sliding_up_panel 

A draggable Flutter widget that makes implementing a SlidingUpPanel much easier! Based on the Material Design bottom sheet component, this widget works on both Android & iOS.

Installing 

Add the following to your pubspec.yaml file:

dependencies:
  sliding_up_panel: ^2.0.0+1

Note that v1.0.0 introduced some breaking changes outlined below.

Maintaining sliding_up_panel 

Thank you everyone for the support surrounding this project! sliding_up_panel has grown far larger than I could have ever imagined, so parsing through all the feature requests and new issues has taken me more time than I’d like. If you’re interested in helping maintain this project, please send me an email at [email protected]. As a sidenote, I’ll always try to make sure that this project is compatible with the latest version of Flutter.

Simple Usage 

There are two ways which the SlidingUpPanel can easily be added to your project.

1. Using the SlidingUpPanel as the root widget for the body (recommended).
2. Nesting the SlidingUpPanel

SlidingUpPanel as the Root (recommended)

This method is recommended as it allows for the least interference with the behavior of other UI elements. For example:

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text("SlidingUpPanelExample"),
    ),
    body: SlidingUpPanel(
      panel: Center(
        child: Text("This is the sliding Widget"),
      ),
      body: Center(
        child: Text("This is the Widget behind the sliding panel"),
      ),
    ),
  );
}

Nesting the SlidingUpPanel

This method isn’t recommended but can still be used. Only use this to avoid refactoring large chunks of code or to implement custom scrolling behavior. For example, the SlidingUpPanel can be nested inside of a Stack (note that there are many other possible implementations that vary on a case-by-case basis).

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text("SlidingUpPanelExample"),
    ),
    body: Stack(
      children: <Widget>[
        Center(child: Text("This is the Widget behind the sliding panel"),),

        SlidingUpPanel(
          panel: Center(child: Text("This is the sliding Widget"),),
        )
      ],
    )
  );
}

Screenshots

Both methods produce the same result:

Custom Usage 

There are several options that allow for more control:

Darkening the Body as the Panel Opens 

If desired, the body can be darkened as the panel is opened by setting backdropEnabled to true. You can also customize the backdropColor, backdropOpacity, and backdropTapClosesPanel. For example:

@override
Widget build(BuildContext context){
  return Material(
    child: SlidingUpPanel(
      backdropEnabled: true,
      panel: Center(
        child: Text("This is the sliding Widget"),
      ),
      body: Scaffold(
        appBar: AppBar(
          title: Text("SlidingUpPanelExample"),
        ),
        body:  Center(
          child: Text("This is the Widget behind the sliding panel"),
        ),
      ),
    ),
  );
}

Notice how the Scaffold is nested inside of the SlidingUpPanel. This because the backdrop is rendered only over the body of the SlidingUpPanel. As a result, if we want the backdrop to appear over the AppBar, then we must nest the Scaffold this way.

Displaying a Different Child When the Panel is Closed 

By assigning a non-null Widget to the collapsed property, you can add a Widget that displays overtop the panel when collapsed. As the panel is opened, this Widget will fade out to display the panel underneath. For example:

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text("SlidingUpPanelExample"),
    ),
    body: SlidingUpPanel(
      panel: Center(
        child: Text("This is the sliding Widget"),
      ),
      collapsed: Container(
        color: Colors.blueGrey,
        child: Center(
          child: Text(
            "This is the collapsed Widget",
            style: TextStyle(color: Colors.white),
          ),
        ),
      ),
      body: Center(
        child: Text("This is the Widget behind the sliding panel"),
      ),
    ),
  );
}

Rounding the Borders 

Modern design principles (especially in the Material Design Refresh) emphasize rounded borders. A similar effect can be easily achieved by providing a non-null BorderRadiusGeometry to the borderRadius property. Note that this only curves the border on the underlying panel sheet: any children passed to panel or collapsed must also have their borders curved separately in order to achieve a uniform effect. For example:

@override
Widget build(BuildContext context) {
  BorderRadiusGeometry radius = BorderRadius.only(
    topLeft: Radius.circular(24.0),
    topRight: Radius.circular(24.0),
  );

  return Scaffold(
    appBar: AppBar(
      title: Text("SlidingUpPanelExample"),
    ),
    body: SlidingUpPanel(
      panel: Center(
        child: Text("This is the sliding Widget"),
      ),

      collapsed: Container(
        decoration: BoxDecoration(
          color: Colors.blueGrey,
          borderRadius: radius
        ),
        child: Center(
          child: Text(
            "This is the collapsed Widget",
            style: TextStyle(color: Colors.white),
          ),
        ),
      ),

      body: Center(
        child: Text("This is the Widget behind the sliding panel"),
      ),

      borderRadius: radius,
    ),
  );
}

Creating A Floating Effect 

To create a fully custom effect, the default panel sheet can be completely hidden and only the children rendered (i.e. only body, panel, and collapsed are rendered). To do this, set the renderPanelSheet property to false. For example, to create a floating effect:

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text("SlidingUpPanelExample"),
    ),
    body: SlidingUpPanel(
      renderPanelSheet: false,
      panel: _floatingPanel(),
      collapsed: _floatingCollapsed(),
      body: Center(
        child: Text("This is the Widget behind the sliding panel"),
      ),
    ),
  );
}

Widget _floatingCollapsed(){
  return Container(
    decoration: BoxDecoration(
      color: Colors.blueGrey,
      borderRadius: BorderRadius.only(topLeft: Radius.circular(24.0), topRight: Radius.circular(24.0)),
    ),
    margin: const EdgeInsets.fromLTRB(24.0, 24.0, 24.0, 0.0),
    child: Center(
      child: Text(
        "This is the collapsed Widget",
        style: TextStyle(color: Colors.white),
      ),
    ),
  );
}

Widget _floatingPanel(){
  return Container(
    decoration: BoxDecoration(
      color: Colors.white,
      borderRadius: BorderRadius.all(Radius.circular(24.0)),
      boxShadow: [
        BoxShadow(
          blurRadius: 20.0,
          color: Colors.grey,
        ),
      ]
    ),
    margin: const EdgeInsets.all(24.0),
    child: Center(
      child: Text("This is the SlidingUpPanel when open"),
    ),
  );
}

Note that a similar effect can be created by simply adding a margin to the SlidingUpPanel.

Adding Scrollable Elements to the Sliding Panel 

The panel itself can contain Scrollable elements. As of v1.0.0, you can link the scroll position of the Scrollable elements with the position of the sliding up panel by using the panelBuilder. For example:

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text("SlidingUpPanelExample"),
    ),
    body: SlidingUpPanel(
      panelBuilder: (ScrollController sc) => _scrollingList(sc),
      body: Center(
        child: Text("This is the Widget behind the sliding panel"),
      ),
    ),
  );
}

Widget _scrollingList(ScrollController sc){
  return ListView.builder(
    controller: sc,
    itemCount: 50,
    itemBuilder: (BuildContext context, int i){
      return Container(
        padding: const EdgeInsets.all(12.0),
        child: Text("$i"),
      );
    },
  );
}

Using the PanelController 

At times, it can be useful to manually change the state of the SlidingUpPanel. This can be easily achieved by using a PanelController and attaching it to an instance of the SlidingUpPanel. Note that since the PanelController modifies the state of a SlidingUpPanel, these methods can only be called after the SlidingUpPanel has been rendered.

PanelController _pc = new PanelController();

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text("SlidingUpPanelExample"),
    ),
    body: SlidingUpPanel(
      controller: _pc,
      panel: Center(
        child: Text("This is the sliding Widget"),
      ),
      body: _body(),
    ),
  );
}

Widget _body(){
  return Container(
    child: Column(
      children: <Widget>[
        RaisedButton(
          child: Text("Open"),
          onPressed: () => _pc.open(),
        ),
        RaisedButton(
          child: Text("Close"),
          onPressed: () => _pc.close(),
        ),
        RaisedButton(
          child: Text("Show"),
          onPressed: () => _pc.show(),
        ),
        RaisedButton(
          child: Text("Hide"),
          onPressed: () => _pc.hide(),
        ),
      ],
    ),
  );
}

Breaking Changes 

v1.0.0 introduced some breaking changes to the PanelController to better adhere to Dart language conventions. The changes are outlined below.

The following PanelController methods now return Future<void> instead of void:

• close()
• open()
• hide()
• show()
• animatePanelToPosition(double value)

The following PanelController methods have changed to Dart properties to better reflect Dart language conventions:

• setPanelPosition() -> panelPosition [as a setter]
• getPanelPosition() -> panelPosition [as a getter]
• isPanelAnimating() -> isPanelAnimating
• isPanelOpen() -> isPanelOpen
• isPanelClosed() -> isPanelClosed
• isPanelShown() -> isPanelShown

For example, here’s how you would have previously used setPanelPosition() and getPanelPosition() vs. how you would now use the panelPosition property:

// OLD, no longer supported
print(pc.getPanelPosition()); // print a value between 0.0 and 1.0
pc.setPanelPosition(0.5);     // sets the panelPosition to 0.5

// NEW
print(pc.panelPosition); // print a value between 0.0 and 1.0
pc.panelPosition = 0.5;  // sets the panelPosition to 0.5

And here’s how you would have previously called isPanelAnimating() vs. how you would now call isPanelAnimating.

panelController.isPanelAnimating(); // OLD, no longer supported

panelController.isPanelAnimating; // NEW

GitHub

Source Code: sliding_up_pannel.