How to use rootBundle in flutter to load images?

Question

I use image plugin (image: ^2.0.4) so I can write something on to the image and later save it new image to device or send via mail. I try to load image using "new File" but got error on Flutter. I ask and search and got a hint that I can use rootBundle to load image in Flutter. I did, and I got this below error.

[ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception: Unable to load asset: packages/myAppName/assets/images/ReceiptRaw_1.jpg

The plugin works when I create a simple dart console app, but couldn't load using flutter. Any help please,

This is the Flutter Code:

    Future<bool> makeReceiptImage() async {

// UPDATE ****************************************

      // load the receipt jpeg
  var imageData = await rootBundle.load('packages/myAppName/dekonts/ReceiptRaw_1.jpg');
  print("imageData: $imageData"); // Prints as imageData: Instance of 
'_ByteDataView'

// UPDATE ****************************************

  Image _receiptImage = await decodeImage(new File(imageData).readAsBytesSync());

      drawString(_receiptImage, arial_48, 440, 30, “Customer Name”, color: 0xFF000000); 

      // Write it to disk as a different jpeg 
      var new_jpeg = await encodeJpg(_receiptImage); 
      String newImagePath = await rootBundle.loadString('packages/myAppName/assets/images/ReceiptRaw_2.jpg'); 
      await new File(‘$newImagePath’).writeAsBytesSync(new_jpeg); 
    }

This is the Dart Console Code:

import 'dart:io';
import 'dart:convert';
import 'dart:async';
import 'package:image/image.dart';

void main() async {
  // load the receipt jpeg
  String mImagePath = 'images/ReceiptRaw_1.jpg';
  Image _receiptImage = decodeImage(new File(mImagePath).readAsBytesSync());
  drawString(_receiptImage, arial_48, 440, 30, “Customer Name”, color: 0xFF000000);

  // Write it to disk as a different jpeg
  var new_jpeg = encodeJpg(_receiptImage);
  new File('images/ReceiptRaw_1.jpg').writeAsBytesSync(new_jpeg);
}

Update-1: When I use below code I get en error as:

Error detected in pubspec.yaml: No file or variants found for asset: packages/myAppName/assets/images/ReceiptRaw_1.jpg

 String imageData = await rootBundle.loadString('packages/myAppName/assets/images/ReceiptRaw_1.jpg');
  Image _receiptImage = await decodeImage(new File(imageData).readAsBytesSync());

Update-2: if I use rootBundle.load I got below error.

Error: A value of type 'dart.typed_data::ByteData' can't be assigned to a variable of type 'dart.core::String'.

var imageData = await rootBundle.load('packages/myAppName/assets/images/ReceiptRaw_1.jpg');
  Image _receiptImage = await decodeImage(new File(imageData).readAsBytesSync());

New Update:

Step 1: Move to ReceiptRaw_1.jpg into lib/dekonts/ folder

Change to:

assets:
  - packages/myAppName/dekonts/ReceiptRaw_1.jpg

Change to:

var imageData = await rootBundle.load('packages/myAppName/dekonts/ReceiptRaw_1.jpg');
print("imageData: $imageData"); 

Result: Prints as

imageData: Instance of '_ByteDataView'

Step 2: Move to /lib/assets/images/ReceiptRaw_1.jpg folder

Change to:

assets:
  - packages/myAppName/lib/assets/images/ReceiptRaw_1.jpg

Change to:

var imageData = await rootBundle.load('packages/myAppName/lib/assets/images/ReceiptRaw_1.jpg');
print("imageData: $imageData"); 

Result: Got Error as:

Resolving dependencies... Running 'gradlew assembleDebug'... Error detected in pubspec.yaml: No file or variants found for asset: packages/myAppName/lib/assets/images/ReceiptRaw_1.jpg

Update:

/// To include, say the first image, the pubspec.yaml of the app should
/// specify it in the assets section:
///
/// assets: /// - packages/fancy_backgrounds/backgrounds/background1.png ///
/// The lib/ is implied, so it should not be included in the asset path.

Answer 1

With @Günter Zöchbauer help, I finally made it. My small contribution to Stack Overflow members.

// TODO: 1 - LOAD EVERYTHING

  Future _loadEverything() async {
    await _requestAppDocumentsDirectory();   // TODO: 2 - GET APP DOCUMENTS DIRECTORY
    _dekontExist = await makeReceiptImage(); // TODO: 3 - MAKE A RECEIPT

    // Show the writen image
    if (_dekontExist == true) {
      setState(() {
        newDekontImage = _appDocumentsDirectory + "/" + widget._currentUserReceiptNo + ".jpg";
        imageOkay = true; // FOR - 4 - MAIN WIDGET BUILD
      });
    }
  }

// TODO: 2 - GET APP DOCUMENTS DIRECTORY

Future _requestAppDocumentsDirectory() async {
  // I choose temp dir because I don’t want to write twice same Receipt
  // Also when user close the app it will destroys the images
  final _directory =
      await getTemporaryDirectory(); //getApplicationDocumentsDirectory();
  setState(() {
    _appDocumentsDirectory = _directory.path;
  });
}

// TODO: 3 - MAKE A RECEIPT

Future<bool> makeReceiptImage() async {

  // I use this as a template:
  // 'packages/mayApp/assets/images/CapitalReceipt.jpg'  

  ByteData imageData = await rootBundle.load('packages/mayApp/assets/images/CapitalReceipt.jpg');
  List<int> bytes = Uint8List.view(imageData.buffer);
  Image _receiptImage = decodeImage(bytes);

  // TODO: WRITE ON TO THE IMAGE
  drawString(_receiptImage, arial_48, 440, 30, “Customer Receipt - Customer Name”, color: 0xFF000000);


  // Write it to disk as a different jpeg
    var new_jpeg = await encodeJpg(_receiptImage);
    String newDekontImage = _appDocumentsDirectory + "/" + "${_currentUserReceiptNo}" + ".jpg";
    await new File(newDekontImage).writeAsBytesSync(new_jpeg);

  return true;
}

// TODO: 4 - MAIN WIDGET BUILD

  @override
  Widget build(BuildContext context) {
    capitalHeight = MediaQuery.of(context).size.height;
    capitalWidth = MediaQuery.of(context).size.width;

    if (imageOkay == true) {
      return new Scaffold(
        resizeToAvoidBottomPadding: true,
        appBar: new AppBar(
          title: new Text("Customer Receipt"),
          backgroundColor: const Color(0xFF7CB342),
          elevation: 0.0,
          actions: <Widget>[
            new Container(
              padding: EdgeInsets.only(right: 10.0),
              child: new Icon(Icons.mail),
            )
          ],
        ),
        body: new Column(
          children: <Widget>[
            new Padding(
              padding: EdgeInsets.fromLTRB(0.0, 0.0, 0.0, 0.0),
              child: new Center(
                child: new Container(
                  width: capitalWidth,
                  height: capitalHeight / 2.3,
                  color: Colors.black54, //capitalLightGreen,
                  child: new Container(
                    width: capitalWidth - 20.0,
                    height: capitalHeight / 2.3,
                    child: Image.file(File('$newDekontImage')),
                  )
                ),
              )
            ),
          ],
        ),
      );
    } else {
      return new Scaffold(
          resizeToAvoidBottomPadding: true,
          appBar: new AppBar(
            title: new Text("Customer Receipt"),
            backgroundColor: const Color(0xFF7CB342),
            elevation: 0.0,
            actions: <Widget>[
              new Container(
                padding: EdgeInsets.only(right: 10.0),
                child: new Icon(Icons.mail),
              )
            ],
          ),
          body: new Center(
            child: new CircularProgressIndicator(),
          ));
    }
  }

Answer 2

The files of pub dependencies are not available as files. They are contained in an archive file.

Add the image to assets in pubspec.yaml

flutter:
  assets:
    - packages/myAppName/assets/images/ReceiptRaw_1.jpg

then load it with

var imageData = await rootBundle.load('packages/myAppName/assets/images/ReceiptRaw_1.jpg');

For this to work the file ReceiptRaw_1.jpg needs to be in

myAppName/lib/assets/images/ReceiptRaw_1.jpg

Where the lib/ part is mandatory.