Add font.compact() to Python API

[ctrlcctrlv]

Adds a function to the Python API that has the identical effect as «Encoding→Compact».

Type of change

• Small new feature

[skef]

A little bird pointed us to the existing SFReencode interface for this, which is to assign the string "compacted" to the encoding.

I don't have any strong opinions about whether to add this interface. (I do wish the python API wasn't so fixated on properties and assignments but it doesn't seem detrimental in this case.)

[ctrlcctrlv]

Yeah the reason I'm adding this is because I made an icon font recently as mentioned at #4378 (comment) ... due to how most icon fonts are expected to work, the icons are always going to be way off screen when opening SFD. I suppose a Custom encoding is usable, but trying to set font.encoding = Custom didn't go so well without a way to compact out the empty blocks, I just got the flood of red question marks.

I'll take a look at SFReencode when I get a chance if you think it's better for adding this function. :-)

[ctrlcctrlv]

Oh and here's my use case:

icons.ttf

https://github.com/mfeq/Qglif/blob/f9052673e60d445015cc7c092e3e29004b8506fa/resources/icons/gen.py#L1-L39

[skef]

@ctrlcctrlv I think the suggestion is to try (with the existing code) a) opening the font in python, b) do fnt.encoding = 'UnicodeFull', and then c) do fnt.encoding = 'compacted' .

I just tried it and it seems to work.

[ctrlcctrlv]

@skef Force pushed, this is now a documentation-only change. Thanks.

[skef]

Looks good!