📜 Curtains

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API References: Curtains | Sensitivity | 👥 package:shadows: 🕴 Elevation

Wrap a scrollable with scrim 📜 Curtains while not at the start or end, alluding to unrevealed content.

There has been a breaking change from 0.9.4+1 to 0.9.5, but it is quite easily fixed.
Package still in pre-release.

A few other small changes have been made that may require minor cleanup
if moving to this version from an older one.

0.10.0 (now)	⬅️	0.9.4+1 (before)	|	0.10.0 (now)	⬅️	0.9.4+1 (before)
Curtains		Curtains.regal	|	Sensitivity sensitivity		List<double> sensitivity
Curtains.instant		Curtains.fancy	|	TextDirection textDirection		TextDirection directionality
Curtains.elevated		Curtains	|	bool endInitVisible ⭐		bool endCurtainInitVisible

⭐ Also now available is bool startInitVisible.

Furthermore either startCurtain or endCurtain now accepts a more abstract Decoration?
as opposed to a restriction to BoxDecoration?.

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📚 Table of Contents

• 📜 Curtains
• 🧫 Examples
  • Elevated 📜 Curtains
  • Instant 📜 Curtains
  • Animated 📜 Curtains
• 📖 Reference
  • 🕴 Elevation
  • Any Decoration
• 🐞 Bugs
• 🐸 More by Zaba

🧫 Examples

See demonstrations of this Flutter package:

• 📜 Curtains Demo source: /example/lib/main.dart
• 📜 Curtains Demo APK

Elevated 📜 Curtains

In lieu of Decorations, provide a simple number-based elevation. Optionally provide a color or specify duration.

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
);

It's that easy!

✝ 👥 Shadows - See: Elevation.asBoxShadows

Instant 📜 Curtains

Special Curtains that offer no animation support.
No AnimationControllers were hurt in the making of this widget.

final curtains = Curtains.instant(
  /// 🕴 Default constructor 📜 [Curtains] employs `Elevation.asBoxDecoration` to
  /// render its decorations; but feel free to use these static methods, too,
  /// if you opt 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}')),
    ),
  ),
);

It's similarly easy!

Animated 📜 Curtains

Each curtain may be customized independently. The spread parameter provides "girth," either width or height depending on axis, to allow the application of Decoration images, gradients, and fills.

Without spread, the only truly valid form of scrim curtain is the List<BoxShadow> from BoxDecoration, ShapeDecoration, etc.

	This instance of 📜 Curtains has custom, animated BoxDecorations as well as sensitivity at the start and end.

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),
  ],
);

final curtains = Curtains(
  startCurtain: buildCurtain(),
  endCurtain: buildCurtain(isStart: false),
  // Provide `spread` to [Curtains] for decoration support beyond [BoxShadow]s.
  // (Gives "girth" to individual curtains; otherwise `0`.)
  spread: 50.0,
  // `start` appears once scrolled `350` px beyond min extent
  // `end` appears once scrolled `175` px beyond (before) max extent
  sensitivity: const Sensitivity.only(start: 350.0, end: 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}')),
    ),
  ),
);

But look here, and we can get pretty complex and creative.

Notice the spread initialization for gradient support.

📖 Reference

Peruse the 📜 Curtains pub.dev documention for a full breakdown.

• This is simple package to use, but it is also a package that was easy to implement.
  • It is, however, overly documented so that any beginners may learn from its code.
  • Utilizes a simple NotificationListener in lieu of ScrollController, which were both elusive when starting Flutter.

🕴 Elevation

The Elevation paradigm is handled by 👥 package:shadows

• Check it out for some neat BoxShadow utilities that mesh with 📜 Curtains.

Any Decoration

	Maybe supplying a DecorationImage is what you need?
	Or consider something with a shape by using a ShapeDecoration for the curtain decoration field.

🐞 Bugs

One known bug:

1. Even with Curtains.spread set non-negligibly, BoxDecoration.backgroundBlendMode does not work correctly.

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🐸 Zaba.app ― simple packages, simple names.

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