gl-react/docs/api/Component.md
Gaëtan Renaudeau bcbb86c97a improve doc
2015-08-27 14:47:45 +02:00

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# Component
**`GL.Component` is the class to extend to implement a GL Component.**
```js
class MyEffect extends GL.Component {
render () {
return <GL.View ...>...</GL.View>;
}
}
```
`GL.Component` allows to **compose** effects:
it tells the `gl-react-core` algorithm to "unfold" the `render()` looking for a `GL.View` to merge with.
> Technically, this is not required to extend `GL.Component` (you can still use `React.Component`),
but this is generally a good idea (you always want to make a component "composable").
## Composing effects
Once you have defined your component that inject children, you can then compose it with another.
**Example:**
```html
<Blur factor={1.2} width={200} height={150}>
<Negative width={200} height={150}>
http://i.imgur.com/qM9BHCy.jpg
</Negative>
</Blur>
```
and you can make generic component out of it:
```js
class BlurNegative extends GL.Component {
render () {
const { width, height, blur, children } = this.props;
return <Blur factor={blur} width={width} height={height}>
<Negative width={width} height={height}>
{children}
</Negative>
</Blur>;
}
}
```
and use it:
```html
<BlurNegative factor={1.2} width={200} height={150}>
http://i.imgur.com/qM9BHCy.jpg
</BlurNegative>
```
## Implementation notes
Effects composition are made efficient using OpenGL Framebuffers:
the rendering is made in the same pipeline.
[`gl-react-core`](https://github.com/ProjectSeptemberInc/gl-react-core)
contains the core logic (shared across both `gl-react` and `gl-react-native`)
that convert the Virtual DOM Tree into `data`, an object tree that represent the rendering pipeline.