Browser side support (sans UI) for desktop notifications....

chrome/browser/notifications/balloons.h

+// Copyright (c) 2009 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.
+
+// Handles the visible notification (or balloons).
+
+#ifndef CHROME_BROWSER_NOTIFICATIONS_BALLOONS_H_
+#define CHROME_BROWSER_NOTIFICATIONS_BALLOONS_H_
+
+#include <deque>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/gfx/point.h"
+#include "base/gfx/rect.h"
+#include "base/gfx/size.h"
+#include "base/scoped_ptr.h"
+#include "chrome/browser/notifications/notification.h"
+
+class Balloon;
+class BalloonView;
+class Profile;
+class SiteInstance;
+
+class BalloonCloseListener {
+ public:
+  virtual ~BalloonCloseListener() { }
+
+  // Called when a balloon is closed.
+  virtual void OnBalloonClosed(Balloon* source) = 0;
+};
+
+class BalloonSpaceChangeListener {
+ public:
+  virtual ~BalloonSpaceChangeListener() { }
+
+  // Called when there is more or less space for balloons due to
+  // monitor size changes or balloons disappearing.
+  virtual void OnBalloonSpaceChanged() = 0;
+};
+
+class BalloonCollectionInterface {
+ public:
+  virtual ~BalloonCollectionInterface() {}
+
+  // Adds a new balloon for the specified notification.
+  virtual void Add(const Notification& notification,
+                   Profile* profile,
+                   SiteInstance* site_instance) = 0;
+
+  // Is there room to add another notification?
+  virtual bool HasSpace() const = 0;
+};
+
+typedef std::deque<Balloon*> Balloons;
+
+// Represents a Notification on the screen.
+class Balloon {
+ public:
+  Balloon(const Notification& notification,
+          Profile* profile,
+          SiteInstance* site_instance,
+          BalloonCloseListener* listener);
+  ~Balloon();
+
+  const Notification& notification() const {
+    return notification_;
+  }
+
+  Profile* profile() const {
+    return profile_;
+  }
+
+  SiteInstance* site_instance() const {
+    return site_instance_;
+  }
+
+  void SetPosition(const gfx::Point& upper_left, bool reposition);
+  void SetSize(const gfx::Size& size);
+  void Show();
+  void Close();
+
+  const gfx::Point& position() const;
+  const gfx::Size& size() const;
+
+ private:
+  Profile* profile_;
+  SiteInstance* site_instance_;
+  Notification notification_;
+  BalloonCloseListener* close_listener_;
+  scoped_ptr<BalloonView> balloon_view_;
+  gfx::Point position_;
+  gfx::Size size_;
+  DISALLOW_COPY_AND_ASSIGN(Balloon);
+};
+
+class BalloonCollection : public BalloonCollectionInterface,
+                          public BalloonCloseListener {
+ public:
+  explicit BalloonCollection();
+
+  BalloonSpaceChangeListener* space_change_listener() { return listener_; }
+  void set_space_change_listener(BalloonSpaceChangeListener* listener) {
+    listener_ = listener;
+  }
+
+  // BalloonCollectionInterface overrides
+  virtual void Add(const Notification& notification,
+                   Profile* profile,
+                   SiteInstance* site_instance);
+  virtual void ShowAll();
+  virtual void HideAll();
+  virtual bool HasSpace() const;
+
+  // BalloonCloseListener interface
+  virtual void OnBalloonClosed(Balloon* source);
+
+ protected:
+  // Overridable by unit tests.
+  virtual Balloon* MakeBalloon(const Notification& notification,
+                               Profile* profile,
+                               SiteInstance* site_instance) {
+    return new Balloon(notification, profile, site_instance, this);
+  }
+
+ private:
+  // The number of balloons being displayed.
+  int count() const { return balloons_.size(); }
+
+  // Calculates layout values for the balloons including
+  // the scaling, the max/min sizes, and the upper left corner of each.
+  class Layout {
+   public:
+    Layout();
+
+    // Refresh the work area and balloon placement.
+    void OnDisplaySettingsChanged();
+
+    int min_balloon_width() const;
+    int max_balloon_width() const;
+    int min_balloon_height() const;
+    int max_balloon_height() const;
+
+    // Returns both the total length available and the maximum
+    // allowed per balloon.
+    //
+    // The length may be a height or length depending on the way that
+    // balloons are laid out.
+    const void GetMaxLengths(int* max_balloon_length, int* total_length) const;
+
+    // Scale the size to count in the system font factor.
+    int ScaleSize(int size) const;
+
+    // Refresh the cached values for work area and drawing metrics.
+    // This is done automatically first time and the application should
+    // call this method to re-acquire metrics after any
+    // resolution or settings change.
+    //
+    // Return true if and only if a metric changed.
+    bool RefreshSystemMetrics();
+
+    // Returns the starting value for NextUpperLeftPosition.
+    gfx::Point GetStartPosition() const;
+
+    // Compute the position for the next balloon.
+    //   Modifies origin.
+    //   Returns the position of the upper left coordinate for the given
+    //   balloon.
+    gfx::Point NextPosition(const gfx::Size& balloon_size,
+                            gfx::Point* origin) const;
+
+   private:
+    enum Placement {
+      HORIZONTALLY_FROM_BOTTOM_LEFT,
+      HORIZONTALLY_FROM_BOTTOM_RIGHT,
+      VERTICALLY_FROM_TOP_RIGHT,
+      VERTICALLY_FROM_BOTTOM_RIGHT
+    };
+
+    // Minimum and maximum size of balloon
+    static const int kBalloonMinWidth = 300;
+    static const int kBalloonMaxWidth = 300;
+    static const int kBalloonMinHeight = 90;
+    static const int kBalloonMaxHeight = 120;
+
+    static Placement placement_;
+    gfx::Rect work_area_;
+    double font_scale_factor_;
+    DISALLOW_COPY_AND_ASSIGN(Layout);
+  };
+
+  // Non-owned pointer to an object listening for space changes.
+  BalloonSpaceChangeListener* listener_;
+
+  Balloons balloons_;
+  Layout layout_;
+  DISALLOW_COPY_AND_ASSIGN(BalloonCollection);
+};
+
+#endif  // CHROME_BROWSER_NOTIFICATIONS_BALLOONS_H_