Adds UI components for desktop notifications, including balloon view classes ...

chrome/browser/notifications/balloon_collection.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_BALLOON_COLLECTION_H_
+#define CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_H_
+
+#include <deque>
+
+#include "base/gfx/point.h"
+#include "base/gfx/rect.h"
+#include "base/gfx/size.h"
+#include "chrome/browser/notifications/balloon.h"
+#include "chrome/browser/notifications/notification.h"
+
+class Balloon;
+class Profile;
+
+class BalloonCollection {
+ public:
+  virtual ~BalloonCollection() {}
+
+  // Adds a new balloon for the specified notification.
+  virtual void Add(const Notification& notification,
+                   Profile* profile) = 0;
+
+  // Is there room to add another notification?
+  virtual bool HasSpace() const = 0;
+};
+
+// A balloon collection represents a set of notification balloons being
+// shown on the screen.  It positions new notifications according to
+// a layout, and monitors for balloons being closed, which it reports
+// up to its parent, the notification UI manager.
+class BalloonCollectionImpl : public BalloonCollection,
+                              public Balloon::BalloonCloseListener {
+ public:
+  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;
+  };
+
+  BalloonCollectionImpl();
+  virtual ~BalloonCollectionImpl();
+
+  BalloonSpaceChangeListener* space_change_listener() {
+    return space_change_listener_;
+  }
+  void set_space_change_listener(BalloonSpaceChangeListener* listener) {
+    space_change_listener_ = listener;
+  }
+
+  // BalloonCollectionInterface overrides
+  virtual void Add(const Notification& notification,
+                   Profile* profile);
+  virtual bool HasSpace() const;
+
+  // Balloon::BalloonCloseListener interface
+  virtual void OnBalloonClosed(Balloon* source);
+
+ protected:
+  // Creates a new balloon. Overridable by unit tests.  The caller is
+  // responsible for freeing the pointer returned.
+  virtual Balloon* MakeBalloon(const Notification& notification,
+                               Profile* profile);
+
+ private:
+  // The number of balloons being displayed.
+  int count() const { return balloons_.size(); }
+
+  // Adjusts the positions of the balloons (e.g., when one is closed).
+  void PositionBalloons(bool is_reposition);
+
+  // 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();
+
+    // TODO(johnnyg): Scale the size to account for the system font factor.
+    int min_balloon_width() const { return kBalloonMinWidth; }
+    int max_balloon_width() const { return kBalloonMaxWidth; }
+    int min_balloon_height() const { return kBalloonMinHeight; }
+    int max_balloon_height() const { return kBalloonMaxHeight; }
+
+    // Returns both the total space available and the maximum
+    // allowed per balloon.
+    //
+    // The size may be a height or length depending on the way that
+    // balloons are laid out.
+    const void GetMaxLinearSize(int* max_balloon_size, int* total_size) const;
+
+    // Refresh the cached values for work area and drawing metrics.
+    // The application should call this method to re-acquire metrics after
+    // any resolution or settings change.
+    // Returns true if and only if a metric changed.
+    bool RefreshSystemMetrics();
+
+    // Returns the origin for the sequence of balloons depending on layout.
+    // Should not be used to place a balloon -- only to call NextPosition().
+    gfx::Point GetLayoutOrigin() const;
+
+    // Compute the position for the next balloon.
+    // Start with *position_iterator = GetLayoutOrigin() and call repeatedly
+    // to get a sequence of positions. Return value is the upper-left coordinate
+    // for each next balloon.
+    gfx::Point NextPosition(const gfx::Size& balloon_size,
+                            gfx::Point* position_iterator) 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_;
+    DISALLOW_COPY_AND_ASSIGN(Layout);
+  };
+
+  // Non-owned pointer to an object listening for space changes.
+  BalloonSpaceChangeListener* space_change_listener_;
+
+  // Queue of active balloons.
+  typedef std::deque<Balloon*> Balloons;
+  Balloons balloons_;
+
+  // The layout parameters for balloons in this collection.
+  Layout layout_;
+
+  DISALLOW_COPY_AND_ASSIGN(BalloonCollectionImpl);
+};
+
+#endif  // CHROME_BROWSER_NOTIFICATIONS_BALLOON_COLLECTION_H_