Now that Nicolas & I have pretty much finished this stage of cleaning up the scanners etc, we have at least achieved the major aim I had in mind; getting back to a single class tree for scanning text. So far as I can tell everything is working ok and I haven't managed to cause any errors. 

The magic keys (cmd - & cmd +) that are supposed to kern the selection do not work, but then they don't in a vanilla 4.5-12461 image from before this work was done. So we didn't break it…

The next thing to do is try to simplify the choices between byte and wide strings, fonts and encodings and language environments. I hate seeing #isKindOf: or #isMemberOf: type tests in running code (you can excuse it in prototypes, for a few minutes at least) and #isByteString is not much better. We have classes and inheritance for a reason; nobody should be writing C code in Smalltalk.

Trying to list the factors involved in working out how to scan a text (and *please* correct whatever I get wrong):-

the String - 
byteString; so far as I can see ByteStrings are single-byte characters (duh) with an assumed encoding. That appears to be 'mac roman' which is almost but not quite latin1 or iso-something-or-other.
wideString; 32 bit characters where the top (ish) 8 bits are used as a leading character (not to be confused with leading in the typographic sense of affecting line spacing - isn't English wonderfully clear…) that defines an EncodedCharSet (or LanguageEnvironment, sigh) which provides for a specific scanning message to use. To complicate life further, a later character in a WideString can change the encoding to use, which may well change the font, oh frabjous day.

the Font - 
we have several classes of fonts, not all in the base image right now.
I think I'd divide them into two phyla at the moment;
a) StrikeFonts and other simple bitmap glyphs. This would include StrikeFont itself, HostFont and TTCFont (since it generates bitmaps that are simply bitblt'd to use)
b) ComplicatedPluginFonts where an interface to a more complex and sophisticated renderer is used to leverage a library such as TrueType, Cairo, Pango, Weyland or whatever. These may well need to completely usurp the actual scanner to do the work.

There's another font aspect that is important too, but for now at least it is tied to a & b above - whether pair-kerning is supported. I'm sure we could make a variant of StrikeFonts that does it  if we wanted but let's keep things tolerably intelligible for now, eh?

I'm going to take a quick swing at changing the scanning to delegate to
1) the string, which will then delegate to 
2) the font, which for all the classes in the image right now will then delegate back to
3) the scanner, but having already worked out which form of scanning is required.

OK; I'm going in! Cover me!

tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
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