feat: EmptyMonitor object on non-Windows systems for better cross-platform compatibility

Author: sentialx

docs/monitor.md

@@ -2,6 +2,10 @@
 
 Control monitors.
 
+> NOTE: Monitors are supported only on `Windows`, but on `macOS` there's a stub object 
+called `EmptyMonitor` for better cross-platform compatibility without checking whether 
+a returned monitor is `undefined`.
+
 ```typescript
 import { windowManager } from 'node-window-manager';
 
@@ -21,22 +25,36 @@ const { height } = windowManager.getPrimaryWindow().getWorkArea();
 
 #### monitor.getBounds() `Windows`
 
+> NOTE: on macOS this method returns `{x: 0, y: 0, width: 0, height: 0}` for compatibility.
+
 - Returns [`Rectangle`](rectangle.md)
 
 #### monitor.getWorkArea() `Windows`
 
+> NOTE: on macOS this method returns `{x: 0, y: 0, width: 0, height: 0}` for compatibility.
+
 Gets monitor working area bounds.
 
 - Returns [`Rectangle`](rectangle.md)
 
 #### monitor.isPrimary() `Windows`
 
+> NOTE: on macOS this method returns `false` for compatibility.
+
 Whether the monitor is primary.
 
 - Returns `boolean`
 
 #### monitor.getScaleFactor() `Windows`
 
+> NOTE: on macOS this method returns `1` for compatibility.
+
 Gets monitor scale factor (DPI).
 
 - Returns `number`
+
+#### monitor.isValid() `Windows` `macOS`
+
+Returns:
+- On `Windows`: `true`
+- On `macOS`: `false`, since it's just an `EmptyMonitor` object.

docs/window-manager.md

@@ -40,10 +40,14 @@ The method is required to call before calling the following methods:
 
 #### windowManager.getMonitors() `Windows`
 
+> NOTE: on macOS this method returns `[]` for compatibility.
+
 - Returns [`Monitor[]`](monitor.md)
 
 #### windowManager.getPrimaryMonitor() `Windows`
 
+> NOTE: on macOS this method returns an `EmptyMonitor` object for compatibility.
+
 - Returns [`Monitor`](monitor.md)
 
 ### Events

docs/window.md

@@ -70,6 +70,8 @@ Returns `number` between 0 and 1.
 
 #### win.getMonitor() `Windows`
 
+> NOTE: on macOS this method returns an `EmptyMonitor` object for compatibility.
+
 Gets monitor which the window belongs to.
 
 Returns [`Monitor`](monitor.md)

src/classes/empty-monitor.ts

@@ -0,0 +1,23 @@
+import { IRectangle } from "../interfaces";
+
+export class EmptyMonitor {
+  getBounds(): IRectangle {
+    return { x: 0, y: 0, width: 0, height: 0 };
+  }
+
+  getWorkArea(): IRectangle {
+    return { x: 0, y: 0, width: 0, height: 0 };
+  }
+
+  isPrimary(): boolean {
+    return false;
+  }
+
+  getScaleFactor(): number {
+    return 1;
+  };
+
+  isValid(): boolean {
+    return false;
+  }
+}

src/classes/monitor.ts

@@ -39,4 +39,8 @@ export class Monitor {
 
     return 1;
   };
+
+  isValid(): boolean {
+    return addon && addon.getMonitorInfo;
+  }
 }

src/classes/window.ts

@@ -2,6 +2,7 @@ import { addon } from "..";
 import extractFileIcon from 'extract-file-icon';
 import { Monitor } from "./monitor";
 import { IRectangle } from "../interfaces";
+import { EmptyMonitor } from "./empty-monitor";
 
 export class Window {
   public id: number;
@@ -59,8 +60,8 @@ export class Window {
     return addon.getWindowTitle(this.id);
   }
 
-  getMonitor(): Monitor {
-    if (!addon || !addon.getMonitorFromWindow) return;
+  getMonitor(): Monitor | EmptyMonitor {
+    if (!addon || !addon.getMonitorFromWindow) return new EmptyMonitor();
     return new Monitor(addon.getMonitorFromWindow(this.id));
   }
 

src/index.ts

@@ -2,6 +2,7 @@ import { Window } from "./classes/window";
 import { EventEmitter } from "events";
 import { platform } from "os";
 import { Monitor } from "./classes/monitor";
+import { EmptyMonitor } from "./classes/empty-monitor";
 
 let addon: any;
 
@@ -72,8 +73,12 @@ class WindowManager extends EventEmitter {
     return addon.getMonitors().map((mon: any) => new Monitor(mon));
   };
 
-  getPrimaryMonitor = (): Monitor => {
-    return this.getMonitors().find(x => x.isPrimary);
+  getPrimaryMonitor = (): Monitor | EmptyMonitor => {
+    if (process.platform === 'win32') {
+      return this.getMonitors().find(x => x.isPrimary);
+    } else {
+      return new EmptyMonitor();
+    }
   }
 }