Font backend: Observations on speed on Windows

Font backend: Observations on speed on Windows

[Óscar Fuentes]

Today I fired a fresh CVS Emacs and, with great surprise, noticed that
the screen is painted with acceptable speed on my old 550 MHz
machine. The second odd thing is that the font used was not the one I
expected. Emacs was using

-raster-MS Sans Serif-normal-normal-normal-sans-16-*-*-*-p-*-iso8859-1

so I changed the default font to

-outline-Courier New-normal-normal-normal-mono-16-*-*-*-c-*-iso8859-1

and the slowness manifested again. It is my impression that it is not so
bad as some weeks ago, though.

Please note that the first font is a raster variable-pitch font, while
the second is a true-type fixed-pitch one. After some experimentation,
the key seems to be true-type. The raster courier font

-raster-Courier-normal-normal-normal-mono-16-*-*-*-c-*-iso8859-1

is fast too.

Another odd thing is that the "Set Font/Fontset" dialog only shows
fixed-pitch fonts.

Hope this helps to locate the place that makes the new font backend so
slow (for certain fonts, it seems).

-- 
Oscar

Re: Font backend: Observations on speed on Windows

[Jason Rumney]

Óscar Fuentes wrote:
> Today I fired a fresh CVS Emacs and, with great surprise, noticed that
> the screen is painted with acceptable speed on my old 550 MHz
> machine. The second odd thing is that the font used was not the one I
> expected. Emacs was using
>
> -raster-MS Sans Serif-normal-normal-normal-sans-16-*-*-*-p-*-iso8859-1
>
> so I changed the default font to
>
> -outline-Courier New-normal-normal-normal-mono-16-*-*-*-c-*-iso8859-1
>
> and the slowness manifested again. It is my impression that it is not so
> bad as some weeks ago, though.
>   

Does the display become similarly fast when anti-aliasing is disabled, 
even with the Courier New font?
How is it with other truetype fonts, particularly sans serif ones, which 
are less likely to overspill the character cell boundaries when antialiased?

Re: Font backend: Observations on speed on Windows

[Óscar Fuentes]

Jason Rumney <jasonr@gnu.org> writes:

> Óscar Fuentes wrote:
>> Today I fired a fresh CVS Emacs and, with great surprise, noticed that
>> the screen is painted with acceptable speed on my old 550 MHz
>> machine. The second odd thing is that the font used was not the one I
>> expected. Emacs was using
>>
>> -raster-MS Sans Serif-normal-normal-normal-sans-16-*-*-*-p-*-iso8859-1
>>
>> so I changed the default font to
>>
>> -outline-Courier New-normal-normal-normal-mono-16-*-*-*-c-*-iso8859-1
>>
>> and the slowness manifested again. It is my impression that it is not so
>> bad as some weeks ago, though.
>>   
>
> Does the display become similarly fast when anti-aliasing is disabled,
> even with the Courier New font?

How do I disable anti-aliasing? (This is Windows2K)

> How is it with other truetype fonts, particularly sans serif ones,
> which are less likely to overspill the character cell boundaries when
> antialiased?

The list of available fonts is quite short. I tried this:

-outline-DejaVu Sans Mono-normal-normal-normal-mono-16-*-*-*-c-*-iso8859-1

and the rendering speed is not worse, although it is not obvious that is
better than Courier New. Sorry, can't be more precise. Can you recommend
a method for measuring font rendering speed on Emacs, so I can give
accurate reports?

-- 
Oscar

Re: Font backend: Observations on speed on Windows

[dhruva]

Hi,

On Wed, Jun 11, 2008 at 2:45 PM, Óscar Fuentes <ofv@wanadoo.es> wrote:

> How do I disable anti-aliasing? (This is Windows2K)

Right-Mouse-Click on the desktop screen, go to
"Properties"->"Appearance"->"Effects..." and disable the checkbox
corresponding to "Use the following method to smooth edges of screen
fonts" or select "Standard" (instead of "ClearType".

By doing so, I see a noticeable increase in speed. I am now going to
profile emacs to see the difference.

-dky

-- 
Contents reflect my personal views only!

Re: Font backend: Observations on speed on Windows

[Juanma Barranquero]

On Wed, Jun 11, 2008 at 11:31, dhruva <dhruvakm@gmail.com> wrote:

> By doing so, I see a noticeable increase in speed. I am now going to
> profile emacs to see the difference.

I don't see any increase in speed, either by disabling it or setting
it to Standard. In all cases Emacs is unable to cope with keyboard
repeat in line-by-line scrolling.

   Juanma

Re: Font backend: Observations on speed on Windows

[Óscar Fuentes]

dhruva <dhruvakm@gmail.com> writes:

>> How do I disable anti-aliasing? (This is Windows2K)
>
> Right-Mouse-Click on the desktop screen, go to
> "Properties"->"Appearance"->"Effects..." and disable the checkbox
> corresponding to "Use the following method to smooth edges of screen
> fonts" or select "Standard" (instead of "ClearType".

The option you mention is on XP. The most similar thing on W2K is
"Smooth edges of screen fonts". Its help text starts with:

"Specifies whether to smooth edges of large fonts to make screen fonts
more readable" ...

I'm not sure this has something to do with anti-aliasing, but turning it
off makes no appreciable change on font rendering speed.

> By doing so, I see a noticeable increase in speed. I am now going to
> profile emacs to see the difference.

-- 
Oscar

Re: Font backend: Observations on speed on Windows

[dhruva]

Hi,

On Wed, Jun 11, 2008 at 3:13 PM, Óscar Fuentes <ofv@wanadoo.es> wrote:

>> By doing so, I see a noticeable increase in speed. I am now going to
>> profile emacs to see the difference.

I apologize for the premature claims. The profiling did not show any
difference either. My earlier claims were based on perceptions and was
flawed because my expectations influenced my perceptions!

-dky

-- 
Contents reflect my personal views only!