RE: char-width of a font? pixel-width of a future frame? NOT SOLVED

RE: char-width of a font? pixel-width of a future frame? NOT SOLVED

[David Reitter]

> How do I find out either
>
>     - what the (average) width of characters of a given font/ 
> fontset is? or
>
> `frame-char-width' or height gives the pixel width or height of the  
> frame's
> default font.

Yes, but they only work with an existing frame as parameter.
I only have a font/fontset or some frame-parameters, but not a frame.


>
>     - what, given a set of frame-parameters (including font and  
> width and
>     height), what the pixel-width and pixel-height of a frame are  
> going
>     to be once it is created?
>
> If the frame is to fit the buffer (you mentioned font size), then  
> you need
> to calculate the line length and number of lines, then multiply  
> these by the
> frame-char-width and frame-char-height. You can see code that  
> calculates
> frame size from buffer size here:
> http://www.emacswiki.org/elisp/fit-frame.el.

I need to know what width a frame is going to have in pixels, before  
it is created. Frames are not fitted by default, and I'm not trying  
to fit frames. I'm just trying to determine a decent position to open  
the frame at.

That's why I was asking for frame-char-width for a given font, to  
calculate the pixel-width.

 > Otherwise, what do you mean by the frame size - it could be  
anything you
 > want. What is the relation between the frame parameters you  
mention and the
 > frame size you want?

Frames are created with whatever is set in the width / height  
specification of the default-frame-alist (or whatever is given to  
make-frame). These specifications are in characters / lines, not  
pixels. I just need to translate to pixels.

Anyone??

- D

RE: char-width of a font? pixel-width of a future frame? NOT SOLVED

[Drew Adams]

    Frames are created with whatever is set in the width / height
    specification of the default-frame-alist (or whatever is given to
    make-frame). These specifications are in characters / lines, not
    pixels. I just need to translate to pixels.

For a given frame: use frame-pixel-width / -height. You can always create a
test frame, perhaps invisible, using default-frame-alist, and get its size
in pixels.

But it sounds like you have want to know the pixel size of a frame that
would be created using default-frame-alist, without creating any such frame.
You might try one of these (untested):

 - (face-attribute 'default :height t t). This can give you the height of a
font in 1/10 pt, but it can also give you a scale factor instead. To convert
points to pixels, perhaps you can use display-pixels-per-inch plus the
number of points in an inch.

 - Get the pixel size from the font name - see pixelsize and x-font-regexp
in faces.el. Multiply by the height parameter in default-frame-alist.

That's all I can think of. Perhaps someone has a simple and direct solution.