Add ContentIsland page with Helmet demo (requires WinAppSDK 1.7 APIs)

[JesseCol]

NOTE: Do not merge until WinAppSDK is updated to 1.7.

Description

Adds a ContentIsland page that uses Scene Node APIs to show a 3D model of a helmet.

Motivation and Context

This shows how apps can use ChildSiteLink to attach a ContentIsland in a Xaml app.

How Has This Been Tested?

• Built and ran packaged
• Built and ran unpackaged

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

[jeffstall]

Can we just check into the experimental branch now, and then merge that branch into main once WASDK 1.7.0 is GA?

[niels9001]

@JesseCol I've updated your PR to resolve major conflicts due to #1732. I've also tweaked the XAML a bit to remove unnecessary XAML and used a WrapPanel vs. the Grid so things are easier to see on a wide-screens.

[JesseCol]

Can we just check into the experimental branch now, and then merge that branch into main once WASDK 1.7.0 is GA?

Hi, there's no dedicated experimental branch for this repo (WinUI-Gallery). I've heard there's a new plan for WindowsAppSDK-Samples where we'll check in code that uses experimental APIs to main, and then conditionally compile that code. Maybe we can do something similar here.

[marcelwgn]

Can we just check into the experimental branch now, and then merge that branch into main once WASDK 1.7.0 is GA?

Hi, there's no dedicated experimental branch for this repo (WinUI-Gallery). I've heard there's a new plan for WindowsAppSDK-Samples where we'll check in code that uses experimental APIs to main, and then conditionally compile that code. Maybe we can do something similar here.

For that, we essentially only need to check for WinUI 1.7 in the csproj and .cs file right?

[JesseCol]

Can we just check into the experimental branch now, and then merge that branch into main once WASDK 1.7.0 is GA?

Hi, there's no dedicated experimental branch for this repo (WinUI-Gallery). I've heard there's a new plan for WindowsAppSDK-Samples where we'll check in code that uses experimental APIs to main, and then conditionally compile that code. Maybe we can do something similar here.

For that, we essentially only need to check for WinUI 1.7 in the csproj and .cs file right?

Well, the problem as I understand it is that:

• 1.7 exp2 DOES have these APIs.
• 1.7 preview1 does NOT have them.
• 1.7 GA WILL have them (we expect).

I'm assuming we'll want to build Gallery with preview1 at some point, and if we did this would break.

Maybe we could query the MicrosoftWindowsAppSDKChannel MSBuild property, and only use these APIs when it's set to "experimental" or "stable" (and not preview), but that seems like it's getting kinda fiddly.

Adding @karkarl as well for more input.