| scrollDirection | Axis.horizontal | If `Axis.horizontal`, the scroll view's children are arranged horizontally in a row instead of vertically in a column. |
| loop | false |Set to `true` to enable continuous loop mode. |
| index | none | Index number of initial slide. if not set , it is controlled by the widget itself,otherwise, it is controlled by another widget, which is returned by `itemBuilder`|
| onPageChanged | void onPageChanged(int index) | Called with the new index when the user swiped |
| duration | new Duration(milliseconds:300) | The milliseconds of every transaction animation costs |
| transformer | none | The most important property of this widget, it returns a `transformed` widget that based on the widget parameter. If the value is null, a `itemBuilder` must be specified |
| itemCount | none | Number of the total items |
| itemBuilder | none | A function that returns a widget based on index,if it's null,a `transformer` must be specified |
### Build-in Parallax
We provide 3 build-in parallaxes, which handle color、image and container
> ParallaxColor
ParallaxColor handles the color transform, which controls the color transform from one to another.
> ParallaxImage
ParallaxImage handles the image, which speed is slower than the `PageView`
> ParallaxContainer
ParallaxContainer handles the text or other staff, which speed is faster than the `PageView`
3 build-in parallaxes are all used in subclass of `PageTransform`,group these parallaxes together, we can create very cool things.
