How to implement a PageView in Flutter.

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How to implement a PageView in Flutter.
How to implement a PageView in Flutter.

Hi, everyone and welcome to a brand new tutorial series on Flutter. Today we’re going learn how to implement PageView in Flutter.

If you haven’t already seen the Flutter Widget of the Week video about how to implement PageView in Flutter, kindly watch it first. The rest of this article is based on it.

Flutter Widget of the week – PageView.

This video showed you the essence of what PageView does. This article will fill out the code for you to play with. Scroll down to the end to get the full code demo, or just get the source code here.

PageView widget allows the user to swipe/transition between different screens in your app. All you need to set it up are a PageViewController and a PageView.

You can use a PageController to control which page is visible in the view. In addition to being able to control the pixel offset of the content inside the PageView, a PageController also lets you control the offset in terms of pages, which are increments of the viewport size.

PageController can also be used to control the PageController.initialPage, which determines which page is shown when the PageView is first constructed, and the PageController.viewportFraction, which determines the size of the pages as a fraction of the viewport size.

Exploring PageView

PageView is a widget that generates scrollable pages on the screen. This can either be a fixed list of pages or a builder function that builds repeating pages. PageView acts similarly to a Listview in the sense of constructing elements.

Three types/Constructor of PageView

we have three types of PageView just like ListView.

1. PageView
2. PageView.builder
3. PageView.custom

PageView (Default constructor)

This type takes a fixed list of children (pages) and makes them scrollable.

        PageView(
          children: <Widget>[
            Container(
              color: Colors.orange,
              child: Center(
                  child: Text(
                'Page 1',
                style: TextStyle(color: Colors.white),
              )),
            ),
            Container(
              color: Colors.blue,
              child: Center(
                  child: Text(
                'Page 2',
                style: TextStyle(color: Colors.white),
              )),
            ),
            Container(
              color: Colors.green,
              child: Center(
                  child: Text(
                'Page 3',
                style: TextStyle(color: Colors.white),
              )),
            ),
          ],
        ),

The above code produce the below screen 👇

PageView.builder

This constructor takes a itemBuilder function and an itemCount similar to ListView.builder.

PageView.builder(
  itemBuilder: (context, index) {
    return _buildPage();
  },
  itemCount: listItemCount, // Can be null
)

Like a ListView.builder, this builds children on demand.

If the itemCount is set to null (not set), an infinite list of pages can be generated.

Example: The below code produce the below screen 👇

      PageView.builder(
        // itemCount: 3,
        itemBuilder: (context, index) {
        return Container(
          color: index % 2 == 0 ? Colors.green : Colors.blue[700],
        );
      }),

Gives an infinite list of pages with alternating pink and cyan colors:

PageView.custom Constructor

PageView.custom(
   {Key key,
   Axis scrollDirection: Axis.horizontal,
   bool reverse: false,
   PageController controller,
   ScrollPhysics physics,
   bool pageSnapping: true,
   ValueChanged<int> onPageChanged,
   @required SliverChildDelegate childrenDelegate,
   DragStartBehavior dragStartBehavior: DragStartBehavior.start,
   bool allowImplicitScrolling: false,
   String restorationId,
   Clip clipBehavior: Clip.hardEdge}
)

PageView.custom works the same way as ListView.custom. It takes a childrenDelegat function similar to ListView.builder.
PageView.custom is more explained with example in the source code.


Customized PageView

I hope you have learned something, kindly subscribe to the newsletter and appreciate this tutorial by sharing it and feel free to ask a question. Thanks for reading.

Complete source code!

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