Add a flag in minimap element to know whether it has been attached to…

… a text editor or not

lib/minimap-element.coffee

@@ -1,6 +1,6 @@
 {debounce} = require 'underscore-plus'
 {CompositeDisposable, Disposable} = require 'event-kit'
-{EventsDelegation} = require 'atom-utils'
+{EventsDelegation, AncestorsMethods} = require 'atom-utils'
 DOMStylesReader = require './mixins/dom-styles-reader'
 CanvasDrawer = require './mixins/canvas-drawer'
 
@@ -22,6 +22,7 @@ class MinimapElement extends HTMLElement
   DOMStylesReader.includeInto(this)
   CanvasDrawer.includeInto(this)
   EventsDelegation.includeInto(this)
+  AncestorsMethods.includeInto(this)
 
   ### Public ###
 
@@ -90,6 +91,7 @@ class MinimapElement extends HTMLElement
     @measureHeightAndWidth()
     @updateMinimapFlexPosition()
     @attached = true
+    @attachedToTextEditor = @parentNode is @getTextEditorElementRoot()
 
     # Uses of `atom.styles.onDidAddStyleElement` instead of
     # `atom.themes.onDidChangeActiveThemes`.
@@ -332,7 +334,6 @@ class MinimapElement extends HTMLElement
     visibleAreaTop = @minimap.getTextEditorScaledScrollTop() - @minimap.getScrollTop()
     visibleWidth = Math.min(@canvas.width / devicePixelRatio, @width)
 
-
     @applyStyles @visibleArea,
       width: visibleWidth + 'px'
       height: @minimap.getTextEditorScaledHeight() + 'px'

spec/minimap-element-spec.coffee

@@ -130,6 +130,9 @@ describe 'MinimapElement', ->
       # and not 20px
       expect(minimapElement.offsetWidth).toBeCloseTo(editorElement.clientWidth / 11, 0)
 
+    it 'knows when attached to a text editor', ->
+      expect(minimapElement.attachedToTextEditor).toBeTruthy()
+
     it 'resizes the canvas to fit the minimap', ->
       expect(canvas.offsetHeight / devicePixelRatio).toBeCloseTo(minimapElement.offsetHeight + minimap.getLineHeight(), 0)
       expect(canvas.offsetWidth / devicePixelRatio).toBeCloseTo(minimapElement.offsetWidth, 0)