Flutter Uint8List从Painter的Png解码为Image.memory

分类：编程问答

如何解决Flutter Uint8List从Painter的Png解码为Image.memory

我用热敏打印机打印功能创建了一个Painter，但是我无法将字节Uint8List解码回Png，我可以将Paint File作为String（Uint8List-Bytes）打印，但我想先绘制并打印它。我该如何打印我的油漆设计到热敏打印机？ 谢谢大家！

import 'dart:ui';
import 'package:esc_pos_utils/esc_pos_utils.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:painter2/painter2.dart';
import 'dart:typed_data';
import 'package:flutter_colorpicker/flutter_colorpicker.dart';
import 'esc_pos_printer.dart';

void KagidaYaz() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Painter2 Example',home: ExamplePage(),);
  }
}

class ExamplePage extends StatefulWidget {
  @override
  _ExamplePageState createState() =>  _ExamplePageState();
}


class _ExamplePageState extends State<ExamplePage> {
  bool _finished;
  PainterController _controller;
   String bytes2;


  @override
  void initState() {
    super.initState();
    _finished = false;
    _controller = newController();
    final PrinterNetworkManager printerManager = PrinterNetworkManager();
    // To discover network printers in your subnet,consider using
    // ping_discover_network package (https://pub.dev/packages/ping_discover_network).
    // Note that most of ESC/POS printers are available on port 9100 by default.
    printerManager.selectPrinter('192.168.178.10',port: 9100);
    
  }

  PainterController newController() {
    PainterController controller = PainterController();
    controller.thickness = 2.0;
    controller.backgroundColor = Colors.white;
    //controller.backgroundImage = Image.network(
      //  'https://cdn-images-1.medium.com/max/1200/1*5-aoK8IBmXve5whBQM90GA.png');
    return controller;
  }

  @override
  Widget build(BuildContext context) {


    List<Widget> actions;
    if (_finished) {
      actions = <Widget>[
        IconButton(
          icon: Icon(Icons.content_copy),tooltip: 'New Painting',onPressed: () => setState(() {
            _finished = false;
            _controller = newController();
          }),),];
    } else {
      actions = <Widget>[
        IconButton(
          icon: Icon(Icons.undo),tooltip: 'Undo',onPressed: () {
            if (_controller.canUndo) _controller.undo();
          },IconButton(
          icon: Icon(Icons.redo),tooltip: 'Redo',onPressed: () {
            if (_controller.canRedo) _controller.redo();
          },IconButton(
          icon: Icon(Icons.delete),tooltip: 'Clear',onPressed: () => _controller.clear(),IconButton(
            icon: Icon(Icons.check),onPressed: () async {
              setState(() {
                _finished = true;
              });

               Uint8List bytes = await _controller.exportAsPNGBytes();
               bytes2 = bytes.toString();




              ipDeneme2(this.bytes2);

              Navigator.of(context)
                  .push(MaterialPageRoute(builder: (BuildContext context) {
                return Scaffold(
                  appBar: AppBar(
                    title: Text('Siparisi Gör'),body: Container(
                    child: Image.memory(bytes),);
                  }));




            }),];
    }
    return Scaffold(
      appBar: AppBar(
          title: Text('Painter2 Example'),actions: actions,bottom: PreferredSize(
            child: DrawBar(_controller),preferredSize: Size(MediaQuery.of(context).size.width,30.0),)),body: Center(
          child: AspectRatio(aspectRatio: 1.0,child: Painter(_controller))),);
  }
}

class DrawBar extends StatelessWidget {
  final PainterController _controller;

  DrawBar(this._controller);

  @override
  Widget build(BuildContext context) {
    return Row(
      mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[
        Flexible(child: StatefulBuilder(
            builder: (BuildContext context,StateSetter setState) {
              return Container(
                  child: Slider(
                    value: _controller.thickness,onChanged: (value) => setState(() {
                      _controller.thickness = value;
                    }),min: 1.0,max: 20.0,activeColor: Colors.white,));
            })),ColorPickerButton(_controller,false),true),],);
  }
}

class ColorPickerButton extends StatefulWidget {
  final PainterController _controller;
  final bool _background;

  ColorPickerButton(this._controller,this._background);

  @override
  _ColorPickerButtonState createState() => new _ColorPickerButtonState();
}

class _ColorPickerButtonState extends State<ColorPickerButton> {
  @override
  Widget build(BuildContext context) {
    return IconButton(
      icon: Icon(_iconData,color: _color),tooltip:
      widget._background ? 'Change background color' : 'Change draw color',onPressed: () => _pickColor(),);
  }

  void _pickColor() {
    Color pickerColor = _color;
    Navigator.of(context)
        .push(MaterialPageRoute(
        fullscreenDialog: true,builder: (BuildContext context) {
          return Scaffold(
              appBar: AppBar(
                title: Text('Pick color'),body: Container(
                  alignment: Alignment.center,child: ColorPicker(
                    pickerColor: pickerColor,onColorChanged: (Color c) => pickerColor = c,)));
        }))
        .then((_) {
      setState(() {
        _color = pickerColor;
      });
    });
  }

  Color get _color => widget._background
      ? widget._controller.backgroundColor
      : widget._controller.drawColor;

  IconData get _iconData =>
      widget._background ? Icons.format_color_fill : Icons.brush;

  set _color(Color color) {
    if (widget._background) {
      widget._controller.backgroundColor = color;
    } else {
      widget._controller.drawColor = color;
    }
  }
}


  void ipDeneme2(String bytes2) async {
  final PrinterNetworkManager printerManager = PrinterNetworkManager();
  // To discover network printers in your subnet,consider using
  // ping_discover_network package (https://pub.dev/packages/ping_discover_network).
  // Note that most of ESC/POS printers are available on port 9100 by default.
  printerManager.selectPrinter('192.168.178.10',port: 9100);

  final PosPrintResult res =
  await printerManager.printTicket(await testTicket2(bytes2));
  print('Print result: ${res.msg}');
}

Future<Ticket> testTicket2(String bytes2) async {
  final profile = await CapabilityProfile.load();
  final Ticket ticket = Ticket(PaperSize.mm80,profile);
  //ticket.text("Arda Restaurant");

  List<int> list = bytes2.codeUnits;
  Uint8List bytes = Uint8List.fromList(list);

  print(bytes);

  //ticket.textEncoded(bytes);


  //print(bytes);
  //ticket.feed(10);
  //ticket.cut();
  return ticket;

}

我的Logcat输出为; 

Launching lib/main.dart on SM N960F in debug mode...
Running Gradle task 'assembleDebug'...
✓ Built build/app/outputs/flutter-apk/app-debug.apk.
Installing build/app/outputs/flutter-apk/app.apk...                23,4s
Waiting for SM N960F to report its views...
I/Choreographer(17344): Skipped 32 frames!  The application may be doing too much work on its main thread.
D/ViewRootImpl@969bd53[MainActivity](17344): Relayout returned: old=(0,720,1480) new=(0,1480) req=(720,1480)0 dur=18 res=0x1 s={true 532228255744} ch=false
D/ViewRootImpl@969bd53[MainActivity](17344): MSG_WINDOW_FOCUS_CHANGED 1 1
D/InputMethodManager(17344): prepareNavigationBarInfo() DecorView@dbb0cb7[MainActivity]
D/InputMethodManager(17344): getNavigationBarColor() -855310
D/InputMethodManager(17344): prepareNavigationBarInfo() DecorView@dbb0cb7[MainActivity]
D/InputMethodManager(17344): getNavigationBarColor() -855310
V/InputMethodManager(17344): Starting input: tba=com.kksio.kksitprobonsystem ic=null mNaviBarColor -855310 mIsGetNaviBarColorSuccess true,NavVisible : true,NavTrans : false
D/InputMethodManager(17344): startInputInner - Id : 0
I/InputMethodManager(17344): startInputInner - mService.startInputOrWindowGainedFocus
D/ViewRootImpl@969bd53[MainActivity](17344): MSG_RESIZED: frame=(0,1480) ci=(0,42,84) vi=(0,84) or=1
D/InputMethodManager(17344): prepareNavigationBarInfo() DecorView@dbb0cb7[MainActivity]
D/InputMethodManager(17344): getNavigationBarColor() -855310
V/InputMethodManager(17344): Starting input: tba=com.kksio.kksitprobonsystem ic=null mNaviBarColor -855310 mIsGetNaviBarColorSuccess true,NavTrans : false
D/InputMethodManager(17344): startInputInner - Id : 0
Debug service listening on ws://127.0.0.1:62630/hOGuYMeLYUo=/ws
Syncing files to device SM N960F...
D/ViewRootImpl@969bd53[MainActivity](17344): ViewPostIme pointer 0
D/ViewRootImpl@969bd53[MainActivity](17344): ViewPostIme pointer 1
D/ViewRootImpl@969bd53[MainActivity](17344): ViewPostIme pointer 0
D/ViewRootImpl@969bd53[MainActivity](17344): ViewPostIme pointer 1
D/ViewRootImpl@969bd53[MainActivity](17344): ViewPostIme pointer 0
D/ViewRootImpl@969bd53[MainActivity](17344): ViewPostIme pointer 1
I/flutter (17344): [91,49,51,55,44,32,56,48,50,54,53,52,53
I/flutter (17344): Print result: Success
D/InputMethodManager(17344): prepareNavigationBarInfo() DecorView@dbb0cb7[MainActivity]
D/InputMethodManager(17344): getNavigationBarColor() -855310

我尝试了所有事情，但是如果我将其添加到Flutter Image Package中，然后又遇到其他问题，则为所有解决方案加油！

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