App list: Added contents view custom animation framework.

ui/app_list/views/contents_animator.h

Index: ui/app_list/views/contents_animator.h
diff --git a/ui/app_list/views/contents_animator.h b/ui/app_list/views/contents_animator.h
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+// 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.
+
+#ifndef UI_APP_LIST_VIEWS_CONTENTS_ANIMATOR_H_
+#define UI_APP_LIST_VIEWS_CONTENTS_ANIMATOR_H_
+
+#include <string>
+
+#include "base/macros.h"
+
+namespace gfx {
+class Rect;
+}
+
+namespace app_list {
+
+class ContentsView;
+
+// Manages an animation between two specific pages of the ContentsView.
+// Different subclasses implement different animations, so we can have a custom
+// animation for each pair of pages. Animations are reversible (if A -> B is
+// implemented, B -> A will implicitly be the inverse animation).
+class ContentsAnimator {
+ public:
+  ContentsAnimator(ContentsView* contents_view);
+
+  virtual ~ContentsAnimator();
+
+  // Gets the name of the animator, for testing.
+  virtual std::string NameForTests() const = 0;
+
+  // Updates the state of the ContentsView. |progress| is the amount of progress
+  // made on the animation, where 0.0 is the beginning and 1.0 is the end. The
+  // animation should be linear (not eased in or out) so that it can be played
+  // forwards or reversed. Easing will be applied by the PaginationModel.
+  virtual void Update(double progress, int from_page, int to_page) = 0;
+
+ protected:
+  ContentsView* contents_view() { return contents_view_; }
+
+  // Gets the origin (the off-screen resting place) for a given launcher page
+  // with index |page_index|.
+  gfx::Rect GetOffscreenPageBounds(int page_index) const;
+
+ private:
+  ContentsView* contents_view_;
+
+  DISALLOW_COPY_AND_ASSIGN(ContentsAnimator);
+};
+
+// Simple animator that slides pages in and out vertically. Appropriate for any
+// page pair.
+class DefaultAnimator : public ContentsAnimator {
+ public:
+  DefaultAnimator(ContentsView* contents_view);
+
+  ~DefaultAnimator() override {}
+
+  // ContentsAnimator overrides:
+  std::string NameForTests() const override;
+  void Update(double progress, int from_page, int to_page) override;
+
+  DISALLOW_COPY_AND_ASSIGN(DefaultAnimator);
+};
+
+// Animator between the start page and apps grid page.
+class StartToAppsAnimator : public ContentsAnimator {
+ public:
+  StartToAppsAnimator(ContentsView* contents_view);
+
+  ~StartToAppsAnimator() override {}
+
+  // ContentsAnimator overrides:
+  std::string NameForTests() const override;
+  void Update(double progress, int start_page, int apps_page) override;
+
+  DISALLOW_COPY_AND_ASSIGN(StartToAppsAnimator);
+};
+
+}  // app_list
+
+#endif  // UI_APP_LIST_VIEWS_CONTENTS_ANIMATOR_H_