Notify launcher page with onTransitionChanged event

chrome/browser/ui/app_list/launcher_page_event_dispatcher_views.cc

Index: chrome/browser/ui/app_list/launcher_page_event_dispatcher_views.cc
diff --git a/chrome/browser/ui/app_list/launcher_page_event_dispatcher_views.cc b/chrome/browser/ui/app_list/launcher_page_event_dispatcher_views.cc
new file mode 100644
index 0000000000000000000000000000000000000000..94815cb6e66ba464a3a50e9d84662bd6de005528
--- /dev/null
+++ b/chrome/browser/ui/app_list/launcher_page_event_dispatcher_views.cc
@@ -0,0 +1,104 @@
+// 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.
+
+#include "chrome/browser/ui/app_list/launcher_page_event_dispatcher_views.h"
+
+#include "ash/shell.h"
+#include "base/basictypes.h"
+#include "base/values.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/ui/app_list/app_list_service.h"
+#include "chrome/browser/ui/app_list/app_list_service_views.h"
+#include "chrome/common/extensions/api/launcher_page_private.h"
+#include "extensions/browser/event_router.h"
+#include "ui/app_list/app_list_model.h"
+#include "ui/app_list/pagination_model.h"
+#include "ui/app_list/views/app_list_view.h"
+#include "ui/app_list/views/contents_view.h"
+
+namespace OnTransitionChanged =
+    extensions::api::launcher_page_private::OnTransitionChanged;
+
+namespace app_list {
+
+LauncherPageEventDispatcherViews::LauncherPageEventDispatcherViews(
+    chrome::HostDesktopType host_desktop,
+    Profile* profile,
+    const std::string& extension_id)
+    : profile_(profile), extension_id_(extension_id), main_view_(nullptr) {
+  AppListView* app_list_view = nullptr;
+  if (host_desktop == chrome::HOST_DESKTOP_TYPE_ASH) {
+    app_list_view = ash::Shell::GetInstance()->GetAppListView();

[tapted, 2014/11/03 00:31:20]

ash::Shell shouldn't be used here - Mac will need to compile this code. It looks
like you could maybe pass in the AppListControllerDelegate instance, and have it
return a gfx::NativeView which must be guaranteed to be non-null here. That will
get rid of the ash dependency.

But I think the lifetime of the event dispatcher overall needs to be improved.

[calamity, 2014/11/06 02:36:31]

Done.

+  } else {
+    AppListServiceViews* service =
+        static_cast<AppListServiceViews*>(AppListService::Get(host_desktop));
+    app_list_view = service->shower().app_list();
+  }
+  CHECK(app_list_view);
+  main_view_ = app_list_view->app_list_main_view();
+  main_view_->AddObserver(this);
+  main_view_->contents_view()->pagination_model()->AddObserver(this);

[Matt Giuca, 2014/11/03 00:57:41]

It might be worth adding a note here about why all the complexity later is
needed.

// Observe the app list's ContentsView's PaginationModel. Note that the
ContentsView can be destroyed and a new one can be created in its place. We
observe these events and remove/add ourselves as an observer of the
PaginationModel as appropriate.

(Or rephrase in your own words.)

[calamity, 2014/11/06 02:36:31]

Code is gone.

+}
+
+LauncherPageEventDispatcherViews::~LauncherPageEventDispatcherViews() {
+  main_view_->RemoveObserver(this);
+  main_view_->contents_view()->pagination_model()->RemoveObserver(this);

[Matt Giuca, 2014/11/03 00:57:41]

Should there be null checks on contents_view() everywhere in this file? (Since
you could be in between OnContentsViewDestroying and OnContentsViewCreated
events, I assume there are therefore times where there is no ContentsView in
existence.)

[calamity, 2014/11/06 02:36:31]

Code is gone.

+}
+
+void LauncherPageEventDispatcherViews::SendEventToLauncherPage(
+    const std::string& event_name,
+    scoped_ptr<base::ListValue> args) {
+  scoped_ptr<extensions::Event> event(
+      new extensions::Event(event_name, args.Pass()));
+  extensions::EventRouter::Get(profile_)
+      ->DispatchEventToExtension(extension_id_, event.Pass());
+}
+
+void LauncherPageEventDispatcherViews::SelectedPageChanged(int old_selected,
+                                                           int new_selected) {
+  ContentsView* contents_view = main_view_->contents_view();
+  if (contents_view->GetStateForPageIndex(old_selected) ==
+      AppListModel::STATE_CUSTOM_LAUNCHER_PAGE) {
+    SendEventToLauncherPage(OnTransitionChanged::kEventName,
+                            OnTransitionChanged::Create(0));
+  } else if (contents_view->GetStateForPageIndex(new_selected) ==
+             AppListModel::STATE_CUSTOM_LAUNCHER_PAGE) {
+    SendEventToLauncherPage(OnTransitionChanged::kEventName,
+                            OnTransitionChanged::Create(1));
+  }
+}
+
+void LauncherPageEventDispatcherViews::TransitionStarted() {
+}
+
+void LauncherPageEventDispatcherViews::TransitionChanged() {
+  ContentsView* contents_view = main_view_->contents_view();

[Matt Giuca, 2014/11/03 00:57:42]

Null check here? (Maybe not necessary as in the destructor, because you wouldn't
get a TransitionChanged event unless there was a PaginationModel... but at least
DCHECK.)

[calamity, 2014/11/06 02:36:31]

Code is gone.

+  PaginationModel* pagination_model = contents_view->pagination_model();
+  const PaginationModel::Transition& transition =
+      pagination_model->transition();
+  app_list::AppListModel::State old_state =
+      contents_view->GetStateForPageIndex(pagination_model->selected_page());
+  app_list::AppListModel::State new_state =
+      contents_view->GetStateForPageIndex(transition.target_page);
+  double progress = 0;
+  if (old_state == AppListModel::STATE_CUSTOM_LAUNCHER_PAGE)
+    progress = 1 - transition.progress;
+  else if (new_state == AppListModel::STATE_CUSTOM_LAUNCHER_PAGE)
+    progress = transition.progress;
+  else
+    return;
+
+  SendEventToLauncherPage(OnTransitionChanged::kEventName,
+                          OnTransitionChanged::Create(progress));
+}
+
+void LauncherPageEventDispatcherViews::OnContentsViewCreated() {
+  main_view_->contents_view()->pagination_model()->AddObserver(this);
+}
+
+void LauncherPageEventDispatcherViews::OnContentsViewDestroying() {
+  main_view_->contents_view()->pagination_model()->RemoveObserver(this);
+}
+
+}  // namespace app_list