flutter中的签名

flutter中的签名

Signature Class

需要修改以响应

VerticalDrag

，我将其重命名为

Signature1

现在签名区域键盘不应该滚动，您可以按照其行为检查下面的完整代码。您会发现Signature区域不再用滚动

SingleChildScrollView

。

import 'package:flutter/material.dart';import 'package:flutter/rendering.dart';import 'dart:async';import 'dart:ui' as ui;void main() => runApp(MyApp());class MyApp extends StatelessWidget {  // This widget is the root of your application.  @override  Widget build(BuildContext context) {    return MaterialApp(      title: 'Flutter Demo',      theme: ThemeData(        primarySwatch: Colors.blue,      ),      home: MyHomePage(title: 'Flutter Demo Home Page'),    );  }}class MyHomePage extends StatefulWidget {  MyHomePage({Key key, this.title}) : super(key: key);  final String title;  @override  _MyHomePageState createState() => _MyHomePageState();}class _MyHomePageState extends State<MyHomePage> {  var color = Colors.black;  var strokeWidth = 3.0;  final _sign = GlobalKey<Signature1State>();  @override  Widget build(BuildContext context) {    return Scaffold(      appBar: AppBar(        title: Text(widget.title),      ),      body:SingleChildScrollView(  child: Column(    children: <Widget>[      _showCategory(),      SizedBox(height: 15),      _showCategory(),      SizedBox(height: 15),      _showCategory(),      SizedBox(height: 15),      _showCategory(),      SizedBox(height: 15),      _showCategory(),      _showCategory(),      SizedBox(height: 15),      _showCategory(),      SizedBox(height: 15),      _showCategory(),      SizedBox(height: 15),      _showCategory(),      SizedBox(height: 15),      _showCategory(),      _showSignaturePad()    ],  ),)      ,    );  }  Widget _showCategory() {    return TextField(        onTap: () {          FocusScope.of(context).requestFocus(FocusNode());        },        style: TextStyle(fontSize: 12.0, height: 1.0),        decoration: InputDecoration(hintText: "TextView"));  }  Widget _showSignaturePad() {    return Container(      width: double.infinity,      height: 200,      child: Padding(        padding: const EdgeInsets.all(8.0),        child: Container(          height: 200,          //color: Colors.red,          child: Signature1( color: color, key: _sign, strokeWidth: strokeWidth,          ),        ),      ),      color: Colors.grey.shade300,    );  }}class Signature1 extends StatefulWidget {  final Color color;  final double strokeWidth;  final CustomPainter backgroundPainter;  final Function onSign;  Signature1({    this.color = Colors.black,    this.strokeWidth = 5.0,    this.backgroundPainter,    this.onSign,    Key key,  }) : super(key: key);  Signature1State createState() => Signature1State();  static Signature1State of(BuildContext context) {    return context.findAncestorStateOfType<Signature1State>();  }}class _SignaturePainter extends CustomPainter {  Size _lastSize;  final double strokeWidth;  final List<Offset> points;  final Color strokeColor;  Paint _linePaint;  _SignaturePainter({@required this.points, @required this.strokeColor, @required this.strokeWidth}) {    _linePaint = Paint()      ..color = strokeColor      ..strokeWidth = strokeWidth      ..strokeCap = StrokeCap.round;  }  @override  void paint(Canvas canvas, Size size) {    _lastSize = size;    for (int i = 0; i < points.length - 1; i++) {      if (points[i] != null && points[i + 1] != null) canvas.drawLine(points[i], points[i + 1], _linePaint);    }  }  @override  bool shouldRepaint(_SignaturePainter other) => other.points != points;}class Signature1State extends State<Signature1> {  List<Offset> _points = <Offset>[];  _SignaturePainter _painter;  Size _lastSize;  Signature1State();  void _onDragStart(DragStartDetails details){    RenderBox referenceBox = context.findRenderObject();    Offset localPostion = referenceBox.globalToLocal(details.globalPosition);    setState(() {      _points = List.from(_points)        ..add(localPostion)        ..add(localPostion);    });  }  void _onDragUpdate (DragUpdateDetails details) {    RenderBox referenceBox = context.findRenderObject();    Offset localPosition = referenceBox.globalToLocal(details.globalPosition);    setState(() {      _points = List.from(_points)..add(localPosition);      if (widget.onSign != null) {        widget.onSign();      }    });  }  void _onDragEnd (DragEndDetails details) => _points.add(null);  @override  Widget build(BuildContext context) {    WidgetsBinding.instance.addPostframeCallback((_) => afterFirstLayout(context));    _painter = _SignaturePainter(points: _points, strokeColor: widget.color, strokeWidth: widget.strokeWidth);    return ClipRect(      child: CustomPaint(        painter: widget.backgroundPainter,        foregroundPainter: _painter,        child: GestureDetector(          onVerticalDragStart: _onDragStart,          onVerticalDragUpdate: _onDragUpdate,          onVerticalDragEnd: _onDragEnd,          onPanStart: _onDragStart,          onPanUpdate: _onDragUpdate,          onPanEnd: _onDragEnd        ),      ),    );  }  Future<ui.Image> getData() {    var recorder = ui.PictureRecorder();    var origin = Offset(0.0, 0.0);    var paintBounds = Rect.fromPoints(_lastSize.topLeft(origin), _lastSize.bottomRight(origin));    var canvas = Canvas(recorder, paintBounds);    if(widget.backgroundPainter != null) {      widget.backgroundPainter.paint(canvas, _lastSize);    }    _painter.paint(canvas, _lastSize);    var picture = recorder.endRecording();    return picture.toImage(_lastSize.width.round(), _lastSize.height.round());  }  void clear() {    setState(() {      _points = [];    });  }  bool get hasPoints => _points.length > 0;  List<Offset> get points => _points;  afterFirstLayout(BuildContext context) {    _lastSize = context.size;  }}