Return data from svg2img via callback

Given the chunks coming from imagemagick are getting stored memory and
then tucked into a cache, this function could as easily return a buffer
via callback. Streaming is just making it more complex. (And trickier to
test!)

gh-badge.js

@@ -62,7 +62,9 @@ if (color[0] === ':') {
 
 badge(badgeData, function produceOutput(svg) {
   if (/png|jpg|gif/.test(format)) {
-    svg2img(svg, format, process.stdout);
+    svg2img(svg, format, function (data) {
+      process.stdout.write(data);
+    });
   } else {
     console.log(svg);
   }

lib/svg-to-img.js

@@ -6,12 +6,12 @@ var imageMagick = gm.subClass({ imageMagick: true });
 // The following is an arbitrary limit (~1.5MB, 1.5kB/image).
 var imgCache = new LruCache(1000);
 
-module.exports = function (svg, format, out, cb) {
+module.exports = function (svg, format, callback) {
   var cacheIndex = format + svg;
   if (imgCache.has(cacheIndex)) {
     // We own a cache for this svg conversion.
-    (new DataStream(imgCache.get(cacheIndex))).pipe(out);
-    cb && cb();
+    var result = imgCache.get(cacheIndex);
+    callback(result);
     return;
   }
 
@@ -24,28 +24,13 @@ module.exports = function (svg, format, out, cb) {
     if (err) { console.error(err); return; }
     var chunks = [];
     stdout.on('data', function(chunk) { chunks.push(chunk); });
-    stdout.on('end', function() { imgCache.set(cacheIndex, chunks); });
-    stdout.pipe(out);
+    stdout.on('finish', function() {
+      var result = Buffer.concat(chunks);
+      imgCache.set(cacheIndex, result);
+      callback(result);
+    });
   });
 };
 
 // To simplify testing.
 module.exports._imgCache = imgCache;
-
-// Fake stream from the cache.
-var Readable = require('stream').Readable;
-var util = require('util');
-function DataStream(data) {
-  Readable.call(this);
-  this.data = data;
-  this.i = 0;
-}
-util.inherits(DataStream, Readable);
-DataStream.prototype._read = function() {
-  while (this.i < this.data.length) {
-    var keepPushing = this.push(this.data[this.i]);
-    this.i++;
-    if (!keepPushing) { return; }
-  }
-  this.push(null);
-};

package.json

@@ -58,7 +58,6 @@
     "eslint": "^3.18.0",
     "is-png": "^1.0.0",
     "is-svg": "^2.1.0",
-    "memory-streams": "^0.1.2",
     "mocha": "^3.2.0",
     "sinon": "^2.1.0"
   }

server.js

@@ -6127,7 +6127,9 @@ function sendSVG(res, askres, end) {
 
 function sendOther(format, res, askres, end) {
   askres.setHeader('Content-Type', 'image/' + format);
-  svg2img(res, format, askres);
+  svg2img(res, format, function (data) {
+    end(null, {template: streamFromString(data)});
+  });
 }
 
 function sendJSON(res, askres, end) {

test/svg-to-img.spec.js

@@ -1,6 +1,5 @@
 const assert = require('assert');
 const sinon = require('sinon');
-const WritableStream = require('memory-streams').WritableStream;
 const isPng = require('is-png');
 
 const badge = require('../lib/badge');
@@ -13,10 +12,8 @@ describe('The rasterizer', function () {
 
   it('should produce PNG', function(done) {
     badge({ text: ['cactus', 'grown'], format: 'svg' }, svg => {
-      const out = new WritableStream();
-
-      svg2img(svg, 'png', out, () => {
-        assert.ok(isPng(out.toBuffer()));
+      svg2img(svg, 'png', data => {
+        assert.ok(isPng(data));
         done();
       });
     });
@@ -24,15 +21,12 @@ describe('The rasterizer', function () {
 
   it('should cache its results', function(done) {
     badge({ text: ['will-this', 'be-cached?'], format: 'svg' }, svg => {
-      const out1 = new WritableStream();
-      const out2 = new WritableStream();
-
-      svg2img(svg, 'png', out1, () => {
-        assert.ok(isPng(out1.toBuffer()));
+      svg2img(svg, 'png', data1 => {
+        assert.ok(isPng(data1));
         assert.equal(cacheGet.called, false);
 
-        svg2img(svg, 'png', out2, () => {
-          assert.ok(isPng(out2.toBuffer()));
+        svg2img(svg, 'png', data2 => {
+          assert.ok(isPng(data2));
           assert.ok(cacheGet.calledOnce);
 
           done();