From a5a80448cb20f198656d62eafae8afba0a77e96b Mon Sep 17 00:00:00 2001
From: Nathan Sobo <nathan@github.com>
Date: Fri, 21 Apr 2017 13:17:13 -0600
Subject: [PATCH] Add intersectsVisibleRowRange on TextEditorElement

---
 spec/text-editor-element-spec.js | 20 ++++++++++++++++++++
 src/text-editor-element.js       | 12 ++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/spec/text-editor-element-spec.js b/spec/text-editor-element-spec.js
index 4a6655714..afa882320 100644
--- a/spec/text-editor-element-spec.js
+++ b/spec/text-editor-element-spec.js
@@ -309,6 +309,26 @@ describe('TextEditorElement', () => {
     })
   )
 
+  describe('::intersectsVisibleRowRange(start, end)', () => {
+    it('returns true if the given row range intersects the visible row range', async () => {
+      const element = buildTextEditorElement()
+      const editor = element.getModel()
+      editor.update({autoHeight: false})
+      element.getModel().setText('x\n'.repeat(20))
+      element.style.height = '120px'
+      await element.getNextUpdatePromise()
+      element.setScrollTop(80)
+      await element.getNextUpdatePromise()
+      expect(element.getVisibleRowRange()).toEqual([4, 11])
+
+      expect(element.intersectsVisibleRowRange(0, 4)).toBe(false)
+      expect(element.intersectsVisibleRowRange(0, 5)).toBe(true)
+      expect(element.intersectsVisibleRowRange(5, 8)).toBe(true)
+      expect(element.intersectsVisibleRowRange(11, 12)).toBe(false)
+      expect(element.intersectsVisibleRowRange(12, 13)).toBe(false)
+    })
+  })
+
   describe('events', () => {
     let element = null
 
diff --git a/src/text-editor-element.js b/src/text-editor-element.js
index 0bcb60a09..947bf3a8e 100644
--- a/src/text-editor-element.js
+++ b/src/text-editor-element.js
@@ -295,6 +295,18 @@ class TextEditorElement extends HTMLElement {
     return this.getModel().getVisibleRowRange()
   }
 
+  intersectsVisibleRowRange (startRow, endRow) {
+    return !(
+      endRow <= this.getFirstVisibleScreenRow() ||
+      this.getLastVisibleScreenRow() <= startRow
+    )
+  }
+
+  selectionIntersectsVisibleRowRange (selection) {
+    const {start, end} = selection.getScreenRange()
+    return this.intersectsVisibleRowRange(start.row, end.row + 1)
+  }
+
   setFirstVisibleScreenColumn (column) {
     return this.getModel().setFirstVisibleScreenColumn(column)
   }