after turning off the internet i gets this error: "Remove network images from cache on any exception during loading"
my app fetch pictures from api. how can i fix this bug how i prevent that?
return Column(children: [
GestureDetector(
child: Image.network(thumbnailUrl))])
You can use the Cached Network Image Plugin if you are developing for android and ios. In Web, the plugin is not working as expected.
Use the following as a widget for your application.
import 'package:cached_network_image/cached_network_image.dart';
Widget commonCacheImageWidget(String? url, {double? width, BoxFit? fit, double? height}) {
if (url!.startsWith('http')) {
return CachedNetworkImage(
placeholder: (context, url) => Image.asset('assets/path....', fit: BoxFit.cover),
imageUrl: url,
height: height,
width: width,
fit: fit,
);
} else {
return Image.asset(url, height: height, width: width, fit: fit);
}
}
In Placeholder you can have any widget, here am using a local image that is stored as an asset.
Or You can check whether the internet connection is there or not before loading the image and change that to some other widget.
Related
I'm using a FutureBuilder to load album thumbnails into a ListTile, as follows:
ListTile _albumTile(Album album, BuildContext context) {
return ListTile(
leading: FutureBuilder<Uint8List>(
future: AndroidContentResolver.instance.loadThumbnail(
uri: album.thumbnailUri,
width: 56,
height: 56,
),
builder: (context, snapshot) {
if (snapshot.hasData) {
return Image.memory(snapshot.data!);
} else {
return const FittedBox(
fit: BoxFit.contain, child: Icon(Icons.album, size: 56));
}
}),
title: Text(album.album),
subtitle: Text(album.artist),
);
}
But, as the image loads, the placeholder icon is replaced with a blank image, and then with the final thumbnail. The blank image has the wrong width, which results in the ListTile title and subtitle jumping around, causing a flicker.
The following sequence of screenshots shows three consecutive frames:
Image placeholders.
Some of the futures have completed, and are showing thumbnails. The other tiles have a blank image (and the text jumps to the left).
All of the futures have completed.
Even when I fix the text jumping around -- by specifying fit: BoxFit.contain, width: 56, height: 56 for the image -- I still get a flash of white before the thumbnail appears.
What am I doing wrong?
Use precacheImage function to prefetch an image into the image cache.
If the image is later used by an Image or BoxDecoration or FadeInImage, it will probably be loaded faster.
I solved it by using frameBuilder. The documentation says:
If this is null, this widget will display an image that is painted as soon as the first image frame is available (and will appear to "pop" in if it becomes available asynchronously).
This describes exactly what I'm seeing.
It continues with the following:
Callers might use this builder to add effects to the image (such as fading the image in when it becomes available) or to display a placeholder widget while the image is loading.
...and the attached example shows how to implement a fade-in effect. For simplicity, however, I opted for the following:
return Image.memory(
snapshot.data!,
frameBuilder: (context, child, frame, wsl) {
if (frame != null) {
return child;
} else {
return _albumThumbnailPlaceholder();
}
},
Widget _albumThumbnailPlaceholder() {
return FittedBox(fit: BoxFit.contain, child: Icon(Icons.album, size: 56));
}
This seems to completely get rid of the blank frame.
Im using Image.Network to display a image based on a URL :
ClipOval(
child: Image.network(
'http://myurl${userId}.png',
width: 100,
height: 100,
fit: BoxFit.cover,
key: profileImageKey,
),
),
I'm trying get the user to upload a new profile image, however, i'm retaining the same filename (userid + .png). Once the user has uploaded the image the above is display is not displaying the new image.
I've tried rebuilding the widget using :
setState(() {
//generateKey();
profileImageKey = ValueKey(new Random().nextInt(100));
userId = userId;
});
I've also tried removing the url from the cache using :
PaintingBinding.instance.imageCache.evict('http://myurl${userId}.png');
However, none of these methods work. Is there a way to update the Image.Network to download and use the new image that was uploaded ?
Thanks
Based on #pskink's comment https://stackoverflow.com/a/60916852/2252830
The solution to this question was to use the evict method on Image. So I refactored my code to below :
Image profileImage;
...
profileImage = Image.network(
'http://myurl${userId}.png',
width: 100,
height: 100,
fit: BoxFit.cover,
key: profileImageKey,
);
...
ClipOval(
child: profileImage,
),
...
profileImage.image.evict();
setState(() {
//generateKey();
profileImageKey = ValueKey(new Random().nextInt(100));
userId = userId;
});
I'm using Image Picker package in my Flutter project
I choose image from gallery then preview it in Image.asset widget
The problem here is if image name "example_name.png" (without spaces) the image is visible on the screen, but if image name "example name.png" (with spaces) the image is invisible like this Screenshot.
Error: Unable to load asset: /storage/emulated/0/Download/images (9).jpeg
File _image;
Image.asset(
_image != null
? "${_image.path}"
: getImage("icon.png"),
fit: BoxFit.cover,
width: 120,
height: 120,
);
...
Future chooseFile() async {
await ImagePicker.pickImage(source: ImageSource.gallery).then((image) {
setState(() {
_image = image;
});
});
}
You are using the wrong Image constructor. Use Image.file instead of Image.asset. Image.asset load files packaged in the application (assets section of pubspec.yaml) and ImagePicker does not have access to them.
in the image_picker (version 0.6.7 + 22) I was able to recover the image with this condition
if (photo == null) {
return Image (
image: AssetImage ('assets / no-image.png'),
height: 300.0,
fit: BoxFit.cover,
);
} else {
return Image.file (
Photo,
height: 300.0,
fit: BoxFit.cover,
);
}
Using Image.file is a good option but you like to display it in an effective way use
Image.file(_image).image this will help you to convert Image file to image provider
The flutter_web docos say to that dart:svg is ported, but how do you use that with the flutter asset / widget system?
Honestly the best solution I've found is to load the image over a network for the web. Store the asset on a CDN somewhere, get it from the CDN on the web version, and retrieve it from your assets locally on iOS/Android.
I've created a CrossPlatformSvg widget using this library: https://pub.dev/packages/flutter_svg, something like:
class CrossPlatformSvg {
static Widget asset(
String assetPath, {
double width,
double height,
BoxFit fit = BoxFit.contain,
Color color,
alignment = Alignment.center,
String semanticsLabel,
}) {
// `kIsWeb` is a special Flutter variable that just exists
// Returns true if we're on web, false for mobile
if (kIsWeb) {
return Image.network(
assetPath,
width: width,
height: height,
fit: fit,
color: color,
alignment: alignment,
);
} else {
return SvgPicture.network(
assetPath,
width: width,
height: height,
fit: fit,
color: color,
alignment: alignment,
placeholderBuilder: (_) => Container(
width: 30,
height: 30,
padding: EdgeInsets.all(30),
child: CircularIndicator(),
),
);
}
}
}
#aterenshkov's approach worked for me (see comments under Jack's answer). Here are the details to implement...
iOS / Android
child: SvgPicture.asset('assets/yourimage.svg')
Web
// remove assets folder reference
child: SvgPicture.asset('yourimage.svg')
Combine these 2 together...
import 'package:flutter/foundation.dart'; // provides kIsWeb property
...
child: kIsWeb ? SvgPicture.asset('yourimage.svg') : SvgPicture.asset('assets/yourimage.svg')
My Flutter web app would render SVGs in a desktop web browser but not a mobile web browser using flutter_svg. I found it necessary to build with canvaskit support in order for SVGs to render on mobile:
flutter build web --web-renderer canvaskit
However, the docs state that canvaskit adds about 2MB in download size, which was a dealbreaker for me. Sad to say, but I will be using raster images until this is resolved.
flutter_svg version 1.0.0 is out since Dec 2, 2021 including web support. So there is no longer a blocker to use svg images inside a Flutter project.
#RumbleFish has nicely but using ternary operation at many can make the code messy.
My approach to this is:
Create an Extension Function on String to replace assets/ from the path.
extension ForWeb on String {
String forWeb({required bool web}) => web ? this.replaceFirst('assets/','') : this;
}
Now in code:
SvgPicture.asset("assets/images/logo.png".forWeb(web: kIsWeb));
I am loading images using Image.network for each item in a list using the following code:
Image getEventImageWidget(AustinFeedsMeEvent event) {
return event.photoUrl.isNotEmpty ?
Image.network(
event.photoUrl,
width: 77.0,
height: 77.0,
) : Image.asset(
'assets/ic_logo.png',
width: 77.0,
height: 77.0,
);
}
When I scroll up and down, the list sometimes hangs when loading the images. Is there a way I can load the images on a background thread? What can I do to help fix scrolling performance?
NOTE: When I looked back at this, I found that the images that I was using were really large.
There are two was to speed up the rendering of your ListView of images.
The first is to set the cacheExtent property to a larger value in your ListView constructor. This property controls how much offscreen widgets are rendered, and will help by causing the rendering to start a bit sooner.
The second is to pre-cache your images using precacheImage. Flutter has an in-memory cache, so it is generally to necessary to cache everything to disk to get good read performance. Instead, you can ask Flutter to download these images ahead of time so that they are ready when the widget is built. For example, if you have a list of urls of your image, then in an initState method you could ask Flutter to cache all of them.
final List<String> imageUrls = [ /* ... */ ];
#override
void initState() {
for (String url in imageUrls) {
precacheImage(new NetworkImage(url), context);
}
super.initState();
}
Are you sure your images are not very heavy? Check the size of the images first.
Also you can use the package named: cache_network_image
It's very simple :
new Image(image: new CachedNetworkImageProvider(url))
UPDATE (Package was updated)
CachedNetworkImage(
imageUrl: "http://via.placeholder.com/350x150",
placeholder: (context, url) => new CircularProgressIndicator(),
errorWidget: (context, url, error) => new Icon(Icons.error),
),
you can also use:
FadeInImage.assetNetwork(
placeholder: 'assets/ic_logo.png',
image: event.photoUrl,
height: 77.0,
width: 77.0,
fit: BoxFit.cover,
fadeInDuration: new Duration(milliseconds: 100),
),
but yeah, per diegoveloper, you sure your images aren't huge? Listview has no problem rendering anything that's close to reasonable in size.
You can create a Stateful Widget that creates the ListView with placeholder images, then have it have an async method you call after build() that loads the images from network (one by one) and then changes the state of the previously mentioned widget to replace the placeholder with the correct image. As a bonus, you can create a cache that stores the images so they don't have to be downloaded each time the ListView enters scope (here you would have the async method look in the cache for the image and if it doesn't find it there, download it).
As a side note, this would obviously require giving each of the images in the ListView an index.