Use a positioned glyph font encoding for Devanagari

[wipfli]

Encodes parts of strings that are in the Devanagari script with a positioned glyph font from https://github.com/wipfli/pgf-encoding.

Usage in style.json

Engish

To show a map localized to English one can do then something like this:

"text-field": [
    "case",
    ["has", "pmap:script"],
    [
        "format",
        [
        "coalesce",
        ["get", "name:en"],
        ["get", "name:de"],
        ["get", "name:fr"]
        ],
        {},
        "\n",
        {},
        ["get", "pmap:pgf:name"],
        {
        "text-font": [
            "case",
            ["==", ["get", "pmap:script"], "Devanagari"],
            ["literal", ["NotoSansDevanagari-Regular-v1"]],
            ["literal", ["Noto Sans Regular"]]
        ]
        }
    ],
    [
        "coalesce",
        ["get", "name:en"],
        ["get", "name"]
    ]
],

Nepali

For Nepali one can on the other hand do something like this:

"text-field": [
    "case",
    ["!=", ["get", "pmap:script"], "Devanagari"],
    [
        "format",
        [
        "coalesce",
        ["get", "pmap:pgf:name:ne"],
        ["get", "pmap:pgf:name:mr"],
        ["get", "pmap:pgf:name:hi"]
        ],
        {
        "text-font": ["literal", ["NotoSansDevanagari-Regular-v1"]]
        },
        "\n",
        {},
        ["get", "pmap:pgf:name"],
        {
        "text-font": [
            "case",
            ["==", ["get", "pmap:script"], "Devanagari"],
            ["literal", ["NotoSansDevanagari-Regular-v1"]],
            ["literal", ["Noto Sans Regular"]]
        ]
        }
    ],
    [
        "format",
        [
        "coalesce",
        ["get", "pmap:pgf:name:ne"],
        ["get", "pmap:pgf:name"]
        ],
        {
        "text-font": ["literal", ["NotoSansDevanagari-Regular-v1"]]
        }
    ]
],

Demo

Planet PMTiles

https://pub-726b01260c98468a9387cc0dfcb7386b.r2.dev/protomaps-planet-pgf-20240627.pmtiles (126 GB)

Nepali

Note: Only the places_locality layer was changed.

https://pub-cf7f11e26ace447db8f7215b61ac0eae.r2.dev/ne.html

English

Note: Only the places_locality layer was changed.

https://pub-cf7f11e26ace447db8f7215b61ac0eae.r2.dev/en.html

Todos

• Remove all todo comments
• Handle errors and exceptions
• Add unit tests
• Remove main() functions
• Store fonts and versions in tilejson metadata

[wipfli]

Thank you for the great feedback @bdon. I think I address all concerns. The naming has been updated and I am currently running a planet build which should be ready for an updated demo in a few hours.

Let me know what else needs to change...

[sonarqubecloud]

Quality Gate failed

Failed conditions
3 Security Hotspots
66.4% Coverage on New Code (required ≥ 80%)
5.1% Duplication on New Code (required ≤ 3%)
C Reliability Rating on New Code (required ≥ A)

See analysis details on SonarCloud

Catch issues before they fail your Quality Gate with our IDE extension SonarLint

[nvkelso]

It wasn't clear to me that pgf stands for "positioned glyph font", consider adding a comment above this line to explain that?

[wipfli]

Good point. I was also wondering if we have a schema documentation somewhere?

[nvkelso]

In addition to the inline comment in the code here, we should probably add a new "names.md" or localization.md file next to https://github.com/protomaps/docs/blob/main/basemaps/layers.md in the Protomaps docs repo?

Tilezen had this, which we should only lightly crib from.

Natural Earth's table of common languages is useful, too, and add a script column to that?

...snip...

[nvkelso]

Stubbed out in new docs PR: https://github.com/protomaps/docs/pull/43/files