docs: function hasFontLoaded (window, fontName) {
      var testSize = 16
      if (!fontTestElement) {
          fontTestElement = window.document.createElement('canvas')
          fontTestElement.width = testSize
          fontTestElement.height = testSize
          fontTestElement.style.display = 'none'
  
          ctx = fontTestElement.getContext('2d')
          window.document.body.appendChild(fontTestElement)
      }
  
      fontTestElement.width = testSize
      ctx.fillStyle = 'rgba(0, 0, 0, 0)'
      ctx.fillRect(0, 0, testSize, testSize)
      ctx.font = testSize + "px __cc2d_" + fontName
      ctx.fillStyle = 'rgba(255, 255, 255, 1)'
      ctx.fillText("M", 0, testSize);
  
      var pixels = ctx.getImageData(0, 0, testSize, testSize).data
  
      for (var i = 0; i < testSize * testSize; i++) {
          if (pixels[i * 4] != 0) {
              fontTestElement.parentNode.removeChild(fontTestElement)
              fontTestElement = null
              return true
          }
      }
  
      return false
  }