disableChromaSubsampling: false -> chromaSubsampling: true

Author: zbjornson

Readme.md

@@ -171,7 +171,7 @@ var stream = canvas.jpegStream({
     bufsize: 4096 // output buffer size in bytes, default: 4096
   , quality: 75 // JPEG quality (0-100) default: 75
   , progressive: false // true for progressive compression, default: false
-  , disableChromaSubsampling: false // true to disable 2x2 subsampling of the chroma components, default: false
+  , chromaSubsampling: true // false to disable 2x2 subsampling of the chroma components, default: true
 });
 ```
 

lib/canvas.js

@@ -90,12 +90,21 @@ Canvas.prototype.createJPEGStream = function(options){
   // Don't allow the buffer size to exceed the size of the canvas (#674)
   var maxBufSize = this.width * this.height * 4;
   var clampedBufSize = Math.min(options.bufsize || 4096, maxBufSize);
+  var chromaFactor;
+  if (typeof options.chromaSubsampling === "number") {
+    // libjpeg-turbo seems to complain about values above 2, but hopefully this
+    // can be supported in the future. For now 1 and 2 are valid.
+    // https://github.com/Automattic/node-canvas/pull/1092#issuecomment-366558028
+    chromaFactor = options.chromaSubsampling;
+  } else {
+    chromaFactor = options.chromaSubsampling === false ? 1 : 2;
+  }
   return new JPEGStream(this, {
       bufsize: clampedBufSize
     , quality: options.quality || 75
     , progressive: options.progressive || false
-    , chromaHSampFactor: options.disableChromaSubsampling ? 1 : 2
-    , chromaVSampFactor: options.disableChromaSubsampling ? 1 : 2
+    , chromaHSampFactor: chromaFactor
+    , chromaVSampFactor: chromaFactor
   });
 };