# React Native Offscreen Toolbar

In material design, there is a common scrolling technique in which the toolbar is smoothly tucked away while scrolling down and is made visible again when scrolling up. This behaviour is fairly straightforward to implement when developing a native android app, but for a react native app, the best solution I found was Janic Duplessis’.

The library I am releasing today is an encapsulation of this behaviour and its implementation is heavily based on Janic Duplessis’ approach.

## How to Use it

Installation:

 npm install react-native-offscreen-toolbar --save


Usage (full example here):

import OffscreenToolbar from 'react-native-offscreen-toolbar';

export default class YourComponent extends React.Component {
render() {
const toolbar = () => (<ToolbarAndroid title={'Title'} />);
const listItem = ({item}) => <Text>{item.key}</Text>;
const scrollable = () => (<FlatList data={DUMMY_DATA} renderItem={listItem}/>);
return (
<View style={styles.container}>
<OffscreenToolbar
toolbar={toolbar}
scrollable={scrollable} />
</View>
);
}
}


You can pass any component you desire as a toolbar, but typically this will be a toolbar/navbar backed by react native or a UI library of your choice, like Native Base.

The scrollable however, will need to be scrollable component such as a ScrollView, ListView, FlatList, etc. The OffscreenToolbar will then create hooks around this component in order to gauge the user’s scrolling behaviour and change toolbar’s animation accordingly.

You can also provide the following properties to the component:

• scrollableOverlay: for a search screen as the one presented above, this component can be used to present an overlay between the scrollable and the toolbar
• toolbarHeight: adjust this property according to your toolbar height. This value is used for the toolbar’s animation
• scrollablePaddingTop: since the scrollable is laying behind the toolbar, this property comes in handy to place the scrollable content below the toolbar