Добавить собственный шрифт в Android Paint объект
Typeface plain = Typeface.createFromAsset(assetManager, pathToFont);
Typeface bold = Typeface.create(plain, Typeface.DEFAULT_BOLD)
Paint paint = new Paint();
paint.setTypeface(bold);
canvas.drawText("Sample text in bold",0,0,paint);
Fair Finch