Add font options to the controller (#48)

* add font options to the controller

* fixes access to the right font instance in me.options and not dataset

* uses toFont (normalizing also lineHeight) instead of toFontString

* uses font.lineHeight instead of font.size to set the text height

src/controller.js

@@ -1,7 +1,7 @@
 'use strict';
 
 import {DatasetController} from 'chart.js';
-import {valueOrDefault, isNullOrUndef} from 'chart.js/helpers';
+import {valueOrDefault, toFont, isNullOrUndef} from 'chart.js/helpers';
 import {layout} from './layout';
 
 /**
@@ -228,11 +228,15 @@ export default class SankeyController extends DatasetController {
    * @private
    */
   _drawLabel(label, y, height, ctx, textX) {
-    const lines = isNullOrUndef(label) ? [] : this.toTextLines(label);
+    const me = this;
+    const font = toFont(me.options.font, me.chart.options.font);
+    const lines = isNullOrUndef(label) ? [] : me.toTextLines(label);
     const linesLength = lines.length;
     const middle = y + height / 2;
     const padding = 7.5;
-    const textHeight = 15;
+    const textHeight = font.lineHeight;
+
+    ctx.font = font.string;
 
     if (linesLength > 1) {
       const top = middle - (textHeight * linesLength / 2) + padding;

types/index.esm.d.ts

@@ -2,7 +2,8 @@ import {
   Chart,
   ChartComponent,
   DatasetController,
-  Element
+  Element,
+  FontSpec
 } from 'chart.js';
 
 declare module 'chart.js' {
@@ -30,6 +31,7 @@ declare module 'chart.js' {
     nodeWidth?: number      /* defaults to 10 */
     color?: string          /* defaults to 'black' */
     borderColor?: string    /* defaults to 'black' */
+    font: FontSpec          /* defaults to chart.options.font */
   }
 
   type FromToElement = {