Smart Emoji Keyboard is a keyboard application for Android with which you can do exactly the same thing as with the normal Google keyboard: type and enter emoji from Hangouts in any textbox you want.
In the settings, you can find some interesting customization options. One of the best is the ability to change the color of the keyboard interface from a handful of different colors. You can also enable and disable autocomplete, suggestions, and corrections.
Inside the main menu, you can download dictionaries in several different languages, including English, Spanish, French, and Chinese. Once downloaded, you can change the keyboard language accordingly.
Smart Emoji Keyboard is an Android keyboard that’s not particularly visually appealing but has a lot of great features. And, of course, you can always use it for just the emoji.