Viewport improvements (#3765)

Content.Client/UserInterface/ViewportExt.cs

@@ -0,0 +1,15 @@
+using Robust.Client.UserInterface.CustomControls;
+
+namespace Content.Client.UserInterface
+{
+    public static class ViewportExt
+    {
+        public static int GetRenderScale(this IViewportControl viewport)
+        {
+            if (viewport is ScalingViewport svp)
+                return svp.CurrentRenderScale;
+
+            return 1;
+        }
+    }
+}