2 files changed, 34 insertions, 0 deletions
diff --git a/app/animation.cc b/app/animation.cc
index 94c99c2..b341d2a 100644
--- a/app/animation.cc
+++ b/app/animation.cc
@@ -4,6 +4,7 @@
 
 #include "app/animation.h"
 
+#include "base/gfx/rect.h"
 #include "base/message_loop.h"
 
 #if defined(OS_WIN)
@@ -47,6 +48,25 @@ double Animation::GetCurrentValue() const {
   return state_;
 }
 
+double Animation::CurrentValueBetween(double start, double target) const {
+  return start + (target - start) * GetCurrentValue();
+}
+
+int Animation::CurrentValueBetween(int start, int target) const {
+  return static_cast<int>(CurrentValueBetween(static_cast<double>(start),
+                                              static_cast<double>(target)));
+}
+
+gfx::Rect Animation::CurrentValueBetween(const gfx::Rect& start_bounds,
+                                         const gfx::Rect& target_bounds) const {
+  return gfx::Rect(CurrentValueBetween(start_bounds.x(), target_bounds.x()),
+                   CurrentValueBetween(start_bounds.y(), target_bounds.y()),
+                   CurrentValueBetween(start_bounds.width(),
+                                       target_bounds.width()),
+                   CurrentValueBetween(start_bounds.height(),
+                                       target_bounds.height()));
+}
+
 void Animation::Start() {
   if (!animating_) {
     start_time_ = Time::Now();
diff --git a/app/animation.h b/app/animation.h
index bd38fb4..bfa7fd0 100644
--- a/app/animation.h
+++ b/app/animation.h
@@ -11,6 +11,10 @@
 
 class Animation;
 
+namespace gfx {
+class Rect;
+}
+
 // AnimationDelegate
 //
 //  Implement this interface when you want to receive notifications about the
@@ -77,6 +81,13 @@ class Animation {
   // however subclasses can override this to provide others.
   virtual double GetCurrentValue() const;
 
+  // Convenience for returning a value between |start| and |target| based on
+  // the current value. This is (target - start) * GetCurrentValue() + start.
+  double CurrentValueBetween(double start, double target) const;
+  int CurrentValueBetween(int start, int target) const;
+  gfx::Rect CurrentValueBetween(const gfx::Rect& start_bounds,
+                                const gfx::Rect& target_bounds) const;
+
   // Start the animation.
   void Start();
 
@@ -98,6 +109,9 @@ class Animation {
   // to give guidance for heavy animations such as "start download" arrow.
   static bool ShouldRenderRichAnimation();
 
+  // Sets the delegate.
+  void set_delegate(AnimationDelegate* delegate) { delegate_ = delegate; }
+
  protected:
   // Overriddable, called by Run.
   virtual void Step();