如果DataContext为null或不使用WPF，如何触发样式更改

I have a page with several controls. The controls are bound to display values which they get from the page's DataContext. What I would like to do is display another look of the page should the DataContext be null. In some cases the controls of the page should display differently if "their" property is set or not.I have a page with several controls. The contro