📝 Add docs comment on new functions

lib/mixins/canvas-drawer.js

@@ -402,6 +402,14 @@ export default class CanvasDrawer extends Mixin {
     renderData.context.fill()
   }
 
+  /**
+   * Returns an array of tokens by line.
+   *
+   * @param  {number} startRow The start row
+   * @param  {number} endRow The end row
+   * @return {Array<Array>} An array of tokens by line
+   * @access private
+   */
   tokenLinesForScreenRows (startRow, endRow) {
     const editor = this.getTextEditor()
     let tokenLines = []
@@ -503,6 +511,15 @@ export default class CanvasDrawer extends Mixin {
     return new RegExp(_.escapeRegExp(regexp.slice(0, -1)), 'g')
   }
 
+  /**
+   * Returns the regexp to replace invisibles substitution characters
+   * in editor lines.
+   *
+   * @param  {Object} line the tokenized line
+   * @return {RegExp} the regular expression to match invisible characters
+   * @deprecated Is used only to support Atom version before display layer API
+   * @access private
+   */
   getInvisibleRegExpForLine (line) {
     if ((line != null) && (line.invisibles != null)) {
       const invisibles = []