I have been reading the following thread.
viewtopic.php?f=3&t=3663
I note that two different platforms are suggested for including mapped glyphs beyond plane 0 in a font and I note the comment of the original enquirer about mappings.
Upon making some small test fonts and trying adding the two platforms, it appears that for one of the two suggested platforms, FontCreator offers an option to copy the existing plane 0 Unicode mappings of glyphs automatically into the new platform, yet for the other platform FontCreator does not appear to offer that option, though there is an option about Postscript names that I have not been able to get to work, though I accept that I might possibly not have tried it correctly.
I am wondering why it is the case that one platform offers to copy mappings directly yet the other does not.
Also, I am wondering what are the advantages and disadvantages of using one platform or the other for mapping a glyph to a codepoint that is beyond plane 0.
How many platform choices are there available to do this please?
I have been using FontCreator 5.6 for my tests. I am aware that that is not the latest version, so readers are asked to bear that in mind please.
William Overington
22 November 2011
Platforms for higher planes
Re: Platforms for higher planes
The higher plane platforms for windows are platform ID=0, encoding ID=4, Cmap format=12 (Cmap format is automatically selected by FCP); also known as Unicode 2.0 and later semantics, Unicode full repertoire; and platform 3, encoding 10 in format 12, which is the Microsoft full Unicode UCS-4, and I'm not really sure what the difference is, although the latter seems to be more common. There are also some other Cmap table formats (8 and 10) that FCP doesn't seem to support that could be used for mapping upper planes, and, of course, the format 14 Cmap, which is used with platform 0, encoding 5 for Variation sequences, which is also not supported by FCP yet. You may be able to copy mappings between these two, but for the most part, I believe that they should be used for mapping only the supplementary characters, with the standard platform 0, encoding 3 (Unicode 2.0 semantics, BMP only) in format 4 is still prefered for mapping all of your BMP characters, so copying mappings doesn't really do you any good anyway.
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William
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Re: Platforms for higher planes
Thank you for your reply.
My situation is that I have added a capability to go beyond plane 0 to a few of my fonts yet I have only ever tried accessing glyphs using those fonts from beyond plane 0 using Microsoft WordPad on a computer running Windows xp. So there may be issues that I do not know about regarding which platforms to add into the font.
In some of my research I started mapping glyphs into the plane 15 private use area so that experience of using codepoints beyond plane 0 could be gained in case the glyphs were later mapped into regular Unicode, which mapping would need to be beyond plane 0 due to the number of glyphs. In the event I found that I later needed to use the plane 0 private use area as well as the plane 15 private use area, and in practice instead of the plane 15 private use area as most of the software that I use cannot access from a font glyphs that are only mapped beyond plane 0.
William Overington
22 November 2011
My situation is that I have added a capability to go beyond plane 0 to a few of my fonts yet I have only ever tried accessing glyphs using those fonts from beyond plane 0 using Microsoft WordPad on a computer running Windows xp. So there may be issues that I do not know about regarding which platforms to add into the font.
In some of my research I started mapping glyphs into the plane 15 private use area so that experience of using codepoints beyond plane 0 could be gained in case the glyphs were later mapped into regular Unicode, which mapping would need to be beyond plane 0 due to the number of glyphs. In the event I found that I later needed to use the plane 0 private use area as well as the plane 15 private use area, and in practice instead of the plane 15 private use area as most of the software that I use cannot access from a font glyphs that are only mapped beyond plane 0.
William Overington
22 November 2011