From 890207daee94b8d7d72ae92b2610b6789dec7f95 Mon Sep 17 00:00:00 2001
From: Dick Choi <fluke8259@gmail.com>
Date: Tue, 19 Jul 2016 08:59:47 +0900
Subject: [PATCH] auto scroll

---
 browser/components/MarkdownEditor.js  |  4 +++-
 browser/components/MarkdownPreview.js | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/browser/components/MarkdownEditor.js b/browser/components/MarkdownEditor.js
index f99f6f77..2e07bc39 100644
--- a/browser/components/MarkdownEditor.js
+++ b/browser/components/MarkdownEditor.js
@@ -48,10 +48,12 @@ class MarkdownEditor extends React.Component {
   handleBlur (e) {
     let { config } = this.props
     if (config.editor.switchPreview === 'BLUR') {
+      let cursorPosition = this.refs.code.getCursorPosition()
       this.setState({
         status: 'PREVIEW'
       }, () => {
         this.refs.preview.focus()
+        this.refs.preview.scrollTo(cursorPosition.row)
       })
     }
   }
@@ -62,7 +64,7 @@ class MarkdownEditor extends React.Component {
 
   handlePreviewMouseUp (e) {
     let { config } = this.props
-    if (config.editor.switchPreview === 'BLUR' && new Date() - this.previewMouseDownedAt < 150) {
+    if (config.editor.switchPreview === 'BLUR' && new Date() - this.previewMouseDownedAt < 200) {
       this.setState({
         status: 'CODE'
       }, () => {
diff --git a/browser/components/MarkdownPreview.js b/browser/components/MarkdownPreview.js
index 97108c3f..45304c11 100644
--- a/browser/components/MarkdownPreview.js
+++ b/browser/components/MarkdownPreview.js
@@ -120,6 +120,24 @@ export default class MarkdownPreview extends React.Component {
     this.refs.root.focus()
   }
 
+  getWindow () {
+    return this.refs.root.contentWindow
+  }
+
+  scrollTo (targetRow) {
+    let lineAnchors = this.getWindow().document.querySelectorAll('a.lineAnchor')
+
+    for (let index = 0; index < lineAnchors.length; index++) {
+      let lineAnchor = lineAnchors[index]
+      let row = parseInt(lineAnchor.getAttribute('data-key'))
+      if (row > targetRow) {
+        let targetAnchor = lineAnchors[index - 1]
+        this.getWindow().scrollTo(0, targetAnchor.offsetTop)
+        break
+      }
+    }
+  }
+
   render () {
     let { className, style, tabIndex } = this.props
     return (