saving signature

example/drawing_page.dart

@@ -1,4 +1,7 @@
 import 'dart:async';
+import 'dart:typed_data';
+import 'dart:ui' as ui;
+
 
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
@@ -17,19 +20,38 @@ class _DrawingPageState extends State<DrawingPage> {
   List<Stroke> lines = <Stroke>[];
 
   Stroke? line;
+  ui.PictureRecorder recorder = ui.PictureRecorder();
 
   StrokeOptions options = StrokeOptions();
+  Canvas? canvas;
+  Sketcher? sketcher;
 
   StreamController<Stroke> currentLineStreamController =
       StreamController<Stroke>.broadcast();
 
   StreamController<List<Stroke>> linesStreamController =
       StreamController<List<Stroke>>.broadcast();
 
+  Uint8List? imageData;
+  bool _isPaintStarted = false;
+
+  set isPaintStarted(bool isStarted) {
+     setState(() {
+       _isPaintStarted = isStarted;
+     });
+  }
+
+  @override
+  void initState() {
+    canvas = Canvas(recorder);
+    super.initState();
+  }
+
   Future<void> clear() async {
     setState(() {
       lines = [];
       line = null;
+      isPaintStarted = false;
     });
   }
 
@@ -40,6 +62,7 @@ class _DrawingPageState extends State<DrawingPage> {
   }
 
   void onPanStart(DragStartDetails details) {
+    isPaintStarted = true;
     final box = context.findRenderObject() as RenderBox;
     final offset = box.globalToLocal(details.globalPosition);
     final point = Point(offset.dx, offset.dy);
@@ -62,6 +85,59 @@ class _DrawingPageState extends State<DrawingPage> {
     linesStreamController.add(lines);
   }
 
+  Future<ui.Image?> toImage() async {
+    sketcher = Sketcher(lines: lines, options: options);
+    if (lines.isEmpty) {
+      return null;
+    }
+
+    double minX = double.infinity, minY = double.infinity;
+    double maxX = 0, maxY = 0;
+    for (int i = 0; i < lines.length; ++i) {
+      var line = lines[i];
+      for (Point point in line.path) {
+        if (point.x < minX) {
+          minX = point.x;
+        }
+        if (point.y < minY) {
+          minY = point.y;
+        }
+        if (point.x > maxX) {
+          maxX = point.x;
+        }
+        if (point.y > maxY) {
+          maxY = point.y;
+        }
+      }
+    }
+
+    final ui.PictureRecorder recorder = ui.PictureRecorder();
+    final ui.Canvas canvas = Canvas(recorder)
+      ..translate(-(minX - options.size), -(minY - options.size));
+    final ui.Paint paint = Paint()..color = Colors.transparent;
+    canvas.drawPaint(paint);
+
+    sketcher?.paint(canvas, Size.infinite);
+    final ui.Picture picture = recorder.endRecording();
+    return picture.toImage(
+      (maxX - minX + options.size * 2).toInt(),
+      (maxY - minY + options.size * 2).toInt(),
+    );
+  }
+
+  saveSignature() async {
+    if (canvas != null) {
+      ui.Image? image = await toImage();
+      ByteData? byteData =
+          await image?.toByteData(format: ui.ImageByteFormat.png);
+      if (byteData != null) {
+        setState(() {
+          imageData = byteData.buffer.asUint8List();
+        });
+      }
+    }
+  }
+
   Widget buildCurrentPath(BuildContext context) {
     return GestureDetector(
       onPanStart: onPanStart,
@@ -223,6 +299,24 @@ class _DrawingPageState extends State<DrawingPage> {
                 style: TextStyle(fontWeight: FontWeight.bold, fontSize: 12),
               ),
               buildClearButton(),
+              (_isPaintStarted)
+                  ? ElevatedButton(
+                      onPressed: () async {
+                        await saveSignature();
+
+                        Navigator.push(
+                            context,
+                            MaterialPageRoute(
+                                builder: (context) => Scaffold(
+                                      body: Center(
+                                        child: Image.memory(imageData ??
+                                            Uint8List.fromList([])),
+                                      ),
+                                    )));
+                        clear();
+                      },
+                      child: const Text("Save"))
+                  : Container(),
             ]));
   }
 

example/main.dart

@@ -1,6 +1,7 @@
-import './drawing_page.dart';
 import 'package:flutter/material.dart';
 
+import './drawing_page.dart';
+
 void main() {
   runApp(const MyApp());
 }

pubspec.yaml

@@ -5,6 +5,7 @@ homepage: https://github.com/steveruizok/perfect-freehand-dart
 repository: https://github.com/steveruizok/perfect-freehand-dart
 documentation: https://github.com/steveruizok/perfect-freehand-dart
 issue_tracker: https://github.com/steveruizok/perfect-freehand-dart/issues
+
 environment:
   sdk: ">=2.12.0 <3.0.0"