From 07a4c5291980f6d0d22ee7600911562bd5cf4e3d Mon Sep 17 00:00:00 2001
From: Cheng Zhao <zcbenz@gmail.com>
Date: Wed, 13 Apr 2016 21:36:43 +0900
Subject: [PATCH] Reduces the IPC messages used for visibilityState

---
 lib/browser/api/browser-window.js | 47 ++++++++++++-------------------
 lib/renderer/override.js          | 39 ++++++++-----------------
 2 files changed, 29 insertions(+), 57 deletions(-)

diff --git a/lib/browser/api/browser-window.js b/lib/browser/api/browser-window.js
index 694cbf6d669..80c1f29eb28 100644
--- a/lib/browser/api/browser-window.js
+++ b/lib/browser/api/browser-window.js
@@ -78,19 +78,23 @@ BrowserWindow.prototype._init = function () {
     app.emit('browser-window-focus', event, this)
   })
 
-  // Evented visibilityState changes
-  this.on('show', () => {
-    this.webContents.send('ELECTRON_RENDERER_WINDOW_VISIBILITY_CHANGE', this.isVisible(), this.isMinimized())
-  })
-  this.on('hide', () => {
-    this.webContents.send('ELECTRON_RENDERER_WINDOW_VISIBILITY_CHANGE', this.isVisible(), this.isMinimized())
-  })
-  this.on('minimize', () => {
-    this.webContents.send('ELECTRON_RENDERER_WINDOW_VISIBILITY_CHANGE', this.isVisible(), this.isMinimized())
-  })
-  this.on('restore', () => {
-    this.webContents.send('ELECTRON_RENDERER_WINDOW_VISIBILITY_CHANGE', this.isVisible(), this.isMinimized())
-  })
+  // Subscribe to visibilityState changes and pass to renderer process.
+  let isVisible = false
+  let visibilityChanged = () => {
+    let newState = this.isVisible() && !this.isMinimized()
+    if (isVisible != newState) {
+      isVisible = newState
+      this.webContents.send('ELECTRON_RENDERER_WINDOW_VISIBILITY_CHANGE', isVisible ? 'visible' : 'hidden')
+    }
+  }
+  this.on('show', visibilityChanged)
+  this.on('hide', visibilityChanged)
+  this.on('minimize', visibilityChanged)
+  this.on('restore', visibilityChanged)
+  this.on('maximize', visibilityChanged)
+
+  // Make renderer process have correct initial state.
+  visibilityChanged()
 
   // Notify the creation of the window.
   app.emit('browser-window-created', {}, this)
@@ -105,6 +109,7 @@ BrowserWindow.prototype._init = function () {
   this.webContents.on('devtools-closed', () => {
     this.emit('devtools-closed')
   })
+
   Object.defineProperty(this, 'devToolsWebContents', {
     enumerable: true,
     configurable: false,
@@ -195,37 +200,21 @@ BrowserWindow.prototype.inspectServiceWorker = function () {
 }
 
 // Deprecated.
-
 deprecate.member(BrowserWindow, 'undo', 'webContents')
-
 deprecate.member(BrowserWindow, 'redo', 'webContents')
-
 deprecate.member(BrowserWindow, 'cut', 'webContents')
-
 deprecate.member(BrowserWindow, 'copy', 'webContents')
-
 deprecate.member(BrowserWindow, 'paste', 'webContents')
-
 deprecate.member(BrowserWindow, 'selectAll', 'webContents')
-
 deprecate.member(BrowserWindow, 'reloadIgnoringCache', 'webContents')
-
 deprecate.member(BrowserWindow, 'isLoading', 'webContents')
-
 deprecate.member(BrowserWindow, 'isWaitingForResponse', 'webContents')
-
 deprecate.member(BrowserWindow, 'stop', 'webContents')
-
 deprecate.member(BrowserWindow, 'isCrashed', 'webContents')
-
 deprecate.member(BrowserWindow, 'print', 'webContents')
-
 deprecate.member(BrowserWindow, 'printToPDF', 'webContents')
-
 deprecate.rename(BrowserWindow, 'restart', 'reload')
-
 deprecate.rename(BrowserWindow, 'loadUrl', 'loadURL')
-
 deprecate.rename(BrowserWindow, 'getUrl', 'getURL')
 
 BrowserWindow.prototype.executeJavaScriptInDevTools = deprecate('executeJavaScriptInDevTools', 'devToolsWebContents.executeJavaScript', function (code) {
diff --git a/lib/renderer/override.js b/lib/renderer/override.js
index 5f808d66300..ba46bdf51e6 100644
--- a/lib/renderer/override.js
+++ b/lib/renderer/override.js
@@ -3,17 +3,6 @@
 const ipcRenderer = require('electron').ipcRenderer
 const remote = require('electron').remote
 
-// Cache browser window visibility
-var _isVisible = true
-var _isMinimized = false
-var initWindow = function initWindow () {
-  var currentWindow
-  currentWindow = remote.getCurrentWindow()
-  _isVisible = currentWindow.isVisible()
-  _isMinimized = currentWindow.isMinimized()
-}
-initWindow()
-
 // Helper function to resolve relative url.
 var a = window.top.document.createElement('a')
 
@@ -200,17 +189,6 @@ if (process.openerId != null) {
   window.opener = BrowserWindowProxy.getOrCreate(process.openerId)
 }
 
-ipcRenderer.on('ELECTRON_RENDERER_WINDOW_VISIBILITY_CHANGE', function (event, isVisible, isMinimized) {
-  var hasChanged = _isVisible !== isVisible || _isMinimized !== isMinimized
-
-  if (hasChanged) {
-    _isVisible = isVisible
-    _isMinimized = isMinimized
-
-    document.dispatchEvent(new Event('visibilitychange'))
-  }
-})
-
 ipcRenderer.on('ELECTRON_GUEST_WINDOW_POSTMESSAGE', function (event, sourceId, message, sourceOrigin) {
   // Manually dispatch event instead of using postMessage because we also need to
   // set event.source.
@@ -249,19 +227,24 @@ Object.defineProperty(window.history, 'length', {
   }
 })
 
+// Subscribe to visibilityState changes.
+let cachedVisibilityState = 'hidden'
+ipcRenderer.on('ELECTRON_RENDERER_WINDOW_VISIBILITY_CHANGE', function (event, visibilityState) {
+  if (cachedVisibilityState != visibilityState) {
+    cachedVisibilityState = visibilityState
+    document.dispatchEvent(new Event('visibilitychange'))
+  }
+})
+
 // Make document.hidden and document.visibilityState return the correct value.
 Object.defineProperty(document, 'hidden', {
   get: function () {
-    return _isMinimized || !_isVisible
+    return cachedVisibilityState != 'visible'
   }
 })
 
 Object.defineProperty(document, 'visibilityState', {
   get: function () {
-    if (_isVisible && !_isMinimized) {
-      return 'visible'
-    } else {
-      return 'hidden'
-    }
+    return cachedVisibilityState
   }
 })