Remove node-pngquant-native dependency

- Unnecessary native dependency
- It was disabled by default
- Has issues on certain platforms
- Not optimal for production use (performance)

docs/config.rst

@@ -21,9 +21,7 @@ Example::
       ],
       "formatQuality": {
         "jpeg": 80,
-        "webp": 90,
+        "webp": 90
-        "pngQuantization": false,
-        "png": 90
       },
       "maxScaleFactor": 3,
       "maxSize": 2048,
@@ -83,8 +81,6 @@ Use ``false`` to disable the front page altogether (404).
 
 Quality of the compression of individual image formats. [0-100]
 
-The value for ``png`` is only used when ``pngQuantization`` is ``true``.
-
 ``maxScaleFactor``
 -----------
 

package.json

@@ -34,7 +34,6 @@
     "handlebars": "4.0.10",
     "http-shutdown": "^1.2.0",
     "morgan": "1.8.2",
-    "node-pngquant-native": "1.0.5",
     "nomnom": "1.8.1",
     "pbf": "3.0.5",
     "proj4": "2.4.4",

publish.js

@@ -23,7 +23,6 @@ packageJson.name += '-light';
 packageJson.description = 'Map tile server for JSON GL styles - serving vector tiles';
 delete packageJson.dependencies['canvas'];
 delete packageJson.dependencies['@mapbox/mapbox-gl-native'];
-delete packageJson.dependencies['node-pngquant-native'];
 delete packageJson.dependencies['sharp'];
 
 delete packageJson.optionalDependencies;

src/serve_rendered.js

@@ -18,7 +18,6 @@ var Canvas = require('canvas'),
     mercator = new (require('@mapbox/sphericalmercator'))(),
     mbgl = require('@mapbox/mapbox-gl-native'),
     mbtiles = require('@mapbox/mbtiles'),
-    pngquant = require('node-pngquant-native'),
     proj4 = require('proj4'),
     request = require('request');
 
@@ -451,16 +450,6 @@ module.exports = function(options, repo, params, id, dataResolver) {
             return res.status(404).send('Not found');
           }
 
-          if (format == 'png') {
-            var usePngQuant =
-                (options.formatQuality || {}).pngQuantization === true;
-            if (usePngQuant) {
-              buffer = pngquant.compress(buffer, {
-                quality: [0, formatQuality || 90]
-              });
-            }
-          }
-
           res.set({
             'Last-Modified': lastModified,
             'Content-Type': 'image/' + format