我想将用户在我的应用中选择的照片发送到Firebase存储。我有一个简单的类，其属性为_imageFile，其设置如下：
File _imageFile;
_getImage() async {
var fileName = await ImagePicker.pickImage();
setState(() {
_imageFile = fileName;
});
}
之后，我发送照片与此代码：
final String rand1 = "${new Random().nextInt(10000)}";
final String rand2 = "${new Random().nextInt(10000)}";
final String rand3 = "${new Random().nextInt(10000)}";
final StorageReference ref = FirebaseStorage.instance.ref().child('${rand1}_${rand2}_${rand3}.jpg');
final StorageUploadTask uploadTask = ref.put(_imageFile);
final Uri downloadUrl = (await uploadTask.future).downloadUrl;
print(downloadUrl);
问题是照片通常非常大。在上传之前，Flutter / Dart中是否有任何压缩和调整照片大小的方法？我很好，质量下降。
image_picker插件目前非常简单。可以直接添加用于指定所选图像的所需大小/质量的选项。如果您这样做，请发送拉货请求！
qazxsw poi插件现在支持qazxsw poi参数。你可以做点什么
image_picker
我遇到了这个并且能够用Dart imageQuality和File compressedImage = await ImagePicker.pickImage(source: ImageSource.camera, imageQuality: 85);
完成压缩/调整大小。你可以看看dart image package和path provider的其他方式和更多的帮助。
这是我做的：
image api
然后我将examples上传到firebase存储。您可以使用quality属性调整jpg保存的质量，在我的情况下，我选择85（满分100）。
希望这可以帮助！如果您有任何疑问，请告诉我。
以下代码是用于使用相机拍摄图像然后压缩它的代码：
import 'package:image/image.dart' as Im;
import 'package:path_provider/path_provider.dart';
import 'dart:math' as Math;
void compressImage() async {
File imageFile = await ImagePicker.pickImage();
final tempDir = await getTemporaryDirectory();
final path = tempDir.path;
int rand = new Math.Random().nextInt(10000);
Im.Image image = Im.decodeImage(imageFile.readAsBytesSync());
Im.Image smallerImage = Im.copyResize(image, 500); // choose the size here, it will maintain aspect ratio
var compressedImage = new File('$path/img_$rand.jpg')..writeAsBytesSync(Im.encodeJpg(image, quality: 85));
}
你可以用这个来调用它：
compressedImage使用import 'dart:async' show Future;
import 'dart:io' show File;
import 'package:flutter/foundation.dart' show compute;
import 'package:flutter/material.dart' show BuildContext;
import 'package:image/image.dart' as Im;
import 'dart:math' as Math;
import 'package:image_picker/image_picker.dart';
import 'package:path_provider/path_provider.dart' show getTemporaryDirectory;
Future<File> takeCompressedPicture(BuildContext context) async {
var _imageFile = await ImagePicker.pickImage(source: ImageSource.camera);
if (_imageFile == null) {
return null;
}
// You can have a loading dialog here but don't forget to pop before return file;
final tempDir = await getTemporaryDirectory();
final rand = Math.Random().nextInt(10000);
_CompressObject compressObject =
_CompressObject(_imageFile, tempDir.path, rand);
String filePath = await _compressImage(compressObject);
print('new path: ' + filePath);
File file = File(filePath);
// Pop loading
return file;
}
Future<String> _compressImage(_CompressObject object) async {
return compute(_decodeImage, object);
}
String _decodeImage(_CompressObject object) {
Im.Image image = Im.decodeImage(object.imageFile.readAsBytesSync());
Im.Image smallerImage = Im.copyResize(
image, 1024); // choose the size here, it will maintain aspect ratio
var decodedImageFile = File(object.path + '/img_${object.rand}.jpg');
decodedImageFile.writeAsBytesSync(Im.encodeJpg(smallerImage, quality: 85));
return decodedImageFile.path;
}
class _CompressObject {
File imageFile;
String path;
int rand;
_CompressObject(this.imageFile, this.path, this.rand);
}
插件并调用选择图像功能
import 'path/to/compress_image.dart' as CompressImage;
// ...
File file = await CompressImage.takeCompressedPicture(context);
将maxHeight和maxWidth更改为您需要的任何大小的图像。
除了提到这个本地图书馆：image_picker
这是一个带有隔离的完全基于dart的压缩器，它可能使压缩与多核CPU中的UI线程并行。
您可能希望使用计算函数，这使得使用隔离器更简单：
Future<File> imageFile = ImagePicker.pickImage(source: ImageSource.gallery , maxHeight: 200 , maxWidth: 200 );https://pub.dartlang.org/packages/flutter_image_compress
https://docs.flutter.io/flutter/foundation/compute.html
https://flutter.io/cookbook/networking/background-parsing/
我正在使用
包：图像/ image.dart
面对以下问题
然后使用下面的插件，同样的工作正常没有任何问题，甚至更快，我所期望的
import 'package:image/image.dart' as ImageLib;
import 'package:path_provider/path_provider.dart';
Future<void> getCompressedImage(SendPort sendPort) async {
ReceivePort receivePort = ReceivePort();
sendPort.send(receivePort.sendPort);
List msg = (await receivePort.first) as List;
String srcPath = msg[0];
String name = msg[1];
String destDirPath = msg[2];
SendPort replyPort = msg[3];
ImageLib.Image image =
ImageLib.decodeImage(await new File(srcPath).readAsBytes());
if (image.width > 500 || image.height > 500) {
image = ImageLib.copyResize(image, 500);
}
File destFile = new File(destDirPath + '/' + name);
await destFile.writeAsBytes(ImageLib.encodeJpg(image, quality: 60));
replyPort.send(destFile.path);
}
Future<File> compressImage(File f) async {
ReceivePort receivePort = ReceivePort();
await Isolate.spawn(getCompressedImage, receivePort.sendPort);
SendPort sendPort = await receivePort.first;
ReceivePort receivePort2 = ReceivePort();
sendPort.send([
f.path,
f.uri.pathSegments.last,
(await getTemporaryDirectory()).path,
receivePort2.sendPort,
]);
var msg = await receivePort2.first;
return new File(msg);
}
上述链接中可用的步骤和方法。