Changing font style and type of text messaging applications such as WHAT"S UP, WECHAT ETC...

NO ROOTING, NO LAUNCHER, NO REBOOT YOU MUST BE ABLE to find a different way OF CHANGING the font type and style of any messaging service directly from your app on Android Device. APP will be Targeting and overriding on the background various chat application such as Wechat, whats app, linechat, facebook, skype, etc.... based on user choice and can get the list of buddy and chat with their buddies with a different font, a special font style and type will be display instead of the regular android font. with this app if you are in a browser like in freelancer , the chat of freelancer, you will be able as an example to type on the browser with the font special font app. Again app is not a chat messaging service. app will be available in all alphabets. With this assignment you need to implement webservices on ngnix servers for supplying data to the app. coder need to know ruby on rails. percona database, amazon etc..