Add option to defined default font

docs/getting_started.md

@@ -170,6 +170,13 @@ numbers to a document.
     // doc.end() will call it for you automatically.
     doc.end();
 
+## Setting default font
+
+The default font is 'Helvetica'. It can be configured by passing `font` option
+
+    // use Courier font by default
+    const doc = new PDFDocument({font: 'Courier'});
+
 ## Setting document metadata
 
 PDF documents can have various metadata associated with them, such as the

lib/document.js

@@ -87,7 +87,7 @@ class PDFDocument extends stream.Readable {
     // Initialize mixins
     this.initColor();
     this.initVector();
-    this.initFonts();
+    this.initFonts(options.font);
     this.initText();
     this.initImages();
     this.initOutline();

lib/mixins/fonts.js

@@ -1,7 +1,7 @@
 import PDFFontFactory from '../font_factory';
 
 export default {
-  initFonts() {
+  initFonts(defaultFont = 'Helvetica') {
     // Lookup table for embedded fonts
     this._fontFamilies = {};
     this._fontCount = 0;
@@ -13,7 +13,9 @@ export default {
     this._registeredFonts = {};
 
     // Set the default font
-    return this.font('Helvetica');
+    if (defaultFont) {
+      this.font(defaultFont);
+    }
   },
 
   font(src, family, size) {

tests/unit/document.spec.js

@@ -0,0 +1,35 @@
+const PDFDocument = require('../../lib/document').default;
+
+describe('PDFDocument', () => {
+  describe('font option', () => {
+    let fontSpy;
+
+    beforeEach(() => {
+      fontSpy = jest.spyOn(PDFDocument.prototype, 'font').mockReturnThis();
+    });
+
+    afterEach(() => {
+      fontSpy.mockRestore();
+    });
+
+    test('not defined', () => {
+      new PDFDocument();
+
+      expect(fontSpy).toBeCalledWith('Helvetica');
+    });
+
+    test('a string value', () => {
+      new PDFDocument({ font: 'Roboto' });
+
+      expect(fontSpy).toBeCalledWith('Roboto');
+    });
+
+    test('a falsy value', () => {
+      new PDFDocument({ font: null });
+      new PDFDocument({ font: false });
+      new PDFDocument({ font: '' });
+
+      expect(fontSpy).not.toBeCalled();
+    });
+  });
+});