Theme makers, on your mark, get set, and go start porting your masterpieces over to the new CyangeonMod theme engine. The popular Android custom ROM has just ported over its shiny new theme engine to Google's shiny new Android Lollipop version and now it is putting out a call to theme designers to do their part to port their designs over there as well. That said, given the large leap from Holo to Material Design, the transition presents a few stumbling blocks for theme designers to take note of.
CyanogenMod developed its new theme engine just recently in time for the launch of CyanogenMod 11S on the OnePlus One smartphone. Though relatively new, the theme engine all revolved around the Holo style that Android has been carrying since the early Jelly Bean days. But with the move to the new Material Design language, theme makers might find their designs not working properly on CyanogenMod 12, unless the particular app happens to be hardcoded to still use the Holo style.
In order to help with the porting work, CyanogenMod is offering a few things designers need to take note of. Aside from remembering that they might need to make a new theme specifically with CM12 in mind, they should also be aware that CM is now becoming more strict with regards to images. To be specific, the theme engine will no longer accept a broken .9.png image and will not install the theme properly. Theme makers must also set the targetSdkVersion to 21 in their Android package to let the system know that they are targeting Android 5.0.
On that note, theme makers should also be aware that at the moment, it's not possible to create a theme that works on both CM12 and CM11 yet, mostly because the CM11 theme engine wouldn't know what to do with theme elements specific to CM12. Fortunately, Google Play Store does allow you to distribute separate APKs for CM11 and CM12 and it will determine which version to provide depending on the version on the user's device. A patch might be forthcoming for the CM11 theme engine that resolve this on the CyanogenMod end, but that should not be expected to be the default behavior everywhere.
SOURCE: +Clark Scheff