addTextWatermarkUint8List method

@override Future<Uint8List?> addTextWatermarkUint8List(Uint8List filePath, String text, int x, int y, int textSize, int color, int? backgroundTextColor, int? backgroundTextPaddingTop, int? backgroundTextPaddingBottom, int? backgroundTextPaddingLeft, int? backgroundTextPaddingRight,)

Adds a text watermark to the image at the specified location with the given parameters.

Returns a Uint8List representing the watermarked image.

Implementation

@override
Future<Uint8List?> addTextWatermarkUint8List(
  Uint8List filePath,
  String text,
  int x,
  int y,
  int textSize,
  int color,
  int? backgroundTextColor,
  int? backgroundTextPaddingTop,
  int? backgroundTextPaddingBottom,
  int? backgroundTextPaddingLeft,
  int? backgroundTextPaddingRight,
) async {
  final ui.Image image = await decodeImageFromList(filePath);

  final recorder = ui.PictureRecorder();
  final canvas = Canvas(recorder);

  // Create a transparent background
  final bgPaint = Paint()..color = Colors.transparent;
  canvas.drawRect(
    Rect.fromLTWH(0, 0, image.width.toDouble(), image.height.toDouble()),
    bgPaint,
  );

  canvas.drawImage(image, Offset.zero, Paint());

  final textStyle = ui.TextStyle(
    color: Color(color),
    fontSize: textSize.toDouble(),
  );

  final paragraphBuilder = ui.ParagraphBuilder(ui.ParagraphStyle(
    textAlign: TextAlign.start,
    fontSize: textSize.toDouble(),
  ))
    ..pushStyle(textStyle)
    ..addText(
      text,
    );

  final paragraph = paragraphBuilder.build()
    ..layout(ui.ParagraphConstraints(width: image.width.toDouble()));

  if (backgroundTextColor != null) {
    final bgPaintText = Paint()..color = Color(backgroundTextColor);
    final backgroundRect = Rect.fromLTRB(
      x.toDouble() - (backgroundTextPaddingLeft ?? 0),
      y.toDouble() - (backgroundTextPaddingTop ?? 0),
      x + paragraph.width + (backgroundTextPaddingRight ?? 0),
      y + paragraph.height + (backgroundTextPaddingBottom ?? 0),
    );
    canvas.drawRect(backgroundRect, bgPaintText);
  }

  canvas.drawParagraph(
    paragraph,
    Offset(x.toDouble(), y.toDouble()),
  );

  final picture = recorder.endRecording();
  final img = await picture.toImage(image.width, image.height);
  final byteData = await img.toByteData(format: ui.ImageByteFormat.png);

  return byteData!.buffer.asUint8List();
}