| 121 |
Hide And Seek in The Head |
If you want your JavaScript-enhanced pages to remain accessible and understandable to scripted and noscript users alike, you have to think before you code. Which functionalities are required (ie. should work without JavaScript)? Which ones are merely nice-to-have (ie. can be scripted)? You should only start creating the site when you’ve taken these decisions.
Special HTML elements
Once you have a clear idea of what will work with and without JavaScript, you’ll likely find that you need a few HTML elements for the noscript version only.
Take this example: A form has a nifty bit of Ajax that automatically and silently sends a request once the user enters something in a form field. However, in order to preserve accessibility, the user should also be able to submit the form normally. So the form should have a submit button in noscript browsers, but not when the browser supports sufficient JavaScript.
Since the button is meant for noscript browsers, it must be hard-coded in the HTML:
<input type="submit" value="Submit form" id="noScriptButton" />
When JavaScript is supported, it should be removed:
var checkJS = [check JavaScript support];
window.onload = function () {
if (!checkJS) return;
document.getElementById('noScriptButton').style.display = 'none';
}
Problem: the load event
Although this will likely work fine in your testing environment, it’s not completely correct. What if a user with a modern, JavaScript-capable browser visits your page, but has to wait for a huge graphic to load? The load event fires only after all assets, including images, have been loaded. So this user will first see a submit button, but then all of a sudden it’s removed. That’s potentially confusing.
Fortunately there’s a simple solution: play a bit of hide and seek in the <head>:
var checkJS = [check JavaScript support];
if (checkJS) {
document.write('<style>#noScriptButton{display: none}</style>');
}
First, check if the browser supports enough JavaScript. If it does, document.write an extra <style> element that hides the button.
The difference with the previous technique is that the document.write command is outside any function, and is therefore executed while the JavaScript is being parsed. Thus, the #noScriptButton{display: none} rule is written into the document before the actual HTML is received.
That’s exactly what we want. If the rule is already present at the moment the HTML for the submit button is received and parsed, the button is hidden immediately. Even if the user (and the load event) have to wait for a huge image, the button is already hidden, and both scripted and noscript users see the interface they need, without any potentially confusing flashes of useless content.
In general, if you want to hide content that’s not relevant to scripted users, give the hide command in CSS, and make sure it’s given before the HTML element is loaded and parsed.
Alternative
Some people won’t like to use document.write. They could also add an empty <link /> element to the <head> and give it an href attribute once the browser’s JavaScript capabilities have been evaluated. The <link /> element is made to refer to a style sheet that contains the crucial #noScriptButton{display: none}, and everything works fine.
Important note: The script needs access to the <link />, and the only way to ensure that access is to include the empty <link /> element before your <script> tag. |
2006 |
Peter-Paul Koch |
ppk |
2006-12-06T00:00:00+00:00 |
https://24ways.org/2006/hide-and-seek-in-the-head/ |
code |
| 125 |
Accessible Dynamic Links |
Although hyperlinks are the soul of the World Wide Web, it’s worth using them in moderation. Too many links becomes a barrier for visitors navigating their way through a page. This difficulty is multiplied when the visitor is using assistive technology, or is using a keyboard; being able to skip over a block of links doesn’t make the task of finding a specific link any easier.
In an effort to make sites easier to use, various user interfaces based on the hiding and showing of links have been crafted. From drop-down menus to expose the deeper structure of a website, to a decluttering of skip links so as not to impact design considerations. Both are well intentioned with the aim of preserving a good usability experience for the majority of a website’s audience; hiding the real complexity of a page until the visitor interacts with the element.
When JavaScript is not available
The modern dynamic link techniques rely on JavaScript and CSS, but regardless of whether scripting and styles are enabled or not, we should consider the accessibility implications, particularly for screen-reader users, and people who rely on keyboard access.
In typical web standards-based drop-down navigation implementations, the rough consensus is that the navigation should be structured as nested lists so when JavaScript is not available the entire navigation map is available to the visitor. This creates a situation where a visitor is faced with potentially well over 50 links on every page of the website. Keyboard access to such structures is frustrating, there’s far too many options, and the method of serially tabbing through each link looking for a specific one is tedious.
Instead of offering the visitor an indigestible chunk of links when JavaScript is not available, consider instead having the minimum number of links on a page, and when JavaScript is available bringing in the extra links dynamically. Santa Chris Heilmann offers an excellent proof of concept in making Ajax navigation optional.
When JavaScript is enabled, we need to decide how to hide links. One technique offers a means of comprehensively hiding links from keyboard users and assistive technology users. Another technique allows keyboard and screen-reader users to access links while they are hidden, and making them visible when reached.
Hiding the links
In JavaScript enhanced pages whether a link displays on screen depends on a certain event happening first. For example, a visitor needs to click a top-level navigation link that makes a set of sub-navigation links appear. In these cases, we need to ensure that these links are not available to any user until that event has happened.
The typical way of hiding links is to style the anchor elements, or its parent nodes with display: none. This has the advantage of taking the links out of the tab order, so they are not focusable. It’s useful in reducing the number of links presented to a screen-reader or keyboard user to a minimum. Although the links are still in the document (they can be referenced and manipulated using DOM Scripting), they are not directly triggerable by a visitor.
Once the necessary event has happened, like our visitor has clicked on a top-level navigation link which shows our hidden set of links, then we can display the links to the visitor and make them triggerable. This is done simply by undoing the display: none, perhaps by setting the display back to block for block level elements, or inline for inline elements. For as long as this display style remains, the links are in the tab order, focusable by keyboard, and triggerable.
A common mistake in this situation is to use visibility: hidden, text-indent: -999em, or position: absolute with left: -999em to position these links off-screen. But all of these links remain accessible via keyboard tabbing even though the links remain hidden from screen view. In some ways this is a good idea, but for hiding sub-navigation links, it presents the screen-reader user and keyboard user with too many links to be of practical use.
Moving the links out of sight
If you want a set of text links accessible to screen-readers and keyboard users, but don’t want them cluttering up space on the screen, then style the links with position: absolute; left: -999em. Links styled this way remain in the tab order, and are accessible via keyboard. (The position: absolute is added as a style to the link, not to a parent node of the link – this will give us a useful hook to solve the next problem).
a.helper {
position: absolute;
left: -999em;
}
One important requirement when displaying links off-screen is that they are visible to a keyboard user when they receive focus. Tabbing on a link that is not visible is a usability mudpit, since the visitor has no visible cue as to what a focused link will do, or where it will go.
The simple answer is to restyle the link so that it appears on the screen when the hidden link receives focus. The anchor’s :focus pseudo-class is a logical hook to use, and with the following style repositions the link onscreen when it receives the focus:
a.helper:focus, a.helper.focus {
top: 0;
left: 0;
}
This technique is useful for hiding skip links, and options you want screen-reader and keyboard users to use, but don’t want cluttering up the page. Unfortunately Internet Explorer 6 and 7 don’t support the focus pseudo-class, which is why there’s a second CSS selector a.helper.focus so we can use some JavaScript to help out. When the page loads, we look for all links that have a class of helper and add in onfocus and onblur event handlers:
if (anchor.className == "helper") {
anchor.onfocus = function() {
this.className = 'helper focus';
}
anchor.onblur = function() {
this.className = 'helper';
}
}
Since we are using JavaScript to cover up for deficiencies in Internet Explorer, it makes sense to use JavaScript initially to place the links off-screen. That way an Internet Explorer user with JavaScript disabled can still use the skip link functionality.
It is vital that the number of links rendered in this way is kept to a minimum. Every link you offer needs to be tabbed through, and gets read out in a screen reader. Offer these off-screen links that directly benefit these types of visitor.
Andy Clarke and Kimberly Blessing use a similar technique in the Web Standards Project‘s latest design, but their technique involves hiding the skip link in plain sight and making it visible when it receives focus. Navigate the page using just the tab key to see the accessibility-related links appear when they receive focus.
This technique is also a good way of hiding image replaced text. That way the screen-readers still get the actual text, and the website still gets its designed look.
Which way?
If the links are not meant to be reachable until a certain event has occurred, then the display: none technique is the preferred approach. If you want the links accessible but out of the way until they receive focus, then the off-screen positioning (or Andy’s hiding in plain sight technique) is the way to go. |
2006 |
Mike Davies |
mikedavies |
2006-12-05T00:00:00+00:00 |
https://24ways.org/2006/accessible-dynamic-links/ |
ux |
| 126 |
Intricate Fluid Layouts in Three Easy Steps |
The Year of the Script may have drawn attention away from CSS but building fluid, multi-column, cross-browser CSS layouts can still be as unpleasant as a lump of coal. Read on for a worry-free approach in three quick steps.
The layout system I developed, YUI Grids CSS, has three components. They can be used together as we’ll see, or independently.
The Three Easy Steps
Choose fluid or fixed layout, and choose the width (in percents or pixels) of the page.
Choose the size, orientation, and source-order of the main and secondary blocks of content.
Choose the number of columns and how they distribute (for example 50%-50% or 25%-75%), using stackable and nestable grid structures.
The Setup
There are two prerequisites: We need to normalize the size of an em and opt into the browser rendering engine’s Strict Mode.
Ems are a superior unit of measure for our case because they represent the current font size and grow as the user increases their font size setting. This flexibility—the container growing with the user’s wishes—means larger text doesn’t get crammed into an unresponsive container. We’ll use YUI Fonts CSS to set the base size because it provides consistent-yet-adaptive font-sizes while preserving user control.
The second prerequisite is to opt into Strict Mode (more info on rendering modes) by declaring a Doctype complete with URI. You can choose XHTML or HTML, and Transitional or Strict. I prefer HTML 4.01 Strict, which looks like this:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
Including the CSS
A single small CSS file powers a nearly-infinite number of layouts thanks to a recursive system and the interplay between the three distinct components. You could prune to a particular layout’s specific needs, but why bother when the complete file weighs scarcely 1.8kb uncompressed? Compressed, YUI Fonts and YUI Grids combine for a miniscule 0.9kb over the wire.
You could save an HTTP request by concatenating the two CSS files, or by adding their contents to your own CSS, but I’ll keep them separate for now:
<link href="fonts.css" rel="stylesheet" type="text/css">
<link href="grids.css" rel="stylesheet" type="text/css">
Example: The Setup
Now we’re ready to build some layouts.
Step 1: Choose Fluid or Fixed Layout
Choose between preset widths of 750px, 950px, and 100% by giving a document-wrapping div an ID of doc, doc2, or doc3. These options cover most use cases, but it’s easy to define a custom fixed width.
The fluid 100% grid (doc3) is what I’ve been using almost exclusively since it was introduced in the last YUI released.
<body>
<div id="doc3"></div>
</body>
All pages are centered within the viewport, and grow with font size. The 100% width page (doc3) preserves 10px of breathing room via left and right margins. If you prefer your content flush to the viewport, just add doc3 {margin:auto} to your CSS.
Regardless of what you choose in the other two steps, you can always toggle between these widths and behaviors by simply swapping the ID value. It’s really that simple.
Example: 100% fluid layout
Step 2: Choose a Template Preset
This is perhaps the most frequently omitted step (they’re all optional), but I use it nearly every time. In a source-order-independent way (good for accessibility and SEO), “Template Presets” provide commonly used template widths compatible with ad-unit dimension standards defined by the Interactive Advertising Bureau, an industry association.
Choose between the six Template Presets (.yui-t1 through .yui-t6) by setting the class value on the document-wrapping div established in Step 1. Most frequently I use yui-t3, which puts the narrow secondary block on the left and makes it 300px wide.
<body>
<div id="doc3" class="yui-t3"></div>
</body>
The Template Presets control two “blocks” of content, which are defined by two divs, each with yui-b (“b” for “block”) class values. Template Presets describe the width and orientation of the secondary block; the main block will take up the rest of the space.
<body>
<div id="doc3" class="yui-t3">
<div class="yui-b"></div>
<div class="yui-b"></div>
</div>
</body>
Use a wrapping div with an ID of yui-main to structurally indicate which block is the main block. This wrapper—not the source order—identifies the main block.
<body>
<div id="doc3" class="yui-t3">
<div id="yui-main">
<div class="yui-b"></div>
</div>
<div class="yui-b"></div>
</div>
</body>
Example: Main and secondary blocks sized and oriented with .yui-t3 Template Preset
Again, regardless of what values you choose in the other steps, you can always toggle between these Template Presets by toggling the class value of your document-wrapping div. It’s really that simple.
Step 3: Nest and Stack Grid Structures.
The bulk of the power of the system is in this third step. The key is that columns are built by parents telling children how to behave. By default, two children each consume half of their parent’s area. Put two units inside a grid structure, and they will sit side-by-side, and they will each take up half the space. Nest this structure and two columns become four. Stack them for rows of columns.
An Even Number of Columns
The default behavior creates two evenly-distributed columns. It’s easy. Define one parent grid with .yui-g (“g” for grid) and two child units with .yui-u (“u” for unit). The code looks like this:
<div class="yui-g">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
Be sure to indicate the “first“ unit because the :first-child pseudo-class selector isn’t supported across all A-grade browsers. It’s unfortunate we need to add this, but luckily it’s not out of place in the markup layer since it is structural information.
Example: Two evenly-distributed columns in the main content block
An Odd Number of Columns
The default system does not work for an odd number of columns without using the included “Special Grids” classes. To create three evenly distributed columns, use the “yui-gb“ Special Grid:
<div class="yui-gb">
<div class="yui-u first"></div>
<div class="yui-u"></div>
<div class="yui-u"></div>
</div>
Example: Three evenly distributed columns in the main content block
Uneven Column Distribution
Special Grids are also used for unevenly distributed column widths. For example, .yui-ge tells the first unit (column) to take up 75% of the parent’s space and the other unit to take just 25%.
<div class="yui-ge">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
Example: Two columns in the main content block split 75%-25%
Putting It All Together
Start with a full-width fluid page (div#doc3). Make the secondary block 180px wide on the right (div.yui-t4). Create three rows of columns: Three evenly distributed columns in the first row (div.yui-gb), two uneven columns (66%-33%) in the second row (div.yui-gc), and two evenly distributed columns in the thrid row.
<body>
<!-- choose fluid page and Template Preset -->
<div id="doc3" class="yui-t4">
<!-- main content block -->
<div id="yui-main">
<div class="yui-b">
<!-- stacked grid structure, Special Grid "b" -->
<div class="yui-gb">
<div class="yui-u first"></div>
<div class="yui-u"></div>
<div class="yui-u"></div>
</div>
<!-- stacked grid structure, Special Grid "c" -->
<div class="yui-gc">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
<!-- stacked grid structure -->
<div class="yui-g">
<div class="yui-u first"></div>
<div class="yui-u"></div>
</div>
</div>
</div>
<!-- secondary content block -->
<div class="yui-b"></div>
</div>
</body>
Example: A complex layout.
Wasn’t that easy? Now that you know the three “levers” of YUI Grids CSS, you’ll be creating headache-free fluid layouts faster than you can say “Peace on Earth”. |
2006 |
Nate Koechley |
natekoechley |
2006-12-20T00:00:00+00:00 |
https://24ways.org/2006/intricate-fluid-layouts/ |
code |
| 127 |
Showing Good Form |
Earlier this year, I forget exactly when (it’s been a good year), I was building a client site that needed widgets which look like this (designed, incidentally, by my erstwhile writing partner, Cameron Adams):
Building this was a challenge not just in CSS, but in choosing the proper markup – how should such a widget be constructed?
Mmm … markup
It seemed to me there were two key issues to deal with:
The function of the interface is to input information, so semantically this is a form, therefore we have to find a way of building it using form elements: fieldset, legend, label and input
We can’t use a table for layout, even though that would clearly be the easiest solution!
Abusing tables for layout is never good – physical layout is not what table semantics mean. But even if this data can be described as a table, we shouldn’t mix forms markup with non-forms markup, because of the behavioral impact this can have on a screen reader:
To take a prominent example, the screen reader JAWS has a mode specifically for interacting with forms (cunningly known as “forms mode”). When running in this mode its output only includes relevant elements – legends, labels and form controls themselves. Any other kind of markup – like text in a previous table cell, a paragraph or list in between – is simply ignored. The user in this situation would have to switch continually in and out of forms mode to hear all the content. (For more about this issue and some test examples, there’s a thread at accessify forum which wanders in that direction.)
One further issue for screen reader users is implied by the design: the input fields are associated together in rows and columns, and a sighted user can visually scan across and down to make those associations; but a blind user can’t do that. For such a user the row and column header data will need to be there at every axis; in other words, the layout should be more like this:
And constructed with appropriate semantic markup to convey those relationships. By this point the selection of elements seems pretty clear: each row is a fieldset, the row header is a legend, and each column header is a label, associated with an input.
Here’s what that form looks like with no CSS:
And here’s some markup for the first row (with most of the attributes removed just to keep this example succinct):
<fieldset>
<legend>
<span>Match points</span>
</legend>
<label>
<span>Win</span>
<input value="3" />
</label>
<label>
<span>Draw</span>
<input value="1" />
</label>
<label>
<span>Lose</span>
<input value="0" />
</label>
<label>
<span>Played</span>
<input value="0" />
</label>
</fieldset>
The span inside each legend is because legend elements are highly resistant to styling! Indeed they’re one of the most stubborn elements in the browsers’ vocabulary. Oh man … how I wrestled with the buggers … until this obvious alternative occurred to me! So the legend element itself is just a container, while all the styling is on the inner span.
Oh yeah, there was some CSS too
I’m not gonna dwell too much on the CSS it took to make this work – this is a short article, and it’s all there in the demo [demo page, style sheet]
But I do want to touch on the most interesting bit – where we get from a layout with headers on every row, to one where only the top row has headers – or at least, so it appears to graphical browsers. For screen readers, as we noted, we need those headers on every row, so we should employ some cunning CSS to partly negate their visual presence, without removing them from the output.
The core styling for each label span is like this:
label span
{
display:block;
padding:5px;
line-height:1em;
background:#423221;
color:#fff;
font-weight:bold;
}
But in the rows below the header they have these additional rules:
fieldset.body label span
{
padding:0 5px;
line-height:0;
position:relative;
top:-10000em;
}
The rendered width of the element is preserved, ensuring that the surrounding label is still the same width as the one in the header row above, and hence a unified column width is preserved all the way down. But the element effectively has no height, and so it’s effectively invisible. The styling is done this way, rather than just setting the height to zero and using overflow:hidden, because to do that would expose an unrelated quirk with another popular screen reader! (It would hide the output from Window Eyes, as shown in this test example at access matters.)
The finished widget
It’s an intricate beast allright! But after all that we do indeed get the widget we want:
Demo page
Style sheet
It’s not perfect, most notably because the legends have to have a fixed width; this can be in em to allow for text scaling, but it still doesn’t allow the content to break into multiple lines. It also doesn’t look quite right in Safari; and some CSS hacking was needed to make it look right in IE6 and IE7.
Still it worked well enough for the purpose, and satisfied the client completely. And most of all it re-assured me in my faith – that there’s never any need to abuse tables for layout. (Unless of course you think this content is a table anyway, but that’s another story!) |
2006 |
James Edwards |
jamesedwards |
2006-12-11T00:00:00+00:00 |
https://24ways.org/2006/showing-good-form/ |
ux |
| 132 |
Tasty Text Trimmer |
In most cases, when designing a user interface it’s best to make a decision about how data is best displayed and stick with it. Failing to make a decision ultimately leads to too many user options, which in turn can be taxing on the poor old user.
Under some circumstances, however, it’s good to give the user freedom in customising their workspace. One good example of this is the ‘Article Length’ tool in Apple’s Safari RSS reader. Sliding a slider left of right dynamically changes the length of each article shown. It’s that kind of awesomey magic stuff that’s enough to keep you from sleeping. Let’s build one.
The Setup
Let’s take a page that has lots of long text items, a bit like a news page or like Safari’s RSS items view. If we were to attach a class name to each element we wanted to resize, that would give us something to hook onto from the JavaScript.
Example 1: The basic page.
As you can see, I’ve wrapped my items in a DIV and added a class name of chunk to them. It’s these chunks that we’ll be finding with the JavaScript. Speaking of which …
Our Core Functions
There are two main tasks that need performing in our script. The first is to find the chunks we’re going to be resizing and store their original contents away somewhere safe. We’ll need this so that if we trim the text down we’ll know what it was if the user decides they want it back again. We’ll call this loadChunks.
var loadChunks = function(){
var everything = document.getElementsByTagName('*');
var i, l;
chunks = [];
for (i=0, l=everything.length; i<l; i++){
if (everything[i].className.indexOf(chunkClass) > -1){
chunks.push({
ref: everything[i],
original: everything[i].innerHTML
});
}
}
};
The variable chunks is stored outside of this function so that we can access it from our next core function, which is doTrim.
var doTrim = function(interval) {
if (!chunks) loadChunks();
var i, l;
for (i=0, l=chunks.length; i<l; i++){
var a = chunks[i].original.split(' ');
a = a.slice(0, interval);
chunks[i].ref.innerHTML = a.join(' ');
}
};
The first thing that needs to be done is to call loadChunks if the chunks variable isn’t set. This should only happen the first time doTrim is called, as from that point the chunks will be loaded.
Then all we do is loop through the chunks and trim them. The trimming itself (lines 6-8) is very simple. We split the text into an array of words (line 6), then select only a portion from the beginning of the array up until the number we want (line 7). Finally the words are glued back together (line 8).
In essense, that’s it, but it leaves us needing to know how to get the number into this function in the first place, and how that number is generated by the user. Let’s look at the latter case first.
The YUI Slider Widget
There are lots of JavaScript libraries available at the moment. A fair few of those are really good. I use the Yahoo! User Interface Library professionally, but have only recently played with their pre-build slider widget. Turns out, it’s pretty good and perfect for this task.
Once you have the library files linked in (check the docs linked above) it’s fairly straightforward to create yourself a slider.
slider = YAHOO.widget.Slider.getHorizSlider("sliderbg", "sliderthumb", 0, 100, 5);
slider.setValue(50);
slider.subscribe("change", doTrim);
All that’s needed then is some CSS to make the slider look like a slider, and of course a few bits of HTML. We’ll see those later.
See It Working!
Rather than spell out all the nuts and bolts of implementing this fairly simple script, let’s just look at in it action and then pick on some interesting bits I’ve added.
Example 2: Try the Tasty Text Trimmer.
At the top of the JavaScript file I’ve added a small number of settings.
var chunkClass = 'chunk';
var minValue = 10;
var maxValue = 100;
var multiplier = 5;
Obvious candidates for configuration are the class name used to find the chunks, and also the some minimum and maximum values. The minValue is the fewest number of words we wish to display when the slider is all the way down. The maxValue is the length of the slider, in this case 100.
Moving the slider makes a call to our doTrim function with the current value of the slider. For a slider 100 pixels long, this is going to be in the range of 0-100. That might be okay for some things, but for longer items of text you’ll want to allow for displaying more than 100 words. I’ve accounted for this by adding in a multiplier – in my code I’m multiplying the value by 5, so a slider value of 50 shows 250 words. You’ll probably want to tailor the multiplier to the type of content you’re using.
Keeping it Accessible
This effect isn’t something we can really achieve without JavaScript, but even so we must make sure that this functionality has no adverse impact on the page when JavaScript isn’t available. This is achieved by adding the slider markup to the page from within the insertSliderHTML function.
var insertSliderHTML = function(){
var s = '<a id="slider-less" href="#less"><img src="icon_min.gif" width="10" height="10" alt="Less text" class="first" /></a>';
s +=' <div id="sliderbg"><div id="sliderthumb"><img src="sliderthumbimg.gif" /></div></div>';
s +=' <a id="slider-more" href="#more"><img src="icon_max.gif" width="10" height="10" alt="More text" /></a>';
document.getElementById('slider').innerHTML = s;
}
The other important factor to consider is that a slider can be tricky to use unless you have good eyesight and pretty well controlled motor skills. Therefore we should provide a method of changing the value by the keyboard.
I’ve done this by making the icons at either end of the slider links so they can be tabbed to. Clicking on either icon fires the appropriate JavaScript function to show more or less of the text.
In Conclusion
The upshot of all this is that without JavaScript the page just shows all the text as it normally would. With JavaScript we have a slider for trimming the text excepts that can be controlled with the mouse or with a keyboard.
If you’re like me and have just scrolled to the bottom to find the working demo, here it is again:
Try the Tasty Text Trimmer
Trimmer for Christmas? Don’t say I never give you anything! |
2006 |
Drew McLellan |
drewmclellan |
2006-12-01T00:00:00+00:00 |
https://24ways.org/2006/tasty-text-trimmer/ |
code |
| 136 |
Making XML Beautiful Again: Introducing Client-Side XSL |
Remember that first time you saw XML and got it? When you really understood what was possible and the deep meaning each element could carry? Now when you see XML, it looks ugly, especially when you navigate to a page of XML in a browser. Well, with every modern browser now supporting XSL 1.0, I’m going to show you how you can turn something as simple as an ATOM feed into a customised page using a browser, Notepad and some XSL.
What on earth is this XSL?
XSL is a family of recommendations for defining XML document transformation and presentation. It consists of three parts:
XSLT 1.0 – Extensible Stylesheet Language Transformation, a language for transforming XML
XPath 1.0 – XML Path Language, an expression language used by XSLT to access or refer to parts of an XML document. (XPath is also used by the XML Linking specification)
XSL-FO 1.0 – Extensible Stylesheet Language Formatting Objects, an XML vocabulary for specifying formatting semantics
XSL transformations are usually a one-to-one transformation, but with newer versions (XSL 1.1 and XSL 2.0) its possible to create many-to-many transformations too. So now you have an overview of XSL, on with the show…
So what do I need?
So to get going you need a browser an supports client-side XSL transformations such as Firefox, Safari, Opera or Internet Explorer. Second, you need a source XML file – for this we’re going to use an ATOM feed from Flickr.com. And lastly, you need an editor of some kind. I find Notepad++ quick for short XSLs, while I tend to use XMLSpy or Oxygen for complex XSL work.
Because we’re doing a client-side transformation, we need to modify the XML file to tell it where to find our yet-to-be-written XSL file. Take a look at the source XML file, which originates from my Flickr photos tagged sky, in ATOM format.
The top of the ATOM file now has an additional <?xml-stylesheet /> instruction, as can been seen on Line 2 below. This instructs the browser to use the XSL file to transform the document.
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<?xml-stylesheet type="text/xsl" href="flickr_transform.xsl"?>
<feed xmlns="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
Your first transformation
Your first XSL will look something like this:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<xsl:output method="html" encoding="utf-8"/>
</xsl:stylesheet>
This is pretty much the starting point for most XSL files. You will notice the standard XML processing instruction at the top of the file (line 1). We then switch into XSL mode using the XSL namespace on all XSL elements (line 2). In this case, we have added namespaces for ATOM (line 4) and Dublin Core (line 5). This means the XSL can now read and understand those elements from the source XML.
After we define all the namespaces, we then move onto the xsl:output element (line 6). This enables you to define the final method of output. Here we’re specifying html, but you could equally use XML or Text, for example. The encoding attributes on each element do what they say on the tin. As with all XML, of course, we close every element including the root.
The next stage is to add a template, in this case an <xsl:template /> as can be seen below:
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<xsl:output method="html" encoding="utf-8"/>
<xsl:template match="/">
<html>
<head>
<title>Making XML beautiful again : Transforming ATOM</title>
</head>
<body>
<xsl:apply-templates select="/atom:feed"/>
</body>
</html>
</xsl:template>
</xsl:stylesheet>
The beautiful thing about XSL is its English syntax, if you say it out loud it tends to make sense.
The / value for the match attribute on line 8 is our first example of XPath syntax. The expression / matches any element – so this <xsl:template/> will match against any element in the document. As the first element in any XML document is the root element, this will be the one matched and processed first.
Once we get past our standard start of a HTML document, the only instruction remaining in this <xsl:template/> is to look for and match all <atom:feed/> elements using the <xsl:apply-templates/> in line 14, above.
<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:atom="http://www.w3.org/2005/Atom"
xmlns:dc="http://purl.org/dc/elements/1.1/">
<xsl:output method="html" encoding="utf-8"/>
<xsl:template match="/">
<xsl:apply-templates select="/atom:feed"/>
</xsl:template>
<xsl:template match="/atom:feed">
<div id="content">
<h1>
<xsl:value-of select="atom:title"/>
</h1>
<p>
<xsl:value-of select="atom:subtitle"/>
</p>
<ul id="entries">
<xsl:apply-templates select="atom:entry"/>
</ul>
</div>
</xsl:template>
</xsl:stylesheet>
This new template (line 12, above) matches <feed/> and starts to write the new HTML elements out to the output stream. The <xsl:value-of/> does exactly what you’d expect – it finds the value of the item specifed in its select attribute. With XPath you can select any element or attribute from the source XML.
The last part is a repeat of the now familiar <xsl:apply-templates/> from before, but this time we’re using it inside of a called template. Yep, XSL is full of recursion…
<xsl:template match="atom:entry">
<li class="entry">
<h2>
<a href="{atom:link/@href}">
<xsl:value-of select="atom:title"/>
</a>
</h2>
<p class="date">
(<xsl:value-of select="substring-before(atom:updated,'T')"/>)
</p>
<p class="content">
<xsl:value-of select="atom:content" disable-output-escaping="yes"/>
</p>
<xsl:apply-templates select="atom:category"/>
</li>
</xsl:template>
The <xsl:template/> which matches atom:entry (line 1) occurs every time there is a <entry/> element in the source XML file. So in total that is 20 times, this is naturally why XSLT is full of recursion. This <xsl:template/> has been matched and therefore called higher up in the document, so we can start writing list elements directly to the output stream. The first part is simply a <h2/> with a link wrapped within it (lines 3-7). We can select attributes using XPath using @.
The second part of this template selects the date, but performs a XPath string function on it. This means that we only get the date and not the time from the string (line 9). This is achieved by getting only the part of the string that exists before the T.
Regular Expressions are not part of the XPath 1.0 string functions, although XPath 2.0 does include them. Because of this, in XSL we tend to rely heavily on the available XML output.
The third part of the template (line 12) is a <xsl:value-of/> again, but this time we use an attribute of <xsl:value-of/> called disable output escaping to turn escaped characters back into XML.
The very last section is another <xsl:apply-template/> call, taking us three templates deep. Do not worry, it is not uncommon to write XSL which go 20 or more templates deep!
<xsl:template match="atom:category">
<xsl:for-each select=".">
<xsl:element name="a">
<xsl:attribute name="rel">
<xsl:text>tag</xsl:text>
</xsl:attribute>
<xsl:attribute name="href">
<xsl:value-of select="concat(@scheme, @term)"/>
</xsl:attribute>
<xsl:value-of select="@term"/>
</xsl:element>
<xsl:text> </xsl:text>
</xsl:for-each>
</xsl:template>
In our final <xsl:template/>, we see a combination of what we have done before with a couple of twists. Once we match atom:category we then count how many elements there are at that same level (line 2). The XPath . means ‘self’, so we count how many category elements are within the <entry/> element.
Following that, we start to output a link with a rel attribute of the predefined text, tag (lines 4-6). In XSL you can just type text, but results can end up with strange whitespace if you do (although there are ways to simply remove all whitespace).
The only new XPath function in this example is concat(), which simply combines what XPaths or text there might be in the brackets. We end the output for this tag with an actual tag name (line 10) and we add a space afterwards (line 12) so it won’t touch the next tag. (There are better ways to do this in XSL using the last() XPath function).
After that, we go back to the <xsl:for-each/> element again if there is another category element, otherwise we end the <xsl:for-each/> loop and end this <xsl:template/>.
A touch of style
Because we’re using recursion through our templates, you will find this is the end of the templates and the rest of the XML will be ignored by the parser. Finally, we can add our CSS to finish up. (I have created one for Flickr and another for News feeds)
<style type="text/css" media="screen">@import "flickr_overview.css?v=001";</style>
So we end up with a nice simple to understand but also quick to write XSL which can be used on ATOM Flickr feeds and ATOM News feeds. With a little playing around with XSL, you can make XML beautiful again.
All the files can be found in the zip file (14k) |
2006 |
Ian Forrester |
ianforrester |
2006-12-07T00:00:00+00:00 |
https://24ways.org/2006/beautiful-xml-with-xsl/ |
code |
| 141 |
Compose to a Vertical Rhythm |
“Space in typography is like time in music. It is infinitely divisible, but a few proportional intervals can be much more useful than a limitless choice of arbitrary quantities.” So says the typographer Robert Bringhurst, and just as regular use of time provides rhythm in music, so regular use of space provides rhythm in typography, and without rhythm the listener, or the reader, becomes disorientated and lost.
On the Web, vertical rhythm – the spacing and arrangement of text as the reader descends the page – is contributed to by three factors: font size, line height and margin or padding. All of these factors must calculated with care in order that the rhythm is maintained.
The basic unit of vertical space is line height. Establishing a suitable line height that can be applied to all text on the page, be it heading, body copy or sidenote, is the key to a solid dependable vertical rhythm, which will engage and guide the reader down the page. To see this in action, I’ve created an example with headings, footnotes and sidenotes.
Establishing a suitable line height
The easiest place to begin determining a basic line height unit is with the font size of the body copy. For the example I’ve chosen 12px. To ensure readability the body text will almost certainly need some leading, that is to say spacing between the lines. A line-height of 1.5em would give 6px spacing between the lines of body copy. This will create a total line height of 18px, which becomes our basic unit. Here’s the CSS to get us to this point:
body {
font-size: 75%;
}
html>body {
font-size: 12px;
}
p {
line-height 1.5em;
}
There are many ways to size text in CSS and the above approach provides and accessible method of achieving the pixel-precision solid typography requires. By way of explanation, the first font-size reduces the body text from the 16px default (common to most browsers and OS set-ups) down to the 12px we require. This rule is primarily there for Internet Explorer 6 and below on Windows: the percentage value means that the text will scale predictably should a user bump the text size up or down. The second font-size sets the text size specifically and is ignored by IE6, but used by Firefox, Safari, IE7, Opera and other modern browsers which allow users to resize text sized in pixels.
Spacing between paragraphs
With our rhythmic unit set at 18px we need to ensure that it is maintained throughout the body copy. A common place to lose the rhythm is the gaps set between margins. The default treatment by web browsers of paragraphs is to insert a top- and bottom-margin of 1em. In our case this would give a spacing between the paragraphs of 12px and hence throw the text out of rhythm. If the rhythm of the page is to be maintained, the spacing of paragraphs should be related to the basic line height unit. This is achieved simply by setting top- and bottom-margins equal to the line height.
In order that typographic integrity is maintained when text is resized by the user we must use ems for all our vertical measurements, including line-height, padding and margins.
p {
font-size:1em;
margin-top: 1.5em;
margin-bottom: 1.5em;
}
Browsers set margins on all block-level elements (such as headings, lists and blockquotes) so a way of ensuring that typographic attention is paid to all such elements is to reset the margins at the beginning of your style sheet. You could use a rule such as:
body,div,dl,dt,dd,ul,ol,li,h1,h2,h3,h4,h5,h6,pre,form,fieldset,p,blockquote,th,td {
margin:0;
padding:0;
}
Alternatively you could look into using the Yahoo! UI Reset style sheet which removes most default styling, so providing a solid foundation upon which you can explicitly declare your design intentions.
Variations in text size
When there is a change in text size, perhaps with a heading or sidenotes, the differing text should also take up a multiple of the basic leading. This means that, in our example, every diversion from the basic text size should take up multiples of 18px. This can be accomplished by adjusting the line-height and margin accordingly, as described following.
Headings
Subheadings in the example page are set to 14px. In order that the height of each line is 18px, the line-height should be set to 18 ÷ 14 = 1.286. Similarly the margins above and below the heading must be adjusted to fit. The temptation is to set heading margins to a simple 1em, but in order to maintain the rhythm, the top and bottom margins should be set at 1.286em so that the spacing is equal to the full 18px unit.
h2 {
font-size:1.1667em;
line-height: 1.286em;
margin-top: 1.286em;
margin-bottom: 1.286em;
}
One can also set asymmetrical margins for headings, provided the margins combine to be multiples of the basic line height. In our example, a top margin of 1½ lines is combined with a bottom margin of half a line as follows:
h2 {
font-size:1.1667em;
line-height: 1.286em;
margin-top: 1.929em;
margin-bottom: 0.643em;
}
Also in our example, the main heading is given a text size of 18px, therefore the line-height has been set to 1em, as has the margin:
h1 {
font-size:1.5em;
line-height: 1em;
margin-top: 0;
margin-bottom: 1em;
}
Sidenotes
Sidenotes (and other supplementary material) are often set at a smaller size to the basic text. To keep the rhythm, this smaller text should still line up with body copy, so a calculation similar to that for headings is required. In our example, the sidenotes are set at 10px and so their line-height must be increased to 18 ÷ 10 = 1.8.
.sidenote {
font-size:0.8333em;
line-height:1.8em;
}
Borders
One additional point where vertical rhythm is often lost is with the introduction of horizontal borders. These effectively act as shims pushing the subsequent text downwards, so a two pixel horizontal border will throw out the vertical rhythm by two pixels. A way around this is to specify horizontal lines using background images or, as in our example, specify the width of the border in ems and adjust the padding to take up the slack.
The design of the footnote in our example requires a 1px horizontal border. The footnote contains 12px text, so 1px in ems is 1 ÷ 12 = 0.0833. I have added a margin of 1½ lines above the border (1.5 × 18 ÷ 12 = 2.5ems), so to maintain the rhythm the border + padding must equal a ½ (9px). We know the border is set to 1px, so the padding must be set to 8px. To specify this in ems we use the familiar calculation: 8 ÷ 12 = 0.667.
Hit me with your rhythm stick
Composing to a vertical rhythm helps engage and guide the reader down the page, but it takes typographic discipline to do so. It may seem like a lot of fiddly maths is involved (a few divisions and multiplications never hurt anyone) but good type setting is all about numbers, and it is this attention to detail which is the key to success. |
2006 |
Richard Rutter |
richardrutter |
2006-12-12T00:00:00+00:00 |
https://24ways.org/2006/compose-to-a-vertical-rhythm/ |
design |
| 143 |
Marking Up a Tag Cloud |
Everyone’s doing it.
The problem is, everyone’s doing it wrong.
Harsh words, you might think. But the crimes against decent markup are legion in this area. You see, I’m something of a markup and semantics junkie. So I’m going to analyse some of the more well-known tag clouds on the internet, explain what’s wrong, and then show you one way to do it better.
del.icio.us
I think the first ever tag cloud I saw was on del.icio.us. Here’s how they mark it up.
<div class="alphacloud">
<a href="/tag/.net" class="lb s2">.net</a>
<a href="/tag/advertising" class=" s3">advertising</a>
<a href="/tag/ajax" class=" s5">ajax</a>
...
</div>
Unfortunately, that is one of the worst examples of tag cloud markup I have ever seen. The page states that a tag cloud is a list of tags where size reflects popularity. However, despite describing it in this way to the human readers, the page’s author hasn’t described it that way in the markup. It isn’t a list of tags, just a bunch of anchors in a <div>. This is also inaccessible because a screenreader will not pause between adjacent links, and in some configurations will not announce the individual links, but rather all of the tags will be read as just one link containing a whole bunch of words. Markup crime number one.
Flickr
Ah, Flickr. The darling photo sharing site of the internet, and the biggest blind spot in every standardista’s vision. Forgive it for having atrocious markup and sometimes confusing UI because it’s just so much damn fun to use. Let’s see what they do.
<p id="TagCloud">
<a href="/photos/tags/06/" style="font-size: 14px;">06</a>
<a href="/photos/tags/africa/" style="font-size: 12px;">africa</a>
<a href="/photos/tags/amsterdam/" style="font-size: 14px;">amsterdam</a>
...
</p>
Again we have a simple collection of anchors like del.icio.us, only this time in a paragraph. But rather than using a class to represent the size of the tag they use an inline style. An inline style using a pixel-based font size. That’s so far away from the goal of separating style from content, they might as well use a <font> tag. You could theoretically parse that to extract the information, but you have more work to guess what the pixel sizes represent. Markup crime number two (and extra jail time for using non-breaking spaces purely for visual spacing purposes.)
Technorati
Ah, now. Here, you’d expect something decent. After all, the Overlord of microformats and King of Semantics Tantek Çelik works there. Surely we’ll see something decent here?
<ol class="heatmap">
<li><em><em><em><em><a href="/tag/Britney+Spears">Britney Spears</a></em></em></em></em></li>
<li><em><em><em><em><em><em><em><em><em><a href="/tag/Bush">Bush</a></em></em></em></em></em></em></em></em></em></li>
<li><em><em><em><em><em><em><em><em><em><em><em><em><em><a href="/tag/Christmas">Christmas</a></em></em></em></em></em></em></em></em></em></em></em></em></em></li>
...
<li><em><em><em><em><em><em><a href="/tag/SEO">SEO</a></em></em></em></em></em></em></li>
<li><em><em><em><em><em><em><em><em><em><em><em><em><em><em><em><a href="/tag/Shopping">Shopping</a></em></em></em></em></em></em></em></em></em></em></em></em></em></em></em></li>
...
</ol>
Unfortunately it turns out not to be that decent, and stop calling me Shirley. It’s not exactly terrible code. It does recognise that a tag cloud is a list of links. And, since they’re in alphabetical order, that it’s an ordered list of links. That’s nice. However … fifteen nested <em> tags? FIFTEEN? That’s emphasis for you. Yes, it is parse-able, but it’s also something of a strange way of looking at emphasis. The HTML spec states that <em> is emphasis, and <strong> is for stronger emphasis. Nesting <em> tags seems counter to the idea that different tags are used for different levels of emphasis. Plus, if you had a screen reader that stressed the voice for emphasis, what would it do? Shout at you? Markup crime number three.
So what should it be?
As del.icio.us tells us, a tag cloud is a list of tags where the size that they are rendered at contains extra information. However, by hiding the extra context purely within the CSS or the HTML tags used, you are denying that context to some users. The basic assumption being made is that all users will be able to see the difference between font sizes, and this is demonstrably false.
A better way to code a tag cloud is to put the context of the cloud within the content, not the markup or CSS alone. As an example, I’m going to take some of my favourite flickr tags and put them into a cloud which communicates the relative frequency of each tag.
To start with a tag cloud in its most basic form is just a list of links. I am going to present them in alphabetical order, so I’ll use an ordered list. Into each list item I add the number of photos I have with that particular tag. The tag itself is linked to the page on flickr which contains those photos. So we end up with this first example. To display this as a traditional tag cloud, we need to alter it in a few ways:
The items need to be displayed next to each other, rather than one-per-line
The context information should be hidden from display (but not from screen readers)
The tag should link to the page of items with that tag
Displaying the items next to each other simply means setting the display of the list elements to inline. The context can be hidden by wrapping it in a <span> and then using the off-left method to hide it. And the link just means adding an anchor (with rel="tag" for some extra microformats bonus points). So, now we have a simple collection of links in our second example.
The last stage is to add the sizes. Since we already have context in our content, the size is purely for visual rendering, so we can just use classes to define the different sizes. For my example, I’ll use a range of class names from not-popular through ultra-popular, in order of smallest to largest, and then use CSS to define different font sizes. If you preferred, you could always use less verbose class names such as size1 through size6. Anyway, adding some classes and CSS gives us our final example, a semantic and more accessible tag cloud. |
2006 |
Mark Norman Francis |
marknormanfrancis |
2006-12-09T00:00:00+00:00 |
https://24ways.org/2006/marking-up-a-tag-cloud/ |
code |
| 144 |
The Mobile Web, Simplified |
A note from the editors: although eye-opening in 2006, this article is no longer relevant to today’s mobile web.
Considering a foray into mobile web development? Following are four things you need to know before making the leap.
1. 4 billion mobile subscribers expected by 2010
Fancy that. Coupled with the UN prediction of 6.8 billion humans by 2010, 4 billion mobile subscribers (source) is an astounding 59% of the planet. Just how many of those subscribers will have data plans and web-enabled phones is still in question, but inevitably this all means one thing for you and me: A ton of potential eyes to view our web content on a mobile device.
2. Context is king
Your content is of little value to users if it ignores the context in which it is viewed. Consider how you access data on your mobile device. You might be holding a bottle of water or gripping a handle on the subway/tube. You’re probably seeking specific data such as directions or show times, rather than the plethora of data at your disposal via a desktop PC.
The mobile web, a phrase often used to indicate “accessing the web on a mobile device”, is very much a context-, content-, and component-specific environment. Expressed in terms of your potential target audience, access to web content on a mobile device is largely influenced by surrounding circumstances and conditions, information relevant to being mobile, and the feature set of the device being used. Ask yourself, What is relevant to my users and the tasks, problems, and needs they may encounter while being mobile? Answer that question and you’ll be off to a great start.
3. WAP 2.0 is an XHTML environment
In a nutshell, here are a few fundamental tenets of mobile internet technology:
Wireless Application Protocol (WAP) is the protocol for enabling mobile access to internet content.
Wireless Markup Language (WML) was the language of choice for WAP 1.0.
Nearly all devices sold today are WAP 2.0 devices.
With the introduction of WAP 2.0, XHTML Mobile Profile (XHTML-MP) became the preferred markup language.
XHTML-MP will be familiar to anyone experienced with XHTML Transitional or Strict.
Summary? The mobile web is rapidly becoming an XHTML environment, and thus you and I can apply our existing “desktop web” skills to understand how to develop content for it. With WML on the decline, the learning curve is much smaller today than it was several years ago. I’m generalizing things gratuitously, but the point remains: Get off yo’ lazy butt and begin to take mobile seriously.
I’ll even pass you a few tips for getting started. First, the DOCTYPE for XHTML-MP is as follows:
<!DOCTYPE html PUBLIC "-//WAPFORUM//DTD XHTML Mobile 1.0//EN"
"http://www.openmobilealliance.org/tech/DTD/xhtml-mobile10.dtd">
As for MIME type, Open Mobile Alliance (OMA) specifies using the MIME type application/vnd.wap.xhtml+xml, but ultimately you need to ensure the server delivering your mobile content is configured properly for the MIME type you choose to use, as there are other options (see Setting up WAP Servers).
Once you’ve made it to the body, the XHTML-MP markup is not unlike what you’re already used to. A few resources worth skimming:
Developers Home XHTML-MP Tutorial – An impressively replete resource for all things XHTML-MP
XHTML-MP Tags List – A complete list of XHTML-MP elements and accompanying attributes
And last but certainly not least, CSS. There exists WAP CSS, which is essentially a subset of CSS2 with WAP-specific extensions. For all intents and purposes, much of the CSS you’re already comfortable using will be transferrable to mobile. As for including CSS in your pages, your options are the same as for desktop sites: external, embedded, and inline. Some experts will argue embedded or inline over external in favor of reducing the number of HTTP connections per page request, yet many popular mobilized sites and apps employ external linking without issue.
Stocking stuffers: Flickr Mobile, Fandango Mobile, and Popurls Mobile. A few sites with whom you can do the View Source song and dance for further study.
4. “Cell phone” is so DynaTAC
If you’re a U.S. resident, listen up: You must rid your vocabulary of the term “cell phone”. We’re one of the few economies on the planet to refer to a mobile phone accordingly. If you care to find yourself in any of the worthwhile mobile development circles, begin using terms more widely accepted: “mobile” or “mobile phone” or “handset” or “handy”. If you’re not sure which, go for “mobile”. Such as, “Yo dog, check out my new mobile.”
More importantly, however, is overcoming the mentality that access to the mobile web can be done only with a phone. Instead, “device” encourages us to think phone, handheld computer, watch, Nintendo DS, car, you name it.
Simple enough? |
2006 |
Cameron Moll |
cameronmoll |
2006-12-19T00:00:00+00:00 |
https://24ways.org/2006/the-mobile-web-simplified/ |
ux |