[Bug 524567] Re: Software list views with variable-height rows scroll slowly

[Matthew McGowan]

Esmaeil, I am not so sure the symptoms you report directly relate to this
bug.  The bug you mentioned I believe this is already tracked in a bug
reported by mpt.

On Sat, Aug 27, 2011 at 4:43 PM, Esmaeil MIRZAEE
<524567 at bugs.launchpad.net>wrote:

> In bug #830258, we got another error like this but it gets worse.
> software-center-gtk3 trunk r2155, Ubuntu Ocelot
> 1. Go to a list view, e.g. the "System" category.
> 2. Click on a list item near the bottom of the screen.
> 3. Press the Down key a few times.
> What happens: Eventually the selection is not visible, because it is off
> the bottom of the window.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/524567
>
> Title:
>   Software list views with variable-height rows scroll slowly
>
> To manage notifications about this bug go to:
>
> https://bugs.launchpad.net/ubuntu/+source/software-center/+bug/524567/+subscriptions
>


-- 
>From the mind of me!

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to software-center in Ubuntu.
https://bugs.launchpad.net/bugs/524567

Title:
  Software list views with variable-height rows scroll slowly

Status in “software-center” package in Ubuntu:
  Fix Released

Bug description:
  Ubuntu Software Center 1.1.12, Ubuntu Lucid

  1. From the main "Get Software" screen, search for "a".
  2. With the arrow keys, scroll through the search results.

  What happens: The scrolling is rather slow. There's a lot of flashing
  of "More Info" and "Install" buttons, visually trailing behind the
  highlighting of the selected item.

  This is because the GTK treeview control has an "equal-height" mode,
  where scrolling is fast for many items; and a non-equal-height mode,
  where scrolling is slow for many items, but the height of rows can
  vary. In stock GTK, you can't have both varying height and fast
  scrolling at the same time, which is what we want.

  Michael Vogt has a patch to GTK that would (iirc) allow the selected
  item to change height even in equal-height mode. But it would make the
  normal case of non-expanding rows slightly slower, so GTK upstream is
  unwilling to accept it.

  Separately, Michael McGowan has a patch that would make the software
  list view equal-height. <http://people.canonical.com/~mvo/tmp
  /Screenshot-Ubuntu%20Software%20Center.png> It doesn't look as good,
  but more importantly, it wouldn't scale to adding a "Choose Add-Ons…"
  button to the row later. And if we solved the problem a different way
  later, we would have inflicted on users three different layouts in
  three successive versions of Ubuntu Software Center.

  A third possibility is to copy, embed, and tweak the GTK treeview code
  inside USC, like Banshee reportedly does. This would be a lot of work.

  This morning I had a hare-brained idea about solving this another way,
  and Cody Russell says it could work:

  * At rest, make the treeview non-equal-height, with the selected row larger as shown in the spec.
      <https://wiki.ubuntu.com/SoftwareCenter#get-software-list-view>

  * The moment the user starts scrolling with the keyboard:
      1. Remove the buttons from the selected row.
      2. Set equal-height on the treeview.
      3. Scroll as normal, *without* adding/removing buttons in each row as you zip past it.

  * When the user has not been scrolling with the keyboard for, say, 0.5 seconds:
      1. Unset equal-height on the treeview.
      2. Enlarge the selected row and add the appropriate buttons.

  This might even look better than any of the other approaches, because
  there wouldn't be so much flashing from buttons being added and then
  removed a moment later.

  For a fifth option, see <https://code.launchpad.net/~mmcg069/software-
  center/fastappview-kinda-working>, which makes scrolling noticably
  faster, though I don't know how.

  (This is not the same as bug 460366, which was apparently happening
  even for 1.0.)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/software-center/+bug/524567/+subscriptions