How can I read (from disk) and resize an image, in Flutter/Dart

In Flutter/Dart, how can I perform the following 3 steps:

1. Read an image from disk,
2. Read its original dimensions (width and height),
3. Resize it.

Note: I must be able to display the final result with a regular Flutter Image widget.

CLARIFICATION: I don't want to save the image, but I do want to actually resize it in memory.

Solution 1:

You can read image from the disk using the image.file constructor.

For more features you can use the Image library

A Dart library providing the ability to load, save and manipulate images in a variety of different file formats.

Sample from the documentation examples

Load a jpeg, resize it and save it as a png

    import 'dart:io' as Io;
    import 'package:image/image.dart';
    void main() {
      // Read a jpeg image from file.
      Image image = decodeImage(new Io.File('test.jpg').readAsBytesSync());

      // Resize the image to a 120x? thumbnail (maintaining the aspect ratio).
      Image thumbnail = copyResize(image, width: 120);

      // Save the thumbnail as a PNG.
      new Io.File('out/thumbnail-test.png')
            ..writeAsBytesSync(encodePng(thumbnail));
    }

Solution 2:

To resize an image that is defined in pubspec.yaml use "BoxFit":

@override
Widget build(BuildContext context) {
  return (new Container(
    width: 250.0,
    height: 250.0,
      alignment: Alignment.center,
      decoration: new BoxDecoration(

      image: DecorationImage(
          image: AssetImage('assets/Launcher_Icon.png'),
          fit: BoxFit.fill
      ),
    ),
  ));
}

also reference how to access images: https://flutter.io/assets-and-images/