Proxy - virtual proxy pattern

Author: mechaniccoder

Proxy/virtual-proxy.ts

@@ -0,0 +1,39 @@
+interface Icon {
+  getIconWidth(): number;
+  getIconHeight(): number;
+  paintIcon(): void;
+}
+
+class ImageProxy implements Icon {
+  private realImage: Image;
+  private url: string;
+
+  constructor(url: string) {
+    this.url = url;
+  }
+
+  getIconWidth(): number {
+    if (this.realImage) {
+      return this.realImage.getIconWidth();
+    } else {
+      return 800;
+    }
+  }
+
+  getIconHeight(): number {
+    if (this.realImage) {
+      return this.realImage.getIconHeight();
+    } else {
+      return 600;
+    }
+  }
+
+  paintIcon(): void {
+    if (!this.realImage) {
+      this.realImage = new Image(this.url);
+    }
+    this.realImage.paintIcon();
+  }
+}
+
+export {};