Refactor app list event handling and prerendering.

ui/app_list/views/apps_container_view.cc

Index: ui/app_list/views/apps_container_view.cc
diff --git a/ui/app_list/views/apps_container_view.cc b/ui/app_list/views/apps_container_view.cc
index 4d6fdaba35dd99961639d1c1970218efaf9edf9f..15743474913ec47bfe9c9ade0220af5d297fab87 100644
--- a/ui/app_list/views/apps_container_view.cc
+++ b/ui/app_list/views/apps_container_view.cc
@@ -11,6 +11,7 @@
 #include "ui/app_list/app_list_constants.h"
 #include "ui/app_list/app_list_folder_item.h"
 #include "ui/app_list/app_list_switches.h"
+#include "ui/app_list/pagination_model.h"
 #include "ui/app_list/views/app_list_folder_view.h"
 #include "ui/app_list/views/app_list_item_view.h"
 #include "ui/app_list/views/app_list_main_view.h"
@@ -20,6 +21,16 @@
 
 namespace app_list {
 
+namespace {
+
+const int kMinMouseWheelToSwitchPage = 20;
+const int kMinScrollToSwitchPage = 20;
+const int kMinHorizVelocityToSwitchPage = 800;
+
+const double kFinishTransitionThreshold = 0.33;
+
+}  // namespace
+
 AppsContainerView::AppsContainerView(AppListMainView* app_list_main_view,
                                      AppListModel* model)
     : model_(model),
@@ -137,6 +148,75 @@ bool AppsContainerView::OnKeyPressed(const ui::KeyEvent& event) {
     return app_list_folder_view_->OnKeyPressed(event);
 }
 
+bool AppsContainerView::OnMouseWheel(const ui::MouseWheelEvent& event) {
+  int offset;
+  if (abs(event.x_offset()) > abs(event.y_offset()))
+    offset = event.x_offset();
+  else
+    offset = event.y_offset();
+
+  if (abs(offset) > kMinMouseWheelToSwitchPage) {
+    if (!GetPaginationModel()->has_transition()) {
+      GetPaginationModel()->SelectPageRelative(offset > 0 ? -1 : 1, true);
+    }
+    return true;
+  }
+
+  return false;
+}
+
+void AppsContainerView::OnGestureEvent(ui::GestureEvent* event) {
+  switch (event->type()) {
+    case ui::ET_GESTURE_SCROLL_BEGIN:
+      GetPaginationModel()->StartScroll();
+      event->SetHandled();
+      return;
+    case ui::ET_GESTURE_SCROLL_UPDATE:
+      // event->details.scroll_x() > 0 means moving contents to right. That is,
+      // transitioning to previous page.
+      GetPaginationModel()->UpdateScroll(event->details().scroll_x() /
+                                         GetContentsBounds().width());
+      event->SetHandled();
+      return;
+    case ui::ET_GESTURE_SCROLL_END:
+      GetPaginationModel()->EndScroll(
+          GetPaginationModel()->transition().progress <
+          kFinishTransitionThreshold);
+      event->SetHandled();
+      return;
+    case ui::ET_SCROLL_FLING_START: {
+      GetPaginationModel()->EndScroll(true);
+      if (fabs(event->details().velocity_x()) > kMinHorizVelocityToSwitchPage) {
+        GetPaginationModel()->SelectPageRelative(
+            event->details().velocity_x() < 0 ? 1 : -1, true);
+      }
+      event->SetHandled();
+      return;
+    }
+    default:
+      break;
+  }
+}
+
+void AppsContainerView::OnScrollEvent(ui::ScrollEvent* event) {
+  if (event->type() == ui::ET_SCROLL_FLING_CANCEL)
+    return;
+
+  float offset;
+  if (std::abs(event->x_offset()) > std::abs(event->y_offset()))
+    offset = event->x_offset();
+  else
+    offset = event->y_offset();
+
+  if (std::abs(offset) > kMinScrollToSwitchPage) {
+    if (!GetPaginationModel()->has_transition()) {
+      GetPaginationModel()->SelectPageRelative(offset > 0 ? -1 : 1, true);
+    }
+    event->SetHandled();
+    event->StopPropagation();
+  }
+}
+
 void AppsContainerView::OnTopIconAnimationsComplete() {
   --top_icon_animation_pending_count_;
 
@@ -200,6 +280,10 @@ Rects AppsContainerView::GetTopItemIconBoundsInActiveFolder() {
   return AppListFolderItem::GetTopIconsBounds(to_container);
 }
 
+PaginationModel* AppsContainerView::GetPaginationModel() {
+  return apps_grid_view_->pagination_model();
+}
+
 void AppsContainerView::CreateViewsForFolderTopItemsAnimation(
     AppListFolderItem* active_folder,
     bool open_folder) {