Precompute text width using a lookup table (#2311)

This simplifies and further optimizes text-width computation by computing the entire width table in advance, and serializing it in the style of QuickTextMeasurer (#1390). This entirely removes the need for PDFKit at runtime. This has the advantage of fixing #1305 – more generally: producing the same result everywhere – without having to deploy a copy of Verdana.

The lifting is delegated to these three libraries, which are housed in a monorepo: https://github.com/metabolize/anafanafo

I'd be happy to move it into the badges org if folks want to collaborate on maintaining them.

QuickTextMeasurer took kerning pairs into account, whereas this implementation does not. I was thinking kerning would be a necessary refinement, though this seems to work well enough.

I dropped in a binary-search package to traverse the data structure, in part to conserve space. This causes a moderate performance regression, though there is ample room for improving on that: https://github.com/badges/shields/pull/2311#issuecomment-439182704

lib/request-handler.js

@@ -6,6 +6,7 @@ const request = require('request')
 const { makeBadgeData: getBadgeData } = require('./badge-data')
 const log = require('./log')
 const LruCache = require('../gh-badges/lib/lru-cache')
+const makeBadge = require('../gh-badges/lib/make-badge')
 const analytics = require('./analytics')
 const { makeSend } = require('./result-sender')
 const queryString = require('query-string')
@@ -88,9 +89,7 @@ function getBadgeMaxAge(handlerOptions, queryParams) {
 // (undesirable and hard to debug).
 //
 // Pass just the handler function as shorthand.
-//
-// Inject `makeBadge` as a dependency.
-function handleRequest(makeBadge, handlerOptions) {
+function handleRequest(handlerOptions) {
   if (typeof handlerOptions === 'function') {
     handlerOptions = { handler: handlerOptions }
   }
@@ -276,8 +275,6 @@ function isInt(number) {
 
 module.exports = {
   handleRequest,
-  makeHandleRequestFn: makeBadge => handlerOptions =>
-    handleRequest(makeBadge, handlerOptions),
   clearRequestCache,
   // Expose for testing.
   _requestCache: requestCache,

lib/request-handler.spec.js

@@ -8,14 +8,11 @@ const Camp = require('camp')
 const analytics = require('./analytics')
 const { makeBadgeData: getBadgeData } = require('./badge-data')
 const {
-  makeHandleRequestFn,
+  handleRequest,
   clearRequestCache,
   _requestCache,
   getBadgeMaxAge,
 } = require('./request-handler')
-const testHelpers = require('../gh-badges/lib/make-badge-test-helpers')
-
-const handleRequest = makeHandleRequestFn(testHelpers.makeBadge())
 
 const baseUri = `http://127.0.0.1:${config.port}`
 

lib/server-config.js

@@ -5,7 +5,6 @@
 
 const url = require('url')
 const envFlag = require('node-env-flag')
-const defaults = require('../gh-badges/lib/defaults')
 
 function envArray(envVar, defaultValue, delimiter) {
   delimiter = delimiter || ','
@@ -69,10 +68,6 @@ const config = {
     },
     trace: envFlag(process.env.TRACE_SERVICES),
   },
-  font: {
-    path: process.env.FONT_PATH || defaults.font.path,
-    fallbackPath: process.env.FALLBACK_FONT_PATH,
-  },
   profiling: {
     makeBadge: envFlag(process.env.PROFILE_MAKE_BADGE),
   },
@@ -80,8 +75,4 @@ const config = {
   handleInternalErrors: envFlag(process.env.HANDLE_INTERNAL_ERRORS, true),
 }
 
-if (config.font.fallbackPath) {
-  console.log('FALLBACK_FONT_PATH is deprecated. Please use FONT_PATH.')
-}
-
 module.exports = config