Determining size of a propertised string

["Elias Mårtenson" <lokedhs@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 914 bytes --]

I have a string with a buch of properties applied (the main one: It uses a
different font). I now need to split the window, making the size of the
window just large enough to contain this text. If the string is not
propertised, I can simply count the number of lines in the text I'll be
inserting into the buffer and pass that as the HEIGHT parameter to
‘split-window’. But since the font used in this text is larger than the
default font, the window becomes slightly too small.

As far as I can tell, there seems to be no standard way of determining what
height to use in order to fit a given string. Is there a correct way to
handle this?

The context of this is the C-c C-k feature in gnu-apl-mode. It is used to
open a window that displays the APL keymap. It's common to use a slightly
larger font for APL since each character is important, and that makes this
problem immediately visible.

[-- Attachment #2: Type: text/html, Size: 987 bytes --]