draw line

draw line

[Jonas Bernoulli]

I would like to draw a one-pixel line. I have tried quite a few things
by now but none of them works.

Here are two ways I have tried. Evaluating them should draw a red line
on the next line, which is only one pixel high.

(insert (concat "\n" (propertize "\n" 'face '(:background "red")
'display '(space :height (1)))))

(insert (concat "\n" (propertize "\n" 'face '(:background "red")
'line-height 1)))

This doesn't sound very promissing:

38.11 Line Height
... However, no matter what you specify, the actual line height can
never be less than the default. ...

But I know that some time ago I managed to draw a one-pixel line. I
just don't remember how I did it. So I don't know if I just can't come
up with the proper way of doing it anymore or if this is just not
possible anymore in 23.0. I have tried the expressions above with 22.1
without success also. But I don't know if I used 21 or 22 back when I
managed to draw a one-pixel line.

Anyways, does anyone know of a way to draw a line?

-- Jonas

Re: draw line

[David Hansen]

On Wed, 19 Mar 2008 22:00:00 +0100 Jonas Bernoulli wrote:

> Anyways, does anyone know of a way to draw a line?

Unicode line drawing characters?  Of course that won't change the line
height.

David

Re: draw line

[Johan Bockgård]

"Jonas Bernoulli" <jonas@bernoulli.cc> writes:

> Anyways, does anyone know of a way to draw a line?

(insert (concat (propertize " "
                            'face '(:background "red")
                            'display '(space :height (1)))
                (propertize "\n"
                            'face '(:background "red")
                            'line-height t)))

-- 
Johan Bockgård

Re: draw line

[Kim F. Storm]

"Jonas Bernoulli" <jonas@bernoulli.cc> writes:

> I would like to draw a one-pixel line. I have tried quite a few things
> by now but none of them works.
>
> Here are two ways I have tried. Evaluating them should draw a red line
> on the next line, which is only one pixel high.
>
> (insert (concat "\n" (propertize "\n" 'face '(:background "red")
> 'display '(space :height (1)))))
>
> (insert (concat "\n" (propertize "\n" 'face '(:background "red")
> 'line-height 1)))
>
> This doesn't sound very promissing:
>
> 38.11 Line Height
> ... However, no matter what you specify, the actual line height can
> never be less than the default. ...

Does this help?

   A newline can have a `line-height' text or overlay property that
controls the total height of the display line ending in that newline.

   If the property value is `t', the newline character has no effect on
the displayed height of the line--the visible contents alone determine
the height.  This is useful for tiling small images (or image slices)
without adding blank areas between the images.


-- 
Kim F. Storm  http://www.cua.dk