image_scaler 0.0.2

Light weight library to rescale *dart:ui* Images.

image_scaler

Light weight flutter library to rescale Images.

Features

Provides following Algorithms:

Algorithm	Speed	Quality
Nearest Neighbour Interpolation (nni)	Extremely fast	Bad
Improved Nearest Neighbour Interpolation (inni)	Very fast	Average
Megak (megak)	Average	Very good
Lanczos (lanczos)	Slow	Very good

Calculations are carried out in a separate isolate, this will make sure the Main-Thread is not blocked.

ScaleAlgorithms are documented more detailed in the Dartdoc comments.

Getting started

Add

flutter pub add image_scaler

Import

import 'package:image_scaler/image_scaler.dart';
import 'package:image_scaler/types.dart';

Usage

Flutter Futurebuilder Example

final Future<ui.Image> = scale(
    image: widget.round,
    newSize: const IntSize(200, 200),
    algorithm: ScaleAlgorithm.megak,
    areaRadius: 2
);

class MyImage extends StatelessWidget {
  final Future<ui.Image> image;
  
  const MyImage(this.image);
  
  @override
  Widget build(BuildContext context) {
    return FutureBuilder<ui.Image>(
      future: image,
      builder: (BuildContext context, AsyncSnapshot<ui.Image> snapshot) {
        if (snapshot.connectionState == ConnectionState.waiting) {
          return const CircularProgressIndicator();
        } else if (snapshot.hasError) {
          return Text("${snapshot.error}");
        } else {
          return RawImage(
            image: snapshot.data,
            fit: BoxFit.cover,
          );
        }
      },
    );
  }
}

Flutter Flame prerendered Sprite Example

// PlayerComponent.dart

Future<Image> prerenderSpriteComponent(Sprite sprite, Size size) async {
  final spriteComp = SpriteComponent(sprite: sprite);

  // Original Image
  final oiRecorder = PictureRecorder();
  final oiCanvas = Canvas(oiRecorder);
  spriteComp.render(oiCanvas);

  final oiImage = await oiRecorder.endRecording().toImage(
    sprite.srcSize.x.toInt(),
    sprite.srcSize.y.toInt(),
  );

  return await scale(oiImage, IntSize(size.width.toInt(), size.height.toInt()), ScaleAlgorithm.lanczos);
}

ui.Image? playerSpriteRendered;

@override
void onLoad() async {
  playerSpriteRendered = await prerenderSpriteComponent(
    playerSpriteSheet.getSprite(0, player.color),
    Size.fromRadius(player.rad),
  );
}

@override
void render(Canvas canvas) {
  super.render(canvas);

  if (playerSpriteRendered!=null) {
    canvas.drawImage(
      playerSpriteRendered!,
      Offset(-player.rad, -player.rad),
      Paint()
    );
  }
}

Example

You will find an example application in the Github Repository.