Determining line-height in pixels

Determining line-height in pixels

[Dmitry Gutov]

Hi all!

How can I programmatically determine full line height in pixels?

I'm planning to use that value for fringe bitmaps, so it needs to
include line spacing.

The docs are saying that it can change from line to line, but the
default value should be good enough.

  (face-attribute 'default :height)

seems to return what I want, only in typographic points. Can I convert
that to pixels?

Best regards,
Dmitry

RE: Determining line-height in pixels

[Doug Lewan]

To get font height in pixels I suspect you're going to have to do the arithmetic yourself.

You might want to look at (display-pixel-height).

,Doug

> -----Original Message-----
> From: help-gnu-emacs-bounces+dougl=shubertticketing.com@gnu.org
> [mailto:help-gnu-emacs-bounces+dougl=shubertticketing.com@gnu.org] On
> Behalf Of Dmitry Gutov
> Sent: Thursday, 2012 June 28 21:50
> To: help-gnu-emacs@gnu.org
> Subject: Determining line-height in pixels
> 
> Hi all!
> 
> How can I programmatically determine full line height in pixels?
> 
> I'm planning to use that value for fringe bitmaps, so it needs to
> include line spacing.
> 
> The docs are saying that it can change from line to line, but the
> default value should be good enough.
> 
>   (face-attribute 'default :height)
> 
> seems to return what I want, only in typographic points. Can I convert
> that to pixels?
> 
> Best regards,
> Dmitry
> 

Re: Determining line-height in pixels

[Dmitry Gutov]

Hi Doug,

On 29.06.2012 16:35, Doug Lewan wrote:
> To get font height in pixels I suspect you're going to have to do the arithmetic yourself.
>
> You might want to look at (display-pixel-height).

This was not it (the function returns vertical screen resolution), but 
it pointed me in the right direction.

(frame-char-height) is the answer, probably along with 
`text-scale-mode-amount' and `text-scale-mode-step'.

Thanks,
Dmitry

RE: Determining line-height in pixels

[Drew Adams]

> (frame-char-height) is the answer, probably along with 
> `text-scale-mode-amount' and `text-scale-mode-step'.

See also variable `line-spacing' and the frame parameter of the same name.  See
also text/overlay property `line-height'.

See (elisp) `Line Height'.

Re: Determining line-height in pixels

[Dmitry Gutov]

On 29.06.2012 20:02, Drew Adams wrote:
>> (frame-char-height) is the answer, probably along with
>> `text-scale-mode-amount' and `text-scale-mode-step'.
>
> See also variable `line-spacing' and the frame parameter of the same name.  See
> also text/overlay property `line-height'.
>
> See (elisp) `Line Height'.

Thanks, but this is what I found first thing actually, and there was no 
mention of `frame-char-height' there.

For the moment I'm trying to reuse bitmaps across lines, and accounting 
for differences between the lines doesn't fit in that. It shouldn't be a 
problem in [text|prog]-mode buffers anyway.

-- Dmitry