How do you prevent Flutter's Image.network from caching?
I am trying to load random images from unsplash with it using one URL that returns a new Image on every query but it is only giving me the same one. Hence I think Image.network is caching.
I wrote this dartpad gist that illustrates the problem:
https://dartpad.dev/3ffc6011cedea9521997cf83bbfeb9c8
You'll notice it loads the same image three times but that link actually produces a different image on each hit.
Try and random number at the end of your request like:
Image.network("https://source.unsplash.com/collection/209138/400x100"),
Image.network("https://source.unsplash.com/collection/209138/400x100?2"),
Image.network("https://source.unsplash.com/collection/209138/400x100?4"),
You can randomise the numbers to make sure you always get new images
Related
I am using Flutter to develop a game. I would like to display 1-2 thousand small images that can move (via a AnimatedPositioned widget for example) on the screen. The resolution will be very low of each individual image of course. I'm unsure if Fluttter has a feature or is able to handle such a feature and would like to know if it's possible, and if so, best method to get there.
I've tried displaying 1000 images using Image.asset('my_image.PNG') in a GridView.builder(), using the profiler, my emulator was only able to achieve 6fps average.
I have a function that returns Stream<List<int>> representing the image content that I want to display on an Image widget.
I know that I can transform this Stream into Uint8List and send it to the Image.memory constructor like this:
Image.memory(Uint8List.fromList(await fileStream.expand((element) => element).toList()));
However, using this method, I have to wait until the Stream is fully completed in order to display something. Which is not what I want.
My requirement is to display the part of the image that is already loaded and to continue updating the display as more bytes are received. This is something that you can see in web browsers when you open a large image, especially when the internet connection is slow.
How can I implement this using an ImageProvider in Flutter? I have no idea about how to start. I have read the official documentation but I can't figure it out. Can you point me to a well-detailed tutorial about this topic?
Flutter recommends to use cached_network_image here https://flutter.dev/docs/cookbook/images/cached-images. I used it and it worked fine. I tried NetworkImage and it worked, too.
I read from the doc that NetworkImage also caches the downloaded image locally. So what's the point in using cached_network_image instead of NetworkImage? Is there a comparison how their caching strategies differentiate from one another? Thanks!
The difference is significant and really helpful too...as you know fetching image from network takes time so cached network image provides you options for space holder to show when loading and error widget when can't load which are not there in NetworkImage. As a developer, you must be ready for every situation so that's the reason for recommending cached network images.
UPDATE:
ImageNetwork now has a loadingBuilder and errorbuilder parameters, so it too can now show a loading indicator similar to cached network image. But in CachedImageNetwork once the image is loaded it's cached in the system until the URL changes, which gives faster loading of the image every time and there are also many more features to explore please see official read me documents.
So still I prefer cachedNetworkImage until NetworkImage has similar features.
Hope you understand! Otherwise, let me know in the comments down below!
The difference is the cashed network image have a loading indicator when the image being fetched from the internet and show error icon if happen something error while fetching the image. While network image don't have this features. https://pub.dev/packages/cached_network_image
I am newly in iOS development.I have to make an application for a car dealer in which i have to show different cars with different colors.Please tell me the best way because i have to fetch lots of images every time from the web server.How can i reduce the rendering time in fetching the images.
Please consider i am very new in ios development and need your help.
If you have any sample application please share it with me.
You can use DB to store images as BLOB and also fetch images only when there is update at server.
First, make sure you send images that are no larger than needed.
If you have a list view that shows pictures of the cars, have a webservice send you premade thumbnails that are (preferably) exactly the right size.
Second, Make sure the images are loaded separately from the data set.
The best place to do this, would be in the controllers for your UITableViewCell.
Just have your UITableViewCell start their own thread to download and display the image as soon as they come into view.
Third; caching.
Make sure you save local copies of the thumbnails, and make sure the Table View Cells search for local copies of the images, and load those instead of downloading them if they are already locally present.
you can do:-
use lazy loading
use paging
use predicates for searches
use fast enumeration
these things in general will keep your app smooth
If you are going to show images in UITableView then you can use lazy loading. It will load images only for the displayed rows and once image for any row index has been downloaded, it will not repeat downloading for that row index. So its faster and useful.
I am trying to lazily load a dynamic thumbnail view.
I have to put images in thumbnail view one by one and until images are not available I have to display temporary image like placeholder. Any guidelines please?
See the accepted answer in this thread. You wouldn't need the last-in first-out stack, but it shows how to load images asynchronously using grand central dispatch, which is quite straightforward. You don't need to think about complicated thread management. :)
You could go about like this -
Create a UIImageView with a default placeholder image.
Fetch your image in a background thread. You want to do it like this
because, fetching image in the main UI thread blocks it till the
image is fetched, which severely hampers UI responsiveness. There
are several libraries available which do this for you. They even
cache the images. SDWebImage is great!
See if you get a valid HTTP 200 response back i.e. a valid image. If yes, then replace the new image with placeholder image. Else let the placeholder image be.
Hope this helps...