Experimental app list: Change transition animations of top-level pages.

ui/app_list/views/contents_view.cc

Index: ui/app_list/views/contents_view.cc
diff --git a/ui/app_list/views/contents_view.cc b/ui/app_list/views/contents_view.cc
index 19c9dd93836895343e2c8637f186e69053dbf31e..3c35593015f523e05b5268d59994bd749a20bcb3 100644
--- a/ui/app_list/views/contents_view.cc
+++ b/ui/app_list/views/contents_view.cc
@@ -203,20 +203,24 @@ void ContentsView::UpdatePageBounds() {
     }
   }
 
-  gfx::Rect incoming_target(rect);
-  gfx::Rect outgoing_target(rect);
-  int dir = target_page > current_page ? -1 : 1;
-
-  // Pages transition vertically.
+  // A page's origin is its off-screen resting place (top). The start page's
+  // origin is above; all other pages' origins are below.
+  int start_page = GetPageIndexForNamedPage(NAMED_PAGE_START);
   int page_height = rect.height();
-  int transition_offset = progress * page_height * dir;
-
-  outgoing_target.set_y(transition_offset);
-  incoming_target.set_y(dir < 0 ? transition_offset + page_height
-                                : transition_offset - page_height);
-
-  view_model_->view_at(current_page)->SetBoundsRect(outgoing_target);
-  view_model_->view_at(target_page)->SetBoundsRect(incoming_target);
+  int current_page_origin =
+      current_page == start_page ? -page_height : page_height;
+  int target_page_origin =
+      target_page == start_page ? -page_height : page_height;
+
+  // Move |current_page| from 0 to its origin. Move |target_page| from its
+  // origin to 0.
+  gfx::Rect current_page_rect(rect);
+  gfx::Rect target_page_rect(rect);
+  current_page_rect.set_y(progress * current_page_origin);
+  target_page_rect.set_y((1 - progress) * target_page_origin);
+
+  view_model_->view_at(current_page)->SetBoundsRect(current_page_rect);
+  view_model_->view_at(target_page)->SetBoundsRect(target_page_rect);

[calamity, 2014/09/09 09:13:21]

I think you need to do an IsExperimentalAppListEnabled() somewhere.

[Matt Giuca, 2014/09/10 01:45:36]

Done.

Whoops.

 }
 
 PaginationModel* ContentsView::GetAppsPaginationModel() {