1591489 - Opaque region should be set on MozContainer subsurface

Status: RESOLVED DUPLICATE of bug 1605120

(Core :: Widget: Gtk, enhancement)

Description

[Jan Alexander Steffens [:heftig]]

The opaque region of a Wayland window should also be set on the MozContainer's subsurface, if it exists. The subsurface is the actual top-level opaque thing that EGL renders to, so if we leave it transparent it will still be composited onto the (opaque) shell window.

Comment 1

[Jan Alexander Steffens [:heftig]]

Attachment: Bug 1591489 - [Wayland] Copy the opaque region to the container; r=stransky

The subsurface for the EGL window is actually the opaque thing we care
most about. Without this, the compositor would alpha-blend the
"transparent" EGL window on top of our "opaque" shell window.

Depends on D50628

Comment 2

[Martin Stránský [:stransky] (ni? me)]

Jan, do you want to review this patch or does it work without it?
Thanks.

Comment 3

[Jan Alexander Steffens [:heftig]]

This patch now has accumulated changes fixing several issues:

• The one actually in the bug title, which is that the subsurface should be opaque
• UpdateOpaqueRegion is called very frequently and we should minimize the work we do
• There's a strip of transparency at the bottom of windows that use CSD but not titlebar rendering (such as the main window with enabled title bar, or the About dialog)
• An attempt to stop GTK from removing the opaque region on mShell, which happens whenever the "style" is updated or mShell does size allocation (which is triggered very frequently; much more often than mContainer's size-allocate)

I'll revisit this when I have time.

Comment 4

[Martin Stránský [:stransky] (ni? me)]

Please let me know when the patch is ready for review, Thanks.

Comment 5

[Martin Stránský [:stransky] (ni? me)]

Jan, I'd rather go with a patch at Bug 1602309 as it's smaller and fixes the root cause here. We can follow up with the region cache and so on from this patch.

Comment 6

[Jan Alexander Steffens [:heftig]]

(In reply to Martin Stránský [:stransky] from comment #5)

Jan, I'd rather go with a patch at Bug 1602309 as it's smaller and fixes the root cause here. We can follow up with the region cache and so on from this patch.

Sure; I've just rebased the patch. Assuming 1602309 works and GTK doesn't touch the region anymore, the additional signals doing region overrides in this patch should be unnecessary. I'll revisit the rest when I have time after 1602309 lands.

Comment 7

[Jan Alexander Steffens [:heftig]]

That said, the original idea of this bug to set the region on the MozContainer subsurface still applies.

Comment 8

[Martin Stránský [:stransky] (ni? me)]

(In reply to Jan Alexander Steffens [:heftig] from comment #7)

That said, the original idea of this bug to set the region on the MozContainer subsurface still applies.

Why do we want to set opaque region on MozContainer when we can set it for mShell (parent of MozContainer)?

Comment 9

[Jan Alexander Steffens [:heftig]]

(In reply to Martin Stránský [:stransky] from comment #8)

Why do we want to set opaque region on MozContainer when we can set it for mShell (parent of MozContainer)?

Because the container's surface is our top level surface. If we leave it transparent, the compositor will still have to blend it with the mShell surface.

Comment 10

[Jan Alexander Steffens [:heftig]]

Obsoleted by bug 1605120