Add font-weight parameter.

README.md

@@ -16,7 +16,13 @@ Create a TinySDF for drawing SDFs based on font parameters:
     var cutoff = 0.25  // Across the board alpha channel reduction
                        // Reduces low-alpha pixels to zero, "thins" SDF overall
 
-    var fontFamily = 'sans-serif'; // css font-family to use
-    var tinySDFGenerator = new TinySDF(fontsize, buffer, radius, cutoff, fontFamily);
+    var fontFamily = 'sans-serif'; // css font-family
+    var fontWeight = 'normal';     // css font-weight
+    var tinySDFGenerator = new TinySDF(fontsize,
+                                       buffer,
+                                       radius,
+                                       cutoff,
+                                       fontFamily,
+                                       fontWeight);
 
     var oneSDF = tinySDFGenerator.draw('泽');

index.js

@@ -4,19 +4,21 @@ module.exports = TinySDF;
 
 var INF = 1e20;
 
-function TinySDF(fontSize, buffer, radius, cutoff, fontFamily) {
+function TinySDF(fontSize, buffer, radius, cutoff, fontFamily, fontWeight) {
     this.fontSize = fontSize || 24;
     this.buffer = buffer === undefined ? 3 : buffer;
     this.cutoff = cutoff || 0.25;
     this.fontFamily = fontFamily || 'sans-serif';
+    this.fontWeight = fontWeight || 'normal';
     this.radius = radius || 8;
     var size = this.size = this.fontSize + this.buffer * 2;
 
     this.canvas = document.createElement('canvas');
     this.canvas.width = this.canvas.height = size;
 
     this.ctx = this.canvas.getContext('2d');
-    this.ctx.font = fontSize + 'px ' + this.fontFamily;
+    /* style | variant | weight | size/line-height | family */
+    this.ctx.font = `normal normal ${this.fontWeight} ${fontSize}px/normal ${this.fontFamily}`;
     this.ctx.textBaseline = 'middle';
     this.ctx.fillStyle = 'black';