Flutter Watermark Plus

A Flutter package that provides watermark functionality for images and widgets with customizable properties.

Features

  • Cross-platform support: Works on both Android and iOS
  • Widget-based watermarks: Add watermarks to any Flutter widget
  • Image-based watermarks: Apply watermarks directly to images
  • Customizable properties: Text style, rotation, opacity, positioning, and spacing
  • Consistent behavior: Shared drawing logic ensures consistent results across different use cases

Architecture

The package has been refactored to eliminate code duplication and improve maintainability:

Core Components

  • Config: Configuration class for watermark properties
  • TextWatermarkWidget: Widget for adding watermarks to Flutter widgets
  • CanvasWatermarkEngine: Engine for applying watermarks to images
  • WatermarkPainterUtil: Shared utility for drawing watermark patterns
  • WatermarkProcessor: High-level processor for image watermark operations

Code Refactoring Benefits

  1. Eliminated Duplication: The watermark drawing logic was duplicated between watermark_widget.dart and canvas_watermark_engine.dart. Now both use the shared WatermarkPainterUtil.

  2. Consistent Behavior: Both widget-based and image-based watermarks now use the same drawing logic, ensuring consistent results.

  3. Better Maintainability: Changes to watermark drawing logic only need to be made in one place.

  4. Clear Separation: Each component has a single responsibility:

    • Config: Configuration management
    • TextWatermarkWidget: Widget rendering
    • CanvasWatermarkEngine: Image processing
    • WatermarkPainterUtil: Drawing logic
    • WatermarkProcessor: High-level operations

Configuration Options

  • textStyle: Text appearance (color, font size, weight, etc.)
  • rotationAngle: Rotation in radians
  • horizontalInterval: Horizontal spacing between watermarks
  • verticalInterval: Vertical spacing between watermarks
  • offset: Position offset from top-left corner
  • backgroundColor: Background color of watermark area
  • textAlign: Text alignment
  • textDirection: Text direction (LTR/RTL)
  • locale: Locale for text rendering

Examples

See the example/ folder for complete demonstrations:

  • flutter_watermark_plus_example.dart: Widget-based watermark examples
  • watermark_processor_example.dart: Image processing watermark examples

Libraries

flutter_watermark_plus