custom_interactive_viewer 0.0.6

A highly customizable alternative for Flutter's InteractiveViewer with advanced keyboard navigation, gesture controls, rotation support, and programmatic transformations.

Custom Interactive Viewer

A highly customizable replacement for Flutter's InteractiveViewer with advanced features including keyboard navigation, custom transformations, and more flexible gesture controls.

Features

• Enhanced Zooming - Zoom with gestures, keyboard controls, or programmatically with animations
• Precise Panning - Pan content with touch, mouse, or keyboard arrow keys
• Optional Rotation - Enable rotation with multi-touch gestures
• Keyboard Navigation - Built-in keyboard controls with customizable key repeat
• Programmable Controls - Full API for controlling the view programmatically
• Bounds Constraints - Optional content constraints to keep content within viewport
• Custom Animation - Animate transformations with customizable durations and curves
• Focal Point Zooming - Zoom to a specific point with proper focal point preservation
• Double Tap Support - Optional double-tap to zoom feature
• Ctrl+Scroll Zooming - Desktop-friendly zoom with keyboard modifier keys
• Region Targeting - Zoom to specific regions of content

Getting Started

Add the package to your pubspec.yaml file:

dependencies:
  custom_interactive_viewer: ^1.0.0

Then import it in your Dart code:

import 'package:custom_interactive_viewer/custom_interactive_viewer.dart';

Usage

Basic Usage

// Create a controller
final controller = CustomInteractiveViewerController();

// Use the widget
CustomInteractiveViewer(
  controller: controller,
  child: Image.asset('assets/image.jpg'),
);

With Content Size and Constraints

CustomInteractiveViewer(
  controller: controller,
  contentSize: const Size(1000, 800),
  constrainBounds: true,
  minScale: 0.5,
  maxScale: 4.0,
  child: Image.asset('assets/map.jpg'),
);

Programmatic Control

// Zoom in to a point
controller.zoomIn(
  factor: 1.5,
  focalPoint: Offset(100, 100),
);

// Fit content to screen
controller.fitToScreen(
  contentSize, 
  viewportSize,
  animate: true,
);

// Reset to initial state
controller.reset();

Package Structure

This package is designed with a clean architecture for maximum maintainability:

lib/
├── custom_interactive_viewer.dart  # Main entry point that exports public API
└── src/
    ├── widget.dart                 # Main widget implementation
    ├── controller.dart             # Controller implementation
    ├── controller/
    │   └── interactive_controller.dart  # Enhanced controller implementation
    ├── handlers/
    │   ├── gesture_handler.dart    # Touch/pointer interaction logic
    │   └── keyboard_handler.dart   # Keyboard interaction logic
    └── models/
        └── transformation_state.dart  # Transformation data model

Core Components

• CustomInteractiveViewer (widget.dart) - The main widget that orchestrates all components
• CustomInteractiveViewerController (controller.dart) - Manages view state and provides API

Models

• TransformationState - An immutable class encapsulating transformation properties:
  • Scale factor
  • Offset (translation)
  • Rotation angle
  • Utility methods for coordinate conversion and constraints

Handlers

• KeyboardHandler - Manages all keyboard interactions:

  • Arrow keys for panning
  • +/- keys for zooming
  • Key repeat logic for continuous movement
  • Home key for reset functionality

• GestureHandler - Handles touch and pointer interactions:

  • Pinch to zoom
  • Drag to pan
  • Double tap to zoom
  • Rotation gestures
  • Ctrl+scroll for desktop zooming

Advanced Configuration

The widget offers extensive configuration options:

CustomInteractiveViewer(
  controller: controller,
  contentSize: contentSize,
  minScale: 0.5,
  maxScale: 4.0,
  enableRotation: true,
  constrainBounds: true,
  enableDoubleTapZoom: true,
  doubleTapZoomFactor: 2.0,
  enableKeyboardControls: true,
  keyboardPanDistance: 20.0,
  keyboardZoomFactor: 1.1,
  enableKeyRepeat: true,
  keyRepeatInitialDelay: const Duration(milliseconds: 500),
  keyRepeatInterval: const Duration(milliseconds: 50),
  enableCtrlScrollToScale: true,
  child: yourWidget,
);

Version Information

This is the first release (0.0.1) of the Custom Interactive Viewer package. The package provides a solid foundation of features while maintaining good performance and a clean API.

Contributing

If you find any issues or have suggestions for improvements, please file an issue or submit a pull request.