fis_lib_measure/lib/img_demo.dart

import 'dart:ui' as ui;
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:vid/us/vid_us_image_data.dart';

class ImageDemoPage extends StatefulWidget {
  const ImageDemoPage({Key? key}) : super(key: key);

  @override
  State<StatefulWidget> createState() => _ImageDemoPageState();
}

class _ImageDemoPageState extends State<ImageDemoPage> {
  /// -255~255,default:0
  int brightness = 0;

  /// -99~99,default:0
  int contrast = 0;

  ui.Image? image;

  @override
  void initState() {
    super.initState();
    _loadImg().then((value) {
      if (mounted) {
        setState(() {
          image = value;
        });
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Material(
      color: Colors.green,
      child: FutureBuilder(
        future: _loadImg(),
        builder: (_, snapshot) {
          if (snapshot.connectionState == ConnectionState.done &&
              snapshot.hasData) {
            final image = snapshot.data! as ui.Image;
            return Column(
              children: [
                RepaintBoundary(
                  child: CustomPaint(
                    size: ui.Size(
                      image.width.toDouble(),
                      image.height.toDouble(),
                    ),
                    painter: _MyPainter(
                      image,
                      brightness: brightness,
                      contrast: contrast,
                    ),
                  ),
                ),
                const SizedBox(height: 8),
                buildBrightnessController(),
                const SizedBox(height: 8),
                buildContrastController(),
              ],
            );
          }
          return const Center(
            child: CircularProgressIndicator(),
          );
        },
      ),
    );
  }

  Widget buildBrightnessController() {
    return Container(
      color: Colors.white,
      height: 50,
      width: 280,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.start,
        children: [
          IconButton(
            onPressed: () {
              if (brightness < -250) return;
              setState(() {
                brightness -= 10;
              });
            },
            icon: const Icon(Icons.remove),
          ),
          IconButton(
            onPressed: () {
              if (brightness > 250) return;
              setState(() {
                brightness += 10;
              });
            },
            icon: const Icon(Icons.add),
          ),
          const SizedBox(width: 10),
          Text("Brightness: $brightness [-255~255]"),
        ],
      ),
    );
  }

  Widget buildContrastController() {
    return Container(
      color: Colors.white,
      height: 50,
      width: 280,
      child: Row(
        mainAxisAlignment: MainAxisAlignment.start,
        children: [
          IconButton(
            onPressed: () {
              if (contrast < -90) return;
              setState(() {
                contrast -= 10;
              });
            },
            icon: const Icon(Icons.remove),
          ),
          IconButton(
            onPressed: () {
              if (contrast > 90) return;
              setState(() {
                contrast += 10;
              });
            },
            icon: const Icon(Icons.add),
          ),
          const SizedBox(width: 10),
          Text("Contrast: $contrast (-100~100)"),
        ],
      ),
    );
  }

  Future<ui.Image> _loadImg() async {
    return await _loadJpgImg();
    final byteData = await rootBundle.load('assets/default.VID');
    final bytes = byteData.buffer.asUint8List();
    final vidData = VidUsImageData(bytes);
    final frame = vidData.getImage(0);
    final img = await decodeImageFromList(frame.imageData);
    return img;
  }

  Future<ui.Image> _loadJpgImg() async {
    final byteData = await rootBundle.load('assets/test.jpg');
    final bytes = byteData.buffer.asUint8List();
    final img = await decodeImageFromList(bytes);
    return img;
  }

  double _calcConstract(int val, double contrast) {
    double pval = val / 255.0;
    pval -= 0.5;
    pval *= contrast;
    pval += 0.5;
    pval *= 255;
    if (pval < 0) pval = 0;
    if (pval > 255) pval = 255;
    return pval;
  }
}

class _MyPainter extends CustomPainter {
  _MyPainter(
    this.image, {
    this.brightness = 0,
    this.contrast = 0,
  });
  final ui.Image image;

  final int brightness;
  final int contrast;

  // ignore: prefer_final_fields
  ui.Paint _paint = ui.Paint()..isAntiAlias = true;

  @override
  void paint(ui.Canvas canvas, ui.Size size) {
    // https://blog.csdn.net/hnulwt/article/details/44755025

    // _paint.colorFilter = const ui.ColorFilter.matrix(<double>[
    //   1, 0, 0, 0, 220, //
    //   0, 1, 0, 0, 220, //
    //   0, 0, 1, 0, 220, //
    //   0, 0, 0, 1, 0, //
    // ]);
    // double lum = brightness.toDouble();
    double scale = 1.0;
    // if (contrast < 0) {
    //   scale = (100 - contrast) / 100.0;
    // } else if (contrast > 0) {
    //   scale = contrast / 100.0 * 2.5 + 1;
    // }

    // if (contrast < 50) {
    //   scale = contrast / 50.0;
    // } else if (contrast > 50) {
    //   scale = (contrast - 50) / 50.0 * 2.5 + 1;
    // }
    double lum = brightness.toDouble();

    double contrast = this.contrast.toDouble();
    if (contrast < -100) contrast = -100;
    if (contrast > 100) contrast = 100;
    contrast = (100.0 + contrast) / 100.0;
    contrast *= contrast;
    // print(contrast);
    print(lum);
    scale = contrast;
    // scale != 1.0 ? brightness * (1.0 - scale) : brightness.toDouble();
    // _paint.colorFilter = ui.ColorFilter.matrix(<double>[
    //   scale, 0, 0, 0, lum, // R
    //   0, scale, 0, 0, lum, // G
    //   0, 0, scale, 0, lum, // B
    //   0, 0, 0, 1, 0, // A
    // ]);
    _paint.colorFilter = ui.ColorFilter.mode(Colors.blue, BlendMode.darken);
    final centerW = size.width / 2;
    final centerH = size.height / 2;
    canvas.translate(centerW, centerH);
    final offset = ui.Offset(-centerW, -centerH);
    canvas.drawImage(image, offset, _paint);
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) => false;
}