我该如何在Flutter中将从照片库选择的jpg图像转换为png图像?
看一下image package。以下是示例部分中可用的片段,该片段将JPEG
转换为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));
}
new File('out/thumbnail-test.png')..writeAsBytesSync(encodePng(thumbnail));
卡住了,之后什么也没有发生。 - Chaythanya Nair首先,您需要导入IMAGE库。然后使用类似下面的自定义函数,您可以将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));
}
jpegToPng(jpegimage){
new File('output.png')
..writeAsBytesSync(encodePng(thumbnail));
}
import 'dart:typed_data';
import 'package:image/image.dart';
Uint8List jpgToPng(Uint8List bytes) {
final jpgImage = decodeImage(bytes);
final pngImage = copyResize(
jpgImage!,
width: jpgImage.width,
height: jpgImage.height,
);
return Uint8List.fromList(encodePng(jpgImage));
}
img.decodeImage(imageFile.readAsBytesSync())..channels = img.Channels.rgba
我还使用 Image/Paint 方法将 Dart UI 图像转换为 .png:import 'dart:ui' as ui;
import 'package:image/image.dart' as img;
ui.Image imageN;
try {
final paint = await PaintingBinding.instance
.instantiateImageCodec(img.encodePng(thumbnail, level: 0));
final nextFrame = await paint.getNextFrame();
imageN = nextFrame.image;
} catch (e, s) {
// handle the exception
}
return imageN;