This week I receive a question related to XAML and a Modern UI Windows 8 application (Metro Apps). They need a method to draw shadows in a XAML application.
When the design team port an application from iPad to Windows 8, they try to reuse a lot of things that were used on iPad. Because of this elements like shadow can appear very easily in the design of a Windows 8 application. In theory, a Windows 8 application should not contains shadows. Because an app for Windows 8 should have a clean and simple design, shadow is saw like an element that will only load the UI.
Also, people that worked with UI effect already know that the shadow effect is one of the effects that use a lot of resources – especially video or processor resource. Having this kind of effects on a tablet could drain our battery very easily.
This is why the XAML don’t contains any kind of support for shadow. You can make some hacks, using lines with different bluer levels and thing like this, but it will be only a hack. By default we don’t have support for this kind of effect.
The first thing that we should do when we receive a request like this is to send back the design and explain that a Modern UI Windows 8 App should not contains shadows.
If you really want the shadow effect you should try using DirectX in combination with C++. Using DirectX from C++ you can make any kind of effect you want. Yes, the implementation is not so trivial, but you will obtain the perfect shadow effect. Because you are using DirectX the performance will be pretty good.
If you don’t want to use C++ and DirectX directly, I recommend http://sharpdx.org/ . This is an open source project that offer support for DirectX from C#. They have a version of the frameworks that works pretty good on Win RT. The only thing that you should remember about Sharpdx is the performance. Because is only a wrapper over DirectX and C++, if you have any kind of problems you should fallback to C++ and write your own code.