scroll_texts_widget 0.1.1

Smooth horizontal marquee scrolling text ticker for Flutter. Supports streaming for long texts, cached rendering, and pause/progress controls.

scroll_texts_widget

A highly efficient and modular Flutter widget for creating scrolling marquee text banners.

Unlike standard marquee widgets that struggle with long strings, force full widget-tree rebuilds, or warp speeds due to device animation scales, scroll_texts_widget uses direct Canvas rendering via CustomPainter and a standalone Ticker to guarantee smooth, 60/120fps scrolling.

✨ Key Features

• 🪟 Dual Render Modes:
  • Cached Mode: Measures text once and clips on the GPU. Delivers 100% typographic fidelity (BiDi, complex scripts, kerning) with zero per-frame layout overhead.
  • Streaming Mode: Employs a sliding window algorithm that measures and renders only the words/chunks currently visible inside the viewport box. Retains strictly $O(\text{viewport})$ memory and eliminates UI freezes even with 50,000-word strings.
  • Auto Mode (Default): Automatically chooses the best mode based on string length.
• 🎮 Full Controller Support: Use ScrollTextsController to programmatically play, pause, toggle pause, read the exact pixel offset, inspect the active text index, or jump directly to any position or announcement in the list.
• ⏱️ Consistent Velocity (Pixels/Sec): Configured via scrollSpeed (px/s), guaranteeing uniform visual velocity regardless of text length.
• ⚙️ Platform-Independent Frame Timing: Uses a direct Ticker with microsecond delta-time tracking ($\Delta x = \text{speed} \times \Delta t$), making the scroll rate immune to OS animation scaling and ProMotion 120Hz refresh rates.
• 🌍 First-Class RTL Support: Full support for TextDirection.rtl (Arabic, Hebrew) adjusting layout and scrolling direction.
• 📏 Intrinsic Auto-Sizing: Measures font metrics upfront to match the exact text height, preventing layout overflow errors.

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💻 Usage

Basic Example

import 'package:flutter/material.dart';
import 'package:scroll_texts_widget/scroll_texts_widget.dart';

class MyMarqueeApp extends StatelessWidget {
  const MyMarqueeApp({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Marquee Demo')),
      body: Center(
        child: Container(
          padding: const EdgeInsets.symmetric(vertical: 8.0),
          color: Colors.blueGrey.shade100,
          child: ScrollTextsWidget(
            texts: const [
              'Welcome to the scroll_texts_widget package.',
              'This text will scroll at a consistent 75 pixels per second!',
            ],
            textStyle: const TextStyle(
              fontSize: 24.0,
              fontWeight: FontWeight.bold,
              color: Colors.deepPurple,
            ),
            scrollSpeed: 75.0,
            pauseDuration: const Duration(seconds: 1),
          ),
        ),
      ),
    );
  }
}

Advanced Example with Controller & Callbacks

final controller = ScrollTextsController(
  initialScrollOffset: 0.0,
  initialTextIndex: 0,
);

// Programmatic controls
controller.pause();
controller.resume();
controller.togglePause();
controller.jumpTo(150.0); // Jump to 150px in the current text
controller.jumpToText(2);  // Skip to 3rd announcement

ScrollTextsWidget(
  texts: myAnnouncements,
  controller: controller,
  renderMode: ScrollTextRenderMode.auto,
  scrollSpeed: 90.0,
  pauseDuration: const Duration(seconds: 2),
  textDirection: TextDirection.ltr,
  onScrollChanged: (offset, textIndex) {
    print('Scrolled to offset: $offset on text #$textIndex');
  },
  onTextCompleted: (completedIndex) {
    print('Completed text #$completedIndex');
  },
)

---

📖 API Reference

ScrollTextsWidget Properties

Property	Type	Default	Description
texts	List<String>	Required	The list of strings to cycle and scroll through.
controller	ScrollTextsController?	null	Optional controller for reading position and programmatic playback/seeking.
scrollSpeed	double	50.0	Velocity in pixels per second (px/s).
pauseDuration	Duration	Duration(seconds: 2)	Duration to pause after a text exits before the next text starts.
initialDelay	Duration	Duration.zero	Optional delay before the very first text begins scrolling.
repeat	bool	true	Whether to continuously loop through the text playlist.
renderMode	ScrollTextRenderMode	.auto	Rendering strategy: .auto, .cached, or .streaming.
textStyle	TextStyle	18px black	Font style applied to the scrolling text.
textDirection	TextDirection	TextDirection.ltr	Layout and scroll direction (.ltr scrolls left, .rtl scrolls right).
initialScrollOffset	double	0.0	Initial starting pixel offset for the active text.
initialTextIndex	int	0	Starting index in texts.
onScrollChanged	Function(double, int)?	null	Callback invoked as the scroll offset changes.
onTextCompleted	Function(int)?	null	Callback invoked when an active text finishes scrolling.

ScrollTextsController API

Member	Type	Description
offset	double (getter)	The current scroll offset in pixels.
maxScrollExtent	double (getter)	The total scroll distance for the active text.
progress	double (getter)	Normalized scroll progress from 0.0 to 1.0.
effectiveRenderMode	ScrollTextRenderMode (getter)	The active render mode engaged (cached or streaming), useful when auto is selected.
currentTextIndex	int (getter)	The index of the active text in the playlist.
isPaused	bool (getter)	Whether scrolling is currently paused.
pause()	void	Pauses the scrolling animation.
resume()	void	Resumes scrolling.
togglePause()	void	Toggles between paused and scrolling states.
jumpTo(double offset)	void	Instantly jumps the active text to the given pixel offset.
jumpToText(int textIndex, {double offset = 0.0})	void	Jumps to a specific text in texts at an optional starting offset.

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🛠️ Installation

Add the following to your pubspec.yaml file:

dependencies:
  scroll_texts_widget: ^0.1.0