that IsAnimationStarted below will also have to be changed to use > rather than
>=.

[Sikugu_, 2014/05/14 14:23:18]

Done.

[Sikugu_, 2014/05/14 14:23:18]

Done.

+      timing_function_(timing_function.Pass()) {
+}
 
 PageScaleAnimation::~PageScaleAnimation() {}
 
 void PageScaleAnimation::ZoomTo(const gfx::Vector2dF& target_scroll_offset,
                                 float target_page_scale_factor,
                                 double duration) {
   target_page_scale_factor_ = target_page_scale_factor;
   target_scroll_offset_ = target_scroll_offset;
   ClampTargetScrollOffset();
-  duration_ = duration;
+  duration_ = TimeDelta::FromSecondsD(duration);
 
   if (start_page_scale_factor_ == target_page_scale_factor) {
     start_anchor_ = start_scroll_offset_;
     target_anchor_ = target_scroll_offset;
     return;
   }
 
   // For uniform-looking zooming, infer an anchor from the start and target
   // viewport rects.
   InferTargetAnchorFromScrollOffsets();
   start_anchor_ = target_anchor_;
 }
 
 void PageScaleAnimation::ZoomWithAnchor(const gfx::Vector2dF& anchor,
                                         float target_page_scale_factor,
                                         double duration) {
   start_anchor_ = anchor;
   target_page_scale_factor_ = target_page_scale_factor;
-  duration_ = duration;
+  duration_ = TimeDelta::FromSecondsD(duration);
 
   // We start zooming out from the anchor tapped by the user. But if
   // the target scale is impossible to attain without hitting the root layer
   // edges, then infer an anchor that doesn't collide with the edges.
   // We will interpolate between the two anchors during the animation.
   InferTargetScrollOffsetFromStartAnchor();
   ClampTargetScrollOffset();
 
   if (start_page_scale_factor_ == target_page_scale_factor_) {
     target_anchor_ = start_anchor_;
@@ skipping 45 matching lines @@
 
 gfx::SizeF PageScaleAnimation::TargetViewportSize() const {
   return gfx::ScaleSize(viewport_size_, 1.f / target_page_scale_factor_);
 }
 
 gfx::SizeF PageScaleAnimation::ViewportSizeAt(float interp) const {
   return gfx::ScaleSize(viewport_size_, 1.f / PageScaleFactorAt(interp));
 }
 
 bool PageScaleAnimation::IsAnimationStarted() const {
-  return start_time_ >= 0;
+  return start_time_ >= base::TimeTicks();
 }
 
-void PageScaleAnimation::StartAnimation(double time) {
-  DCHECK_GT(0, start_time_);
+void PageScaleAnimation::StartAnimation(base::TimeTicks time) {
+  DCHECK(start_time_ < base::TimeTicks());
   start_time_ = time;
 }
 
-gfx::Vector2dF PageScaleAnimation::ScrollOffsetAtTime(double time) const {
-  DCHECK_GE(start_time_, 0);
+gfx::Vector2dF PageScaleAnimation::ScrollOffsetAtTime(
+    base::TimeTicks time) const {
+  DCHECK(start_time_ >= base::TimeTicks());
   return ScrollOffsetAt(InterpAtTime(time));
 }
 
-float PageScaleAnimation::PageScaleFactorAtTime(double time) const {
-  DCHECK_GE(start_time_, 0);
+float PageScaleAnimation::PageScaleFactorAtTime(base::TimeTicks time) const {
+  DCHECK(start_time_ >= base::TimeTicks());
   return PageScaleFactorAt(InterpAtTime(time));
 }
 
-bool PageScaleAnimation::IsAnimationCompleteAtTime(double time) const {
-  DCHECK_GE(start_time_, 0);
+bool PageScaleAnimation::IsAnimationCompleteAtTime(base::TimeTicks time) const {
+  DCHECK(start_time_ >= base::TimeTicks());
   return time >= end_time();
 }
 
-float PageScaleAnimation::InterpAtTime(double time) const {
-  DCHECK_GE(start_time_, 0);
-  DCHECK_GE(time, start_time_);
-  if (IsAnimationCompleteAtTime(time))
+float PageScaleAnimation::InterpAtTime(base::TimeTicks monotonic_time) const {
+  DCHECK(start_time_ >= base::TimeTicks());
+  DCHECK(monotonic_time >= start_time_);
+  if (IsAnimationCompleteAtTime(monotonic_time))
     return 1.f;
-
-  const double normalized_time = (time - start_time_) / duration_;
+  const double normalized_time =
+      (monotonic_time - start_time_).InSecondsF() / duration_.InSecondsF();
   return timing_function_->GetValue(normalized_time);
 }
 
 gfx::Vector2dF PageScaleAnimation::ScrollOffsetAt(float interp) const {
   if (interp <= 0.f)
     return start_scroll_offset_;
   if (interp >= 1.f)
     return target_scroll_offset_;
 
   return AnchorAt(interp) - ViewportRelativeAnchorAt(interp);
@@ skipping 27 matching lines @@
 
   // Linearly interpolate the magnitude in log scale.
   float diff = target_page_scale_factor_ / start_page_scale_factor_;
   float log_diff = log(diff);
   log_diff *= interp;
   diff = exp(log_diff);
   return start_page_scale_factor_ * diff;
 }
 
 }  // namespace cc