fix: do not register new ipc event listener when main screen componen…

…t is loaded (fixes #176)

docs/src/electron-how-to/preload-script.md

@@ -13,8 +13,13 @@ Vutron's preload script is located in the `src/preload` folder. To create a new
 
 When sending events from renderer to main, you access the `window.mainApi` object instead of `ipcRenderer.send`. The `mainApi` is the name you set in your Vutron template and can be changed.
 
-Here are the supported functions for mainApi: (To change and modify this, you need to modify `exposeInMainWorld` in `src/preload/index.ts`).
+Here are the supported functions for mainApi:
 
 - `send`: Send an event to main.
-- `receive`: A listener to receive events sent by main.
+- `sendSync`: Send an event to main. It can be used when receiving a return value. The UI may be frozen until the operation is complete.
+- `on`: A listener to receive events sent by main.
+- `once`: A listener to receive events sent by main. (Handle only one call)
+- `off`: Remove an event listener
 - `invoke`: Functions that can send events to main and receive data asynchronously.
+
+To change and modify this, you need to modify `exposeInMainWorld` in `src/preload/index.ts`.

src/main/IPCs.ts

@@ -1,18 +1,18 @@
-import { BrowserWindow, ipcMain, shell } from 'electron'
+import { ipcMain, shell, IpcMainEvent } from 'electron'
 import Constants from './utils/Constants'
 
 /*
  * IPC Communications
  * */
 export default class IPCs {
-  static initialize(window: BrowserWindow): void {
+  static initialize(): void {
     // Get application version
-    ipcMain.on('msgRequestGetVersion', () => {
-      window.webContents.send('msgReceivedVersion', Constants.APP_VERSION)
+    ipcMain.on('msgRequestGetVersion', (event: IpcMainEvent) => {
+      event.returnValue = Constants.APP_VERSION
     })
 
     // Open url via web browser
-    ipcMain.on('msgOpenExternalLink', async (event, url: string) => {
+    ipcMain.on('msgOpenExternalLink', async (event: IpcMainEvent, url: string) => {
       await shell.openExternal(url)
     })
   }

src/main/MainRunner.ts

@@ -41,7 +41,7 @@ export const createMainWindow = async (mainWindow: BrowserWindow): Promise<Brows
   })
 
   // Initialize IPC Communication
-  IPCs.initialize(mainWindow)
+  IPCs.initialize()
 
   if (Constants.IS_DEV_ENV) {
     await mainWindow.loadURL(Constants.APP_INDEX_URL_DEV)

src/preload/index.ts

@@ -1,22 +1,43 @@
-import { contextBridge, ipcRenderer } from 'electron'
+import { contextBridge, ipcRenderer, IpcRendererEvent } from 'electron'
 
 // Whitelist of valid channels used for IPC communication (Send message from Renderer to Main)
 const mainAvailChannels: string[] = ['msgRequestGetVersion', 'msgOpenExternalLink']
-const rendererAvailChannels: string[] = ['msgReceivedVersion']
+const rendererAvailChannels: string[] = []
 
 contextBridge.exposeInMainWorld('mainApi', {
   send: (channel: string, ...data: any[]): void => {
     if (mainAvailChannels.includes(channel)) {
       ipcRenderer.send.apply(null, [channel, ...data])
     } else {
-      throw new Error(`Send failed: Unknown ipc channel name: ${channel}`)
+      throw new Error(`Unknown ipc channel name: ${channel}`)
     }
   },
-  receive: (channel: string, cbFunc: Function): void => {
+  sendSync: (channel: string, ...data: any[]): void => {
+    if (mainAvailChannels.includes(channel)) {
+      return ipcRenderer.sendSync.apply(null, [channel, ...data])
+    }
+
+    throw new Error(`Unknown ipc channel name: ${channel}`)
+  },
+  on: (channel: string, listener: (event: IpcRendererEvent, ...args: any[]) => void): void => {
+    if (rendererAvailChannels.includes(channel)) {
+      ipcRenderer.on(channel, listener)
+    } else {
+      throw new Error(`Unknown ipc channel name: ${channel}`)
+    }
+  },
+  once: (channel: string, listener: (event: IpcRendererEvent, ...args: any[]) => void): void => {
+    if (rendererAvailChannels.includes(channel)) {
+      ipcRenderer.once(channel, listener)
+    } else {
+      throw new Error(`Unknown ipc channel name: ${channel}`)
+    }
+  },
+  off: (channel: string, listener: (event: IpcRendererEvent, ...args: any[]) => void): void => {
     if (rendererAvailChannels.includes(channel)) {
-      ipcRenderer.on(channel, (event, ...args) => cbFunc(event, ...args))
+      ipcRenderer.off(channel, listener)
     } else {
-      throw new Error(`Receive failed: Unknown ipc channel name: ${channel}`)
+      throw new Error(`Unknown ipc channel name: ${channel}`)
     }
   },
   invoke: async (channel: string, ...data: any[]): Promise<any> => {
@@ -25,6 +46,6 @@ contextBridge.exposeInMainWorld('mainApi', {
       return result
     }
 
-    throw new Error(`Invoke failed: Unknown ipc channel name: ${channel}`)
+    throw new Error(`Unknown ipc channel name: ${channel}`)
   }
 })

src/renderer/screens/MainScreen.vue

@@ -17,12 +17,13 @@ onMounted((): void => {
   languages.value = availableLocales
 
   // Get application version from package.json version string (Using IPC communication)
-  window.mainApi.receive('msgReceivedVersion', (event: Event, version: string) => {
-    appVersion.value = version
-  })
-  window.mainApi.send('msgRequestGetVersion')
+  getApplicationVersionFromMainProcess()
 })
 
+const getApplicationVersionFromMainProcess = (): void => {
+  appVersion.value = window.mainApi.sendSync('msgRequestGetVersion')
+}
+
 const handleChangeTheme = (): void => {
   theme.global.name.value = theme.global.current.value.dark ? 'light' : 'dark'
 }