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bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font
From: |
martin rudalics |
Subject: |
bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes |
Date: |
Thu, 27 Nov 2014 19:35:25 +0100 |
> I think you are totally right. To keep the buffer and window
> distinction properly, my note should probably be read as a feature
> request, not a bug report. The request is for a function such as
> `buffer-body-width' that would return the width of the current displayed
> buffer in em-length units.
What is the width of a buffer? What are em-lenght units?
> Sounds promising! I just pressed C-x C-- which runs `text-scale-adjust'
> to the effect: "Decrease the default face height by one step".
That's incorrect. The doc-string of `text-scale-decrease' tells it more
accurately: "Decrease the height of the default face in the current
buffer by DEC steps."
> The step
> is `text-scale-mode-step', unchanged from its default value of 1.2. The
> number of steps looks to be stored buffer-locally as
> `text-scale-mode-amount'.
>
> ... So a candidate function would be:
>
> (defun buffer-body-width (&optional buffer pixelwise)
> (let ((width (window-body-width (get-buffer-window (or buffer
> (current-buffer)))
> pixelwise)))
> (floor (cond
> ((eq text-scale-mode-amount 0)
> width)
> ((> text-scale-mode-amount 0)
> (/ width (* text-scale-mode-step text-scale-mode-amount)))
> ((< text-scale-mode-amount 0)
> (* width (* -1 text-scale-mode-step text-scale-mode-amount)))))))
We could start from here. But:
(1) `text-scale-mode-amount' is not autoloaded, so we get an error
calling this with emacs -Q.
(2) `text-scale-mode-amount' is buffer-local. So we have to choose the
right buffer before evaluating it.
(3) `text-scale-mode-amount' constitutes a request to the display engine
to scale a face height. What shall we do when our target machine
can't display the character with the requested height and uses, for
example, the nearest available height instead?
(4) I don't know whether and how the frame's `font' parameter can/should
affect the height of the "default face". Likely this is not a
problem - Eli will tell.
As I said before, I'd rather have a buffer-local equivalent of the
variable `frame-char-height', something like `buffer-char-height',
instead of having to find out by myself what the correct value is.
Next we should try to incorporate this in `window-body-height', either
by overloading the PIXELWISE argument - for example, if this is the
symbol `lines-scaled' we'd return the scaled lines - or with an extra
BUFFER argument which would also allow to retrieve the body height of a
window as if it displayed BUFFER or with something better yet ...
As a consequence, we'd probably have to rename the current C routine
`window-body-height' to `window-body-height-internal' and write the new
`window-body-height' in Elisp on top of that.
And finally we would have to do that for all related functions like
`window-total-height', `split-window' or `window-resize' and decide how
a user can specify that, when splitting a window via say C-4 C-x 2, the
top window should have four lines counted in the original window
buffer's text scaling.
martin
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Joe Corneli, 2014/11/26
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Stefan Monnier, 2014/11/26
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Eli Zaretskii, 2014/11/26
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, martin rudalics, 2014/11/27
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Joe Corneli, 2014/11/27
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes,
martin rudalics <=
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Eli Zaretskii, 2014/11/27
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, martin rudalics, 2014/11/27
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Eli Zaretskii, 2014/11/27
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, martin rudalics, 2014/11/28
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Eli Zaretskii, 2014/11/28
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, martin rudalics, 2014/11/28
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Eli Zaretskii, 2014/11/28
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Joe Corneli, 2014/11/27
- bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, martin rudalics, 2014/11/28
bug#19194: 24.4.50; `window-body-width' is not dynamic relative to font size changes, Eli Zaretskii, 2014/11/27