Is Default face a per frame attribute or a global one?

Is Default face a per frame attribute or a global one?

[Alexandros Prekates]

Continuing little experiments to better undestand the relation among 
fonts, faces, frames etc, i noticed
that  if i have 2 frames (A and B) and  i evaluate from ielm in frame A 
(set-frame-font "liberation serif" nil nil) . when i check the default 
face's font i see different values in frame A from frame B.

So it seems that default face is a frame's variable.

i mean every frame has its own default face? Is that right?

Alexandros

Re: Is Default face a per frame attribute or a global one?

[Alex Kost]

Alexandros Prekates (2014-08-25 03:29 +0400) wrote:

> Continuing little experiments to better undestand the relation among
> fonts, faces, frames etc, i noticed
> that  if i have 2 frames (A and B) and  i evaluate from ielm in frame A
> (set-frame-font "liberation serif" nil nil) . when i check the default
> face's font i see different values in frame A from frame B.
>
> So it seems that default face is a frame's variable.
>
> i mean every frame has its own default face? Is that right?

As you can see after "C-h f set-frame-font":

“...
If FRAMES is nil, apply the font to the selected frame only.
...”

So the second nil in your expression means you set a font only for the
current frame A.

Re: Is Default face a per frame attribute or a global one?

[Alexandros Prekates]

On 25/08/2014 08:54 πμ, Alex Kost wrote:
> Alexandros Prekates (2014-08-25 03:29 +0400) wrote:
>
>> Continuing little experiments to better undestand the relation among
>> fonts, faces, frames etc, i noticed
>> that  if i have 2 frames (A and B) and  i evaluate from ielm in frame A
>> (set-frame-font "liberation serif" nil nil) . when i check the default
>> face's font i see different values in frame A from frame B.
>>
>> So it seems that default face is a frame's variable.
>>
>> i mean every frame has its own default face? Is that right?
> As you can see after "C-h f set-frame-font":
>
> “...
> If FRAMES is nil, apply the font to the selected frame only.
> ...”
>
> So the second nil in your expression means you set a font only for the
> current frame A.
>
>
So default face is not a global emacs session variable. It's an 
attribute per frame.

Re: Is Default face a per frame attribute or a global one?

[Alex Kost]

Alexandros Prekates (2014-08-25 14:07 +0400) wrote:

> On 25/08/2014 08:54 πμ, Alex Kost wrote:
>> Alexandros Prekates (2014-08-25 03:29 +0400) wrote:
>>
>>> Continuing little experiments to better undestand the relation among
>>> fonts, faces, frames etc, i noticed
>>> that  if i have 2 frames (A and B) and  i evaluate from ielm in frame A
>>> (set-frame-font "liberation serif" nil nil) . when i check the default
>>> face's font i see different values in frame A from frame B.
>>>
>>> So it seems that default face is a frame's variable.
>>>
>>> i mean every frame has its own default face? Is that right?
>> As you can see after "C-h f set-frame-font":
>>
>> “...
>> If FRAMES is nil, apply the font to the selected frame only.
>> ...”
>>
>> So the second nil in your expression means you set a font only for the
>> current frame A.
>>
>>
> So default face is not a global emacs session variable. It's an
> attribute per frame.

I thought you were talking about frame fonts.  AFAIU there is only one
‘default’ face (defined in "faces.el"), if that's what you mean.

Re: Is Default face a per frame attribute or a global one?

[Alexandros Prekates]

On 25/08/2014 03:03 μμ, Alex Kost wrote:
> Alexandros Prekates (2014-08-25 14:07 +0400) wrote:
>
>> On 25/08/2014 08:54 πμ, Alex Kost wrote:
>>> Alexandros Prekates (2014-08-25 03:29 +0400) wrote:
>>>
>>>> Continuing little experiments to better undestand the relation among
>>>> fonts, faces, frames etc, i noticed
>>>> that  if i have 2 frames (A and B) and  i evaluate from ielm in frame A
>>>> (set-frame-font "liberation serif" nil nil) . when i check the default
>>>> face's font i see different values in frame A from frame B.
>>>>
>>>> So it seems that default face is a frame's variable.
>>>>
>>>> i mean every frame has its own default face? Is that right?
>>> As you can see after "C-h f set-frame-font":
>>>
>>> “...
>>> If FRAMES is nil, apply the font to the selected frame only.
>>> ...”
>>>
>>> So the second nil in your expression means you set a font only for the
>>> current frame A.
>>>
>>>
>> So default face is not a global emacs session variable. It's an
>> attribute per frame.
> I thought you were talking about frame fonts.  AFAIU there is only one
> ‘default’ face (defined in "faces.el"), if that's what you mean.
>

But the assumption that there is only one global default face 
contradicts with what i see.

In two frames (of the same emacs session)  M-x describe-face (default) 
gives me different font families ( i changed in each frame the font with 
set-frame-font.)

Alexandros

Re: Is Default face a per frame attribute or a global one?

[Alex Kost]

Alexandros Prekates (2014-08-26 03:07 +0400) wrote:

> On 25/08/2014 03:03 μμ, Alex Kost wrote:
>> Alexandros Prekates (2014-08-25 14:07 +0400) wrote:
>>
>>> On 25/08/2014 08:54 πμ, Alex Kost wrote:
>>>> Alexandros Prekates (2014-08-25 03:29 +0400) wrote:
>>>>
>>>>> Continuing little experiments to better undestand the relation among
>>>>> fonts, faces, frames etc, i noticed
>>>>> that  if i have 2 frames (A and B) and  i evaluate from ielm in frame A
>>>>> (set-frame-font "liberation serif" nil nil) . when i check the default
>>>>> face's font i see different values in frame A from frame B.
>>>>>
>>>>> So it seems that default face is a frame's variable.
>>>>>
>>>>> i mean every frame has its own default face? Is that right?
>>>> As you can see after "C-h f set-frame-font":
>>>>
>>>> “...
>>>> If FRAMES is nil, apply the font to the selected frame only.
>>>> ...”
>>>>
>>>> So the second nil in your expression means you set a font only for the
>>>> current frame A.
>>>>
>>>>
>>> So default face is not a global emacs session variable. It's an
>>> attribute per frame.
>> I thought you were talking about frame fonts.  AFAIU there is only one
>> ‘default’ face (defined in "faces.el"), if that's what you mean.
>>
>
> But the assumption that there is only one global default face
> contradicts with what i see.
>
> In two frames (of the same emacs session)  M-x describe-face (default)
> gives me different font families ( i changed in each frame the font with
> set-frame-font.)

I didn't mean there is always only one global value of a face for all
frames.  As you could see it is possible to set face attributes for a
particular frame.  Here is a paragraph from (info "(elisp) Faces"):

“...
   By default, each face name corresponds to the same set of attributes
in all frames.  But you can also assign a face name a special set of
attributes in one frame (*note Attribute Functions::).
”

You can look at (info "(elisp) Attribute Functions") to read how it can
be done.  And ‘set-frame-font’ does exactly that: it calls
‘set-face-attribute’ to specify a font for the current frame.

Re: Is Default face a per frame attribute or a global one?

[Alexandros Prekates]

On 26/08/2014 07:55 πμ, Alex Kost wrote:
> Alexandros Prekates (2014-08-26 03:07 +0400) wrote:
>
>> On 25/08/2014 03:03 μμ, Alex Kost wrote:
>>> Alexandros Prekates (2014-08-25 14:07 +0400) wrote:
>>>
>>>> On 25/08/2014 08:54 πμ, Alex Kost wrote:
>>>>> Alexandros Prekates (2014-08-25 03:29 +0400) wrote:
>>>>>
>>>>>> Continuing little experiments to better undestand the relation among
>>>>>> fonts, faces, frames etc, i noticed
>>>>>> that  if i have 2 frames (A and B) and  i evaluate from ielm in frame A
>>>>>> (set-frame-font "liberation serif" nil nil) . when i check the default
>>>>>> face's font i see different values in frame A from frame B.
>>>>>>
>>>>>> So it seems that default face is a frame's variable.
>>>>>>
>>>>>> i mean every frame has its own default face? Is that right?
>>>>> As you can see after "C-h f set-frame-font":
>>>>>
>>>>> “...
>>>>> If FRAMES is nil, apply the font to the selected frame only.
>>>>> ...”
>>>>>
>>>>> So the second nil in your expression means you set a font only for the
>>>>> current frame A.
>>>>>
>>>>>
>>>> So default face is not a global emacs session variable. It's an
>>>> attribute per frame.
>>> I thought you were talking about frame fonts.  AFAIU there is only one
>>> ‘default’ face (defined in "faces.el"), if that's what you mean.
>>>
>> But the assumption that there is only one global default face
>> contradicts with what i see.
>>
>> In two frames (of the same emacs session)  M-x describe-face (default)
>> gives me different font families ( i changed in each frame the font with
>> set-frame-font.)
> I didn't mean there is always only one global value of a face for all
> frames.  As you could see it is possible to set face attributes for a
> particular frame.  Here is a paragraph from (info "(elisp) Faces"):
>
> “...
>     By default, each face name corresponds to the same set of attributes
> in all frames.  But you can also assign a face name a special set of
> attributes in one frame (*note Attribute Functions::).
> ”
>
> You can look at (info "(elisp) Attribute Functions") to read how it can
> be done.  And ‘set-frame-font’ does exactly that: it calls
> ‘set-face-attribute’ to specify a font for the current frame.
>

Thanks. That makes things more clear now.

set-frame-font --> set-face-attribute --> 
internal-set-lisp-face-attribute (c function).
That last one somehow implements the 
http://www.emacswiki.org/emacs/FacesPerFrame funtionality.

Although i 'm curious  of how you do  that in a non-OO language :-)

Alexandros