How do you determine if WPF is using Hardware or Software Rendering?

Check RenderCapability.Tier

• Graphics Rendering Tiers
• RenderCapability Class

[UPDATE]

• RenderCapability.IsPixelShaderVersionSupported - Gets a value that indicates whether the specified pixel shader version is supported.
• RenderCapability.IsShaderEffectSoftwareRenderingSupported - Gets a value that indicates whether the system can render bitmap effects in software.
• RenderCapability.Tier - Gets a value that indicates the rendering tier for the current thread.
• RenderCapability.TierChanged - Occurs when the rendering tier has changed for the Dispatcher object of the current thread.

RenderCapability.Tier >> 16

• Rendering Tier 0 - No graphics hardware acceleration. The DirectX version level is less than version 7.0.
• Rendering Tier 1 - Partial graphics hardware acceleration. The DirectX version level is greater than or equal to version 7.0, and lesser than version 9.0.
• Rendering Tier 2 - Most graphics features use graphics hardware acceleration. The DirectX version level is greater than or equal to version 9.0.

.NET 4.0 provides the ability to force software rendering in code:

public partial class App : Application {        protected override void OnStartup(StartupEventArgs e)        {                 if (WeThinkWeShouldRenderInSoftware())                        RenderOptions.ProcessRenderMode = RenderMode.SoftwareOnly;        }}

See this post for more information.

Based on the RenderingTier links, here is some code:

        logger.InfoFormat("WPF Tier = {0}",RenderCapability.Tier / 0x10000);        RenderCapability.TierChanged +=            (sender, args) => logger.InfoFormat("WPF Tier Changed to {0}",                                                RenderCapability.Tier / 0x10000);

I'm still testing and working on this. See future edits/answers for what I find.