' + hcard.html() + '
'\n);\nmapstraction.addMarker(marker);\n\nWe\u2019ve wrapped the bubble in a div with class bubble to make it easier to style. Google Maps can behave strangely if you don\u2019t provide an explicit width for your info bubbles, so we\u2019ll add that to our CSS now:\n\n.bubble {\n\twidth: 300px;\n}\n\nThat\u2019s everything we need: let\u2019s combine our code together:\n\njQuery(function() {\n\t// First create a div to host the map\n\tvar themap = jQuery('').css({\n\t\t'width': '90%',\n\t\t'height': '400px'\n\t}).insertBefore('ul.restaurants');\n\t// Now initialise the map\n\tvar mapstraction = new Mapstraction('themap','google');\n\tmapstraction.addControls({\n\t\tzoom: 'large',\n\t\tmap_type: true\n\t});\n\t// Show map centred on Brighton\n\tmapstraction.setCenterAndZoom(\n\t\tnew LatLonPoint(50.82423734980143, -0.14007568359375),\n\t\t15 // Zoom level appropriate for Brighton city centre\n\t);\n\t// Geocode each hcard and add a marker\n\tjQuery('.vcard').each(function() {\n\t\tvar hcard = jQuery(this);\n\t\tvar streetaddress = hcard.find('.street-address').text();\n\t\tvar postcode = hcard.find('.postal-code').text();\n\t\tvar geocoder = new MapstractionGeocoder(function(result) {\n\t\t\tvar marker = new Marker(result.point);\n\t\t\tmarker.setInfoBubble(\n\t\t\t\t'' + hcard.html() + '
'\n\t\t\t);\n\t\t\tmapstraction.addMarker(marker);\n\t\t}, 'google');\t \n\t\tgeocoder.geocode({'address': streetaddress + ', ' + postcode});\n\t});\n});\n\nHere\u2019s the finished code.\n\nThere\u2019s one last shortcut we can add: jQuery provides the $ symbol as an alias for jQuery. We could just go through our code and replace every call to jQuery() with a call to $(), but this would cause incompatibilities if we ever attempted to use our script on a page that also includes the Prototype library. A more robust approach is to start our code with the following:\n\njQuery(function($) {\n\t// Within this function, $ now refers to jQuery\n\t// ...\n});\n\njQuery cleverly passes itself as the first argument to any function registered to the DOM ready event, which means we can assign a local $ variable shortcut without affecting the $ symbol in the global scope. This makes it easy to use jQuery with other libraries.\n\nLimitations of Geocoding\n\nYou may have noticed a discrepancy creep in to the last example: whereas my original list included seven restaurants, the geocoding example only shows five. This is because the Google Maps geocoder incorporates a rate limit: more than five lookups in a second and it starts returning error messages instead of regular results.\n\nIn addition to this problem, geocoding itself is an inexact science: while UK postcodes generally get you down to the correct street, figuring out the exact point on the street from the provided address usually isn\u2019t too accurate (although Google do a pretty good job).\n\nFinally, there\u2019s the performance overhead. We\u2019re making five geocoding requests to Google for every page served, even though the restaurants themselves aren\u2019t likely to change location any time soon. Surely there\u2019s a better way of doing this?\n\nMicroformats to the rescue (again)! The geo microformat suggests simple classes for including latitude and longitude information in a page. We can add specific points for each restaurant using the following markup:\n\nE-Kagen
\n\t\n\t\t
\n\t22-23 Sydney Street
\n\t\tBrighton, UK
\n\t\tBN1 4EN
\n\tTelephone: +44 (0)1273 687 068
\n\tLat/Lon: \n\t\t50.827917, \n\t\t-0.137764\n\t
\n' + hcard.html() + '
'\n\t);\n\tmapstraction.addMarker(marker);\n});\n\nAnd here\u2019s the finished geo example.\n\nFurther reading\n\nWe\u2019ve only scratched the surface of what\u2019s possible with microformats, jQuery (or just regular JavaScript) and a bit of imagination. If this example has piqued your interest, the following links should give you some more food for thought.\n\n\n\tThe hCard specification\n\tNotes on parsing hCards\n\tjQuery for JavaScript programmers \u2013 my extended tutorial on jQuery.\n\tDann Webb\u2019s Sumo \u2013 a full JavaScript library for parsing microformats, based around some clever metaprogramming techniques.\n\tJeremy Keith\u2019s Adactio Austin \u2013 the first place I saw using microformats to unobtrusively plot locations on a map. Makes clever use of hEvent as well.", "year": "2007", "author": "Simon Willison", "author_slug": "simonwillison", "published": "2007-12-12T00:00:00+00:00", "url": "https://24ways.org/2007/unobtrusively-mapping-microformats-with-jquery/", "topic": "code"}
{"rowid": 165, "title": "Transparent PNGs in Internet Explorer 6", "contents": "Newer breeds of browser such as Firefox and Safari have offered support for PNG images with full alpha channel transparency for a few years. With the use of hacks, support has been available in Internet Explorer 5.5 and 6, but the hacks are non-ideal and have been tricky to use. With IE7 winning masses of users from earlier versions over the last year, full PNG alpha-channel transparency is becoming more of a reality for day-to-day use.\n\nHowever, there are still numbers of IE6 users out there who we can\u2019t leave out in the cold this Christmas, so in this article I\u2019m going to look what we can do to support IE6 users whilst taking full advantage of transparency for the majority of a site\u2019s visitors.\n\nSo what\u2019s alpha channel transparency?\n\nCast your minds back to the Ghost of Christmas Past, the humble GIF. Images in GIF format offer transparency, but that transparency is either on or off for any given pixel. Each pixel\u2019s either fully transparent, or a solid colour. In GIF, transparency is effectively just a special colour you can chose for a pixel.\n\nThe PNG format tackles the problem rather differently. As well as having any colour you chose, each pixel also carries a separate channel of information detailing how transparent it is. This alpha channel enables a pixel to be fully transparent, fully opaque, or critically, any step in between.\n\nThis enables designers to produce images that can have, for example, soft edges without any of the \u2018halo effect\u2019 traditionally associated with GIF transparency. If you\u2019ve ever worked on a site that has different colour schemes and therefore requires multiple versions of each graphic against a different colour, you\u2019ll immediately see the benefit. \n\nWhat\u2019s perhaps more interesting than that, however, is the extra creative freedom this gives designers in creating beautiful sites that can remain web-like in their ability to adjust, scale and reflow.\n\nThe Internet Explorer problem\n\nUp until IE7, there has been no fully native support for PNG alpha channel transparency in Internet Explorer. However, since IE5.5 there has been some support in the form of proprietary filter called the AlphaImageLoader. Internet Explorer filters can be applied directly in your CSS (for both inline and background images), or by setting the same CSS property with JavaScript. \n\nCSS:\n\nimg {\n\tfilter: progid:DXImageTransform.Microsoft.AlphaImageLoader(...);\n}\n\nJavaScript:\n\nimg.style.filter = \"progid:DXImageTransform.Microsoft.AlphaImageLoader(...)\";\n\nThat may sound like a problem solved, but all is not as it may appear. Firstly, as you may realise, there\u2019s no CSS property called filter in the W3C CSS spec. It\u2019s a proprietary extension added by Microsoft that could potentially cause other browsers to reject your entire CSS rule. \n\nSecondly, AlphaImageLoader does not magically add full PNG transparency support so that a PNG in the page will just start working. Instead, when applied to an element in the page, it draws a new rendering surface in the same space that element occupies and loads a PNG into it. If that sounds weird, it\u2019s because that\u2019s precisely what it is. However, by and large the result is that PNGs with an alpha channel can be accommodated.\n\nThe pitfalls\n\nSo, whilst support for PNG transparency in IE5.5 and 6 is possible, it\u2019s not without its problems.\n\nBackground images cannot be positioned or repeated\n\nThe AlphaImageLoader does work for background images, but only for the simplest of cases. If your design requires the image to be tiled (background-repeat) or positioned (background-position) you\u2019re out of luck. The AlphaImageLoader allows you to set a sizingMethod to either crop the image (if necessary) or to scale it to fit. Not massively useful, but something at least.\n\nDelayed loading and resource use\n\nThe AlphaImageLoader can be quite slow to load, and appears to consume more resources than a standard image when applied. Typically, you\u2019d need to add thousands of GIFs or JPEGs to a page before you saw any noticeable impact on the browser, but with the AlphaImageLoader filter applied Internet Explorer can become sluggish after just a handful of alpha channel PNGs.\n\nThe other noticeable effect is that as more instances of the AlphaImageLoader are applied, the longer it takes to render the PNGs with their transparency. The user sees the PNG load in its original non-supported state (with black or grey areas where transparency should be) before one by one the filter kicks in and makes them properly transparent.\n\nBoth the issue of sluggish behaviour and delayed load only really manifest themselves with volume and size of image. Use just a couple of instances and it\u2019s fine, but be careful adding more than five or six. As ever, test, test, test.\n\nLinks become unclickable, forms unfocusable \n\nThis is a big one. There\u2019s a bug/weirdness with AlphaImageLoader that sometimes prevents interaction with links and forms when a PNG background image is used. This is sometimes reported as a z-index issue, but I don\u2019t believe it is. Rather, it\u2019s an artefact of that weird way the filter gets applied to the document almost outside of the normal render process. \n\nOften this can be solved by giving the links or form elements hasLayout using position: relative; where possible. However, this doesn\u2019t always work and the non-interaction problem cannot always be solved. You may find yourself having to go back to the drawing board.\n\nSidestepping the danger zones\n\nFrankly, it\u2019s pretty bad news if you design a site, have that design signed off by your client, build it and then find out only at the end (because you don\u2019t know what might trigger a problem) that your search field can\u2019t be focused in IE6. That\u2019s an absolute nightmare, and whilst it\u2019s not likely to happen, it\u2019s possible that it might. It\u2019s happened to me. So what can you do?\n\nThe best approach I\u2019ve found to this scenario is\n\n\n\tIsolate the PNG or PNGs that are causing the problem. Step through the PNGs in your page, commenting them out one by one and retesting. Typically it\u2019ll be the nearest PNG to the problem, so try there first. Keep going until you can click your links or focus your form fields.\n\tThis is where you really need luck on your side, because you\u2019re going to have to fake it. This will depend on the design of the site, but some way or other create a replacement GIF or JPEG image that will give you an acceptable result. Then use conditional comments to serve that image to only users of IE older than version 7.\n\n\nA hack, you say? Well, you started it chum.\n\nApplying AlphaImageLoader\n\nBecause the filter property is invalid CSS, the safest pragmatic approach is to apply it selectively with JavaScript for only Internet Explorer versions 5.5 and 6. This helps ensure that by default you\u2019re serving standard CSS to browsers that support both the CSS and PNG standards correct, and then selectively patching up only the browsers that need it. \n\nSeveral years ago, Aaron Boodman wrote and released a script called sleight for doing just that. However, sleight dealt only with images in the page, and not background images applied with CSS. Building on top of Aaron\u2019s work, I hacked sleight and came up with bgsleight for applying the filter to background images instead. That was in 2003, and over the years I\u2019ve made a couple of improvements here and there to keep it ticking over and to resolve conflicts between sleight and bgsleight when used together. However, with alpha channel PNGs becoming much more widespread, it\u2019s time for a new version.\n\nIntroducing SuperSleight\n\nSuperSleight adds a number of new and useful features that have come from the day-to-day needs of working with PNGs.\n\n\n\tWorks with both inline and background images, replacing the need for both sleight and bgsleight\n\tWill automatically apply position: relative to links and form fields if they don\u2019t already have position set. (Can be disabled.)\n\tCan be run on the entire document, or just a selected part where you know the PNGs are. This is better for performance.\n\tDetects background images set to no-repeat and sets the scaleMode to crop rather than scale.\n\tCan be re-applied by any other JavaScript in the page \u2013 useful if new content has been loaded by an Ajax request.\n\n\n Download SuperSleight \n\nImplementation\n\nGetting SuperSleight running on a page is quite straightforward, you just need to link the supplied JavaScript file (or the minified version if you prefer) into your document inside conditional comments so that it is delivered to only Internet Explorer 6 or older.\n\n\n\nSupplied with the JavaScript is a simple transparent GIF file. The script replaces the existing PNG with this before re-layering the PNG over the top using AlphaImageLoaded. You can change the name or path of the image in the top of the JavaScript file, where you\u2019ll also find the option to turn off the adding of position: relative to links and fields if you don\u2019t want that.\n\nThe script is kicked off with a call to supersleight.init() at the bottom. The scope of the script can be limited to just one part of the page by passing an ID of an element to supersleight.limitTo(). And that\u2019s all there is to it.\n\nUpdate March 2008: a version of this script as a jQuery plugin is also now available.", "year": "2007", "author": "Drew McLellan", "author_slug": "drewmclellan", "published": "2007-12-01T00:00:00+00:00", "url": "https://24ways.org/2007/supersleight-transparent-png-in-ie6/", "topic": "code"}
{"rowid": 157, "title": "Capturing Caps Lock", "contents": "One of the more annoying aspects of having to remember passwords (along with having to remember loads of them) is that if you\u2019ve got Caps Lock turned on accidentally when you type one in, it won\u2019t work, and you won\u2019t know why. Most desktop computers alert you in some way if you\u2019re trying to enter your password to log on and you\u2019ve enabled Caps Lock; there\u2019s no reason why the web can\u2019t do the same. What we want is a warning \u2013 maybe the user wants Caps Lock on, because maybe their password is in capitals \u2013 rather than something that interrupts what they\u2019re doing. Something subtle.\n\nBut that doesn\u2019t answer the question of how to do it. Sadly, there\u2019s no way of actually detecting whether Caps Lock is on directly. However, there\u2019s a simple work-around; if the user presses a key, and it\u2019s a capital letter, and they don\u2019t have the Shift key depressed, why then they must have Caps Lock on! Simple. \n\nDOM scripting allows your code to be notified when a key is pressed in an element; when the key is pressed, you get the ASCII code for that key. Capital letters, A to Z, have ASCII codes 65 to 90. So, the code would look something like:\n\non a key press\n\tif the ASCII code for the key is between 65 and 90 *and* if shift is pressed\n\t\twarn the user that they have Caps Lock on, but let them carry on\n\tend if\nend keypress\n\nThe actual JavaScript for this is more complicated, because both event handling and keypress information differ across browsers. Your event handling functions are passed an event object, except in Internet Explorer where you use the global event object; the event object has a which parameter containing the ASCII code for the key pressed, except in Internet Explorer where the event object has a keyCode parameter; some browsers store whether the shift key is pressed in a shiftKey parameter and some in a modifiers parameter. All this boils down to code that looks something like this:\n\nkeypress: function(e) {\n\tvar ev = e ? e : window.event;\n\tif (!ev) {\n\t\treturn;\n\t}\n\tvar targ = ev.target ? ev.target : ev.srcElement;\n\t// get key pressed\n\tvar which = -1;\n\tif (ev.which) {\n\t\twhich = ev.which;\n\t} else if (ev.keyCode) {\n\t\twhich = ev.keyCode;\n\t}\n\t// get shift status\n\tvar shift_status = false;\n\tif (ev.shiftKey) {\n\t\tshift_status = ev.shiftKey;\n\t} else if (ev.modifiers) {\n\t\tshift_status = !!(ev.modifiers & 4);\n\t}\n\n\t// At this point, you have the ASCII code in \u201cwhich\u201d, \n\t// and shift_status is true if the shift key is pressed\n}\n\nThen it\u2019s just a check to see if the ASCII code is between 65 and 90 and the shift key is pressed. (You also need to do the same work if the ASCII code is between 97 (a) and 122 (z) and the shift key is not pressed, because shifted letters are lower-case if Caps Lock is on.)\n\nif (((which >= 65 && which <= 90) && !shift_status) || \n\t((which >= 97 && which <= 122) && shift_status)) {\n\t// uppercase, no shift key\n\t/* SHOW THE WARNING HERE */\n} else {\n\t/* HIDE THE WARNING HERE */\n}\n\nThe warning can be implemented in many different ways: highlight the password field that the user is typing into, show a tooltip, display text next to the field. For simplicity, this code shows the warning as a previously created image, with appropriate alt text. Showing the warning means creating a new