Flutter iOS中jpg图像到png图像的转换

看看 image package . 以下是 examples section JPEG 到 PNG :

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

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

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

你要做的第一件事就是导入 IMAGE 图书馆。然后使用下面类似的自定义函数可以将JPG转换为PNG

import 'package:flutter/material.dart';
import 'dart:io';
import 'dart:convert';
import 'package:image/image.dart' as Im;
import 'dart:math' as Math;
void jpgTOpng(path) async {
  File imagePath = File(path);
  //get temporary directory
  final tempDir = await getTemporaryDirectory();
  int rand = new Math.Random().nextInt(10000);
  //reading jpg image
  Im.Image image = Im.decodeImage(imagePath.readAsBytesSync());
  //decreasing the size of image- optional
  Im.Image smallerImage = Im.copyResize(image, width:800);
      //get converting and saving in file
  File compressedImage = new File('${tempDir.path}/img_$rand.png')..writeAsBytesSync(Im.encodePng(smallerImage, level:8));     
}

使用 image 图书馆你可以这样做

jpegToPng(jpegimage){
new File('output.png')
    ..writeAsBytesSync(encodePng(thumbnail));
}