[PATCH weston 06/17] xdg-shell: Require a buffer and a wl_surface.commit for mapping a window

[Jasper St. Pierre]

On Tue, Apr 7, 2015 at 6:03 PM, Bryce Harrington <bryce at osg.samsung.com> wrote:
> On Tue, Apr 07, 2015 at 05:01:21PM +0800, Jonas Ådahl wrote:
>> Require the client to have attached (either previously committed, or
>> newly) a buffer to the corresponding wl_surface, and that the window
>> will not be potentially mapped until calling wl_surface.commit after
>> having created the window. This is required to make valid double
>> buffered xdg_surface state possible when creating a window.
>>
>> Currently there is no double buffered state in xdg_popup, but it should
>> behave the same as xdg_surface, and for making it future proof in case
>> we want to add double buffered state to xdg_popup.
>>
>> Signed-off-by: Jonas Ådahl <jadahl at gmail.com>
>> ---
>>  protocol/xdg-shell.xml | 8 ++++++++
>>  1 file changed, 8 insertions(+)
>>
>> diff --git a/protocol/xdg-shell.xml b/protocol/xdg-shell.xml
>> index 0b6c999..d316e06 100644
>> --- a/protocol/xdg-shell.xml
>> +++ b/protocol/xdg-shell.xml
>> @@ -149,6 +149,10 @@
>>        It provides requests to treat surfaces like windows, allowing to set
>>        properties like maximized, fullscreen, minimized, and to move and resize
>>        them, and associate metadata like title and app id.
>> +
>> +      For a xdg_surface to be mapped by the compositor, the wl_surface must
>> +      have a buffer attached to it, and wl_surface.commit must have been called
>> +      after having created the xdg_surface object.
>
> That reads a bit awkward to me; could it be improved with the following?
>
>     In order for the compositor to map a created xdg_surface object, a
>     buffer must first be attached to the wl_surface and
>     wl_surface.commit called.

It doesn't describe the full story. wl_surface.commit needs to be
called *after* the xdg_surface is created.

I believe the wl_surface.attach and get_xdg_surface can happen in
either order, though it might be nice to establish some form of
standard order for that.

>>      </description>
>>
>>      <request name="destroy" type="destructor">
>> @@ -473,6 +477,10 @@
>>        The x and y arguments specify where the top left of the popup
>>        should be placed, relative to the local surface coordinates of the
>>        parent surface.
>> +
>> +      For a xdg_popup to be mapped by the compositor, the wl_surface must
>> +      have a buffer attached to it, and wl_surface.commit must have been
>> +      called after having created the xdg_popup object.
> As above
>
>>      </description>
>>
>>      <request name="destroy" type="destructor">
>> --
>> 2.1.4
>>
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-- 
  Jasper