WP7 project on WP8

Question

We wan't to support both platforms, because the code is 100% portable to Windows Phone 7 from our Windows Phone 8 project, but i have noticed a strange problem.

So to support both platforms we need to create WP7 project and it will be installable on WP8, but:

On small devices like WVGA, application looks normal, but when i open it on 720p it doesn't use 100% height.

Example:

What the hell? If i open the same xaml in WP8 project all works perfect.

PS Full design is rubber - no hardcode in pixels or %. How to fix it?

Answer 1

Unfortunately, this is not possible. The WP7 apps running on WP8 devices are constrained in a 480x800 container.

To take advantage of the 720p screen, you'll have to build a WP8 version of your app.

Answer 2

That's because the different screen sizes and screen ratios. WP8 can run WP7 Apps, but at certain resolutions it uses a black rectangle to avoid lengthening the screen.