이미지 색깔 변경

RGB가 아니라 RGBA(A:투명도)라서 i+4 해야함

import 'dart:typed_data';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

import 'package:image/image.dart' as Img;

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

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

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: const MyHomePage(),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      // body: Image.asset("assets/aaaa.png"),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            // BlendMode 위젯을 통해 이미지 변환 수행
            BlendMode(
              removeColorRGB: [255, 0, 0],
              addColorRGB: [33, 33, 33],
            ),
          ],
        ),
      ),
    );
  }
}

class BlendMode extends StatelessWidget {
  final List<int> removeColorRGB;
  final List<int> addColorRGB;

  const BlendMode({required this.removeColorRGB, required this.addColorRGB, super.key});

  static Future<Uint8List> changeBackgroundOfImage(
      {required Uint8List bytes, required List<int> removeColorRGB, required List<int> addColorRGB}) async {
    Img.Image? image = Img.decodeImage(bytes);
    Img.Image newImage = await _customeColor(src: image, removeColorRGB: removeColorRGB, addColorRGB: addColorRGB);
    var newPng = Img.encodePng(newImage);
    return newPng;
  }

  static Future<Img.Image> _customeColor({Img.Image? src, required List<int> removeColorRGB, required List<int> addColorRGB}) async {
    var pixels = src!.getBytes();

    for (int i = 0, len = pixels.length; i < len; i += 4) {
      if (pixels[i] == removeColorRGB[0] && pixels[i + 1] == removeColorRGB[1] && pixels[i + 2] == removeColorRGB[2]) {
        // if (pixels[i] == removeColorRGB[0] && pixels[i + 1] == removeColorRGB[1] && pixels[i + 2] == removeColorRGB[2] && pixels[i + 3] == 255) {
        pixels[i] = addColorRGB[0];
        pixels[i + 1] = addColorRGB[1];
        pixels[i + 2] = addColorRGB[2];
      }
    }

    return src;
  }

  convertImage() async {
    ByteData imageData1 = await rootBundle.load("assets/cccc.png");
    Uint8List bytes = imageData1.buffer.asUint8List();

    // Uint8List newbyte = await AppUtils.changeBackgroundOfImage(bytes: bytes, removeColorRGB: [0, 0, 0], addColorRGB: [66, 245, 120]);

    Uint8List newbyte = await changeBackgroundOfImage(bytes: bytes, removeColorRGB: removeColorRGB, addColorRGB: addColorRGB);

    return newbyte;
  }

  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: convertImage(),
      builder: (context, snapshot) {
        if (snapshot.connectionState == ConnectionState.done) {
          // 이미지 변환 결과를 Image.memory로 표시
          // return Image.memory(snapshot.data as Uint8List);

          if (snapshot.data != null) {
            return Image.memory(snapshot.data! as Uint8List);
          } else {
            // 데이터가 아직 로드되지 않은 경우에 대한 처리
            return CircularProgressIndicator();
          }
        } else {
          // 로딩 중이면 로딩 스피너 표시
          return CircularProgressIndicator();
        }
      },
    );
  }
}