Hi, mccanny@ and sgabriel@, through this issue, we found that when shelf is auto-hide (shelf is still visible when there is no visible window), shelf icons can't be dragged via touch but can be dragged via mouse.
In issue 748253, we scale the icons to 120% when it is in the drag-gable state via touch.

I have some questions for the behavior here,
1. Should we make the behavior consistent for touch and mouse events if shelf is auto-hide. Both can or can not drag the items?

2. If we make the icons can be dragged when shelf is auto-hide via both touch and mouse, do we need to scale up the icons via mouse too?

Thanks.

Hey Min,

1. I'd prefer to make the icons draggable by both mouse and touch when the shelf is auto-hide - is there a reason we shouldn't?

2. Yeah, I think we should scale up to 120% when either input is in a reorder mode

We should be ale to drag items even from auto-hidden shelf. At the moment if I make the hidden shelf appear and long-press, it hides it again so I cannot re-order icon, feels weird, I wasn't aware of this behavior.

Ben, I am not quite sure why the old logic is to make the icons not draggable when shelf is auto-hide. But I think we maybe able to change it.

sgabriel@, auto-hide shelf will be shown (when there is visible window, shelf will always be shown when there is no visible window) if mouse cursor stays in the shelf's bounds, take a look of this  issue 657251 .

Why we should hide the shelf again if long-press the shelf? Long-press on the shelf icons or shelf will open the context menu, and if there is opened context menu, the logic now is not to hide the shelf.

>Why we should hide the shelf again if long-press the shelf? Long-press on the shelf icons or shelf will open the context menu, and if there is opened context menu, the logic now is not to hide the shelf.

Sorry not sure I understood what you meant. Long-pressing the shelf displays a contextual menu. Long pressing an icon on the shelf, regardless of the shelf is in auto-hide or not should follow the long-press behavior implemented when shelf auto-hide is off.

I see. I think what do you mean in #6 is that the behavior long-press hides the auto-hide shelf is weird. I think this behavior has been fixed in  issue 657251 .

So, here we need to make the icons draggable regardless of the shelf is in auto-hide or not. And should scale up the icons if it is in draggable state.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2a4edb39bc15c3b8aa854dd0597c7511ea913a1e

commit 2a4edb39bc15c3b8aa854dd0597c7511ea913a1e
Author: MinChen <minch@chromium.org>
Date: Thu Oct 12 22:24:23 2017

Make shelf items can be dragged when shelf is auto-hide.

Changes,
1. Only let ShelfLayoutManager help process the gesture events when
   shelf is not visible. Then shelf items can be dragged when shelf is
   auto-hide.
2. Remove the logic in ShelfView that only transfer gesture events from
   owner to the MenuHost when shelf is not auto-hide.
3. Scale up the shelf items for mouse events.

Test: ShelfLayoutManagerTest*
Bug:  772459 
Change-Id: I33c9767216bb5d95048b151347fdc7ed8f69a302
Reviewed-on: https://chromium-review.googlesource.com/705575
Commit-Queue: min c <minch@chromium.org>
Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#508505}
[modify] https://crrev.com/2a4edb39bc15c3b8aa854dd0597c7511ea913a1e/ash/shelf/shelf.cc
[modify] https://crrev.com/2a4edb39bc15c3b8aa854dd0597c7511ea913a1e/ash/shelf/shelf_button.cc
[modify] https://crrev.com/2a4edb39bc15c3b8aa854dd0597c7511ea913a1e/ash/shelf/shelf_button.h
[modify] https://crrev.com/2a4edb39bc15c3b8aa854dd0597c7511ea913a1e/ash/shelf/shelf_layout_manager.cc
[modify] https://crrev.com/2a4edb39bc15c3b8aa854dd0597c7511ea913a1e/ash/shelf/shelf_view.cc