[3/3] gdiplus: Make GdipMeasureCharacterRanges/GdipMeasureString/GdipDrawString add extra space around the text.

[Vincent Povirk]

> These APIs use different logic for adding extra space, so at the moment
> I don't see how gdip_format_string() can be used to do this in one place,
> but if somebody has an idea how to do that - patches are welcome.

That is highly unlikely, particularly given that
MeasureCharacterRanges is the accepted practice for highlighting parts
of a string.

You should make sure you do your tests so the size in pixels is the em
size of the font, or at least at a consistent size between them, as
native may cut into the padding if hinting makes the characters
proportionally larger (this is the point of having the padding, but
for the record I think it is behavior that we shouldn't try to
duplicate).

Do you have a visual test program for this? I'd like to see something
that draws a string overlayed with the measurements, to confirm that
the functions are not consistent on Windows (or, if they are, confirm
that they are consistent with your patch). If not, I'll write one and
send you the source code.

+    /* FIXME: GenericTypographic format prevents extra margins */

Since no margins is the current behavior, won't that cause a
regression? It should be fairly easy to include that exception.

Then again, I think I've heard reports that GenericTypographic doesn't work.