The space is a character that you can edit the advance width of in Fontlab. If you want to make any sequence of glyphs be the same width, then you must make it so in the two fonts, that they have identical advance widths (and kerning).

Perhaps this is already being done, but....

In terms of the relationship between upright and italic, generally after you slant* the italic, you need to also shift all the glyphs slightly to the left, to compensate for their new lean to the right.

The amount of the shift is arguable. Do you do the compensation based on making up for the italics at half the x-height, or half the cap height, or something in between? I tend to go about 50-60% of x-height....

So the amount of shift is about 1/2 * xheight * [sin (italic angle)].

* Of course it is usually more than just slanting.

[EDIT: fixed error in formula!]

Hi, thanks, yes the word space is actually the same. When the italic is selected in InDesign it slightly does not keep the right word space/bearing/side measurement, the attached image might help as well? When the italic is selected it looks like it is nearly touching the roman weight?

Are you saying that is not an accurate reflection of how the italic "h" sits between its sidebearings? What I'm seeing there makes it look as if you have not made the left shift I described above. The purpose of that is essentially to re-center the x-height portion of the letter between the sidebearings.

T

.... When the italic is selected it looks like it is nearly touching the roman weight?

If you work with FL, you have 4 options as a reference to slant transformation: "Zero Point, Center of Selection, Bottom Left Corner, and Reference Point". What happens to your description seems to use the reference "zero point" or "Bottom left corner". If you choose the "center of selection", then you'll get a glyph (some still do) amid heavy point glyph box. This will solve the problem of individual glyphs. But will most likely change the composition of the kerning and metrics when applied to all existing glyphs.

IMHO, indeed more appropriate to use the reference "zero point" or "Bottom left corner" but it should do a re-adjustment as the value that has been suggested by Thomas. Or a practical way: subtract the left bearing with a specified value (eg -10) but you have to add +10 on the right bearing. This is I called a "zero sum balance" aims to glyph still get the same size of glyph box. This method is more stable against possibility of changing the composition of kerning

@Thomas ... Thanks for your formula. it's interesting to try

Best Regatds.

OOPS, error in my formula! Should be 1/2 * xheight * [sin (italic angle)]. Somehow I got a divide instead of a multiply. (I went back and edited it in my original post, too. I just don't want to leave anybody messed up who just reads it there.)

Note also that if you use Excel, it expects angles in radians rather than degrees. The Excel version of my formula would be:
=0.5*SIN(RADIANS(n))*x

Where "n" is the italic angle and "x" is the x-height. You can bump up that 0.5 a little to maybe even 0.6, if you want to accomodate caps and letters with ascenders a bit more.

BTW, the "average" results of my formula, with a 1000-unit em, a 500-unit x-height, and an 11 degree italic angle, should be about 47 units to shift.

* * * *

"IMHO, indeed more appropriate to use the reference "zero point" "

I agree whole-heartedly. For a starting point for italics, that's about the only sane thing to do. Then do the global left shift on the whole font.

Of course, that transformed glyph may be just a placeholder for one that has been properly reshaped. Even in a sans serif, you'll need to do something else to get your round letters the right shape. But having that initial auto-transform might still be helpful for positioning/spacing.

Of course, I suck at spacing anyway, feel free to ignore me. :)

Cheers,

T

@Thomas, I've tried.

Your formula is a mathematical approach that makes the most sense. And I think it's also a good reason that we should not use the value arbitrarily. :-)

Thanks

Best regards