I'm developing an application which must work for both WP7 and WP8. And want to create multi resolution splashscreen and Tiles. I know that it can be done easily for WP8 (http://msdn.microsoft.com/en-us/library/windowsphone/develop/ff769511(v=vs.105).aspx)
But how can I do it for WP7 application?
How can I make my application (developed for WP7.5) closer to WP8 but still working on WP7.5-7.8.
I just want my application looks good for both WP7 and WP8 devices.
You can run your app designed for WP7 on WP8 device too, but then you will have problems with screen resolution on some devices. You can develop two versions app WP7 and WP8. Porting is not that difficult, if correctly to this approach. In the articles you can find good advice http://www.developer.nokia.com/Community/Wiki/Maintaining_a_WP7_and_WP8_version_of_a_same_Silverlight_application and http://www.developer.nokia.com/Community/Wiki/Introduction_to_multiple-resolution_support_on_Windows_Phone_8_apps .
Since WP7 devices are all (and always will be) WVGA, there's no point to supporting multiple resolutions. What you can do, though, is support multiple tile sizes on 7.8+, and I'd suggest using Mangopollo for that.
Just reuse your WVGA tile assets from the WP8 version of your app, and make the appropriate changes in your app's WMAppManifest.xml:
<AppExtra xmlns="" AppPlatformVersion="8.0">
<Extra Name="Tiles"/>
</AppExtra>
This should be placed inside the <Deployment> tag before <App>. Then you just need to make sure to change your primary tile's type and assets on first run using Mangopollo, and to use the library when creating or updating any secondary tiles.
That's as close to multi-resolution that WP7 will ever get.
