ibus-bopomofo or ibus-pinyin-bopomofo is a Chinese input method using bopomofo (also called zhuyin, 注音). It utilized an existing project named ibus-pinyin, which was developed by the original author of ibus. ibus-bopomofo converts users' input to pinyin (拼音) forms, and then invokes the integrated core engine of ibus-pinyin to produce Chinese phrases and sentences.
The user interface of ibus-bopomofo is different from most bopomofo IMEs because I pulled many features from popular pinyin IMEs. Some users could not get used to ibus-bopomofo, while the others love this anti-traditional interface.
For the phrases of ibus-pinyin are Simplified Chinese, I developed an engine for conversion from Simplified Chinese to Traditional Chinese. At first, the engine was integrated in ibus-bopomofo. Subsequently I found it was useful for many aspects. Therefore OpenCC was born.
Now both ibus-bopomofo and OpenCC are pre-installed in many Linux distributions such as Ubuntu, Fedora, etc. It might be your default Chinese input method if you use Ubuntu and ibus.