I've created and published a simple app(USMC Knowledge), and right now I'm in the process of adding some more features. They should be simple to implement but I can't find any literature on how to learn to do these things. If anyone can provide a link to a site with instructions or help with coding that'd be great. Here's my agenda: Make an image that is displayed zoomable --I already am displaying the image in a LinearLayout with an ImageView inside and it works fine. But I can't find a way to make it zoomable, I've found a way to add the buttons but it's not functional. I would like to add a pdf file to the app, and make it zoomable/searchable. Finally I want to make a custom calculator. IE 3 designated inputs will give a single specific output. Any kind of information is GREATLY appreciated. I can't find anything on the web for any of this..