Re: Em's, ex's and %ages

Subject: Re: Em's, ex's and %ages
From: Paul Prescod <papresco@xxxxxxxxxxxxxxxxxxxxxxxxx>
Date: Sun, 20 Apr 1997 13:04:19 -0400
James Clark wrote:
> .5em is the same as (* (actual-font-size) .5)

Okay, if I don't think too much about that, it seems simple. But if I
do, I wonder: "how does the 'interpreter' know the actual font size for
a flow object that is just about to be created." Is the case, then, that
make-expressions can use the result of evaluating some arguments in
evaluating others?

> start-indent: (+ (inherited-start-indent)
>                  (* (- (display-size)
>                        (inherited-start-indent)
>                        (inherited-end-indent))
>                     .2))
> in DSSSL (ie the indent of this element is the indent for the parent element
> plus 20% of the available horizontal space for this element).

Okay. That's easy enough. I thought that the (display-size) was the area
that the finished flow object actually takes up, as opposed to the area
available to it.

Since we have the nice quantity notation, it would be nice to be able to
specify things like percentages and ems in it. If there are other units
like this it might be useful to be able to bind quantities to procedures
taking a single argument.

 Paul Prescod

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