I have a web application running on local host. The requirement is to load multiple rectangular jpg images (96 images, average 7k in size each) and show on home page when it runs. Images are showed in a grid of 8x12 rows/columns. I am loading image by setting the 'src' attribute of the 'img' in javascript. The url assigned to the 'src' attribute is same for all images but the image id is different. Images are loading but the main issue is that they are not loading very quickly and they are some what loading in a sequence means 1,2,3,4... and so on but some images are not loaded in sequence. I want to improve the performance of this page. I have tried the figure out the timings at different points like:
When call is originated form client (image src attribute is set)
When server is receiving call. (the page on server which serve individual image)
When server is about to return the image.
When on client side image is received/showed (image loaded event called in javascript)
It turned out after looking at the collected data that main time is lost between 1 and 2 above that is between the client side call is originated and server is receiving call for a particular image.
I have also tried setting parameters like maxWorkerThreads, minWorkerThreads, requestQueueLimit and maxconnection in machine.config but no significant improvement yet.
Can someone please help me in this situation as i am stuck here since many days and i am really short of time now. Desperately needs to improve the performance of these images loads.
Thanks in advance.
Since you stress the lack of time, I would advise you to try a jQuery plugin that loads images on demand. The gallery in which you load the pictures, does the user scroll in it? Or is it 1 big field?
If it's a gallery the user can scroll in, I'd strongly suggest you take a look at lazyload. What this plugin does, is it fetches the image only when it is needed. As long as it's not on the screen, it will not be loaded. For a brief example, have a look at this demo.
I hope this can help you out.
Related
I am displaying images from the internet in a vertical ListView. I fetch the images using http.get (not using cached network image cuz I do not want to cache the images). Then I insert the image Uint8List into image.memory(). What happens is that as the user scrolls the list and images are loading, the ram keeps increasing until the whole app crashes. Any ideas what to do ?
Yeah, this is the normal behavior. I don't know why exactly. My theory is that the images by default are disposed if the dart objects holding references to them are garbage collected rather then when the widgets are knocked off the widgets tree, but don't take my word for it- that's just my personal reasoning. It may be completely wrong.
To get around this, I use Extended Image pakcage It's constructors take a bool clearMemoryCacheWhenDispose which disposes of images in RAM in scroll lists. You may do that or visit the package code to see how he's doing it, and replicate it.
Other advice I can give is to make sure your images are of the appropriate size. If you are loading your images locally check this part of the documentation to have different dimensions selected for different screen sizes https://flutter.dev/docs/development/ui/assets-and-images#loading-images
If you are fetching your images from network which is more likely, make sure their sizes are appropriate, and have different sizes served if you can. If you don't have control over that set cacheWidth and cacheHeight in Image.memory these will reduce the cached image in memory (RAM). You see by default Flutter caches images in full resolution despite their apparent size in the device/app. For example if you want your image to display in 200x200 box then set cacheWidth to 200 * window.devicePixelRatio.ceil() you will find window in dart:ui, and if you only set cacheWidth, the ratio of your images will remain true. Same true if you only set cacheHeight. Also do use ListView.builder as suggested.
I am disappointed at how little is said about this in Flutter docs. Most of the time people discover this problem when their apps start crashing. Do check your dev tools regularly for memory consumption. It's the best indicator out there.
Cheers and good luck
I was having the same issue and found a fix thanks to #moneer!
Context:
Users in my app can create shared image galleries which can easily contain several hundred images. Those are all displayed in a SliverGrid widget. When users scrolled down the list, too many images were loaded into RAM and the app would crash.
Things I had already implemented:
Image resizing on the server side and getting the appropriate sized images on the client based on the device pixel ratio and the tile size in the gallery
I made sure that my image widgets were properly disposing when out of view, but the memory size kept building up as the user scrolled through all the images anyway
Implement cacheHeight to limit the size of the cached image to the exact size of the displayed image
All these things helped but the app would eventually still crash every time the user scrolled down far enough.
The fix:
After some googling I stumbled upon this thread and tried the extended_image_package as #moneer suggested. Setting the clearMemoryCacheWhenDispose flag to true fixed the issue of the app crashing as it was now properly clearing the images from memory when they were out of view. Hooray! However, in my app users can tap on an image and the app navigates to an image detail page with a nice Hero animation. When navigating back the image would rebuild and this would cause a rebuild 'flicker'. Not that nice to look at and kind of distracting.
I then noticed that there's also an enableMemoryCache flag. I tried setting this to false and that seems to work nicely for me. The Network tab in Dart DevTools seems to show that all images are only fetched from the network once when scrolling up and down the gallery multiple times. The app does not crash anymore.
I'll have to more testing to see if this leads to any performance issues (if you can think of any please let me know).
The final code:
ExtendedImage.network(
_imageUrl,
cacheHeight: _tileDimension,
fit: BoxFit.cover,
cache: true, // store in cache
enableMemoryCache: false, // do not store in memory
enableLoadState: false, // hide spinner
)
I had a similar issue when I loaded images from files in a ListView.
[left-side: old code, right-side: new code]
The first huge improvement for me: not to load the whole list at once
ListView(children:[...]) ---> ListView.builder(...).
The second improvement was that images are no longer loaded at full-size:
Image.file("/path") ---> Image.file("/path", cacheWidth: X, cacheHeight: Y)
These two things solved my memory problems completely
Ideally caching happens kind of by default after some conditions are fulfilled. So its upon your app to be responsible to handle and control how the caching will happen.
Checkout this answer
https://stackoverflow.com/a/24476099/12264865
recently I made a website for my photography. htttp://www.simotamas.com
I am a newbie, so its not the best site but it works fine for me, I got only one problem, when a site is loaded on a device for the first time, the gallery loading time takes up to 1-2 seconds.
Could you guys please check if I mess up something with the code?
Or should I made the pictures even smaller?
Any way I could increase the loading performance.
I would be really thankful for any advice.
Some points you can consider
Use thumbnails for preview (low resolution) , while clicking load actual image.
Load images of only visible part first then load the images in bottom. (May affect user experience)
if you have cpu power , use any libraries like cache tools or compression tools like
https://nielse63.github.io/php-image-cache/ . benchmark it carefully.
use gzip if you are not using gzip compression for your server.
The fact your website doesn't wait for the image to load is considered a plus (look into asynchronous web page content loading for a good read) that said you should compress your images before uploading them.. tinypng.com is a nice tool for it... But if it's a photography website doing so would reduce picture quality... Try to play with Photoshop save settings to find your ideal compromise between quality and size with respect to "memory" size... Pictures are heavy.. high definition and resolution will obviously result in heavier files to download
Update: another thing you could do is actually display (smaller) thumbnail and only load the full picture on request. I.e: user clicks and image opens in new tab
It would help if you create smaller thumb versions of your images so the browser can initially load these ones for the overview and no need for scaling way to big images down while rendering the page. An image should always be downloaded in the dimension it's going to be presented.
My website for architectural visualization: http://www.greenshell3d.com
I noticed on the networking tab / incognito it takes 15 seconds or so to load the above-the-fold content. (most notably the image slideshow.)
Some of the images in the slideshow load at the very end instead of the beginning of the website load process. Now I understand the browser handles this order, but perhaps there is another way. As it stands, the bounce-rate is too high and I expect it is because of load time.
I've seen a jquery snippet on github that allows one to control the order of image loads - do you think this is a good option? I'd be glad to hear any opinions before investing the time to fix this.
Any ideas? Thanks!
You said you are interested in any opinions as well, so first some general thoughts: There is no page fold. The web that we produce content for exists in so many different screen sizes + resolutions that it’s impossible to say "The fold is below this big image!". Yes, Google changed the pagespeed insights tool to make people load stuff on top of the page first, but I think their wording there is really bad.
Now to your image loading issue:
The first thing I would recommend is to reduce the size of all the images. They seem to be around 280 - 300 kb per image and you have a few of them. Since there is a translucent overlay over them anyways you can probably get away with reducing the image quality without people noticing it (because they don’t see the image directly). Play around with the values here.
I would then look into optimizing the code for the slider to load the first image first, then the rest of the page and the other images asynchronously maybe after that. Another trick could be to increase the slide fade time from the first slide to other slides so the slider doesn’t change if the next image isn’t ready yet. You said you found a jQuery script to implement that, that’s where I’d start.
As a general guideline: the position of requests in the source code usually determines the load order of things on the page. If your images are requested by JavaScript at the end of the page, that lead to the images being loaded later than you want them to be loaded.
I have an app that allows users to take pictures and store them in the IsolatedStorage. These images are then retrieved to display them in a list. The app suffers from performance issues when there are more than 30+ images in the list. It is taking a long time to retrieve these images from the storage and bind them to the list. A lot of times, the app is just closed by OS because it takes too long.
Also, I think as better resolution devices are coming in the market, the images are getting created with bigger sizes and affecting performance even more.
I need some guidance on how to resolve this. Couple of things I have though about:
1) how can I asynchronously retrieve every image to be retrieved from IS so the page can load but the images are being retrieved in async fashion. Any sample code is appreciated.
2) the other approach will be where I create a thumbnail photo of the actual photo (smaller size and resolution) while storing the original photo and use this thumbnail photo in binding to the list later. If this should be done, then how should I go about processing the image on the fly to create a smaller size thumbnail version of the original photo.
Any other ideas are appreciated as well.
Thanks for your time.
If you are able to, I would recommend using the Async CTP and making the code that loads images from isolated storage async. The methods that generate the thumbnails can be async as well.
If you cannot do this (add these dependencies to your project), use a BackgroundWorker. Perhaps this article can help you get started.
This will allow your UI to be responsive while processing continues on threads in the background.
Do not pretend the Isolated Storage as a SQL Server. There will be great performance difference. If you want to process too much data, send them to server.
However, there is a method for getting a thumbnail. You can use it:
http://msdn.microsoft.com/en-us/library/system.drawing.image.getthumbnailimage.aspx
Also, please check this answer:
Create thumbnail image
We use large background images (hi-res photos, up to 700 KB) for our page design.
It's part of the experience of the site that as you browse around, you see different images.
At the moment a different (random) image is loaded on each page request, from a pool of ~15 images, which could grow over time.
I'm looking for a sane way to optimize this:
To avoid the user having to download a big image file on every page view
To reduce load on the server (is this an issue, will the server keep the images in memory?)
The ideas I have so far include:
A timer which loads a different image at set intervals
Progressively loading other images in the background with ajax
Associating images with specific content (pages, tags)
The question is, how to keep it feeling somewhat random, while minimizing page load times and server hit?
I usually avoid sites with huge images, I am very impatient. I would rethink your design.
As a first step you should make sure, that the images can be properly cached:
use sane urls (no session id's etc)
set appropriate http headers ETag
Firstly, hearing that the background-images alone are 700kb astounds me. In addition to the content ON screen...that is a pretty heavy site.
For starters, I would try to use image compression tools. Two tools come to mind Imagemagick and PNGCrush. PNGCrush is excellent in reducing all the extraneous metadata attached to photos, without compromising photo quality.
I only recommend this as compressing the images will assist you in enabling the user to download a smaller quantity of content, which means quicker load times, which...at the end of the day...is what users want.
I would also cache the images, such that when a user re-visits the site, the image is already cached on their end. This minimises the HTTP requests that are made each time a user visits your site.
An example of where this technique is used on a commercial site is www.reactive.com. If you look the /js/headerImages.js file, they make use of image caching. Funnily enough, you will find the same src code at: http://javascript.internet.com/miscellaneous/random-image.html
Considering that you have mentioned that images are randomly loaded, I am assuming you are using a Javascript library such as jQuery to create the effect.
If you are, you can minimize page load times by using a CDN as opposed to referencing to a local copy of the jQuery lib which is stored on your server. I have performed performance testing on a site I made for a client, and over an average of 20 hits, saved 1.6 seconds through this technique!
Hope that helps for now :)