[Views] App Menu Animated Icon

chrome/browser/ui/views/toolbar/app_menu_animation.h

+// Copyright 2017 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 CHROME_BROWSER_UI_VIEWS_TOOLBAR_APP_MENU_ANIMATION_H_
+#define CHROME_BROWSER_UI_VIEWS_TOOLBAR_APP_MENU_ANIMATION_H_
+
+#include "base/time/time.h"
+#include "third_party/skia/include/core/SkColor.h"
+#include "ui/gfx/animation/animation_delegate.h"
+#include "ui/gfx/animation/slide_animation.h"
+
+namespace gfx {
+class Canvas;
+class PointF;
+}  // namespace gfx
+
+class AppMenuButton;
+
+// This class is used for animating and drawing the app menu icon.
+class AppMenuAnimation : public gfx::AnimationDelegate {
+ public:
+  AppMenuAnimation(AppMenuButton* owner, bool should_animate_closed);
+
+  ~AppMenuAnimation() override;
+
+  // Paints the app menu icon.
+  void PaintAppMenu(gfx::Canvas* canvas, const gfx::Rect& bounds);
+
+  // Updates the icon colors.
+  void SetIconColors(SkColor start_color, SkColor severity_color);
+
+  // Starts the animation if it's not already running.
+  void StartAnimation();
+
+  // gfx::AnimationDelegate:
+  void AnimationEnded(const gfx::Animation* animation) override;
+  void AnimationProgressed(const gfx::Animation* animation) override;
+
+ private:
+  // This class is used to represent and paint a dot on the app menu.
+  class AppMenuDot {
+   public:
+    // The class constructor. The params |delay|, |width_open_interval|, and

[msw, 2017/04/13 23:05:24]

This doesn't explain the semantics of the arguments. I suppose the members are
sufficiently documented and I should not have asked for separate explanations
here; just remove this.

[spqchan, 2017/04/13 23:48:21]

Done.

+    // |stroke_open_interval| are used to populate the variables |delay|,
+    // |width_open_interval|, and |stroke_open_interval| respectively.
+    AppMenuDot(base::TimeDelta delay,
+               float width_open_interval,
+               float stroke_open_interval);
+
+    // Paints the dot on the given |canvas| according to the progress of
+    // |animation|. The size of the dot is calculated to fit in |bounds|.
+    // |center_point| is the dot's position on the canvas. The dot's color is
+    // a transition from |start_color| to |final_color|.
+    void Paint(const gfx::PointF& center_point,
+               SkColor start_color,
+               SkColor final_color,
+               gfx::Canvas* canvas,
+               const gfx::Rect& bounds,
+               const gfx::SlideAnimation* animation);
+
+   private:
+    // The delay before the dot starts animating in ms.
+    const base::TimeDelta delay_;
+
+    // The percentage of the overall animation duration it takes to animate the
+    // width and stroke to their open state.
+    const float width_open_interval_;
+    const float stroke_open_interval_;
+
+    DISALLOW_COPY_AND_ASSIGN(AppMenuDot);
+  };
+
+  AppMenuButton* const owner_;
+
+  // True if the animation should close after it finishes opening.
+  const bool should_animate_closed_;
+
+  std::unique_ptr<gfx::SlideAnimation> animation_;
+
+  AppMenuDot bottom_dot_;
+  AppMenuDot middle_dot_;
+  AppMenuDot top_dot_;
+
+  // The starting color of the dots. The animation is expected to transition
+  // from this color to |severity_color_|.
+  SkColor start_color_;
+
+  // The severity color of the dots. This is final color at the end of the
+  // animation.
+  SkColor severity_color_;
+
+  DISALLOW_COPY_AND_ASSIGN(AppMenuAnimation);
+};
+
+#endif  // CHROME_BROWSER_UI_VIEWS_TOOLBAR_APP_MENU_ANIMATION_H_