{ "openapi": "3.1.1", "info": { "title": "OpenType Feature Playground API", "version": "1.0.0", "summary": "See which OpenType features and variable axes a font has, and what they do to your text.", "description": "Every endpoint performs the same calculation as the human page and returns inputs, result, units, assumptions, sources, warnings and computedAt. MCP endpoint: /mcp." }, "servers": [ { "url": "https://luminafontfeatures.usefulweb.site" } ], "paths": { "/api/v1/calculate": { "post": { "operationId": "calculate", "summary": "See which OpenType features and variable axes a font has, and what they do to your text.", "description": "Upload a TTF, OTF or WOFF font to list its scripts, languages and OpenType features (ligatures, small caps, figures, stylistic sets, kerning …) and its variation axes. Switch features on or off and set axis values: the text is shaped with the font's own GSUB and GPOS lookups and drawn from its outlines, next to the browser defaults, with the features that change your text marked.\n\nMethodology:\n- Scripts, language systems and features are read from the ScriptList and FeatureList of GSUB and GPOS; names follow the OpenType Layout tag registry (ssXX = stylistic set, cvXX = character variant).\n- Default features match what browsers apply to horizontal text (ccmp, locl, rlig, rclt, calt, liga, clig, rvrn, kern, mark, mkmk, dist, abvm, blwm, curs); your switches turn features on (smcp) or off (-liga). All selected GSUB lookups run in lookup-list order (types 1–7, the first alternate for type 3), then GPOS (types 1, 2 and 4–9).\n- Arabic and Devanagari text first gets Lumina's required shaping (joining forms, Indic reordering); other scripts are shaped from the character map in logical order on one line without bidi reordering.\n- Axis values are clamped to each axis range; outlines and advances come from gvar and HVAR at that location. GPOS adjustments are the default-instance values (variation deltas of GPOS are not applied). A feature \"changes this text\" when toggling it alone changes a glyph or a position.\n\nOutlines are drawn for TrueType (glyf) fonts; CFF fonts list their features but are not drawn. WOFF2 is not read. Browsers can differ in details (font fallback, bidi, justification).", "tags": [ "apps" ], "x-mcp-tool": "lumina_font_features", "x-owner-app": "lumina", "requestBody": { "required": true, "content": { "application/json": { "schema": { "$ref": "#/components/schemas/LuminaFontFeaturesInput" }, "examples": { "example1": { "summary": "Variable starter font: kerning off at a bold weight", "value": { "font": { "filename": "LuminaStarter-VF.ttf", "contentType": "font/ttf", "contentBase64": 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}, "text": "VOLT TOT", "features": "-kern", "axes": "wght=650", "script": "auto", "lang": "" } }, "example2": { "summary": "Ligature font: standard ligatures on and off", "value": { "font": { "filename": "LuminaStarterLigature.ttf", "contentType": "font/ttf", "contentBase64": 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}, "text": "HOLT VOLT", "features": "-liga", "axes": "", "script": "auto", "lang": "" } } } } } }, "responses": { "200": { "description": "Calculation result envelope.", "content": { "application/json": { "schema": { "$ref": "#/components/schemas/LuminaFontFeaturesResult" } } } }, "400": { "description": "Malformed JSON body.", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "422": { "description": "Invalid input (see errors[]).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } }, "429": { "description": "Rate limit exceeded (see Retry-After).", "content": { "application/problem+json": { "schema": { "$ref": "#/components/schemas/Problem" } } } } } } }, "/api/v1/tool": { "get": { "operationId": "getToolDefinition", "summary": "Inputs, output schema and examples for this tool", "responses": { "200": { "description": "Tool definition.", "content": { "application/json": { "schema": { "type": "object" } } } } } } } }, "components": { "schemas": { "Problem": { "type": "object", "description": "RFC 9457 problem details. 422 responses include per-field `errors`.", "required": [ "type", "title", "status", "detail" ], "properties": { "type": { "type": "string" }, "title": { "type": "string" }, "status": { "type": "integer" }, "detail": { "type": "string" }, "code": { "type": "string" }, "errors": { "type": "array", "items": { "type": "object", "required": [ "field", "message" ], "properties": { "field": { "type": "string" }, "message": { "type": "string" } } } } } }, "LuminaFontFeaturesInput": { "type": "object", "additionalProperties": false, "properties": { "font": { "title": "Font (TTF, OTF or WOFF; up to 10 MB; uploaded to the server)", "type": "object", "description": "Upload as {filename, contentType?, contentBase64}. Max 9766 KiB. Accepts .ttf,.otf,.woff.", "additionalProperties": false, "required": [ "filename", "contentBase64" ], "properties": { "filename": { "type": "string" }, "contentType": { "type": "string" }, "contentBase64": { "type": "string" } } }, "text": { "title": "Sample text", "type": "string", "maxLength": 200, "default": "Office 1/2 AVATAR" }, "features": { "title": "Feature switches (e.g. smcp, onum, -liga, ss01)", "type": "string", "maxLength": 600, "default": "" }, "axes": { "title": "Axis values for variable fonts (e.g. wght=650, wdth=90)", "type": "string", "maxLength": 300, "default": "" }, "script": { "title": "OpenType script tag (auto = from the text)", "type": "string", "maxLength": 4, "default": "auto" }, "lang": { "title": "OpenType language system tag (optional, e.g. DEU, TRK)", "type": "string", "maxLength": 4, "default": "" } }, "required": [ "font" ] }, "LuminaFontFeaturesResult": { "type": "object", "additionalProperties": false, "required": [ "schemaVersion", "tool", "computedAt", "inputs", "summary", "result", "units", "assumptions", "sources", "warnings", "presentation", "links" ], "properties": { "schemaVersion": { "type": "string", "const": "1.0" }, "tool": { "type": "object", "additionalProperties": false, "required": [ "id", "name", "version" ], "properties": { "id": { "type": "string" }, "name": { "type": "string" }, "version": { "type": "string" } } }, "computedAt": { "type": "string", "format": "date-time" }, "inputs": { "type": "object", "description": "Normalised inputs actually used, including applied defaults." }, "summary": { "type": "string" }, "result": { "type": "object", "additionalProperties": false, "required": [ "family", "style", "unitsPerEm", "glyphCount", "outlines", "axes", "instances", "location", "scripts", "features", "base", "shaped", "changed", "missing" ], "properties": { "family": { "type": "string" }, "style": { "type": "string" }, "unitsPerEm": { "type": "integer" }, "glyphCount": { "type": "integer" }, "outlines": { "enum": [ "TrueType", "OpenType CFF" ] }, "axes": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "tag", "name", "min", "default", "max" ], "properties": { "tag": { "type": "string" }, "name": { "type": "string" }, "min": { "type": "number" }, "default": { "type": "number" }, "max": { "type": "number" } } } }, "instances": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "name", "location" ], "properties": { "name": { "type": "string" }, "location": { "type": "object", "additionalProperties": { "type": "number" } } } } }, "location": { "type": "object", "additionalProperties": { "type": "number" } }, "scripts": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "table", "script", "languages" ], "properties": { "table": { "enum": [ "GSUB", "GPOS" ] }, "script": { "type": "string" }, "languages": { "type": "array", "items": { "type": "string" } } } } }, "features": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "tag", "name", "tables", "lookups", "defaultOn", "on", "changesText" ], "properties": { "tag": { "type": "string" }, "name": { "type": "string" }, "tables": { "type": "array", "items": { "enum": [ "GSUB", "GPOS" ] } }, "lookups": { "type": "integer" }, "defaultOn": { "type": "boolean" }, "on": { "type": "boolean" }, "changesText": { "type": "boolean" } } } }, "base": { "type": "object", "additionalProperties": false, "required": [ "width", "features", "glyphs" ], "properties": { "width": { "type": "number" }, "features": { "type": "array", "items": { "type": "string" } }, "glyphs": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "gid", "name", "text", "x", "y", "advance" ], "properties": { "gid": { "type": "integer" }, "name": { "type": "string" }, "text": { "type": "string" }, "x": { "type": "number" }, "y": { "type": "number" }, "advance": { "type": "number" } } } } } }, "shaped": { "type": "object", "additionalProperties": false, "required": [ "width", "features", "glyphs" ], "properties": { "width": { "type": "number" }, "features": { "type": "array", "items": { "type": "string" } }, "glyphs": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "gid", "name", "text", "x", "y", "advance" ], "properties": { "gid": { "type": "integer" }, "name": { "type": "string" }, "text": { "type": "string" }, "x": { "type": "number" }, "y": { "type": "number" }, "advance": { "type": "number" } } } } } }, "changed": { "type": "integer" }, "missing": { "type": "array", "items": { "type": "string" } } } }, "units": { "type": "object", "additionalProperties": { "type": "string" } }, "assumptions": { "type": "array", "items": { "type": "string" } }, "sources": { "type": "array", "items": { "type": "object", "additionalProperties": false, "required": [ "title" ], "properties": { "title": { "type": "string" }, "url": { "type": "string" }, "publisher": { "type": "string" }, "retrievedAt": { "type": "string" }, "note": { "type": "string" } } } }, "warnings": { "type": "array", "items": { "type": "string" } }, "presentation": { "type": "array", "items": { "type": "object" }, "description": "Display blocks used by the human page (same data)." }, "links": { "type": "object", "additionalProperties": false, "required": [ "human", "api", "openapi", "methodology" ], "properties": { "human": { "type": "string", "format": "uri" }, "api": { "type": "string", "format": "uri" }, "openapi": { "type": "string", "format": "uri" }, "methodology": { "type": "string", "format": "uri" } } } } } } } }