Guides

Add Text Watermark

ComPDFKit supports two ways to add text watermarks:

API

Use document.createWatermark to create a text watermark. This method is suitable for scenarios where watermarks need to be generated automatically in code.

late CPDFReaderWidgetController _controller;

@override
Widget build(BuildContext context) {
  return Scaffold(
    resizeToAvoidBottomInset: false,
    appBar: AppBar(),
    body: Column(children: [
      TextButton(onPressed: () async{
        await _controller.document.createWatermark(CPDFWatermark.text(
          textContent: 'ComPDFKit',
          scale: 1.0,
          fontSize: 60,
          rotation: 0,
          horizontalAlignment: CPDFWatermarkHorizontalAlignment.center,
          verticalAlignment: CPDFWatermarkVerticalAlignment.center,
          textColor: Colors.red,
          pages: [0, 1, 2, 3]));
      }, child: const Text('Add Text Watermark')),
      Expanded(child: CPDFReaderWidget(
        document: widget.documentPath,
        configuration: CPDFConfiguration(),
        onCreated: (controller) {
          setState(() {
            _controller = controller;
          });
        },
      ))
    ],));
}

UI Popup Approach

• Configure default watermark properties in CPDFConfiguration, such as default text, color, font size.
• Call controller.showAddWatermarkView() to open the interactive watermark popup.

// Set default text watermark in configuration
final configuration = CPDFConfiguration(
  globalConfig: const CPDFGlobalConfig(
    watermark: CPDFWatermarkConfig(
      text: 'ComPDFKit-Flutter',
      textColor: Colors.red,
      textSize: 36,
      opacity: 120,
      rotation: -45
    )
  )
);

// Open watermark popup
controller.showAddWatermarkView(
  config: CPDFGlobalConfig(
    watermark: CPDFWatermarkConfig(
      text: 'ComPDFKit-Flutter',
      textColor: Colors.red,
      textSize: 36,
      opacity: 120,
      rotation: -45
    )
  )
);