Curtains class

📜 Curtains

images of curtains as 📜 Curtains Wraps a scrollable child with scrim decorations while not at the start or end, alluding to unrevealed content.

Choose animated Curtains or Curtains.instant to provide custom
Decorations, or select Curtains.elevated for a simpler syntax
with double elevation instead of individual Decorations.

With non-negative Sensitivity, the scrims of this 📜 Curtains
will change state before the scrollable reaches a min/max extent.

  • sensitivity.start defines startCurtain tolerance to min extent.
  • sensitivity.end defines endCurtain tolerance to max extent.

Before any scrolling occurs endCurtain initializes visible, even if
the 📜 Curtains wrap a scrollable not long enough to scroll.

{@tool snippet}

Elevated 📜 Curtains

Provide a scrolling child.
Specify scrim shadows by double elevation property.

  • Default elevation is 9.0
  • color may be overridden, but the Material-defined opacity is maintained

Initialize scrollDirection to match scrollable child:

✝ See: Elevation.asBoxShadows

final curtains = Curtains.elevated(
  child: ListView(
    children: List.generate(
      25,
      (i) => ListTile(title: Text('ListTile #: ${i+1}')),
    ),
  ),
  elevation: 24.0 // optional, defaults to `9.0`
  // Optional color; will maintain Material elevation opacities.✝
  color: Colors.red
);

{@end-tool}

{@tool snippet}

Instant 📜 Curtains

All the ease of positioning provided by the Curtains.elevated constructor,
but swap out the bespoke elevation double and provide one or both of
full-fat Decorations startCurtain and endCurtain.

Leaving a Curtain parameter null will render an empty decoration in that position.

Optionally define Curtains.spread for "girthier" scrims,
allowing, for example, BoxDecoration.gradient passes.

final curtains = Curtains.instant(
  /// 🕴 Named constructor 📜 [Curtains.elevated] employs
  /// `Elevation.asBoxDecoration` to render its decorations; but feel free
  /// to use these static methods, too, opting for 👥 [package:shadows].
  startCurtain: const BoxDecoration(. . .) // Elevation.asBoxDecoration(12.0), // 🕴
  endCurtain: BoxDecoration(boxShadow: Elevation.asBoxShadows(12.0)), // 🕴
  child: ListView(
    children: List.generate(
      25,
      (i) => ListTile(title: Text('ListTile #${i+1}')),
    ),
  ),
);

{@end-tool}

{@tool snippet}

Animated 📜 Curtains

All the ease of positioning provided by the Curtains.elevated constructor,
and the customization support of Curtains.instant, but animations support
means these 📜 Curtains intrinsically morph with a duration and/or curve; or leave it up to the defaults.

final curtains = Curtains(
  startCurtain: buildCurtain(),
  endCurtain: buildCurtain(isStart: false),
  // Provide `spread` to [Curtains] for decoration support beyond [BoxShadow]s.
  // (Gives "girth" to individual [_Curtain] containers; otherwise `0`.)
  spread: 50.0,
  // `start` appears once scrolled `350` px beyond start
  // `end` appears once scrolled `175` px beyond end
  sensitivity: const Sensitivity(350.0, 175.0),
  // 📜 Curtains are animated:
  duration: const Duration(milliseconds: 600),
  curve: Curves.fastOutSlowIn,
  // ↔ If wrapping a horizontal scrollable, initialize here, too:
  scrollDirection: Axis.horizontal, // ↔
  child: ListView(
    scrollDirection: Axis.horizontal, // ↔
    itemExtent: 100.0,
    children: List.generate(
      25,
      (i) => ListTile(title: Text('ListTile #${i+1}')),
    ),
  ),
);

BoxDecoration buildCurtain({bool isStart = true}) => BoxDecoration(
  gradient: LinearGradient(
    colors: [Colors.green[400]!, Colors.green[400]!.withOpacity(0)],
    begin: (isStart) ? Alignment.centerLeft : Alignment.centerRight,
    end: (isStart) ? Alignment.centerRight : Alignment.centerLeft,
  ),
  boxShadow: const [
    BoxShadow(color: Color(0x22FF0000), spreadRadius: 0.0, blurRadius: 5.0),
    BoxShadow(color: Color(0x66FF0000), spreadRadius: 10.0, blurRadius: 30.0),
    BoxShadow(color: Color(0x22FF0000), spreadRadius: 60.0, blurRadius: 150.0),
  ],
);

{@end-tool}

Inheritance

Constructors

Curtains({Key? key, Axis scrollDirection = Axis.vertical, Decoration? startCurtain, Decoration? endCurtain, double spread = 0.0, Sensitivity sensitivity = Sensitivity.none, bool startInitVisible = false, bool endInitVisible = true, AlignmentGeometry? alignment, TextDirection? textDirection, Clip clipBehavior = Clip.hardEdge, required Widget child, Duration? duration = _350ms, Curve? curve = Curves.easeOut})
images of curtains as 📜 Curtains Wraps a scrollable child with scrim decorations while not at the start or end, alluding to unrevealed content.
const
Curtains.drawn({Key? key, Axis? axis = Axis.vertical, Decoration? startCurtain, Decoration? endCurtain, double spread = 0.0, Sensitivity sensitivity = Sensitivity.none, bool isStartVisible = true, bool isEndVisible = true, AlignmentGeometry? alignment, TextDirection? textDirection, Clip clipBehavior = Clip.hardEdge, Widget? child, Duration? duration = _350ms, Curve? curve = Curves.easeOut})
These Curtains behave a little differently.
Instead of toggling visibility based on the scrollable child's extent, the startCurtain and endCurtain are static.
const
Curtains.elevated({Key? key, Axis scrollDirection = Axis.vertical, double? elevation = 9.0, Color? color, Sensitivity sensitivity = Sensitivity.none, bool startInitVisible = false, bool endInitVisible = true, AlignmentGeometry? alignment, TextDirection? textDirection, Clip clipBehavior = Clip.hardEdge, required Widget child, Duration? duration = _350ms, Curve? curve = Curves.easeOut})
Wraps a scrollable child with scrim shadows while
not at the start or end, alluding to unrevealed content.
const
Curtains.instant({Key? key, Axis scrollDirection = Axis.vertical, Decoration? startCurtain, Decoration? endCurtain, double spread = 0.0, Sensitivity sensitivity = Sensitivity.none, bool startInitVisible = false, bool endInitVisible = true, AlignmentGeometry? alignment, TextDirection? textDirection, Clip clipBehavior = Clip.hardEdge, required Widget child})
images of curtains as 📜 Curtains Wraps a scrollable child with scrim decorations while not at the start or end, alluding to unrevealed content.
const

Properties

alignment → AlignmentGeometry?
Override the alignment of the child within the Stack that houses it and these 📜 Curtains.
final
child → Widget
The scrollable child of this 📜 Curtains.
final
clipBehavior → Clip
By default this 📜 Curtains is ClipRect-ed for easy BoxShadow support.
final
color → Color?
When using elevation to style this 📜 Curtains, a color may be provided to stylize the Material elevation-like shadows.
final
curve → Curve?
When drawing 📜 Curtains, state changes are intrinsically animated over this curve.
final
duration → Duration?
When drawing 📜 Curtains, state changes are intrinsically animated over this duration.
final
elevation → double?
Recreation of Material.elevation utilizing Flutter's native Map<int, List<BoxShadow> kElevationToShadow.
final
endCurtain → Decoration?
The Decoration to display at the end of the scrollable child when there is content beyond/underneath it. (When the end of the scrollable has not been reached.)
final
endInitVisible → bool
This 📜 Curtains controls its visibility by ScrollUpdateNotifications. Override initialization visibility of this curtain with this bool.
final
hashCode → int
The hash code for this object.
no setterinherited
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
scrollDirection → Axis
Match scrollDirection to the scrolling direction of child.
final
sensitivity → Sensitivity
With non-negative Sensitivity, the scrims of this 📜 Curtains will change state before the scrollable reaches a min/max extent.
final
spread → double
For scenarios where startCurtain or endCurtain necessitate curtains with girth ― either height or width, considering axis.
final
startCurtain → Decoration?
The Decoration to display at the start of the scrollable child when there is content behind/underneath it. (When the start of the scrollable has been scrolled away from.)
final
startInitVisible → bool
This 📜 Curtains controls its visibility by ScrollUpdateNotifications. Override initialization visibility of this curtain with this bool.
final
textDirection → TextDirection?
The local TextDirection. If left null, the ambient Directionality.of(context) is obtained.
final

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → _CurtainsState
Creates the mutable state for this widget at a given location in the tree.
override
debugDescribeChildren() → List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String
A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a one-line detailed description of the object.
inherited
toStringShort() → String
A short, textual description of this widget.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited