Change the DidChangeView update to take a new ViewChanged resource.

ppapi/cpp/view.h

+// Copyright (c) 2011 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 PPAPI_CPP_VIEW_H_
+#define PPAPI_CPP_VIEW_H_
+
+#include "ppapi/cpp/resource.h"
+#include "ppapi/cpp/rect.h"
+#include "ppapi/cpp/size.h"
+
+namespace pp {
+
+class View : public Resource {
+ public:
+  /// Default constructor for creating an is_null() <code>View</code> object.
+  View();
+
+  /// Creates a View resource, taking and holding an additional reference to
+  /// the given resource handle.
+  View(PP_Resource view_resource);
+
+  /// <code>GetRect()</code> returns the rectangle of the instance
+  /// associated with the view changed notification relative to the upper left
+  /// of the browser viewport. This position changes when the page is scrolled.
+  ///
+  /// The returned rectangle may not be inside the visible portion of the
+  /// viewport if the instance is scrolled off the page. Therefore, the
+  /// position may be negative or larger than the size of the page. The size
+  /// will always reflect the size of the plugin were it to be scrolled
+  /// entirely into view.
+  ///
+  /// In general, most plugins will not need to worry about the position of the
+  /// instance in the viewport, and only need to use the size.
+  ///
+  /// @return The rectangle of the instance. The default return value for
+  /// an invalid View is the empty rectangle.
+  Rect GetRect() const;
+
+  /// <code>IsFullscreen()</code> returns whether the instance is currently
+  /// displaying in fullscreen mode.
+  ///
+  /// @return <code>true</code> if the instance is in full screen mode,
+  /// or <code>false</code> if it's not or the resource is invalid.
+  bool IsFullscreen() const;
+
+  /// <code>IsVisible()</code> returns true if the instance is plausibly
+  /// visible to the user. You should use this flag to throttle or stop updates
+  /// for invisible plugins.
+  ///
+  /// Thie measure incorporates both whether the instance is scrolled into
+  /// view (whether the clip rect is nonempty) and whether the page is
+  /// plausibly visible to the user (<code>IsPageVisible()</code>).
+  ///
+  /// @return <code>true</code> if the instance is plausibly visible to the
+  /// user, <code>false</code> if it is definitely not visible.
+  bool IsVisible() const;
+
+  /// <code>IsPageVisible()</code> determines if the page that contains the
+  /// instance is visible. The most common cause of invisible pages is that
+  /// the page is in a background tab in the browser.
+  ///
+  /// Most applications should use <code>IsVisible()</code> rather than
+  /// this function since the instance could be scrolled off of a visible
+  /// page, and this function will still return true. However, depending on
+  /// how your plugin interacts with the page, there may be certain updates
+  /// that you may want to perform when the page is visible even if your
+  /// specific instance isn't.
+  ///
+  /// @return <code>true</code> if the instance is plausibly visible to the
+  /// user, <code>false</code> if it is definitely not visible.
+  bool IsPageVisible() const;
+
+  /// <code>GetClip()</code> returns the clip rectangle relative to the upper
+  /// left corner of the instance. This rectangle indicates which parts of the
+  /// instance are scrolled into view.
+  ///
+  /// If the instance is scrolled off the view, the return value will be
+  /// (0, 0, 0, 0). this state. This clip rect does <i>not</i> take into account
+  /// page visibility. This means if the instance is scrolled into view but the
+  /// page itself is in an invisible tab, the return rect will contain the
+  /// visible rect assuming the page was visible. See
+  /// <code>IsPageVisible()</code> and <code>IsVisible()</code> if you want
+  /// to handle this case.
+  ///
+  /// Most applications will not need to worry about the clip. The recommended
+  /// behavior is to do full updates if the instance is visible as determined by
+  /// <code>IsUserVisible()</code> and do no updates if not.
+  ///
+  /// However, if the cost for computing pixels is very high for your
+  /// application or the pages you're targeting frequently have very large
+  /// instances with only portions visible, you may wish to optimize further.
+  /// In this case, the clip rect will tell you which parts of the plugin to
+  /// update.
+  ///
+  /// Note that painting of the page and sending of view changed updates
+  /// happens asynchronously. This means when the user scrolls, for example,
+  /// it is likely that the previous backing store of the instance will be used
+  /// for the first paint, and will be updated later when your application
+  /// generates new content. This may cause flickering at the boundaries when
+  /// scrolling. If you do choose to do partial updates, you may want to think
+  /// about what color the invisible portions of your backing store contain
+  /// (be it transparent or some background color) or to paint a certain
+  /// region outside the clip to reduce the visual distraction when this
+  /// happens.
+  ///
+  /// @return The rectangle representing the visible part of the instance.
+  /// If the resource is invalid, the empty rect is returned.
+  Rect GetClipRect() const;
+};
+
+}  // namespace pp
+
+#endif  // PPAPI_CPP_VIEW_H_