我正在使用滑块(如Instagram)创建图像编辑器应用程序,并且正在使用库image / image.dart。 问题在于,一旦移动滑块,它就会更新图像,但是只是在那个时候,如果再次移动它,它就不会更新。
我已经按照预期设置了所有内容,setState()函数随颤动地询问,但我不知道为什么它不会再次更新。
import 'dart:io';
import 'dart:ui';
import 'package:flutter/material.dart';
import 'package:image/image.dart' as br;
import 'package:path_provider/path_provider.dart';
import 'package:image_picker/image_picker.dart';
class ImageManager extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return _ImageManagerState();
}
}
class _ImageManagerState extends State<ImageManager> {
File imageFile;
br.Image image;
Image _imageWidget;
Future<String> get _localPath async {
final directory = await getapplicationDocumentsDirectory();
return directory.path;
}
// get tmp file
Future<File> get _localFile async {
final path = await _localPath;
return File('$path/tmp.jpg');
}
// pick image on button click
Future<void> _pickImage(ImageSource source) async{
File selectedFile = await ImagePicker.pickImage(source: source);
br.Image selectedImage;
if (selectedFile != null){
selectedImage = br.decodeImage(selectedFile.readAsBytesSync());
br.grayscale(selectedImage);
selectedFile.writeAsBytesSync(br.encodeJpg(selectedImage));
}
setState((){
image = selectedImage;
imageFile = selectedFile;
_imageWidget = Image.file(imageFile);
});
}
// MAIN PROBLEM,UPDATING THE CONTRAST WILL ONLY DO IT ONCE
Future<void> updateContrast(value) async{
File contrastFile = imageFile;
br.Image contrast = br.decodeImage(contrastFile.readAsBytesSync());
contrast = br.adjustColor(contrast,contrast: value);
contrastFile.writeAsBytesSync(br.encodeJpg(contrast));
// Save the thumbnail as a jpg.
File path = await _localFile;
path.writeAsBytesSync(br.encodeJpg(contrast));
setState(() {
image = contrast;
imageFile = contrastFile;
if(path != null){
_imageWidget = Image.file(path);
print(value);
}
});
}
//
Widget _buildImage(BuildContext context){
return Column(
children: [
Container(
width: MediaQuery.of(context).size.width,height: MediaQuery.of(context).size.width,child: _imageWidget,),Column(
children: [
Container(
padding: const EdgeInsets.only(left: 8,right: 8),child: Column(
children: <Widget>[
// contrast
Text("Contraste"),Padding(
padding: const EdgeInsets.only(bottom: 4.0,top: 0.0),child: Container(
child: Slider(
min: 0.0,max: 1.0,divisions: 100,value: _contrast,activeColor: Colors.blue[500],inactiveColor: Colors.blue[50],label: "${(_contrast *100).round()}",onChanged: (value) async{
changeContrast(value);
},onChangeEnd: (value) async{
updateContrast(value);
},],]
);
}
我希望每次更换滑块时图像都会更新。