feat(add 这些组件：1.canvas 2. cricleProgressBarPainter 3.PainterPath 4. PainterSketch): add 这些组件：1.canva

add 这些组件：1.canvas 2. cricleProgressBarPainter 3.PainterPath 4. PainterSketch

lib/components/full_screen_code_dialog.dart

@@ -20,6 +20,7 @@ class _FullScreenCodeDialogState extends State<FullScreenCodeDialog> {
 
   @override
   void didChangeDependencies() {
+    print('widget.filePath=======${widget.filePath}');
     getExampleCode(context,'${widget.filePath}', DefaultAssetBundle.of(context))
         .then<void>((String code) {
       if (mounted) {

lib/resources/widget_name_to_icon.dart

@@ -78,6 +78,9 @@ class WidgetName2Icon {
     "IconData":Icons.date_range,
     "IconThemeData":Icons.insert_comment,
     "Canvas":Icons.edit,
+    "PainterPath":Icons.gesture,
+    "CircleProgressBarPainter":Icons.av_timer,
+    "PainterSketch":Icons.touch_app,
     "Material":Icons.android,
     "MaterialApp":Icons.android,
     "MaterialButton":Icons.speaker,

lib/utils/provider.dart

@@ -59,6 +59,7 @@ class Provider {
     //Get a location using getDatabasesPath
     String databasesPath = await getDatabasesPath();
     String path = join(databasesPath, 'flutter.db');
+    print(path);
     try {
       db = await openDatabase(path);
     } catch (e) {

lib/widgets/elements/Media/Canvas/Canvas/demo.dart

@@ -0,0 +1,203 @@
+/**
+ * Created with Android Studio.
+ * User: ryan
+ * Date: 2019/1/20
+ * Time: 上午11:34
+ * email: zhu.yan@alibaba-inc.com
+ * tartget: Canvas 的示例
+ */
+import 'package:flutter/material.dart';
+import 'dart:ui';
+import 'dart:ui' as ui;
+import 'dart:typed_data';
+import 'package:flutter/services.dart' show rootBundle;
+
+CustomPaint graph;
+var image;
+
+class CustomViewPage extends StatefulWidget {
+  
+  final String type;
+  CustomViewPage({this.type='drawLine'}) : super();
+
+  @override
+  State<StatefulWidget> createState() => CustomViewPageState();
+}
+
+class CustomViewPageState extends State<CustomViewPage>
+    with SingleTickerProviderStateMixin {
+
+  static Future<ui.Image> getImage(String asset) async {
+    ByteData data = await rootBundle.load(asset);
+    Codec codec = await ui.instantiateImageCodec(data.buffer.asUint8List());
+    FrameInfo fi = await codec.getNextFrame();
+    return fi.image;
+  }
+
+  @override
+  void initState() {
+    super.initState();
+    getImage("assets/images/painterImg.jpeg").then((data) {
+      setState(() {
+        image = data;
+      });
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    graph = CustomPaint(
+        painter: DrawPainter(type:widget.type)
+    );
+    return Container(
+        width: MediaQuery.of(context).size.width,
+        height: MediaQuery.of(context).size.width * 0.6,
+        margin: EdgeInsets.all(10.0),
+        //padding: EdgeInsets.all(10.0),
+        child: graph
+        //child:Center(child: graph)
+    );
+  }
+
+
+  @override
+  void reassemble() {
+    super.reassemble();
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+  }
+}
+
+///新建类继承于CustomPainter并且实现CustomPainter里面的paint（）和shouldRepaint方法
+class DrawPainter extends CustomPainter {
+  Paint painter;
+  final type;
+
+  DrawPainter ({this.type}){
+    //    Paint painter = Paint()
+    //    ..color = Colors.blueAccent //画笔颜色
+    //    ..strokeCap = StrokeCap.round //画笔笔触类型
+    //    ..isAntiAlias = true //是否启动抗锯齿
+    //    ..blendMode = BlendMode.exclusion //颜色混合模式
+    //    ..style = PaintingStyle.fill //绘画风格，默认为填充
+    //    ..colorFilter = ColorFilter.mode(Colors.blueAccent,BlendMode.exclusion) //颜色渲染模式，一般是矩阵效果来改变的,但是flutter中只能使用颜色混合模式
+    //    ..maskFilter = MaskFilter.blur(BlurStyle.inner, 3.0) //模糊遮罩效果，flutter中只有这个
+    //    ..filterQuality = FilterQuality.high //颜色渲染模式的质量
+    //    ..strokeWidth = 15.0 ;//画笔的宽度
+
+    painter = new Paint()
+      ..color = Colors.blueAccent
+      ..strokeCap = StrokeCap.round
+      ..isAntiAlias = true
+      ..strokeWidth = 5.0
+      ..filterQuality = FilterQuality.high
+      ..style = PaintingStyle.stroke;
+  }
+  ///Flutter中负责View绘制的地方，使用传递来的canvas和size即可完成对目标View的绘制
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    switch(type) {
+      case 'drawPoints':
+        const List<Offset> points1 = [Offset(20.0, 0.0), Offset(100.0, 50.0), Offset(150.0, 0.0),Offset(300.0, 0.0)];
+        const List<Offset> points2 = [Offset(20.0, 100.0), Offset(100.0, 100.0), Offset(150.0, 100.0), Offset(300.0, 100.0)];
+        const List<Offset> points3 = [Offset(20.0, 150.0), Offset(100.0, 150.0), Offset(150.0, 180.0), Offset(300.0, 150.0)];
+        //绘制点
+        canvas.drawPoints(
+            ///PointMode的枚举类型有三个，points（点），lines（线，隔点连接），polygon（线，相邻连接）
+            PointMode.points,
+            points1,
+            painter..color = Colors.redAccent // 这里可以追加修改 painter 属性
+                   ..strokeWidth = 10.0
+        );
+        canvas.drawPoints(
+          ///PointMode的枚举类型有三个，points（点），lines（线，隔点连接），polygon（线，相邻连接）
+            PointMode.lines,
+            points2,
+            painter..color = Colors.orange // 这里可以追加修改 painter 属性
+              ..strokeWidth = 10.0
+        );
+        canvas.drawPoints(
+          ///PointMode的枚举类型有三个，points（点），lines（线，隔点连接），polygon（线，相邻连接）
+            PointMode.polygon,
+            points3,
+            painter..color = Colors.blue // 这里可以追加修改 painter 属性
+              ..strokeWidth = 10.0
+        );
+        break;
+      case 'drawLine':
+        //绘制直线
+        canvas.drawLine(Offset(20.0, 0.0), Offset(size.width*0.8, 200), painter ..color = Colors.redAccent);
+        break;
+      case 'rawCircle':
+        //绘制圆 参数(圆心，半径，画笔)
+        canvas.drawCircle(
+          Offset(size.width/2, 100.0),
+          100.0,
+          painter
+          ..color = Colors.greenAccent
+          ..style = PaintingStyle.stroke //绘画风格改为stroke
+        );
+        break;
+      case 'drawOval':
+        // 绘制椭圆
+        // 使用左上和右下角坐标来确定矩形的大小和位置,椭圆是在这个矩形之中内切的形状
+        Rect rect1 = Rect.fromPoints(Offset(0.0, 0.0), Offset(size.width, 200.0));
+        canvas.drawOval(rect1, painter ..color = Colors.indigo);
+        break;
+      case 'drawArc':
+        // 绘制圆弧
+        // Rect来确认圆弧的位置，还需要开始的弧度、结束的弧度、是否使用中心点绘制、以及paint弧度
+        const PI = 3.1415926;
+        Rect rect1 = Rect.fromCircle(center: Offset(20, 50.0), radius: 100.0);
+        canvas.drawArc(rect1, 0.0, PI / 2, false, painter ..color = Colors.pink);
+
+        Rect rect2 = Rect.fromCircle(center: Offset(size.width*0.6, 50.0), radius: 100.0);
+        canvas.drawArc(rect2, 0.0, PI / 2, true, painter ..color = Colors.deepPurple);
+        break;
+      case 'drawRRect':
+        /// fromPoints(Offset a, Offset b)
+        /// 使用左上和右下角坐标来确定矩形的大小和位置
+        /// fromCircle({ Offset center, double radius })
+        /// 使用圆的圆心点坐标和半径和确定外切矩形的大小和位置
+        /// fromLTRB(double left, double top, double right, double bottom)
+        /// 使用矩形左边的X坐标、矩形顶部的Y坐标、矩形右边的X坐标、矩形底部的Y坐标来确定矩形的大小和位置
+        /// fromLTWH(double left, double top, double width, double height)
+        /// 使用矩形左边的X坐标、矩形顶部的Y坐标矩形的宽高来确定矩形的大小和位置
+        // 用Rect构建一个边长50,中心点坐标为50,100的矩形
+        Rect rect1 = Rect.fromCircle(center: Offset(80.0, 100.0), radius: 50.0);
+        Rect rect2 = Rect.fromCircle(center: Offset(250.0, 100.0), radius: 50.0);
+        // 根据上面的矩形,构建一个圆角矩形
+        RRect rrect1 = RRect.fromRectAndRadius(rect1, Radius.circular(0.0));
+        canvas.drawRRect(rrect1, painter);
+        RRect rrect2 = RRect.fromRectAndRadius(rect2, Radius.circular(20.0));
+        canvas.drawRRect(rrect2, painter);
+        break;
+      case 'drawDRRect':
+        //绘制两个矩形
+        Rect rect1 = Rect.fromCircle(center: Offset(size.width/2, 100.0), radius: 60.0);
+        Rect rect2 = Rect.fromCircle(center: Offset(size.width/2, 100.0), radius: 40.0);
+        //分别绘制外部圆角矩形和内部的圆角矩形
+        RRect outer = RRect.fromRectAndRadius(rect1, Radius.circular(30.0));
+        RRect inner = RRect.fromRectAndRadius(rect2, Radius.circular(5.0));
+        canvas.drawDRRect(outer, inner, painter ..color = Colors.lime);
+        break;
+      case 'drawImage':
+        // canvas.drawImage(image, Offset(0.0, 0.0), painter);
+        final src = Rect.fromLTWH(0.0, 0.0, 684.0, 442.0);
+        final dst = Rect.fromLTWH(0.0, 0.0, size.width, size.height);
+        canvas.drawImageRect(image, src, dst, painter);
+        break;
+    }
+    //canvas.drawColor(Colors.red, BlendMode.colorDodge);
+  }
+
+  ///控制自定义View是否需要重绘的，返回false代表这个View在构建完成后不需要重绘。
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) {
+    return false;
+  }
+}

lib/widgets/elements/Media/Canvas/Canvas/index.dart

@@ -0,0 +1,90 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_go/components/widget_demo.dart';
+import './demo.dart' as demoBoxs;
+
+const Text = '''
+### **简介**
+> 用于操作图形的界面;
+- canvas 对象用于创建图片对象，这些对象本身可以与 SceneBuilder 一起用于构建场景;
+''';
+const Text1 = '''
+### **基本用法**
+- 它可以使用“平移”、“缩放”、“旋转”、“倾斜”和“变换”方法进行修改;
+- 可以使用 clipRect、clipCorrect 和 clipPath 方法进行修改;
+- 可以使用由 save、savelayer和 restore 方法管理的堆栈来保存和还原当前的转换和剪辑。
+- 以下是绘制点，线，面的基本用法
+''';
+
+const Text2 = '''
+> 绘制点
+- 绘制点有三种模式, points（点），lines（线，隔点连接），polygon（线，相邻连接）
+''';
+
+const Text3 = '''
+> 绘制直线
+''';
+
+const Text4 = '''
+> 绘制圆
+''';
+
+const Text5 = '''
+> 绘制椭圆
+- 使用左上和右下角坐标来确定矩形的大小和位置,椭圆是在这个矩形之中内切的形状
+''';
+
+const Text6 = '''
+> 绘制圆弧
+- Rect 来确认圆弧的位置，还需要开始的弧度、结束的弧度、是否使用中心点绘制、以及 paint 弧度
+''';
+
+const Text7 = '''
+> 绘制矩形，圆角矩形
+- 用 Rect构建矩形
+- 根据上面的矩形,构建一个圆角矩形
+''';
+
+const Text8 = '''
+> 绘制两个相套矩形
+''';
+
+const Text9 = '''
+> 绘制图片到canvas
+''';
+
+class Demo extends StatefulWidget {
+  static const String routeName = '/element/Media/Canvas/PainterPath';
+
+  _DemoState createState() => _DemoState();
+}
+
+class _DemoState extends State<Demo> {
+  @override
+  Widget build(BuildContext context) {
+    return WidgetDemo(
+      title: 'Canvas',
+      codeUrl: 'elements/Media/Canvas/Canvas/demo.dart',
+      contentList: [
+        Text,
+        Text1,
+        Text2,
+        demoBoxs.CustomViewPage(type:'drawPoints'),
+        Text3,
+        demoBoxs.CustomViewPage(type:'drawLine'),
+        Text4,
+        demoBoxs.CustomViewPage(type:'rawCircle'),
+        Text5,
+        demoBoxs.CustomViewPage(type:'drawOval'),
+        Text6,
+        demoBoxs.CustomViewPage(type:'drawArc'),
+        Text7,
+        demoBoxs.CustomViewPage(type:'drawRRect'),
+        Text8,
+        demoBoxs.CustomViewPage(type:'drawDRRect'),
+        Text9,
+        demoBoxs.CustomViewPage(type:'drawImage')
+      ],
+      docUrl: 'https://docs.flutter.io/flutter/dart-ui/Canvas-class.html',
+    );
+  }
+}

lib/widgets/elements/Media/Canvas/CircleProgressBarPainter/demo.dart

@@ -0,0 +1,103 @@
+/**
+ * Created with Android Studio.
+ * User: ryan
+ * Date: 2019/1/20
+ * Time: 上午11:34
+ * email: zhu.yan@alibaba-inc.com
+ * tartget: CircleProgressBarPainter 的示例
+ */
+import 'dart:ui';
+import 'package:flutter/material.dart';
+
+class CustomViewPage extends StatefulWidget {
+  @override
+  State<StatefulWidget> createState() => CustomViewPageState();
+}
+
+class CustomViewPageState extends State<CustomViewPage>
+    with SingleTickerProviderStateMixin {
+  Animation<double> _doubleAnimation;
+  AnimationController _controller;
+  CurvedAnimation curvedAnimation;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller =
+        AnimationController(vsync: this, duration: Duration(seconds: 2));
+    curvedAnimation =
+        CurvedAnimation(parent: _controller, curve: Curves.decelerate);
+    _doubleAnimation = Tween(begin: 0.0, end: 360.0).animate(_controller);
+
+    _controller.addListener(() {
+      this.setState(() {});
+    });
+    onAnimationStart();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+        width: 100.0,
+        height: 100.0,
+        margin: EdgeInsets.all(8.0),
+        child: CustomPaint(
+            child: Center(
+                child: Text((_doubleAnimation.value / 3.6).round().toString())),
+            painter: CircleProgressBarPainter(_doubleAnimation.value)
+        ),
+      );
+  }
+
+  void onAnimationStart() {
+    _controller.forward(from: 0.0);
+  }
+
+  @override
+  void reassemble() {
+    super.reassemble();
+    onAnimationStart();
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+    _controller.dispose();
+  }
+}
+
+class CircleProgressBarPainter extends CustomPainter {
+  Paint _paintBackground;
+  Paint _paintFore;
+  final double pi = 3.1415926;
+  var jindu;
+
+  CircleProgressBarPainter(this.jindu) {
+    _paintBackground = Paint()
+      ..color = Colors.grey
+      ..strokeCap = StrokeCap.round
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = 10.0
+      ..isAntiAlias = true;
+    _paintFore = Paint()
+      ..color = Colors.red
+      ..strokeCap = StrokeCap.round
+      ..style = PaintingStyle.stroke
+      ..strokeWidth = 10.0
+      ..isAntiAlias = true;
+  }
+  @override
+  void paint(Canvas canvas, Size size) {
+    canvas.drawCircle(Offset(size.width / 2, size.height / 2), size.width / 2,_paintBackground);
+    Rect rect = Rect.fromCircle(
+      center: Offset(size.width / 2, size.height / 2),
+      radius: size.width / 2,
+    );
+    canvas.drawArc(rect, 0.0, jindu * 3.14 / 180, false, _paintFore);
+  }
+
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) {
+    return false;
+  }
+}

lib/widgets/elements/Media/Canvas/CircleProgressBarPainter/index.dart

@@ -0,0 +1,37 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_go/components/widget_demo.dart';
+import './demo.dart' as demoBoxs;
+
+const Text = '''
+### **简介**
+> 操作图形的界面;
+
+''';
+const Text1 = '''
+### **基本用法**
+- canvas + Animation 实现一个 loading 效果;
+''';
+
+
+class Demo extends StatefulWidget {
+  static const String routeName = '/element/Media/Canvas/CircleProgressBarPainter';
+
+  _DemoState createState() => _DemoState();
+}
+
+class _DemoState extends State<Demo> {
+  @override
+  Widget build(BuildContext context) {
+    return WidgetDemo(
+      title: 'Canvas',
+      codeUrl: 'elements/Media/Canvas/CircleProgressBarPainter/demo.dart',
+      contentList: [
+        Text,
+        Text1,
+        demoBoxs.CustomViewPage()
+      ],
+      docUrl: 'https://docs.flutter.io/flutter/dart-ui/Canvas-class.html',
+    );
+  }
+}
+

lib/widgets/elements/Media/Canvas/PainterPath/demo.dart

@@ -0,0 +1,180 @@
+/**
+ * Created with Android Studio.
+ * User: ryan
+ * Date: 2019/1/20
+ * Time: 上午11:34
+ * email: zhu.yan@alibaba-inc.com
+ * tartget: PainterPath 的示例
+ */
+import 'dart:ui';
+import 'package:flutter/material.dart';
+CustomPaint graph;
+
+class CustomViewPage extends StatefulWidget {
+  
+  final String type;
+  CustomViewPage({this.type='simpleline'}) : super();
+
+  @override
+  State<StatefulWidget> createState() => CustomViewPageState();
+}
+
+class CustomViewPageState extends State<CustomViewPage>
+    with SingleTickerProviderStateMixin {
+
+  @override
+  void initState() {
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    graph = CustomPaint(
+        painter: DrawPainter(type:widget.type)
+    );
+    return Container(
+        width: MediaQuery.of(context).size.width,
+        height: MediaQuery.of(context).size.width * 0.6,
+        margin: EdgeInsets.all(50.0),
+        //padding: EdgeInsets.all(10.0),
+        child: graph
+        //child:Center(child: graph)
+    );
+  }
+
+
+  @override
+  void reassemble() {
+    super.reassemble();
+  }
+
+  @override
+  void dispose() {
+    super.dispose();
+  }
+}
+
+///新建类继承于CustomPainter并且实现CustomPainter里面的paint（）和shouldRepaint方法
+class DrawPainter extends CustomPainter {
+  Paint painter;
+  final type;
+
+  DrawPainter ({this.type}){
+    //    Paint painter = Paint()
+    //    ..color = Colors.blueAccent //画笔颜色
+    //    ..strokeCap = StrokeCap.round //画笔笔触类型
+    //    ..isAntiAlias = true //是否启动抗锯齿
+    //    ..blendMode = BlendMode.exclusion //颜色混合模式
+    //    ..style = PaintingStyle.fill //绘画风格，默认为填充
+    //    ..colorFilter = ColorFilter.mode(Colors.blueAccent,BlendMode.exclusion) //颜色渲染模式，一般是矩阵效果来改变的,但是flutter中只能使用颜色混合模式
+    //    ..maskFilter = MaskFilter.blur(BlurStyle.inner, 3.0) //模糊遮罩效果，flutter中只有这个
+    //    ..filterQuality = FilterQuality.high //颜色渲染模式的质量
+    //    ..strokeWidth = 15.0 ;//画笔的宽度
+
+    painter = new Paint()
+      ..color = Colors.blueAccent
+      ..strokeCap = StrokeCap.round
+      ..isAntiAlias = true
+      ..strokeWidth = 5.0
+      ..style = PaintingStyle.stroke;
+  }
+  ///Flutter中负责View绘制的地方，使用传递来的canvas和size即可完成对目标View的绘制
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    //canvas.drawColor(Colors.red, BlendMode.colorDodge);
+    Path path = new Path();
+    drawThisPath(canvas, size, path);
+    path.close();
+    canvas.drawPath(path, painter);
+  }
+
+  void drawThisPath(Canvas canvas, Size size, Path path,) {
+    switch(type) {
+      case 'simpleline':
+      //新建了一个path,然后将路径起始点移动到坐标(100,100)的位置
+        Path path = new Path()..moveTo(0.0, 0.0);
+        path.lineTo(200.0, 200.0);
+        canvas.drawPath(path, painter);
+        break;
+      case 'polyline':
+        Path path = new Path()..moveTo(100.0, 10.0);
+
+        path.lineTo(200.0, 150.0);
+        path.lineTo(100.0, 200.0);
+
+        canvas.drawPath(path, painter);
+        break;
+      case 'Besizerline2':
+        Path path = new Path()..moveTo(0.0, 0.0);
+        Rect rect1 = Rect.fromCircle(center: Offset(50.0, 100.0), radius: 60.0);
+        path.arcTo(rect1, 0.0, 3.14, false);
+        canvas.drawPath(path, painter);
+
+        Rect rect2 = Rect.fromCircle(center: Offset(200.0, 100.0), radius: 60.0);
+        path.arcTo(rect2, 0.0, 3.14*2, true);
+        canvas.drawPath(path, painter);
+        break;
+      case 'Besizerline3':
+        var width = size.width;
+        var height = 300;
+        Path path = new Path()..moveTo(width / 2, height / 4);
+        path.cubicTo((width * 6) / 7, height / 9, (width * 13) / 13,
+            (height * 2) / 5, width / 2, (height * 7) / 12);
+        canvas.drawPath(path, painter
+          // ..style = PaintingStyle.fill
+          // ..color = Colors.red
+        );
+
+        Path path2 = new Path();
+        path2.moveTo(width / 2, height / 4);
+        path2.cubicTo(width / 7, height / 9, width / 21, (height * 2) / 5,
+            width / 2, (height * 7) / 12);
+        canvas.drawPath(path2, painter);
+        break;
+      case 'drawArc':
+      // 绘制圆弧
+      // Rect来确认圆弧的位置，还需要开始的弧度、结束的弧度、是否使用中心点绘制、以及paint弧度
+        const PI = 3.1415926;
+        Rect rect1 = Rect.fromCircle(center: Offset(size.width/2, 0.0), radius: 100.0);
+        canvas.drawArc(rect1, 0.0, PI / 2, false, painter ..color = Colors.pink);
+
+        Rect rect2 = Rect.fromCircle(center: Offset(size.width/2, 150.0), radius: 100.0);
+        canvas.drawArc(rect2, 0.0, PI / 2, true, painter ..color = Colors.deepPurple);
+        break;
+      case 'drawRRect':
+      /// fromPoints(Offset a, Offset b)
+      /// 使用左上和右下角坐标来确定矩形的大小和位置
+      /// fromCircle({ Offset center, double radius })
+      /// 使用圆的圆心点坐标和半径和确定外切矩形的大小和位置
+      /// fromLTRB(double left, double top, double right, double bottom)
+      /// 使用矩形左边的X坐标、矩形顶部的Y坐标、矩形右边的X坐标、矩形底部的Y坐标来确定矩形的大小和位置
+      /// fromLTWH(double left, double top, double width, double height)
+      /// 使用矩形左边的X坐标、矩形顶部的Y坐标矩形的宽高来确定矩形的大小和位置
+      // 用Rect构建一个边长50,中心点坐标为50,100的矩形
+        Rect rect1 = Rect.fromCircle(center: Offset(50.0, 50.0), radius: 50.0);
+        Rect rect2 = Rect.fromCircle(center: Offset(200.0, 50.0), radius: 50.0);
+        // 根据上面的矩形,构建一个圆角矩形
+        RRect rrect1 = RRect.fromRectAndRadius(rect1, Radius.circular(0.0));
+        canvas.drawRRect(rrect1, painter);
+        RRect rrect2 = RRect.fromRectAndRadius(rect2, Radius.circular(20.0));
+        canvas.drawRRect(rrect2, painter);
+        break;
+      case 'drawDRRect':
+      //绘制两个矩形
+        Rect rect1 = Rect.fromCircle(center: Offset(size.width/2, 100.0), radius: 60.0);
+        Rect rect2 = Rect.fromCircle(center: Offset(size.width/2, 100.0), radius: 40.0);
+        //分别绘制外部圆角矩形和内部的圆角矩形
+        RRect outer = RRect.fromRectAndRadius(rect1, Radius.circular(30.0));
+        RRect inner = RRect.fromRectAndRadius(rect2, Radius.circular(5.0));
+        canvas.drawDRRect(outer, inner, painter ..color = Colors.lime);
+        break;
+    }
+  }
+
+  ///控制自定义View是否需要重绘的，返回false代表这个View在构建完成后不需要重绘。
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) {
+    return false;
+  }
+}

lib/widgets/elements/Media/Canvas/PainterPath/index.dart

@@ -0,0 +1,65 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_go/components/widget_demo.dart';
+import './demo.dart' as demoBoxs;
+
+//const Text = '''
+//### **简介**
+//> 在 canvas 上绘制时使用的样式说明;
+//-  canvas 上的大多数API都使用一个绘画对象来描述用于该操作的样式。
+//''';
+const Text = '''
+### **简介**
+> 在 canvas 上绘制的图案;
+-  canvas + paint 的应用。
+''';
+
+const Text1 = '''
+### **基本用法**
+- canvas 的 painter 的自定义绘制线的方法;
+''';
+
+const Text2 = '''
+> 绘制简单直线
+''';
+
+const Text3 = '''
+> 绘制折线
+''';
+
+const Text4 = '''
+> 二阶贝塞尔曲线
+''';
+
+const Text5 = '''
+> 三阶贝塞尔曲线
+''';
+
+
+class Demo extends StatefulWidget {
+  static const String routeName = '/element/Media/Canvas/Canvas';
+
+  _DemoState createState() => _DemoState();
+}
+
+class _DemoState extends State<Demo> {
+  @override
+  Widget build(BuildContext context) {
+    return WidgetDemo(
+      title: 'PainterPath',
+      codeUrl: 'elements/Media/Canvas/PainterPath/demo.dart',
+      contentList: [
+        Text,
+        Text1,
+        Text2,
+        demoBoxs.CustomViewPage(type:'simpleline'),
+        Text3,
+        demoBoxs.CustomViewPage(type:'polyline'),
+        Text4,
+        demoBoxs.CustomViewPage(type:'Besizerline2'),
+        Text5,
+        demoBoxs.CustomViewPage(type:'Besizerline3'),
+      ],
+      docUrl: 'https://docs.flutter.io/flutter/dart-ui/Paint-class.html',
+    );
+  }
+}

lib/widgets/elements/Media/Canvas/PainterSketch/demo.dart

@@ -0,0 +1,213 @@
+/**
+ * Created with Android Studio.
+ * User: ryan
+ * Date: 2019/1/20
+ * Time: 上午11:34
+ * email: zhu.yan@alibaba-inc.com
+ * tartget: PainterSketchDome 的示例
+ */
+
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+
+class PainterSketchDome extends StatefulWidget {
+  PainterSketchDome({Key key, this.title}) : super(key: key);
+
+  final String title;
+
+  @override
+  _PainterSketchDomeState createState() => new _PainterSketchDomeState();
+}
+
+class _PainterSketchDomeState extends State<PainterSketchDome> {
+
+  List<LinePoints> lines = <LinePoints>[];
+  List<Offset> nowPoints = <Offset>[];
+  Color nowColor = Colors.redAccent;
+
+  void moveGestureDetector(DragUpdateDetails detail){
+    RenderBox box = context.findRenderObject();
+    final Offset xy = box.globalToLocal(detail.globalPosition);// 重要需要转换以下坐标位置
+    Offset p = Offset(xy.dx, xy.dy - 60);
+    //Offset p = Offset(detail.globalPosition.dx, detail.globalPosition.dy - 60);
+    setState(() {
+      nowPoints.add(p);
+    });
+  }
+
+  void newGestureDetector(DragStartDetails detail) {
+    if (nowPoints.length != 0) {
+      LinePoints l = LinePoints(new List<Offset>.from(nowPoints), nowColor);
+      lines.add(l);
+      nowPoints.clear();
+    }
+    RenderBox box = context.findRenderObject();
+    final Offset xy = box.globalToLocal(detail.globalPosition);// 重要需要转换以下坐标位置
+    Offset p = Offset(xy.dx, xy.dy - 60);
+    //Offset p = Offset(detail.globalPosition.dx, detail.globalPosition.dy - 60);
+    setState(() {
+      nowPoints.add(p);
+    });
+  }
+
+  void changeColor (Color c){
+    if (nowPoints.length != 0) {
+      LinePoints l = LinePoints(new List<Offset>.from(nowPoints), nowColor);
+      lines.add(l);
+    }
+    setState(() {
+      nowPoints.clear();
+      nowColor = c;
+    });
+  }
+
+  List<Color> colors = <Color>[
+    Colors.redAccent,
+    Colors.pink,
+    Colors.greenAccent,
+    Colors.blueAccent,
+    Colors.amber,
+    Colors.purpleAccent,
+    Colors.deepPurpleAccent,
+    Colors.lightBlueAccent,
+    Colors.lightGreenAccent,
+    Colors.cyanAccent,];
+
+  void _tapClear(){
+    setState(() {
+      lines.clear();
+      nowPoints.clear();
+    });
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    List<Widget> pallet = <Widget>[];
+    for (int i = 0; i < colors.length; i++) {
+      Color c = colors[i];
+      pallet.add(ColorPallet(color: c,changeColor: changeColor,isSelect: c==nowColor,));
+    }
+
+    return SizedBox(
+          width: MediaQuery.of(context).size.width * 0.9,
+          height: MediaQuery.of(context).size.height * 0.6,
+          child:new Scaffold(
+            primary: false,
+            body: new Container(
+              decoration: BoxDecoration(
+                  color: Colors.white
+              ),
+              child:new Flex(
+                direction: Axis.vertical,
+                children: <Widget>[
+                  Container(
+                    decoration:BoxDecoration(
+                        color: Colors.black12
+                    ),
+                    child: ListView(
+                      scrollDirection: Axis.horizontal,
+                      children: pallet
+                      ,
+                    ),
+                    height: 60.0,
+                  ),
+                  Expanded(
+                    child: AspectRatio(
+                      aspectRatio: 1.0,
+                      child: GestureDetector(
+                        child: CustomPaint(
+                          painter: PaintCanvas(lines,nowPoints,nowColor),
+                        ),
+                        onHorizontalDragUpdate: moveGestureDetector,
+                        onVerticalDragUpdate: moveGestureDetector,
+                        onHorizontalDragStart: newGestureDetector,
+                        onVerticalDragStart: newGestureDetector,
+                      ),
+                    ),
+                  )
+                ],
+              ),
+            ),
+            floatingActionButton: FloatingActionButton(
+              onPressed: _tapClear,
+              backgroundColor: Colors.redAccent,
+              foregroundColor: Colors.white,
+              child: Icon(Icons.delete),
+            ),
+          )
+      );
+  }
+}
+
+class PaintCanvas extends CustomPainter{
+
+  final List<LinePoints> lines;
+  final List<Offset> nowPoints;
+  final Color nowColor;
+
+  PaintCanvas(this.lines, this.nowPoints, this.nowColor);
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    Paint p = new Paint()
+      ..color = Colors.redAccent
+      ..strokeCap = StrokeCap.round
+      ..strokeWidth = 5.0;
+    canvas.save();
+    for (int i = 0; i < lines.length; i++) {
+      LinePoints l = lines[i];
+      for (int j = 1; j < l.points.length; j++){
+        Offset p1 = l.points[j - 1];
+        Offset p2 = l.points[j];
+        p.color = l.lineColor;
+        canvas.drawLine(p1, p2, p);
+      }
+    }
+    for (int i = 1; i < nowPoints.length; i++){
+      Offset p1 = nowPoints[i - 1];
+      Offset p2 = nowPoints[i];
+      p.color = nowColor;
+      canvas.drawLine(p1, p2, p);
+    }
+
+    canvas.restore();
+  }
+  @override
+  bool shouldRepaint(CustomPainter oldDelegate) {
+    return true;
+  }
+}
+
+class LinePoints{
+  final List<Offset> points;
+  final Color lineColor;
+  LinePoints(this.points, this.lineColor);
+}
+
+class ColorPallet extends StatelessWidget {
+  final Color color;
+  final Function changeColor;
+  const ColorPallet({Key key, this.color, this.changeColor, this.isSelect}) : super(key: key);
+  final bool isSelect;
+
+  void onPressed(){
+    changeColor(color);
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return new RawMaterialButton(
+        onPressed: onPressed,
+        constraints: BoxConstraints(minWidth: 60.0,minHeight: 50.0),
+        child: new Container(
+          margin: EdgeInsets.only(top: 5.0,bottom: 5.0),
+          width: 50.0,
+          height: 50.0,
+          decoration: BoxDecoration(
+              color: color,
+              borderRadius: BorderRadius.all(Radius.circular(25.0)),
+              border: Border.all(color: Colors.white,width: isSelect?3.0:0.0)
+          ),
+        )) ;
+  }
+}

lib/widgets/elements/Media/Canvas/PainterSketch/index.dart

@@ -0,0 +1,37 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_go/components/widget_demo.dart';
+import './demo.dart' as demoBoxs;
+
+const Text = '''
+### **简介**
+> 操作图形的界面;
+
+''';
+const Text1 = '''
+### **基本用法**
+- canvas + paint + GestureDetector 实现一个 简易的画板;
+''';
+
+
+class Demo extends StatefulWidget {
+  static const String routeName = '/element/Media/Canvas/PainterSketch';
+
+  _DemoState createState() => _DemoState();
+}
+
+class _DemoState extends State<Demo> {
+  @override
+  Widget build(BuildContext context) {
+    return WidgetDemo(
+      title: 'Canvas',
+      codeUrl: 'elements/Media/Canvas/PainterSketch/demo.dart',
+      contentList: [
+        Text,
+        Text1,
+        demoBoxs.PainterSketchDome()
+      ],
+      docUrl: 'https://docs.flutter.io/flutter/dart-ui/Paint-class.html',
+    );
+  }
+}
+

lib/widgets/elements/Media/Canvas/index.dart

@@ -1 +1,31 @@
-// import 'package:flutter/material.dart';
+import 'package:flutter_go/model/widget.dart';
+import "package:flutter/material.dart";
+
+import 'PainterSketch/index.dart' as PainterSketch;
+import 'Canvas/index.dart' as Canvas;
+import 'PainterPath/index.dart' as PainterPath;
+import 'CircleProgressBarPainter/index.dart' as CircleProgressBarPainter;
+
+
+List<WidgetPoint> widgetPoints = [
+  WidgetPoint(
+    name: 'PainterSketch',
+    routerName: PainterSketch.Demo.routeName,
+    buildRouter: (BuildContext context) => PainterSketch.Demo(),
+  ),
+  WidgetPoint(
+    name: 'Canvas',
+    routerName: Canvas.Demo.routeName,
+    buildRouter: (BuildContext context) => Canvas.Demo(),
+  ),
+  WidgetPoint(
+    name: 'PainterPath',
+    routerName: PainterPath.Demo.routeName,
+    buildRouter: (BuildContext context) => PainterPath.Demo(),
+  ),
+  WidgetPoint(
+    name: 'CircleProgressBarPainter',
+    routerName: CircleProgressBarPainter.Demo.routeName,
+    buildRouter: (BuildContext context) => CircleProgressBarPainter.Demo(),
+  )
+];

lib/widgets/elements/Media/index.dart

@@ -6,10 +6,12 @@
  */
 import 'Image/index.dart' as Image;
 import 'Icon/index.dart' as Icon;
+import 'Canvas/index.dart' as Canvas;
 
 List getWidgets() {
   List result = [];
   result.addAll(Image.widgetPoints);
   result.addAll(Icon.widgetPoints);
+  result.addAll(Canvas.widgetPoints);
   return result;
 }

pubspec.yaml

@@ -159,6 +159,10 @@ flutter:
     - lib/widgets/elements/Media/Image/paintImage/paint_image_demo.dart
     - lib/widgets/elements/Media/Image/precacheImage/precache_image_demo.dart
     - lib/widgets/elements/Media/Image/RawImage/raw_image_demo.dart
+    - lib/widgets/elements/Media/Canvas/Canvas/demo.dart
+    - lib/widgets/elements/Media/Canvas/CircleProgressBarPainter/demo.dart
+    - lib/widgets/elements/Media/Canvas/PainterPath/demo.dart
+    - lib/widgets/elements/Media/Canvas/PainterSketch/demo.dart
     - lib/widgets/themes/Material/MaterialApp/demo.dart
     - lib/widgets/themes/Material/MaterialButton/demo.dart
     - lib/widgets/themes/Material/MaterialColor/demo.dart