4q-s-r-o / signature Goto Github PK

Flutter plugin that creates a canvas for writing down a signature

License: MIT License

Java 0.44% Objective-C 0.12% Dart 92.66% Swift 1.23% HTML 5.55%

signature's Introduction

signature

A Flutter plugin providing performance optimized signature canvas with ability to set custom style, boundaries and initial state. This is native flutter implementation, so it supports all platforms.

Why

In time of creation of this plugin, there was no available solution that had:

required performance on wide range of devices
ability to set canvas boundaries
ability to initialize using previously saved state

Migration to 5.0.0+

This version no longer wraps Signature in Expanded widget if you are using it without specifying dimensions
This removes error Incorrect use of ParentDataWidget, see this issue for more information.
If you are passing dimensions to widget, you do not have to change anything.
If you are using widget without dimensions inside Row, Column or Flex widgets, you have to wrap Signature inside Expanded yourself.
If you are using widget without dimensions, but not inside mentioned widgets you do not have change anything and error should dissapear from your logs :)

Usage

To use this plugin, add signature as a dependency in your pubspec.yaml file.

Example

Take a look at our example project as well: Signature Demo

// IMPORT PACKAGE
import 'package:signature/signature.dart';

// Initialise a controller. It will contains signature points, stroke width and pen color.
// It will allow you to interact with the widget
final SignatureController _controller = SignatureController(
    penStrokeWidth: 5,
    penColor: Colors.red,
    exportBackgroundColor: Colors.blue,
);

// INITIALIZE. RESULT IS A WIDGET, SO IT CAN BE DIRECTLY USED IN BUILD METHOD 
var _signatureCanvas = Signature(
  controller: _controller,
  width: 300,
  height: 300,
  backgroundColor: Colors.lightBlueAccent,
);

// CLEAR CANVAS
_controller.clear();

// EXPORT BYTES AS PNG
// The exported image will be limited to the drawn area
_controller.toPngBytes();

// isEmpty/isNotEmpty CAN BE USED TO CHECK IF SIGNATURE HAS BEEN PROVIDED
_controller.isNotEmpty; //true if signature has been provided
_controller.isEmpty; //true if signature has NOT been provided

// EXPORT POINTS (2D POINTS ROUGHLY REPRESENTING WHAT IS VISIBLE ON CANVAS)
var exportedPoints = _controller.points;

//EXPORTED POINTS CAN BE USED TO INITIALIZE PREVIOUS CONTROLLER
final SignatureController _controller = SignatureController(points: exportedPoints);

//DONT FORGET TO DISPOSE IT IN THE `dispose()` METHOD OF STATEFUL WIDGETS
@override
void dispose() {
  _controller.dispose();
  super.dispose();
}

Contribution and Support

Contributions are welcome!
If you want to contribute code please create a PR
If you find a bug or want a feature, please fill an issue

signature's People

Contributors

Stargazers

Watchers

Forkers

stevenspiel anythingth2 danvick cuixingrui pk115 jhboing sujindra-maharjan sulazo sxtsoft jeanmatthieud vivek2089 alamusitl danielkono brianegarcia pangyake dalosy-projecten-bv rickyazharipratama leonardarnold svadhis tban flutterworks cortrano morristech lnddev3 dmlzj tiloc andersonmendess trustmefelix djinn-digital justrox vickyleu cmcmhjr123 lukasliebl gwsh monkeyxdd tmavrin marcusjtl munyaaa h7x4 osamamohammed98 elaget kiritodv madsane29 bestfastfire rahi0 yurtemre7 giuseppe5 arbyazra123 saschaernst zmgithub jrbaena prabal23 katherineqian fleetimee larsziemert alexandremaillot kirioxx dingzuhua byshenliuan jeronimocabezuelo 258223433 zyf540860996 laolang07 see000 voyagerclass zsliu666 dubydu pye52 seeyoung envile yvdjee stenlee johncharris anderscheow hamidullo7 aetesyindan bmonson widiyanto9876 rohitbhoite miso-0 amr-samy

signature's Issues

Plans for null-safety?

Are you going to provide a null-safety version of this great plug-in?

Cannot continue drawing when the signature is interrupted

issue.mov

The user might accidentally touch the status bar like in the video, and the Listener object does not handle the cancellation callback, so the user can not continue drawing while this is happening.

Add Listener.onPointerCancel may solves this problem :

class SignatureState extends State<Signature> {
  
  @override
  Widget build(BuildContext context) {
    ...
    Listener(
      ...
      onPointerCancel: (PointerCancelEvent event) {
           if (activePointerId == event.pointer) {
              _addPoint(event, PointType.tap);
              widget.controller.onDrawEnd?.call();
              activePointerId = null;
            }
      },
    );
  }
}

Here are the results:

fix.mov

Signing quickly leaves gaps in-between points

Signing quickly on iOS or android makes the signature have gaps in-between points. Any idea what may be causing this?

Feature Request: pressure-sensitive capture

Current version seems to draw points/lines with fixed penStrokeWidth. By utilizing the pressure property in PointEvent one could in theory capture and simulate a more realistic hand-written signature.

exportBytes not working

Hi i have the following code.

 if (_signatureCanvas.isEmpty) {
                    Scaffold.of(context).showSnackBar(
                      SnackBar(
                        content: Text(
                            'Error could not save signed document. Please sign before saving'),
                        duration: Duration(seconds: 3),
                      ),
                    );
                  } else {
                    print('1');
                     _signatureCanvas.exportBytes().then((bytes) {
                      print(bytes);
                      _service.setSignature(bytes);
                      _service.submitSignature();
                    }).catchError((e) {
                      print(e);
                    });

                    print('2');
                  }

The exportBytes is not working and only 1 and 2 is printed

flutter doctor

Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel beta, v1.12.13+hotfix.6, on Microsoft Windows [Version 10.0.18362.535], locale en-ZA)

[√] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
[√] Chrome - develop for the web
[!] Android Studio (version 3.1)
    X Flutter plugin not installed; this adds Flutter specific functionality.
    X Dart plugin not installed; this adds Dart specific functionality.
[√] VS Code, 64-bit edition (version 1.41.1)
[√] Connected device (2 available)

! Doctor found issues in 1 category.

Running Flutter web though

`toPngBytes` throws with Exception

Hi, I try to export a signature as a png byte but I always get this exception:
VERBOSE-2:dart_vm_initializer.cc(41)] Unhandled Exception: 'package:signature/signature.dart': Failed assertion: line 413 pos 9: '((width ?? defaultWidth!) - defaultWidth!) >= 0.0': Exported width cannot be smaller than actual width

This is my widget:

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

  @override
  State<SignaturePage> createState() => _SignaturePageState();
}

class _SignaturePageState extends State<SignaturePage> {
  final SignatureController _controller = SignatureController(
    penStrokeWidth: 5,
    penColor: Colors.black,
    exportBackgroundColor: Colors.transparent,
  );

  @override
  Widget build(BuildContext context) {
    return BlocBuilder<SendMeToTheMoonBloc, SendMeToTheMoonState>(
      builder: (context, stateMoon) {
        return Scaffold(
          body: SafeArea(
            child: Container(
              padding: const EdgeInsets.only(top: 20, left: 15, right: 20),
              child: BlocBuilder<SignOffBloc, SignOffState>(
                builder: (context, state) {
                  return Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [
                      Text('Thanks, ${state.signOffSigner!.firstName}.'),
                      const Text('Can you sign here to complete the job?'),
                      const SizedBox(height: 20),
                      LayoutBuilder(builder: (context, constraints) {
                        return ConstrainedBox(
                          constraints: BoxConstraints(
                            maxWidth: constraints.maxWidth,
                            maxHeight: 500,
                          ),
                          child: Card(
                            child: Stack(
                              children: [
                                const Padding(
                                  padding: EdgeInsets.all(8.0),
                                  child: Text('Signature'),
                                ),
                                Signature(
                                  controller: _controller,
                                  backgroundColor: Colors.transparent,
                                ),
                              ],
                            ),
                          ),
                        );
                      }),
                      Center(
                        child: ElevatedButton(
                          onPressed: () async {
                            final image = await _controller.toPngBytes();
                            if (image != null && mounted) {
                              final signature = UploadImage(
                                bucket: 'some_bucket',
                                filePath: 'some/path',
                                file: image,
                              );
                              context.read<SendMeToTheMoonBloc>().add(
                                    SignatureSubmitted(
                                      signature: signature,
                                    ),
                                  );
                            }
                          },
                          child: const Icon(Icons.arrow_forward),
                        ),
                      )
                    ],
                  );
                },
              ),
            ),
          ),
        );
      },
    );
  }
}

Is there something that I'm doing wrong when I wrap the signature?
Thanks!

Unexpected draw behaviour

If i set signature inside expanded in row widget and don't specify width i am able to draw out side of signature widget.
For test purpose:
Row( children: [ Expanded(child: AutoSizeText("Citizen Signature")), Flexible( flex: 2, child: Signature( controller: SignatureController( penStrokeWidth: 5, penColor: Colors.black, exportBackgroundColor: Colors.blue, ), height: height * 0.1, backgroundColor: Colors.grey[300]!, ) ) ], )

toPngBytes() always return 400x500 px image

Hi,

after upgrading to 5.2.1 all my signatures are saved as 400x500px and cannot be resized.

I find this part of code:

//WIDTH AND HEIGHT IS OPTIONAL. IMAGE WILL BE CENTERED
 final ui.Image? image = await toImage(height: 500, width: 400);

How can I use toPngBytes() to get an image in the proper size, based on image data?
In old version that part works fine.

Bug report: Incorrect use of ParentDataWidget

Consider the following example app:

main.dart

import 'package:flutter/material.dart';
import 'package:signature/signature.dart';

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

class MyApp extends StatelessWidget {
  final SignatureController controller = SignatureController();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Signature Demo',
      home: Scaffold(
        appBar: AppBar(),
        body: Stack(
          children: [
            Signature(
              controller: controller,
              backgroundColor: Colors.black12,
            ),
            IconButton(
              icon: Icon(Icons.delete),
              onPressed: () => controller.clear(),
            )
          ],
        ),
      ),
    );
  }
}

When drawing, the console keeps spitting out this error message:

Another exception was thrown: Incorrect use of ParentDataWidget.

After looking a little bit around, I found that the causing line was the last part of the build function of SignatureState:

    if (widget.width != null || widget.height != null) {
      //IF DOUNDARIES ARE DEFINED, USE LIMITED BOX
      return Center(
        child: LimitedBox(
          maxWidth: maxWidth,
          maxHeight: maxHeight,
          child: signatureCanvas,
        ),
      );
    } else {
      //IF NO BOUNDARIES ARE DEFINED, USE EXPANDED
      return Expanded(child: signatureCanvas);
    }

Wrapping the canvas inside an Expanded widget only makes sense if the canvas is a child of Column, Row or Flex. See StackOverflow.

Although Expanded is needed when wrapped inside either of those three widgets, I think it would be better to let the user decide if the canvas should be expanded or not.

toPngBytes method is not working

When calling the toPngBytes method, an exception is thrown:

Unhandled Exception: Exception: operation failed

This exception occurs at line 189 of signature.dart:

picture.toImage( (maxX - minX + penStrokeWidth * 2).toInt(), (maxY - minY + penStrokeWidth * 2).toInt());

covert base64 string and pass the predefined signature to it's controller, is it possible?

I have a api respose of signature in base64 String so how can I covert base64 string and pass the predefined signature to it's controller, is it possible

Export Signature to PDF

Hi,

I want to export the signature to a pdf file. Is it possible to do that? And how could I implement it?

Thanks for helping me

Add a GIF showcase to Readme

Hello! ✌️

Thank you for the package! Just thought that it would be really nice to see an example of it as a GIF in the readme.

Pixellated Signatures on Flutter Web

It is possible to draw outside of boundaries

It is not fixed. You still can draw outside of the boundaries to the right and to the bottom.

Plans to migrate to null safety?

Export and upload to server in JSON

Hi I'm looking to export the signature and send it to the server in a json string.
What is the best method to achieve this?

I was thinking..
Uint8List signature = await _signatureController.toPngBytes();
String signature64 = base64Encode(signature);

But this is giving me an error
Unhandled Exception: type '_InternalLinkedHashMap<String, String>' is not a subtype of type 'String'

Swiping in a tab

If you put the signature widget in a tabbarpage and you try to swipe horizontal it will still swipe the entire tab and you can't draw.. Do you know any fix for that? ty!

Can I set the background to an image?

My work needs a signature on the space like the image below.
If can show this background with an image, the user will sign with ease.
(My work needs to print this image with signature.)

Feature Request: onChanged callback.

Good work on this useful plugin.

Is there possibility of adding an onChanged(updatedData) callback that will notify when user interaction has stopped sending back the byte data for users to react to?

SIGNATURE NOT WORKING

[signature-teste] flutter pub get
Running "flutter pub get" in signature-teste...
Error on line 30, column 3 of pubspec.yaml: A package may not list itself as a dependency.
╷
30 │ signature: ^4.1.1
│ ^^^^^^^^^
╵
pub get failed (65; ╵)
exit code 65

Import a previous signature

how can i open a previous signature from bytes stored in a blob column in database?,
Im expecting something like _controller.fromBytes(Uint8List), but, i just found the _controller.points(List<Point>) but i cant figure out how store this on db

Unable to export signature when the widget not accessible

Hi have a form containing the signature.
When the form is submitted, the widget is replaced by an image. By doing so, the user cannot edit the signature anymore, during the submission (which can take few seconds).

Sadly, as the export method is more than linked to the drawing canvas, the export fails.

key property does not created!

Code for reproducing:

class _SomePageState extends State<SomePage> {
  Signature signaturePad;
  
  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    signaturePage = Signature(
      height: 300.0,
      penColor: Theme.of(context).accentColor,
    );
    signaturePad.clear() // Here I have a crash "the method clear was called on null"
  }
}

At break point I see that inner key is null. It looks like createState method is not called.

toImage() returns defineable size image?

Hi there,
at the moment controller.toImage() and .toPngBytes() return various size images, depending on the painted dots area.
Since the backend i have to upload signature images expects fixed size images i was wondering if it wouldn't be possible to let callers of those 2 methods define optional width and height parameters which (if defined) would be used as the size of the returned image, where the signature then is centered.
If the width and/or height are smaller than the signature those values would be used.

Or how could i reach this by myself after receiving a ui.Image from controller.toImage() ?

'toByteData' isn't defined for the class 'Future<Image>'

This is a breaking change as noted here

Here is the error message and backtrace:

[VERBOSE-2:ui_dart_state.cc(148)] Unhandled Exception: 'package:signature/signature.dart': error: file:///Users/steven/flutter/.pub-cache/hosted/pub.dartlang.org/signature-1.0.3/lib/signature.dart:201:29: Error: The method 'toByteData' isn't defined for the class 'Future<Image>'.
 - 'Future' is from 'dart:async'.
 - 'Image' is from 'dart:ui'.
Try correcting the name to the name of an existing method, or defining a method named 'toByteData'.
    var bytes = await image.toByteData(format: ImageByteFormat.png);
                            ^^^^^^^^^^
#0      _AsyncAwaitCompleter.start (dart:async/runtime/libasync_patch.dart:49:6)
#1      _SignaturePainter.export (package:signature/signature.dart:187:27)
#2      SignatureState.exportBytes (package:signature/signature.dart:65:26)
<asynchronous suspension>
#3      Signature.exportBytes (package:signature/signature.dart:34:35)
<asynchronous suspension>
#4      Drawable.build.<anonymous closure> (package:zboviq/pages/shared/drawable.dart:81:74)
#5      _InkRe<…>
[VERBOSE-2:ui_dart_state.cc(148)] Unhandled Exception: 'package:signature/signature.dart': error: file:///Users/steven/flutter/.pub-cache/hosted/pub.dartlang.org/signature-1.0.3/lib/signature.dart:201:29: Error: The method 'toByteData' isn't defined for the class 'Future<Image>'.
 - 'Future' is from 'dart:async'.
 - 'Image' is from 'dart:ui'.
Try correcting the name to the name of an existing method, or defining a method named 'toByteData'.
    var bytes = await image.toByteData(format: ImageByteFormat.png);
                            ^^^^^^^^^^
#0      _AsyncAwaitCompleter.start (dart:async/runtime/libasync_patch.dart:49:6)
#1      _SignaturePainter.export (package:signature/signature.dart:187:27)
#2      SignatureState.exportBytes (package:signature/signature.dart:65:26)
<asynchronous suspension>
#3      Signature.exportBytes (package:signature/signature.dart:34:35)
<asynchronous suspension>
#4      Drawable.build.<anonymous closure> (package:zboviq/pages/shared/drawable.dart:81:74)
#5      _InkRe<…>

A strange dot at onPointerUp

It doesn't looks right to me leaving a dot at the and of every pointer up. I don't now why the signature was implemented this way, but i think it would be useful if the user (dev) want it or not. Sorry if i'm not clear, this is my first issue on open source.

Error on saving sign to gallery

I faced this error when I tried to save the image after generated :
E/flutter ( 3742): [ERROR:flutter/lib/ui/ui_dart_state.cc(209)] Unhandled Exception: MissingPluginException(No implementation found for method saveImageToGallery on channel image_gallery_saver)
E/flutter ( 3742): #0 MethodChannel._invokeMethod (package:flutter/src/services/platform_channel.dart:154:7)
E/flutter ( 3742):
E/flutter ( 3742): #1 ImageGallerySaver.saveImage (package:image_gallery_saver/image_gallery_saver.dart:20:9)
E/flutter ( 3742):
E/flutter ( 3742): #2 _GetdocsignState.build. (package:gsdoc_mobile_v2/getdoc/getdocsign.dart:207:60)
E/flutter ( 3742):
E/flutter ( 3742):

Flutter Web toPngBytes failing

Image.toByteData is not supported in Flutter for Web
The byte generation is failing on flutter web. I need a solution which works equally for web and the other platforms.

I managed it to get it work by using the package image:
https://pub.dev/packages/image

It doesn't feel so right: For flutter web the signature points get redrawn with the image package (I did it almost equally how you did with the normal canvas). So it feels a bit duplicated and with an additional package, but maybe it's a starting point.

I am using Flutter Channel dev, 1.20.0-1.0.pre

Error: Exception: operation failed
    at Object.createErrorWithStack (http://localhost:59763/dart_sdk.js:4479:12)
    at Object._rethrow (http://localhost:59763/dart_sdk.js:37395:16)
    at async._AsyncCallbackEntry.new.callback (http://localhost:59763/dart_sdk.js:37389:13)
    at Object._microtaskLoop (http://localhost:59763/dart_sdk.js:37221:13)
    at _startMicrotaskLoop (http://localhost:59763/dart_sdk.js:37227:13)
    at http://localhost:59763/dart_sdk.js:32849:9Error: Exception: Image.toByteData is not supported in Flutter for Web
    at Object.throw_ [as throw] (http://localhost:59763/dart_sdk.js:4465:11)
    at Object.futurize (http://localhost:59763/dart_sdk.js:166948:17)
    at _engine.HtmlImage.new.toByteData (http://localhost:59763/dart_sdk.js:142412:22)
    at signature.SignatureController.new.toPngBytes (http://localhost:59763/packages/signature/signature.dart.lib.js:792:34)
    at toPngBytes.next (<anonymous>)
    at http://localhost:59763/dart_sdk.js:37106:33
    at _RootZone.runUnary (http://localhost:59763/dart_sdk.js:36960:58)
    at _FutureListener.thenAwait.handleValue (http://localhost:59763/dart_sdk.js:32047:29)
    at handleValueCallback (http://localhost:59763/dart_sdk.js:32594:49)
    at Function._propagateToListeners (http://localhost:59763/dart_sdk.js:32632:17)
    at _Future.new.[_completeWithValue] (http://localhost:59763/dart_sdk.js:32475:23)
    at async._AsyncCallbackEntry.new.callback (http://localhost:59763/dart_sdk.js:32497:35)
    at Object._microtaskLoop (http://localhost:59763/dart_sdk.js:37221:13)
    at _startMicrotaskLoop (http://localhost:59763/dart_sdk.js:37227:13)
    at http://localhost:59763/dart_sdk.js:32849:9

Auto-generate signature

I would like to propose a feature for auto-generating the signature or prepopulating the SignaturePad's canvas by supplying an initial text.

Something like:

TextPainter _buildTextPainter(Size canvasSize) {
  //Determins the scale of the generated text so it
  //fits the most appropriatelly basen on it's length
  final defaultScaleCharWidth = 9.0;
  final maxCharacters = canvasSize.width / defaultScaleCharWidth;
  final initialTextScaleFactor = maxCharacters / text.length;
  final textScaleFactor = (initialTextScaleFactor == 0 ? 1 : initialTextScaleFactor) * 0.8;

  //Define text style, maybe later add custom font that's more appropriate for a signature...
  final span = TextSpan(
    text: text,
    style: const TextStyle(color: Colors.black, fontStyle: FontStyle.italic),
  );

  //Build the text painter to compute all the
  //points that are required to render the text on canvas
  final textPainter = TextPainter(
    text: span,
    textAlign: TextAlign.left,
    textDirection: painting.TextDirection.ltr,
    textScaleFactor: textScaleFactor,
  );

  textPainter.layout();

  return textPainter;
}


// ...


final textPainter = _buildTextPainter(size);

textPainter.paint(
  canvas,
  Offset(
    _horizontalOffset(size, textPainter),
    _verticalOffset(size, textPainter),
  ),
);

Orientation change clears canvas on iOS

Hi,
One of our customers reported that changing the device orientations wipes or clears the signature they have added. This issue is happening only on iOS, android works fine.
Do you think it is a bug in the libraries, if so, do you have any recommendations for us until the issue is fixed?
Thanks

Transparent background image

Is there a way to export a signature image with transparent background? Thanks

Is there a way to once you call clear(), it will clear the canvas? cause I think now it's still there until you rewrite on top of it

thank you

isDirty()

Image resoultion for saving image .

When the signature is drawn on canvas , resolution is good , when the right mark is clicked , the resolution of the png goes bad . 2. When stroke width is 5, i can see crack in signature

How to convert pngBytes to base64?

I'm trying to save the signature to the Database, so i need to convert the signature which is current in pngbytes. But I need to show the saved image in a base64 format. So how to convert a pngbytes to base64?

Disable multitap?

If i accidentally tap on screen while drawing it draws a line between this two points. Can i disable multitap?

Export as a file

Hey
How I can export signature as a file ??? I need it for saving on a table.

_controller.clear() bug.

_controller.clear() doesn't work when called. The user must call the function and then start drawing again before it clears.

Feature Request: exportSVG()

Please add support to export signature data as SVG.

Feature Request: Add onDrawMove callback

I'm currently using the signature plugin in order to create writing data which will be sent to an API.
This API requires me to timestamp every point, and this is not possible without a callback on the onPointerMove method.

Adding exportPenColor

Please consider that would be nice to have the exportPenColor property. For black theming ideal penColor will probably be white, while exporting penColor should be black or darker color.

Thanks in advance,

Add undo functionality

It will be great we can have a undo functionality so that users can undo their steps if they make any mistakes while drawing signature instead of reseting whole canvas.

Drawing should not scroll a container

If the Signature widget is part of a scrolling container, drawing gestures cause unwanted scrolling. My expectation is that drawing inside the widget will work just fine and the container doesn't scroll.

Attached is a simple example that demonstrates the problem. If you try to draw something inside the amber signature widget, the ListView scrolls and subscribing is nearly impossible.

Perhaps using a GestureDetector instead of a Listener widget would help?

How to stop painting?

Hi,

I have used this plugin and it really helped me thank you for this work.

but I have a question which is how to stop listening to the signature widget for any painting.

I mean it will be unpaintable.

Thank you,

onPressed: () async {
if (_controller.isNotEmpty) {

                  final Uint8List? data = await _controller.toPngBytes();
                  if (data != null) {
                    Directory? directory = await getExternalStorageDirectory();
                    String path = directory!.path;
                    print(path);
                    var pngImage = await image.toByteData(format: _controller.ImageByteFormat.png);
                    await Directory('$path/assinaturaUser').create(recursive: true);
                    File('$path/$directoryName/$_controller').writeAsBytesSync(data.buffer.asUint8List());
                    final SharedPreferences prefs = await SharedPreferences.getInstance();
                    String base64Image = base64Encode(data);
                    prefs.setString("image", base64Image);
                    print(base64Image);
                  }
                }
              },

points setter in SignatureController does nothing

The assignment at line 157 has no effect.

How cann i show signature from url?

I'm saving signature to server and server gives me an url. So kindly can you tell how can i show signature from url?