PdfPreview renders inaccurate colors on Android

[malo-leon-adeo]

Describe the bug
The colors don't seem to be correct when applying transparency to colors on Android in the previewPdf. Here's an example you can easily reproduce. When there's no transparency, the color displayed on the web and on Android are the same; however, as soon as transparency is applied, it differs on Android. Note that the color is correct when opening the PDF in the native PDF viewer on Android. The bug only appears in the PDF preview.

To Reproduce
Code snippet to reproduce the behavior:

import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:printing/printing.dart';
import 'package:syncfusion_flutter_pdf/pdf.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: PdfPreview(build: (format) => _generatePdf()),
    );
  }

  Future<Uint8List> _generatePdf() async {
    final document = PdfDocument();

    // Global page settings
    document.pageSettings.size = PdfPageSize.a4; // 595
    document.pageSettings.setMargins(28.8, 28.8, 25.9, 28.8);
    document.fileStructure.incrementalUpdate = false;

    // Add first page
    document.pages.add();

    final graphics = document.pages[0].graphics;
    final state = graphics.save();

    graphics.setTransparency(0.5, alphaBrush: 0.5, mode: PdfBlendMode.darken);
    graphics.drawString(
        'Hello World !', PdfStandardFont(PdfFontFamily.helvetica, 50),
        brush: PdfSolidBrush(PdfColor(60, 165, 85)),
        bounds: const Rect.fromLTWH(10, 10, 300, 500));
    graphics.restore(state);

    final saved = document.saveSync();
    document.dispose();
    return Uint8List.fromList(saved);
  }
}

Expected behavior
I expect the pdfPreview to display the same colors on Android as on other platforms when applying transparency.

Screenshots
Android result using printing:

Web result using printing:

Android native viewer result:

Flutter Doctor
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.16.9, on macOS 14.2.1 23C71
darwin-arm64, locale fr-FR)
[✓] Android toolchain - develop for Android devices (Android SDK
version 34.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 15.0)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2023.1)
[✓] IntelliJ IDEA Ultimate Edition (version 2023.3.5)
[✓] VS Code (version 1.87.2)
[✓] Connected device (4 available)
! Error: Browsing on the local area network for iPad de
Hugo. Ensure the device is unlocked and attached with a
cable or associated with the same local area network as
this Mac.
The device must be opted into Developer Mode to connect
wirelessly. (code -27)
[✓] Network resources

• No issues found!

Desktop (please complete the following information):

• iOS
• [X ] Android
• Browser
• Windows
• Linux

Smartphone (please complete the following information):

• Device: sdk_gphone64_arm64
• OS: Android 14