added viewMode shortcuts (#486)

added viewMode shortcuts

src/components/editor/editor.tsx

@@ -13,6 +13,7 @@ import { DocumentRenderPane } from './document-renderer-pane/document-render-pan
 import { EditorPane } from './editor-pane/editor-pane'
 import { editorTestContent } from './editorTestContent'
 import { DualScrollState, ScrollState } from './scroll/scroll-props'
+import { shortcutHandler } from './shortcut/shortcut'
 import { Splitter } from './splitter/splitter'
 import { YAMLMetaData } from './yaml-metadata/yaml-metadata'
 
@@ -64,6 +65,13 @@ export const Editor: React.FC = () => {
     updateDocumentTitle()
   }, [updateDocumentTitle])
 
+  useEffect(() => {
+    document.addEventListener('keyup', shortcutHandler, false)
+    return () => {
+      document.removeEventListener('keyup', shortcutHandler, false)
+    }
+  }, [])
+
   useEffect(() => {
     setFirstDraw(false)
   }, [])
@@ -101,7 +109,7 @@ export const Editor: React.FC = () => {
               content={markdownContent}
               scrollState={scrollState.editorScrollState}
               onScroll={onEditorScroll}
-              onMakeScrollSource={() => scrollSource.current = ScrollSource.EDITOR}
+              onMakeScrollSource={() => (scrollSource.current = ScrollSource.EDITOR)}
             />
           }
           showRight={editorMode === EditorMode.PREVIEW || (editorMode === EditorMode.BOTH)}

src/components/editor/shortcut/shortcut.ts

@@ -0,0 +1,19 @@
+import { setEditorMode } from '../../../redux/editor/methods'
+import { EditorMode } from '../app-bar/editor-view-mode'
+import { isMac } from '../utils'
+
+export const shortcutHandler = (event: KeyboardEvent): void => {
+  const modifierKey = isMac ? event.metaKey : event.ctrlKey
+
+  if (modifierKey && event.altKey && event.key === 'b') {
+    setEditorMode(EditorMode.BOTH)
+  }
+
+  if (modifierKey && event.altKey && event.key === 'v') {
+    setEditorMode(EditorMode.PREVIEW)
+  }
+
+  if (modifierKey && event.altKey && event.key === 'e') {
+    setEditorMode(EditorMode.EDITOR)
+  }
+}