No width linking of brace layers

[schriftgestalt]

it was getting it form the master they are attached too and that is supposed to have a different width

[anthrotype]

it's not clear to me what this is doing (or no longer doing), can you please clarify?

[schriftgestalt]

This is mostly a hot fix for a specific project. Brace layer almost always have a different width than the master layers they are attached too. Linking to that width will mess things up. There might be some extra layer that might benefit from linking, so this needs more testing. Until then, this is a draft.

[belluzj]

I rebased this branch on top of main and will add a test file that has a bad case and gets solved correctly by this branch. I think the required scenario is this (font with Weight and ROUND axes):

• Glyph /a
  • Regular (400, 0): advance width = 100
    • Brace layer {500, 0}: advance width = 200
  • Bold (700, 0): advance width = 300
  • Regular ROUND (400, 1); advance width = 100
    • This master layer has a "metricsSource" pointing to Regular (400, 0) to ensure the widths are consistent
    • Brace layer {500, 1}: advance width = 200
      • This brace layer is under consideration for the test
  • Bold ROUND (700, 1): advance width = 300

Previously, the advance width of the brace layer {500, 1} would be forcibly taken from the metricsSource of the master layer Regular ROUND (400, 1) to which the brace layer {500, 1} was attached, and so it would get 100 instead of 200.

With this patch, the advance width of the layer {500, 1} will not be changed, because the the layer {500, 1} does not define itself a metricsSource.

@schriftgestalt is that an accurate description of what this patch does?

[schriftgestalt]

That is correct.

[belluzj]

@anthrotype @simoncozens This is ready for review. I added a test, and I checked locally that the test was failing before the patch (the glyph had width == 100) and is green after (width == 200 as specified in the file).

[belluzj]

This line is the important change of the patch, it says to only consider the master of this layer (if any) for the metrics source, and never the "associated master". For intermediate layers it means that there's no metrics source, whereas previously they used the metrics source of their parent layer, which was wrong.