My webpage uses a lot (1000+) gifs and displays different gifs using 'if' and 'getElementbyId', would it run quicker if I dropped the if(map(x,y)!=0){... to change the scr and just used a gif which was transparent?
Googled to heck but it's a hard question to word, if a same/similar has been posted please point me there.
Many Thanks
First you said about getElementById which is a part of javascript - A client side scripting language, so that is not a big reason to be worried about.
You said 1000+ .gif images.
Use concept of Sprites in this case
This will allow you to download all your images in one go.
This will also reduce some of downloading burden from your server.
To work with sprite technology, Visit this link, I believe this is what you need.
Create an Object Pool with Images and load them on the initialization step. Load them in batches and extend pool with new images if required.
While loading images show spinner. It will be loaded long for a first time, after that a browser will put them in cache.
If you have an opportunity to combine different little images in one (sprite), do it! because it is faster to load one big image, then a lot of little.
Related
I want to know what are the ways to load images gracefully in a html website. I'm sure you know what I'm talking about. There is plenty of websites where images load slowly, slow down loading of the website core/content and make user experience really bad.
I'm looking for ways which let the
website core/content to be loaded
first, and images to be loaded last.
I found this while searching:
Javascript/jQuery preloader tutorial
Working example of above tutorial
However, this seems to be cosmetic, it doesn't actually pre-load anything and doesn't boost performance either. It simply displays a .gif until the image has fully loaded.
I've also seen websites where images
first appear very croppy and their
quality improves over a couple
seconds. How is this done?
It is called lazy loading.
There are a lot of results about it on google.
I've also seen websites where images first appear very croppy and their quality improves over a couple seconds. How is this done?
This happens when the images are interlaced. PNG files, among other types, can be interlaced.
Wikipedia Link for Interlacing
This is done when the image is created/saved.
Can any of you help me to be able to show pictures as fast as facebook does!
Facebook is incredible to watch pictures at, because the pictures are kind of preloaded I think.
Often ved you view galleries on other sites, it is a pain in the a**, because it is so slow every time you change picture.
I think you need javascript to do it!?
Depending on your implementation, you could do this with some ajax and hidden dom elements.
Suppose you have a gallery with a slideshow.. You could insert a hidden dom element with the picture next picture of the slide show for each load. This would cause the image to be loaded. If you then were to use JS to insert that same image tag later, the browser would rely on it's cache rather than fetching it form the server since it already has that photo.
This is kind of a broad question but I think this approach would work. You would probally be better off not reinventing the wheel and seeing what Image prefetch librarbies based on JQuery or whatever are available to you..
Facebook compresses images to extremes. Try it yourself, take an image you are having trouble with and upload it to Facebook. Then check the size of the image, you will know why. Once I did a small test by uploading 17429 bytes image and it compressed it to 18757 bytes, a complete 7% increase from the original size!
At that compressed size, you can implement some sort of prefetch next image for display. Along with, I think, they have extremely good infrastructure.
Facebook uses Bigpipe, there is an open implementation in the works called openpipe
Bigpipe pushes the content to the browser when server stopped processing, so user will notice that it is faster.
It basically loads pagelets, when they are ready for the user, at the browser the implementation is Javascript based, and you must push the info to the client with your preferred server language.
First of all, facebook heavilycompresses images. Many other websites don't. Facebook also has a faster network than most other websites.
With the small image size, the client can prefetch the next image.
Preloaded would mean loading when the page is loaded, which is what happens with an <img> tag. No, it's simply because the file size is smaller.
If your wanting images to be viewed quicker on your site first make sure the images are decently compressed and aren't any bigger than they have to be. The amount of times I have seen websites using an extremely large image scaled down to fit in an element 5 times smaller is just ridiculous.
You can check out these sites that has many implementations and links on how to pre-load / pre-fetch images (css, JavaScript, ajax)
http://perishablepress.com/press/2009/12/28/3-ways-preload-images-css-javascript-ajax/
Since your question was tagged with 'jquery' here is one just for that.
http://engineeredweb.com/blog/09/12/preloading-images-jquery-and-javascript
My demo is here.
Basically, I have a HUGE image (19160px × 512px to be exact, just under 2MB) that I transition the backgroundx using javascript to make it appear as if a transformation was happening.
I cannot compress the image much more without ruining its quality dramatically. Is there another way that I can achieve this with the same level of cross-browser and not rely on plugins like flash, but have it load faster?
Have you considered making this a video?
It might improve loading time somewhat.
Also, another idea. Have you tried using only the first and last image, putting the last one on top of the first, give it opacity:0 and fade it in using JavaScript (e.g. jQuery)?
The effect won't be 100% identical to what you have now, but it might look good enough to please the client, and it would reduce loading time to a bare minimum.
If both ideas won't work for you, I think the first 10-12 frames could be compressed more effectively as GIF images. (It's an estimate, I haven't tried.) You would have to split the image into multiple div s to do that and change the method you use to switch the images, and you would have more requests, but it could be worth it.
If it is a jpeg, you can always use progressive encoding. it will become clearer as it is downloaded.
There is also an interlaced
"Progressive JPEG" format, in which
data is compressed in multiple passes
of progressively higher detail. This
is ideal for large images that will be
displayed while downloading over a
slow connection, allowing a reasonable
preview after receiving only a portion
of the data. -Wikipedia
Slice it like Google Maps.
If you want to change that many pixels on the screen at once, you'll have to get them to the client somehow. You could chunk it into multiple images and use something other than background-x, but then you expose yourself to other potential network interruptions along the way.
The only alternative I can think of to precomputed images like this one is to do the computation on the client - start with the full-colour image and manipulate it using the client's CPU. Your options here involve canvas or CSS3 or a plugin.
I'm not a big fan of Flash but in this case it seems like the right tool for the job (unless you need it work on the iPhone). If you don't have the Flash authoring tool you can use the free Flex compiler.
See http://www.insideria.com/2008/03/image-manipulation-in-flex.html
Make it into an animated gif? Break it up into individual parts to remove all the area that is obscured by content.
UPDATE: This question is outdated, please disregard
So.. my idea is to load a full manga/comics at once, with a progress bar included, and make sort of a stream, like:
My page loads the basic (HTML+CSS+JS) (of course)
As done, I start loading the imgs(the URLs are stored on JS var) from my server, one a time (or some faster way) so I can make a sort of progress bar.
ALTERNATIVE: Is there a way to load a compresses file with all imgs and uncompress at the browser?
ALTERNATIVE: I was also thinking of saving then as strings and then decode, they are mostly .jpg
The images don't have to show right away, i just need the callback when they are done.
XTML and HTML5 is acceptable
What is the fastest way to load a series of images for my website?
EDIT
Since #Oded comment.. the question is truly what is the best tech for loading images and the user don't have to wait everytime is turns the 'page'. Targeting a more similar experience like when you read comics in real life.
EDIT2
As some people helped me realize, I'm looking for a pre-loader on steroids
EDIT3
No css techs will do
If you split large images into smaller parts, they'll load faster on modern browsers due to pipelining.
ALTERNATIVE: Is there a way to load a compresses file with all imgs and uncompress at the browser?
Image formats are already compressed. You would gain nothing by stitching and trying to further compress them.
You can just stick the images together and use background-position to display different parts of them: this is called ‘spriting’. But spriting's mostly useful for smaller images, to cut down the number of HTTP requests to the server and somewhat reduce latency; for larger images like manga pages the benefit is not so large, possibly outweighed by the need to fetch one giant image all at once even if the user is only going to read the first few pages.
ALTERNATIVE: I was also thinking of saving then as strings and then decode
What would that achieve? Transferring as string would, in most cases, be considerably slower than raw binary. Then to get them from JavaScript strings into images you'd have to use data: URLs, which don't work in IE6-IE7, and are limited to how much data you can put in them. Again, this is meant primarily for small images.
I think all you really want is a bog-standard image preloader.
You could preload the images in javascript using:
var x = new Image();
x.src = "someurl";
This would work like the one you described as "saving the image in strings".
Spriting
Just have a look how facebook does it: http://b.static.ak.fbcdn.net/rsrc.php/z3JQK/hash/11cngjg0.png
One image that loads FASTER than series of small images. To display the icon you simply create a div with fixed dimensions, and move the background inside it. Your div works as a viewport for the big image. You use background-position to move to appropriate part of the image. Everything else is hidden.
Different domains
Something you probably didn't know - Internet Explorer has a limit of connections per server. You can read about it here: http://support.microsoft.com/?scid=kb;en-us;183110&x=17&y=11 (here are exact numbers).
What it means - if user is using IE7, he will be able to load ONLY 4 (or 2) files at the same time from your server regardless his internet connection speed.
To speed things up, you could create few subdomains: server1.mydomain.com, server2.mydomain.com, server3.mydomain.com etc - and then user can download many files a lot quicker, because you use different hosts to serve different files.
As done, I start loading the imgs(the
URLs are stored on JS var) from my
server, one a time (or some faster
way) so I can make a sort of progress
bar.
Your browser already downloads the HTML first, that's how it knows to load any JS/images you reference. You are trying to invent something that already exists.
Just make sure your manga is made up of lots of images of a known size, which you specify in your img tags. Most browsers have some sort of progress bar to show that it's loading resources for you. You're not going to make loading large images faster unless you improve either the speed at which your server serves them, or your user's internet connection, or you compress them to make your image files smaller (likely at the cost of image quality).
Note: JPG and PNG are already compressed.
You can try using a "CSS sprites" technique. Basically the idea is you use your favorite image editing program to stich all your images into a single image. It's faster to send this because you lose the per/file overhead in terms of encoding the image and sending the image. On the client side you use CSS to only select the portion of the total image that is used in any one place.
http://www.alistapart.com/articles/sprites/
http://www.fiftyfoureleven.com/weblog/web-development/css/css-sprites-images-optimization
AND/OR
You can use lazy loading to only load images when they come into view.
http://www.appelsiini.net/projects/lazyload
Image preloaders have been around for ages. You really do not need to load them all at once, you can do it on demand [when the person loads the next page, you can fetch the image after it]
My page loads the basic (HTML+CSS+JS) (of course)
As done, I start loading the imgs(the URLs are stored on JS var) from my
server, one a time (or some faster way) so I can make a sort of progress bar.
The images don't have to show right away, i just need the callback
when they are done.
If you want to load 10 images as fast as possible, place 10 <img> tags on the page, one for each image. Use Javascript to hide all the but the currently viewed image; add next/back links that use JS to hide the current image and show the next one. Many browser already have some form of progress bar, and by doing things with regular old HTML, it will function correctly.
You're trying to re-invent all this functionality with Javascript for no good reason. You're not going to do it better than the browser.
All that said, this is probably a bad idea. You might dump 15MB of comic pages into the browser window only to have the user leave after reading the first page. Rather than trying to pre-load all images, you should use JS to always keep the next page (or two) pre-loaded, not the entire thing.
Here's something you can try, which by happenstance I just coded up:
(function() {
var imgs = [ "image1.png", "image2.png", ... /* all your image names */ ],
index = 0,
img;
function loader() {
if (index >= imgs.length) return;
(img = new Image()).onload = loader;
setTimeout(function() { img.src = "/path/to/images/" + imgs[index++]; }, 1);
}
loader();
})();
Plop all your image names (or the ones you want to preload) into the array, and make sure this script starts up when your page(s) start loading. It'll work its way through the list of images, loading them, and then moving on to the next one when each image finishes. (The setTimeout call is to make sure that the "onload" handler doesn't get called while you're still inside a handler.)
You'd probably want to do this for lots of the "nuts and bolts" images for your whole site - in other words, each page would try to load images for everything. Once they're in the cache, of course, this won't take a significant amount of time. Alternatively, you could run this script only on a couple pages, like "login" screens and the main "home" page. Of course, if you've got a site like Flickr, then you probably wouldn't want to preload all your images :-)
I am loading a bunch of images for a GUI which will pick attributes for my clients product.
Is it best to pre-load all the images at the start (which I'm guessing would take some time) and then have the GUI have full functionality or is it better to load images on the fly.
Essentially i am working on a picture/poster framing application. I have about 20+ frames that will be able to be selected by the user and when a frame is clicked I change the images for the frame on the display in the GUI.
I am using Jquery. Any insight would be helpful as to the best case scenario for this.
And if I will be pre-loading all the images how do I put one of those loading bars on the screen like you see in Flash or a loading gif like i've seen in Ajax?
Thanks
Mike
Why not do both?
You can load images lazily, but also hook $(document).ready() to pre-load the images. That way, if the user accesses an image before it's preloaded, it comes in then; if the user waits long enough it will be instantaneous.
This technique is common with things like menubar roll-overs.
Depends on frame images' size...if they are small like 1 - 2K, I'd load the images dynamicaly, otherwise you can preload, but be sure to set the headers right so only once are read and fetched from cache next time.
As for progress bar, I suggest you check this article (talks about preloading images in jQuery and includes progress bar) on Ajaxian.
The correct answer depends on many factors. How large are the images and how many are there? Will loading all images at the start cause severe lag? As Jeff Atwood said Performance is a feature.
I would err on the side of a better performing app, rather than loading everything up front.