Font overview phase 1

[ollimeier]

Part of #102

This implements a very basic font overview. It needs some followups for refinement, but the core functionality is there and mergable.

[ollimeier]

@justvanrossum

TODOs and Questions:

1. I am wondering if it would make sense to refactor GlyphsSearch into two web components:
   1. GlyphsSearch: Includes the search field, only. Access the list of glyphs with eg. glyphsListItemsController.
   2. GlyphsSearchForEditor which uses GlyphsSearch and adds the glyph list.
2. We may want to move sortedSourceIdentifiers to a more general location like utils. Follow up task?
3. Do we want to make the sidebar scalable? If so, we may want to refactor sidebar-resize-gutter or at least have a look at it. Follow up task?
4. Context menu is implemented in the overview, yet. We may want to add them. Is this a follow up task?
5. Maybe use https://www.npmjs.com/package/unicode-properties for overview sections. Also, how to we handle unencoded glyphs? Follow up task?
6. Add top menu bar, please see: [font overview] Menu bar for font overview #1845
7. When opening a glyph in the editor via double click, there is an error: It says error while interpolating font sources '{message: 'objects have incompatible number of entries: 7 != 6', type: 'interpolation-error'}'. But this is not true. I don't know why this is happening.

[ollimeier]

Little demo of the current stage:

fontra-font-overview-sneak-preview.mp4

[justvanrossum]

Next steps:

• Figure out "cell view" API,
  • getSelectedGlyphNames()
  • setSelectedGlyphNames()
  • addEventListener("selectionChanged", (event) => ...)
• Selection behavior:
  • Click to select glyph
  • Shift click to deselect glyph, or add glyph to selection
  • Click-drag, to "paint" selection? Can be followup.
  • Arrow key navigation. Can be followup.
  • Typing a character (and glyphname?) selects the matching glyph. Can be followup.
• Fix cell layout so cells "flow" ("inline block"), see "Related Glyphs" panel
• Fix cell glyph load/draw so it only loads once the cell becomes visible (currently it seems all glyphs are loaded, also the ones outside the scroll area)

Question:

• Should the cell view be an accordion view, so sections can be folded/hidden?

[justvanrossum]

Minor bug: double clicking the / glyph results in an empty canvas. Since it is the prefix for glyph names, if you want to type a slash, it should be doubled. So I think we should special-case the / to become // in the text entry.

[justvanrossum]

I made a small change to glyph-cell.js, that fixes the lazy loading: d510469. You should notice a vast improvement in performance, as only glyphs that are in view will be loaded.

One small bug that I don't quite understand: in Egitto, double-clicking on the "tulip" glyph does not open the right glyph. Maybe the source data contains ambiguous code points. Ohh, the code point is U+1F337, so this may again be a UTF-16 issue. It was, and I fixed it.

[justvanrossum]

By default, I think the default source should be selected. You can easily get it with the fontController.fontSourcesInstancer.defaultSourceIdentifier property.

We should store the selected source identifier in the URL fragment.