I've recently bumped into facelift, an alternative to sIFR and I was wondering if those who have experience with both sIFR and FLIR could shed some light on their experience with FLIR.
For those of you who've not yet read about how FLIR does it, FLIR works by taking the text from targeted elements using JavaScript to then make calls to a PHP app that uses PHP's GD to render and return transparent PNG images that get placed as background for the said element, where the overflow is then set to hidden and padding is applied equal to the elements dimensions to effectively push the text out of view.
This is what I've figured so far:
The good
No flash (+for mobiles)
FLIR won't break the layout
Images range from some 1KB (say one h3 sentence) to 8KB (very very large headline)
Good documentation
Easy to implement
Customizable selectors
Support for jQuery/prototype/scriptaculous/mooTools
FLIR has implemented cache
Browsers cache the images themselves!
The bad
Text can't be selected
Requests are processed from all sources (you need to restrict FLIR yourself to process requests from your domain only)
My main concerns are about how well does it scale, that is, how expensive is it to work with the GD library on a shared host, does anyone have experience with it?; second, what love do search engines garner for sIFR or FLIR implementations knowing that a) text isn't explicitly hidden b) renders only on a JavaScript engine.
Over the long term, sIFR should cache better because rendering is done on the client side, from one single Flash movie. Flash text acts more like browser text than an image, and it's easy to style the text within Flash (different colors, font weights, links, etc). You may also prefer the quality of text rendered in Flash, versus that rendered by the server side image library. Another advantage is that you don't need any server side code.
Google has stated that sIFR is OK, since it's replacing HTML text by the same text, but rendered differently. I'd say the same holds true for FLIR.
I know that with sIFR, and I assume with FLIR that you perform your markup in the same way as usual, but with an extra class tag or similar, so it can find the text to replace. Search engines will still read the markup as regular text so that shouldn't be an issue.
Performance-wise: if you're just using this for headings (and they're not headings which will change each page load), then the caching of the images in browsers, and also presumably on the server's disk should remove any worries about performance. Just make sure you set up your HTTP headers correctly!
since FLIR is IMAGES and sIFR is flash i would imagine that it would be a bit more resource intensive to use sIFR. I havent run any tests but it seems logical.
Search engines search sIFR better than FLIR because some search engines can go into the text of a flash document
I don't know much about sIFR because FLIR worked, and it "felt" better to me than Flash. Just looking at the sIFR 3 beta demo page I noticed that it doesn't seem to react to browser preference text resizing. That is, I increase my font-size in Firefox (ctrl-+) and reload the page, the headings stay the same size.
To those who know sIFR, is this an actual limitation of the script or did they just do the demo page wrong?
If it actually doesn't handle this, I'd call that a major advantage for FLIR, which does work this way. People with impaired vision who don't use screen readers probably don't appreciate that the text doesn't resize to their preference.
That said, from a quick glance at sIFR's API, you should be able to make resized text work in sIFR. I'd consider it a bug to be fixed, not an essential disadvantage of the method.
Woff files is the best solution.
http://www.fontsquirrel.com/tools/webfont-generator
Related
I am looking for a proper way to implement lazy loading of images without harming printability and accessibility, and without introducing layout shift (content jump), preferrably using native loading=lazy and a fallback for older browsers. Answers to the question How lazy loading images using JavaScript works?
included various solutions none of which completely satisfy all of these requirements.
An elegant solution should be based on valid and complete html markup, i.e. using <img src, srcset, sizes, width, height, and loading attributes instead of putting the data into data- attributes, like the popular javascript libraries lazysizes and vanilla-lazyload do. There should be no need to use <noscript> elements either.
Due to a bug in chrome, the first browser to support native lazyloading, images that have not yet been loaded will be missing in the printed page.
Both javascript libraries mentioned above, require either invalid markup without any src attribute at all, or an empty or low quality placeholder (LQIP), while the src data is put into data-src instead, and srcset data put into data-srcset, all of which only works with javascript. Is this considered an acceptable or even best practice in 2020, and does this neither harm the site accessibility, cross-device compatibility, nor search engine optimization?
Update:
I tried a workaround for the printing bug using only HTML and CSS #media print background images in this codepen . Even if this worked as intended, there would be a necessary css directive for each and every image, which is neither elegant nor generic. Unfortunately there is no way to use media queries inside the <picture> element either.
There is another workaround by Houssein Djirdeh at at lazy-load-with-print-ctl1l4wu1.now.sh using javascript to change loading=lazy to loading=eager when a "print" button is clicked. The same function could also be used onbeforeprint.
I made a codepen using lazysizes.
I made another codepen using vanilla-lazyload .
I thought about forking a javascript solution to make it work using src and srcset, but this must probably have been tried before, the tradeoff would be that once the lazyloading script starts to act on the image elements, the browser might have already started downloading the source files.
Just show me your hideous code, I don't want to read!
If you don't want to read my ramblings the final section "Demo" contains a fiddle you can investigate (commented reasonably well in the code) with instructions.
Or there is a link to the demo on a domain I control here that is easier to test against if you want to use that.
There is also a version that nearly works in IE here, for some reason the "preparing for print" screen doesn't disappear before printing but all other functionality works (surprisingly)!
Things to try:
Try it at different browser sizes to see the dynamic image requesting
try it on a slower connection and check the network tab to see the lazy loading in action and the dynamic change in how lazy loading works depending on connection speed.
try pressing CTRL + P when the network connection is slow (without scrolling the page) to see how we load in images not yet in the DOM before printing
try loading the page with a slow network connection and then using FILE > PRINT to see how we handle images that have not yet loaded in that scenario.
Version 0.1, proof of concept
So there is still a long way to go, but I thought I would share my solution so far.
It is complex (and flawed) but it is about 90% of what you asked for and potentially a better solution than current image lazy loading.
Also as I am awful at writing clean JS when prototyping an idea. I can only apologise to any of you brave enough to try and understand my code at this stage!
only tested in chrome - so as you can imagine it might not work in other browsers, especially as grabbing the content of a <noscript> tag is notoriously inconsistent. However eventually I hope this will be a production ready solution.
Finally it was too much work to build an API at this stage, so for the image resizing I utilised https://placehold.it - so there are a few lines of redundant code to be removed there.
Key features / Benefits
No wasted image bytes
This solution calculates the actual size of the image to be requested. So instead of adding breakpoints in something like a <picture> element we actually say we want an image that is 427px wide (for example).
This obviously requires a server-side image resizing solution (which is beyond the scope of a stack overflow answer) but the benefits are massive.
First of all if you change all of your breakpoints on the site it doesn't matter, so no updating picture elements everywhere.
Secondly the difference between a 320px and 400px wide image in terms of kb is over 40% so picking a "similarly sized" image is not ideal (which is basically what the <picture> element does).
Thirdly if people (like me) have massive 4K monitors and a decent connection speed then you can actually serve them a 4K image (although connection speed detection is an improvement I need to make in version 0.2).
Fourthly, what if an image is 50% width of it's parent container at one screen size, 25% width of it's parent container at another, but the container is 60% screen width at one screen size and 80% screen width at another.
Trying to get this right in a <picture> element can be frustrating at best. It is even worse if you then decide to change the layout as you have to recalculate all of the width percentages etc.
Finally this saves time when crafting pages / would work well with a CMS as you don't need to teach someone how to set breakpoints on an image (as I have yet to see a CMS handle this better than just setting the breakpoints as if every image is full width on the screen).
Minimal Markup (and semantically correct markup)
Although you wanted to not use <noscript> and avoid data attributes I needed to use both.
However the markup you write / generate is literally an <img> element written how you normally would wrapped in a <noscript> tag.
Once an image has fully loaded all clutter is removed so your DOM is left with just an <img> element.
If you ever want to replace the solution (if browser technology improves etc.) then a simple replace on the <noscripts> would get you to a standard HTML markup ready for improving.
WebP
Of course this solution requests WebP images if supported (its all about performance!). On the server side you would need to process these accordingly (for example if an image is a PNG with transparency you send that back even if a WebP image is requested).
Printing
Oh this was a fun one!
There is nothing we can do if we send a document to print and an image has not loaded yet, I tried all sorts of hacks (such as setting background images) but it just isn't possible (or I am not clever enough to work it out....more likely!)
So what I have done is think of real world scenarios and cover them as gracefully as possible.
If the user is on a fast connection we lazy load the images, but we don't wait for scroll to do this. This could mean a bit more load on our servers but I am acting like printing is highly important (second only to speed).
If the user is on a slow connection then we use traditional lazy loading.
If they press CTRL + P we intercept the print command and display a message while the images are loading. This concept is taken from the example OP gave by Houssein Djirdeh but using our lazy loading mechanism.
If a user prints using FILE > PRINT then we instead display a placeholder for images that have not yet loaded explaining that they need to scroll the page to display the image. (the placeholders are approximately the same size as the image will be).
This is the best compromise I could think of for now.
No layout shifts (assuming content to be lazy loaded is off-screen on page load).
Not a 100% perfect solution for this but as "above the fold" content shouldn't be lazy loaded and 95% of page visits start at the top of the page it is a reasonable compromise.
We use a blank SVG (created at the correct proportions "on the fly") using a data URI as a placeholder for the image and then swap the src when we need to load an image. This avoids network requests and ensures that when the image loads there is no Layout Shift.
This also means the page is semantically correct at all times, no empty hrefs etc.
The layout shifts occur if a user has already scrolled the page and then reloads. This is because the <img> elements are created via JavaScript (unless JavaScript is disabled in which case the image displays from the <noscript> version of the image). So they don't exist in the DOM as it is parsed.
This is avoidable but requires compromises elsewhere so I have taken this as an acceptable hit for now.
Works without JavaScript and clean markup
The original markup is simply an image inside a <noscript> tag. No custom markup or data-attributes etc.
The markup I have gone with is:
<noscript class="lazy">
<img src="https://placehold.it/1500x500" alt="an image" width="1500px" height="500px"/>
</noscript>
It doesn't get much more standard and clean as that, it doesn't even need the class="lazy" if you don't use <noscript> tags elsewhere, it is purely for collisions.
You could even omit the width and height attributes if you didn't care about Layout Shift but as Cumulative Layout Shift (CLS) is a Core Web Vital I wouldn't recommend it.
Accessibility
The images are just standard images and alt attributes are carried over.
I even added an additional check that if alt attributes are empty / missing a big red border is added to the image via a CSS class.
Issues / compromises
Layout Shift if page already scrolled
As mentioned previously if a page is already scrolled then there will be massive layout shifts similar to if a standard image was added to a page without width and height attributes.
Accessibility
Although the image solution itself is accessible the screen that appears when pressing CTRL + P is not. This is pure laziness on my part and easy to resolve once a more final solution exists.
The lack of Internet Explorer support (see below) however is a big accessibility issue.
IE
UPDATE
There is a version that nearly works in IE11 here. I am investigating if I can get this to work all the way back to IE9.
Also tested in Firefox, Edge and Safari (mobile), seems to work there.
ORIGINAL
Although this isn't tested in Firefox, Safari etc. it is easy enough to get to work there if there are issues.
However accessing the content of <noscript> tags is notoriously difficult (and impossible in some versions) in IE and other older browsers and as such this solution will probably never work in IE.
This is important when it comes to accessibility as a lot of screen reader users rely on IE as it works well with JAWS.
The solution I have in mind is to use User Agent sniffing on the server and serve different markup and JavaScript, but that is complex and very niche so I am not going to do that within this answer.
Checking Latency
I am using a rather crude way of checking latency (to try and guess if someone is on a 3G / 4G connection) of downloading a tiny image twice and measuring the load time.
2 unneeded network requests is not ideal when trying to go for maximum performance (not due to the 100bytes I download, but due to the delay on high latency connections before initialising things).
This needs a complete rethink but it will do for now while I work on other bits.
Demo
Couldn't use an inline fiddle due to character count limitation of 30,000 characters!
So here is the current JS Fiddle - https://jsfiddle.net/9d5qs6ba/.
Alternatively as mentioned previously the demo can be viewed and tested more easily on a domain I control at https://inhu.co/so/image-concept.php.
I know it isn't the "done thing" linking to your own domains but it is difficult to test printing on a jsfiddle etc.
The proper solution for printable lazy loading in 2022 is using the native loading attribute.
<img loading=lazy>
The recommendation to use a custom print button has been obsoleted as chromium issue 875403 got fixed.
Prior recommendations included adding a custom print button (which did not fix the problem when using the native browser print functionality) or using JavaScript to load images onBeforePrint the latter not being considered a good solution, as loading=lazy, as a "DOM-only" solution, must not rely on JavaScript.
Beware that, even after the bug fix, some of your users might still visit your site with a buggy browser version.
#Ingo Steinke Before one dwells into answers for the concerns that you have raised, one has to go back and think about why lazy loading came about and for what detriment it solved on initiation as framework of thought. Keyword framework of thought... it is not a solution and I would go on a leaf to say it has never been a solution but framework of thought.
Why we wanted it:
Minimise unnecessary file fetching from server - this is bandwidth critical if one is running a large user base. So it was the internet version of just in time as in industrial production.
Legacy browser versions and before async and defer were popularised in JS/HTML, interactivity with the browser window remained hampered until all content was loaded.
Now broad band as we know it has only been around since the last 6-7 years in real sense of manner and penetration. We wanted it because we didn't want to encounter no.2 on low bandwidth. To be honest, there was and still is a growing concern and ideology of minifying and zipping JS and CSS files - all because that round trip to server and back should be minimised so that next item in the list could be fetched. Do keep in mind browsers tend to limit simultaneous downloading connections to around 6 at a time per window or active window. There is reasons why Google popularised the 3 second rule. If above were to let run on as it than 3 second rule will fall on its head as if it did not have legs.
So came along thought frameworks.
Image as CSS background: This came as it did not mess up the visual aspect of the page. Everything remained as it is in its place and then suddenly became colourful. It was time when web pages seemed to have elastic fit i.e. it was that bag which once filled with air suddenly poped-transformed into jumping castle. This was increasingly become bad idea as front end developer. So fixing height and with of the container then run images as background helped and HTML5 background alignment properties upgraded them self accordingly. There was even variant and still used as in use multiple backgrounds one being loading spiril or low end blured image version on top of which actual intended image was fetched. Since level down bacground would be fetched and populated everywhere in single instance of downloading it created a more pleasing visual and user knew what to expect. worked in printing as well even if intended image did not download.
Then came JS version of it by hijacking DOM either through data-src, invalid image tags removing src, and what not. only trigger the change when content is scrolled to. Obviously there would be lag but that was either countered through CSS approach implemented in JS or calculating scroll points and triggering event couple of pixel ahead. They all still work on the same premise.
There is one question that begs to be asked and you have touched it in your pretext .... none of it controls or alters browser native functionality. Browser might as will go fetch the item even before your script had anything to do with any thing.
This is the main issue here. BOM does not care and even want to care about what your script is asking to do all it knows if there is a src property fetch the content. None of the solutions have changed that. If we could change that functionality then thought framework would become solution.
I still believe browsers should not change that just for the sake of it and thus never gained tracking in debates. What browsers have done is pre-fetching known as speculative or look-ahead pre-parser, It is the single biggest improvement in browsers that deserves it credit. Just as we type url in address bar on every chnage of string browser is pre-fetching the content even though I had not typed the whole url. I had specially developed a programme where I grabbed anything that was received at server from these look-ahead pre-parsers. It takes less than second to get response at most times and browsers begin to process it all including images and JS. This was counter the jerky delayed elastic prone display as discussed in No.1 and No.2. It did not reduce the server hit however. The reason why we are doing lazy loading any ways. But some JS workaround gained traction as there was no src property so pre-parser did not fetch the image and was only done so when user actually sent to the page and events were triggered. Some browser have toyed with the idea of lazy loading them self but let go if it as it did not assume universal consistency in standard.
Universal Standard is simple if there is src property browser will fetch the item no if and buts. Imagine if that was not the case OMG hell would break loose on poor front-end developer.
So deep down what you are raising in debate is the question regarding BOM functionality as I have discussed above. There is no work around for it. In your case both for screen and print version of display. How to make sure images are loaded when print command is sent. Answer is simple for BOM print is after the fact. Fact ebing screen display and before the fact being everything before that at BOM/DOM propagation level. Again you cannot change that.
So you have to make trade off. Trade off would come in the form of another thought framework. rather than assuming everything is print ready make it print ready on user command. There is div that pops up and shows printed version of document and then print from there on. UI could be anything it would only take second or so as majority of the content would be loaded any ways and rest will take short amount of time. CSS rules for print could mighty handy in this respect. You can almost see it in action in may places on the internet.
conclusion as we stand today where we are with BOM functionality bundling the screen display and print display with lazy load is not what lazy lading was intended for thus does not provide any better solution then mere hacks. So you have to create your UI based on your context separating the two, to make it work properly.
Im currently building a practice responsive website, what I am doing is taking an exising website, building it up using twitter bootsrap js and css, meaning it will be fully responsive for mobile.
The issue is that there are some large carousels and images on the site. Ideally I would like to just completely remove certain elements, like a carousel for instance, and instead have the options within the carousel as a standard list menu.
It seems the main option is display:none based on media queries, but I am starting to foresee that I will run into big problems for loading time if the entire desktop site is still going to be loaded on the mobile, only elements hidden.
Are there ways to completely exclude html based on browser size? If anyone has any good links or articles that would be great. Or even just opinions, on whether there is actually need to exclude html or not.
Thank you
First off it is really good to see that although you're talking about display:none; you actually still want to display the content without the bells and whistles of the image. Well done you.
The next thing I would look at is if you don't want to load images for a mobile then why are you adding it for the larger sites. If the image isn't providing a function, assisting in explaining the content better, then why not just drop it for the desktop size as well?
If in fact it does help tell a story then you can include the images and some of the popular image services like adaptive images, hiSRC, or PictureFill which will serve the mobile version of the image first and replace with a larger image at higher viewports (but remember, there's no bandwidth test).
Finally, if you do want to serve some different content, then take the advice of fire around including more content with ajax. The South Street toolbox from Filament group can help you out, pay particular attention to the AjaxInclude pattern (it also has a link to the picturefill).
You could consider storing heavy data JSON-encoded, and then creating elements and loading them on demand like so
var heavyImage = new Image();
heavyImage.src=imageList[id];
Then you can append image element to a desired block. From my experience with mobiles this is more robust than requesting <img> via AJAX, since AJAX could be pretty slow sometimes.
You may also 'prefetch' images with this method (like 2-3 adjacent to visible at the moment), thus improving UX.
You could pull in the heavy elements via AJAX so they wouldn't sit on the page initially, making it load faster. You could decide to do the AJAX call only if the screen size is larger than X.
If you want you can use visibility:hidden, or if you use jQuery you can use
$(element).remove() //to remove completely
$(element).hide() //to hide
$(element).fadeOut(1) //to fadeout
I am working on a project that consists of a online store, to sell Printed Circuit Boards.
But the hole system will be automated, and will be able to view online the Gerber files (Gerber are the files that has the machine code for the pcb).
I need to choose the best way to "output" this file uploaded by the user, to the webpage. Only for viewing the PCB before buying.
I have done the entire PHP code to process the Gerber, but, I can't decide if the file will be proccesed, and then:
I will save as a PNG file (rendering will be done with the PHP image library {that is a shit}), and if the user zoom, or do anything, it will not be perfect... (I would need to render in a high resolutiong, and would take a lot of space, and also time to load)
Render as an SVG file (Vector file), and show on the HTML as an mbeded element (Does it work on all new browsers? Is it slow to proccess?), The SVG file are awsome in terms of drawing lines...
And the last but not least way to doit, is to create a list of JavaScript commands, that draws on a Canvas Element (I have already implemented this, and works really good, but I don't like to think, that I'm actualy 'rendering' to a code...)
Anyway, what do you think I should use, and if I didn't tought in another way of doing it, please tell me!
Here is an example of the output as Canvas (With the source being a JavaScript function object, that has many drawLine commands):
I'm opting for SVG file, even if it's slower than canvas, but considering that won't be real time drawing process in terms of user interaction with the drawing object it's a good choice. SVG's are actually vectors, hence the images won't be crispy on large images. There are some quite good libraries out there which are working with svg-s like:
http://processingjs.org
http://d3js.org/
http://fabricjs.com/
http://raphaeljs.com/
I think d3 is one of the best. I definitely wont' recommend PHP image library.
I need some opinions on using PHP to make completely "scalable" websites.. For instance, using viewport resolution and resizing images, applying dynamic css styles..... In my mind doing this just add's to the complexity and should not be done, it should be fixed or fluid using strictly css and no server-side languages to generate layouts based on the device size..
I need some input and maybe some philosophy on why using this approach is not used at all..
Manipulating a web page in this way is the domain of CSS controlled by Javascript (or a library such as JQuery, see CSS docs). You shouldn't be wasting your server's processor cycles when client-side implementations will be far more responsive for the user and allow all the flexibility you require. Changing font size etc can be done almost instantly in the browser without the user having to request another page from your (remote) server, which would result in a slower user experience.
Really, really DON'T
As Andy says it is the domain of CSS.
Trying to adapt a design with PHP will make your code unmaintainable. You should really learn to use CSS efficiently to avoid this kind of hack.
The only reason for which you could use PHP to detect browser and adapt content is mobile browser.
Given the number of the existing User Agent tokens, it'll be almost impossible to make y scalable websites.
I've created a website for a relative. However, after making the whole thing, the relative says she didn't understand that the design pictures I sent her were scaled 1:1, so she wants the website "bigger" (basically the same thing as pressing Ctrl+plus in Firefox).
Do I have to redo all CSS and design, or is there a better way to do this?
There's going to be some css work, but how much depends a lot on how you built it.
I would have thought you're going to have to resize images etc, but you may well just be able to increase the size of your frame and page sections relatvice to each other and up the text size a bit.
This should get you part way there...
You have several options, but either way you're looking at rewriting some CSS. Your choice will depend upon the actual website.
Move to a larger fixed width site. Keep in mind that 960px wide is about your maximum for this. This will account for browser chrome at 1024x768.
Change over to a fluid width site. This site will expand to fit your browser. If your site is heavy on graphic elements, this might not be your best option. However, many people like a site expanding to fit their whole browser window.
If you use a CSS framework like YAML it has support for "zooming" the whole page.
I don't think the zoom property in CSS is reliable enough yet, so I'm afraid you will have to go back to the drawing board. Now for future reference, you know to send them a sample of the work before it is completely finished!
That's just one advantage of only using variable values for any styling like em or even better ex... With them you'd just have to adjust your basic font-size a few pxs higher and boom; everything's got bigger.
Still, to your question: Depends on how many fix values you used, the more, the longer it will take to adjust it to be "bigger".
But for the future I really encourage you to use variable sizes for almost anything as there is no disadvantage in it and it makes your website 100% resizable.