Watermark center shift

[SpirikleOfficial]

Issue
Using the defined PositionTypes, I used PositionType.Center and angle was pi/2. However, Instead of showing vertical text in the center, the text is shifted to right.

Use the following params in the example folder of this package:

double opacity = 50.0;
Color color = Colors.black;
double size = 100.0;
double angle = pi / 2;
PositionType position = PositionType.center;

final params = PDFWatermarkParams(
    pdfPath: pdfPath!,
    text: watermarkText!,
    positionType: position,
    fontSize: size,
    opacity: opacity,
    watermarkColor: color,
    rotationAngle: angle,
  );

Expected behavior
The text is expected to be in the center of the pdf.

Screenshots
screenshots are attached.

Smartphone:

• Device: POCO F4
• Android Version 13

Flutter Doctor

flutter doctor -v
[√] Flutter (Channel stable, 3.13.7, on Microsoft Windows [Version 10.0.22621.2715], locale en-CA)
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[√] Windows Version (Installed version of Windows is version 10 or higher)

[√] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
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[√] Connected device (4 available)
    • 22021211RI (mobile) • 15693259 • android-arm64  • Android 13 (API 33)
    • Windows (desktop)   • windows  • windows-x64    • Microsoft Windows [Version 10.0.22621.2715]
    • Chrome (web)        • chrome   • web-javascript • Google Chrome 119.0.6045.200
    • Edge (web)          • edge     • web-javascript • Microsoft Edge 119.0.2151.97

[√] Network resources
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• No issues found!

How can I solve this?