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• How to delete/edit files from readonly filesystem

  - by Santosh Linkha

  I am having problem with my memory device (actually a memory card that act external memory device like pendrive). experimentx@workmateX:/var/www/zendtest$ sudo rm /media/A88F-8788/python-2.7.1-docs-html.zip rm: cannot remove `/media/A88F-8788/python-2.7.1-docs-html.zip': Read-only file system I tried to change the file permission of the system but that doesn't work experimentx@workmateX:/var/www/zendtest$ sudo chmod 0777 /media/A88F-8788/python-2.7.1-docs-html.zip chmod: changing permissions of `/media/A88F-8788/python-2.7.1-docs-html.zip': Read-only file system But it perfectly works on windows. UPDATE On opening the drive and running command sudo mount -o remount,rw /media/A88F-8788 /var/log/syslog: Mar 23 15:29:48 workmateX kernel: [18042.257407] fat_get_cluster: 11 callbacks suppressed Mar 23 15:29:48 workmateX kernel: [18042.257414] FAT: Filesystem error (dev sdb1) Mar 23 15:29:48 workmateX kernel: [18042.257418] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:29:48 workmateX kernel: [18042.257425] FAT: Filesystem has been set read-only Mar 23 15:29:48 workmateX kernel: [18042.258187] FAT: Filesystem error (dev sdb1) Mar 23 15:29:48 workmateX kernel: [18042.258194] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.333787] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.333795] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.335949] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.335957] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.354903] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.354911] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.357213] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.357221] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.359547] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.359555] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.361929] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.361936] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.377416] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.377424] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.379384] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.379392] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.381898] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.381906] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:35 workmateX kernel: [18149.383764] FAT: Filesystem error (dev sdb1) Mar 23 15:31:35 workmateX kernel: [18149.383772] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.569747] fat_get_cluster: 11 callbacks suppressed Mar 23 15:31:40 workmateX kernel: [18154.569754] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.569758] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.569765] FAT: Filesystem has been set read-only Mar 23 15:31:40 workmateX kernel: [18154.572022] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.572029] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.582933] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.582941] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.585921] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.585929] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.587819] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.587827] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.597547] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.597555] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.599503] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.599511] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.602896] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.602905] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.615338] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.615346] fat_get_cluster: invalid cluster chain (i_pos 0) Mar 23 15:31:40 workmateX kernel: [18154.618574] FAT: Filesystem error (dev sdb1) Mar 23 15:31:40 workmateX kernel: [18154.618581] fat_get_cluster: invalid cluster chain (i_pos 0) var/log/message: Mar 23 15:29:48 workmateX kernel: [18042.257407] fat_get_cluster: 11 callbacks suppressed Mar 23 15:31:40 workmateX kernel: [18154.569747] fat_get_cluster: 11 callbacks suppressed

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• The Challenge with HTML5 – In Pictures

  - by dwahlin

  I love working with Web technologies and am looking forward to the new functionality that HTML5 will ultimately bring to the table (some of which can be used today). Having been through the div versus layer battle back in the IE4 and Netscape 4 days I think we’re headed down that road again as a result of browsers implementing features differently. I’ve been spending a lot of time researching and playing around with HTML5 samples and features (mainly because we’re already seeing demand for training on HTML5) and there’s a lot of great stuff there that will truly revolutionize web applications as we know them. However, browsers just aren’t there yet and many people outside of the development world don’t really feel a need to upgrade their browser if it’s working reasonably well (Mom and Dad come to mind) so it’s going to be awhile. There’s a nice test site at http://www.HTML5Test.com that runs through different HTML5 features and scores how well they’re supported. They don’t test for everything and are very clear about that on the site: “The HTML5 test score is only an indication of how well your browser supports the upcoming HTML5 standard and related specifications. It does not try to test all of the new features offered by HTML5, nor does it try to test the functionality of each feature it does detect. Despite these shortcomings we hope that by quantifying the level of support users and web developers will get an idea of how hard the browser manufacturers work on improving their browsers and the web as a development platform. The score is calculated by testing for the many new features of HTML5. Each feature is worth one or more points. Apart from the main HTML5 specification and other specifications created the W3C HTML Working Group, this test also awards points for supporting related drafts and specifications. Some of these specifications were initially part of HTML5, but are now further developed by other W3C working groups. WebGL is also part of this test despite not being developed by the W3C, because it extends the HTML5 canvas element with a 3d context. The test also awards bonus points for supporting audio and video codecs and supporting SVG or MathML embedding in a plain HTML document. These test do not count towards the total score because HTML5 does not specify any required audio or video codec. Also SVG and MathML are not required by HTML5, the specification only specifies rules for how such content should be embedded inside a plain HTML file. Please be aware that the specifications that are being tested are still in development and could change before receiving an official status. In the future new tests will be added for the pieces of the specification that are currently still missing. The maximum number of points that can be scored is 300 at this moment, but this is a moving goalpost.” It looks like their tests haven’t been updated since June, but the numbers are pretty scary as a developer because it means I’m going to have to do a lot of browser sniffing before assuming a particular feature is available to use. Not that much different from what we do today as far as browser sniffing you say? I’d have to disagree since HTML5 takes it to a whole new level. In today’s world we have script libraries such as jQuery (my personal favorite), Prototype, script.aculo.us, YUI Library, MooTools, etc. that handle the heavy lifting for us. Until those libraries handle all of the key HTML5 features available it’s going to be a challenge. Certain features such as Canvas are supported fairly well across most of the major browsers while other features such as audio and video are hit or miss depending upon what codec you want to use. Run the tests yourself to see what passes and what fails for different browsers. You can also view the HTML5 Test Suite Conformance Results at http://test.w3.org/html/tests/reporting/report.htm (a work in progress). The table below lists the scores that the HTML5Test site returned for different browsers I have installed on my desktop PC and laptop. A specific list of tests run and features supported are given when you go to the site. Note that I went ahead and tested the IE9 beta and it didn’t do nearly as good as I expected it would, but it’s not officially out yet so I expect that number will change a lot. Am I opposed to HTML5 as a result of these tests? Of course not - I’m actually really excited about what it offers.  However, I’m trying to be realistic and feel it'll definitely add a new level of headache to the Web application development process having been through something like this many years ago. On the flipside, developers that are able to target a specific browser (typically Intranet apps) or master the cross-browser issues are going to release some pretty sweet applications. Check out http://html5gallery.com/ for a look at some of the more cutting-edge sites out there that use HTML5. Also check out the http://www.beautyoftheweb.com site that Microsoft put together to showcase IE9. Chrome 8 Safari 5 for Windows     Opera 10 Firefox 3.6     Internet Explorer 9 Beta (Note that it’s still beta) Internet Explorer 8

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• A Few of My Favorite HTML5 and CSS3 Online Tools

  - by dwahlin

  I really enjoy coding up HTML5, CSS3, and JavaScript applications but there are some things that I’m better off writing with the help of a development tool. For example, CSS3 gradients aren’t exactly the most fun thing to write by hand and the same could be said for animations, transforms, or styles that require various vendor extensions. There are a lot of online tools that can simplify building HTML5/CSS3 sites and increase productivity in the process so I thought I’d put together a post on a few of my favorites tools. HTML5 Boilerplate HTML5 Boilerplate provides a great way to get started building HTML5 sites. It includes many best practices out of the box and even includes a few tricks that many people don’t even know about. The custom download option allows you to pick the features that you want to include in the files that’s generated. You can read more about it here.   Initializr Although HTML5 Boilerplate provides a great foundation for starting HTML5 sites, it focuses on providing a starting shell structure (namely an html page, JavaScript files, and a CSS stylesheet) and doesn’t include much in the way of page content to get started with. Initializer builds on HTML5 Boilerplate and provides an initial test page that can be tweaked to meet your needs. It also provides several different customization options to include/exclude features. CSS3 Maker CSS3 provides a lot of great features ranging from gradient support to rounded corners. Although many of the features are fairly straightforward there are some that are pretty involved such as gradients, animations, and really any styles that require custom vendor extensions to use across browsers. Sure, you can type everything by hand, but sites such as CSS3 Maker provide a visual way to generate CSS3 styles. CSS3, Please! CSS3, Please! is a code generation tool that can be used to generate cross-browser CSS3 styles quickly and easily. All of the main things you can do with CSS3 are available including a clever way to visually generate CSS3 transform styles.       Ultimate CSS Gradient Generator CSS3 Maker (above) has a gradient generator built-in but my favorite tool for creating CSS3 gradients is the Ultimate CSS Gradient Generator. If you’ve created gradients in tools like Photoshop then you’ll love what this tool has to offer especially since it makes it extremely straightforward to work with different gradient stops. @font-face Fonts Although @font-face has been available for awhile, I think fonts are cool and wanted to mention a site that provides a lot of font choices. When used correctly fonts can really enhance a page and when used incorrectly (think Comic Sans) they can absolutely ruin a page. Several sites exist that provide fonts that can be used with @font-face definitions in CSS style sheets. One of my favorites is Font Squirrel.   HTML5 & CSS3 Support and Tests Interested in knowing what HTML5 and CSS3 features a given browser supports? Want to know how various browsers stack up with each other as far as HTML5/CSS3 support. Look no further than the HTML5 & CSS3 Support page or the HTML5 Test page.   CSS3 Easing Animation Tool CSS3 animations aren’t widely supported across browsers right now (I’m not really using them at this point) but they do offer a lot of promise. Creating easings for animations can definitely be a challenge but they’re something that are critical for adding that “professional touch” to your animations. Fortunately you can use the Ceaser CSS Easing Animation Tool to simplify the process and handle animation easing with…...ease.   There are several other online tools that I like but these are some of the ones I find myself using the most. If you have any favorite online tools that simplify working with HTML5 or CSS3 let me know.     For more information about onsite or online training, mentoring and consulting solutions for HTML5, jQuery, .NET, SharePoint or Silverlight please visit http://www.thewahlingroup.com.

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• How to Hide the code of HTML5 games [closed]

  - by jeyanthinath

  Possible Duplicate: HTML5 game obfuscation I am begin to develop games in HTML5 and I had doubt that , when we use the game in online its source can be visible to others even if we use complex code and reference to java-script files , then what is the use of HTML5 even everyone can be able to download the code and still use their updated version Is it possible to hide the code of HTML5 in web page games OR there some other way it can made it not visible to the users !!! If not what is the use of HTML5 as it is open to user as well !!!

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• Detecting HTML5/CSS3 Features using Modernizr

  - by dwahlin

  HTML5, CSS3, and related technologies such as canvas and web sockets bring a lot of useful new features to the table that can take Web applications to the next level. These new technologies allow applications to be built using only HTML, CSS, and JavaScript allowing them to be viewed on a variety of form factors including tablets and phones. Although HTML5 features offer a lot of promise, it’s not realistic to develop applications using the latest technologies without worrying about supporting older browsers in the process. If history has taught us anything it’s that old browsers stick around for years and years which means developers have to deal with backward compatibility issues. This is especially true when deploying applications to the Internet that target the general public. This begs the question, “How do you move forward with HTML5 and CSS3 technologies while gracefully handling unsupported features in older browsers?” Although you can write code by hand to detect different HTML5 and CSS3 features, it’s not always straightforward. For example, to check for canvas support you need to write code similar to the following:   <script> window.onload = function () { if (canvasSupported()) { alert('canvas supported'); } }; function canvasSupported() { var canvas = document.createElement('canvas'); return (canvas.getContext && canvas.getContext('2d')); } </script> If you want to check for local storage support the following check can be made. It’s more involved than it should be due to a bug in older versions of Firefox. <script> window.onload = function () { if (localStorageSupported()) { alert('local storage supported'); } }; function localStorageSupported() { try { return ('localStorage' in window && window['localStorage'] != null); } catch(e) {} return false; } </script> Looking through the previous examples you can see that there’s more than meets the eye when it comes to checking browsers for HTML5 and CSS3 features. It takes a lot of work to test every possible scenario and every version of a given browser. Fortunately, you don’t have to resort to writing custom code to test what HTML5/CSS3 features a given browser supports. By using a script library called Modernizr you can add checks for different HTML5/CSS3 features into your pages with a minimal amount of code on your part. Let’s take a look at some of the key features Modernizr offers.   Getting Started with Modernizr The first time I heard the name “Modernizr” I thought it “modernized” older browsers by added missing functionality. In reality, Modernizr doesn’t actually handle adding missing features or “modernizing” older browsers. The Modernizr website states, “The name Modernizr actually stems from the goal of modernizing our development practices (and ourselves)”. Because it relies on feature detection rather than browser sniffing (a common technique used in the past – that never worked that great), Modernizr definitely provides a more modern way to test features that a browser supports and can even handle loading additional scripts called shims or polyfills that fill in holes that older browsers may have. It’s a great tool to have in your arsenal if you’re a web developer. Modernizr is available at http://modernizr.com. Two different types of scripts are available including a development script and custom production script. To generate a production script, the site provides a custom script generation tool rather than providing a single script that has everything under the sun for HTML5/CSS3 feature detection. Using the script generation tool you can pick the specific test functionality that you need and ignore everything that you don’t need. That way the script is kept as small as possible. An example of the custom script download screen is shown next. Notice that specific CSS3, HTML5, and related feature tests can be selected. Once you’ve downloaded your custom script you can add it into your web page using the standard <script> element and you’re ready to start using Modernizr. <script src="Scripts/Modernizr.js" type="text/javascript"></script>   Modernizr and the HTML Element Once you’ve add a script reference to Modernizr in a page it’ll go to work for you immediately. In fact, by adding the script several different CSS classes will be added to the page’s <html> element at runtime. These classes define what features the browser supports and what features it doesn’t support. Features that aren’t supported get a class name of “no-FeatureName”, for example “no-flexbox”. Features that are supported get a CSS class name based on the feature such as “canvas” or “websockets”. An example of classes added when running a page in Chrome is shown next:   <html class=" js flexbox canvas canvastext webgl no-touch geolocation postmessage websqldatabase indexeddb hashchange history draganddrop websockets rgba hsla multiplebgs backgroundsize borderimage borderradius boxshadow textshadow opacity cssanimations csscolumns cssgradients cssreflections csstransforms csstransforms3d csstransitions fontface generatedcontent video audio localstorage sessionstorage webworkers applicationcache svg inlinesvg smil svgclippaths"> Here’s an example of what the <html> element looks like at runtime with Internet Explorer 9:   <html class=" js no-flexbox canvas canvastext no-webgl no-touch geolocation postmessage no-websqldatabase no-indexeddb hashchange no-history draganddrop no-websockets rgba hsla multiplebgs backgroundsize no-borderimage borderradius boxshadow no-textshadow opacity no-cssanimations no-csscolumns no-cssgradients no-cssreflections csstransforms no-csstransforms3d no-csstransitions fontface generatedcontent video audio localstorage sessionstorage no-webworkers no-applicationcache svg inlinesvg smil svgclippaths">   When using Modernizr it’s a common practice to define an <html> element in your page with a no-js class added as shown next:   <html class="no-js">   You’ll see starter projects such as HTML5 Boilerplate (http://html5boilerplate.com) or Initializr (http://initializr.com) follow this approach (see my previous post for more information on HTML5 Boilerplate). By adding the no-js class it’s easy to tell if a browser has JavaScript enabled or not. If JavaScript is disabled then no-js will stay on the <html> element. If JavaScript is enabled, no-js will be removed by Modernizr and a js class will be added along with other classes that define supported/unsupported features. Working with HTML5 and CSS3 Features You can use the CSS classes added to the <html> element directly in your CSS files to determine what style properties to use based upon the features supported by a given browser. For example, the following CSS can be used to render a box shadow for browsers that support that feature and a simple border for browsers that don’t support the feature: .boxshadow #MyContainer { border: none; -webkit-box-shadow: #666 1px 1px 1px; -moz-box-shadow: #666 1px 1px 1px; } .no-boxshadow #MyContainer { border: 2px solid black; }   If a browser supports box-shadows the boxshadow CSS class will be added to the <html> element by Modernizr. It can then be associated with a given element. This example associates the boxshadow class with a div with an id of MyContainer. If the browser doesn’t support box shadows then the no-boxshadow class will be added to the <html> element and it can be used to render a standard border around the div. This provides a great way to leverage new CSS3 features in supported browsers while providing a graceful fallback for older browsers. In addition to using the CSS classes that Modernizr provides on the <html> element, you also use a global Modernizr object that’s created. This object exposes different properties that can be used to detect the availability of specific HTML5 or CSS3 features. For example, the following code can be used to detect canvas and local storage support. You can see that the code is much simpler than the code shown at the beginning of this post. It also has the added benefit of being tested by a large community of web developers around the world running a variety of browsers.   $(document).ready(function () { if (Modernizr.canvas) { //Add canvas code } if (Modernizr.localstorage) { //Add local storage code } }); The global Modernizr object can also be used to test for the presence of CSS3 features. The following code shows how to test support for border-radius and CSS transforms:   $(document).ready(function () { if (Modernizr.borderradius) { $('#MyDiv').addClass('borderRadiusStyle'); } if (Modernizr.csstransforms) { $('#MyDiv').addClass('transformsStyle'); } });   Several other CSS3 feature tests can be performed such as support for opacity, rgba, text-shadow, CSS animations, CSS transitions, multiple backgrounds, and more. A complete list of supported HTML5 and CSS3 tests that Modernizr supports can be found at http://www.modernizr.com/docs.   Loading Scripts using Modernizr In cases where a browser doesn’t support a specific feature you can either provide a graceful fallback or load a shim/polyfill script to fill in missing functionality where appropriate (more information about shims/polyfills can be found at https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills). Modernizr has a built-in script loader that can be used to test for a feature and then load a script if the feature isn’t available. The script loader is built-into Modernizr and is also available as a standalone yepnope script (http://yepnopejs.com). It’s extremely easy to get started using the script loader and it can really simplify the process of loading scripts based on the availability of a particular browser feature. To load scripts dynamically you can use Modernizr’s load() function which accepts properties defining the feature to test (test property), the script to load if the test succeeds (yep property), the script to load if the test fails (nope property), and a script to load regardless of if the test succeeds or fails (both property). An example of using load() with these properties is show next: Modernizr.load({ test: Modernizr.canvas, yep: 'html5CanvasAvailable.js’, nope: 'excanvas.js’, both: 'myCustomScript.js' }); In this example Modernizr is used to not only load scripts but also to test for the presence of the canvas feature. If the target browser supports the HTML5 canvas then the html5CanvasAvailable.js script will be loaded along with the myCustomScript.js script (use of the yep property in this example is a bit contrived – it was added simply to demonstrate how the property can be used in the load() function). Otherwise, a polyfill script named excanvas.js will be loaded to add missing canvas functionality for Internet Explorer versions prior to 9. Once excanvas.js is loaded the myCustomScript.js script will be loaded. Because Modernizr handles loading scripts, you can also use it in creative ways. For example, you can use it to load local scripts when a 3rd party Content Delivery Network (CDN) such as one provided by Google or Microsoft is unavailable for whatever reason. The Modernizr documentation provides the following example that demonstrates the process for providing a local fallback for jQuery when a CDN is down:   Modernizr.load([ { load: '//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.js', complete: function () { if (!window.jQuery) { Modernizr.load('js/libs/jquery-1.6.4.min.js'); } } }, { // This will wait for the fallback to load and // execute if it needs to. load: 'needs-jQuery.js' } ]); This code attempts to load jQuery from the Google CDN first. Once the script is downloaded (or if it fails) the function associated with complete will be called. The function checks to make sure that the jQuery object is available and if it’s not Modernizr is used to load a local jQuery script. After all of that occurs a script named needs-jQuery.js will be loaded. Conclusion If you’re building applications that use some of the latest and greatest features available in HTML5 and CSS3 then Modernizr is an essential tool. By using it you can reduce the amount of custom code required to test for browser features and provide graceful fallbacks or even load shim/polyfill scripts for older browsers to help fill in missing functionality. 

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• Detecting HTML5/CSS3 Features using Modernizr

  - by dwahlin

  HTML5, CSS3, and related technologies such as canvas and web sockets bring a lot of useful new features to the table that can take Web applications to the next level. These new technologies allow applications to be built using only HTML, CSS, and JavaScript allowing them to be viewed on a variety of form factors including tablets and phones. Although HTML5 features offer a lot of promise, it’s not realistic to develop applications using the latest technologies without worrying about supporting older browsers in the process. If history has taught us anything it’s that old browsers stick around for years and years which means developers have to deal with backward compatibility issues. This is especially true when deploying applications to the Internet that target the general public. This begs the question, “How do you move forward with HTML5 and CSS3 technologies while gracefully handling unsupported features in older browsers?” Although you can write code by hand to detect different HTML5 and CSS3 features, it’s not always straightforward. For example, to check for canvas support you need to write code similar to the following:   <script> window.onload = function () { if (canvasSupported()) { alert('canvas supported'); } }; function canvasSupported() { var canvas = document.createElement('canvas'); return (canvas.getContext && canvas.getContext('2d')); } </script> If you want to check for local storage support the following check can be made. It’s more involved than it should be due to a bug in older versions of Firefox. <script> window.onload = function () { if (localStorageSupported()) { alert('local storage supported'); } }; function localStorageSupported() { try { return ('localStorage' in window && window['localStorage'] != null); } catch(e) {} return false; } </script> Looking through the previous examples you can see that there’s more than meets the eye when it comes to checking browsers for HTML5 and CSS3 features. It takes a lot of work to test every possible scenario and every version of a given browser. Fortunately, you don’t have to resort to writing custom code to test what HTML5/CSS3 features a given browser supports. By using a script library called Modernizr you can add checks for different HTML5/CSS3 features into your pages with a minimal amount of code on your part. Let’s take a look at some of the key features Modernizr offers.   Getting Started with Modernizr The first time I heard the name “Modernizr” I thought it “modernized” older browsers by added missing functionality. In reality, Modernizr doesn’t actually handle adding missing features or “modernizing” older browsers. The Modernizr website states, “The name Modernizr actually stems from the goal of modernizing our development practices (and ourselves)”. Because it relies on feature detection rather than browser sniffing (a common technique used in the past – that never worked that great), Modernizr definitely provides a more modern way to test features that a browser supports and can even handle loading additional scripts called shims or polyfills that fill in holes that older browsers may have. It’s a great tool to have in your arsenal if you’re a web developer. Modernizr is available at http://modernizr.com. Two different types of scripts are available including a development script and custom production script. To generate a production script, the site provides a custom script generation tool rather than providing a single script that has everything under the sun for HTML5/CSS3 feature detection. Using the script generation tool you can pick the specific test functionality that you need and ignore everything that you don’t need. That way the script is kept as small as possible. An example of the custom script download screen is shown next. Notice that specific CSS3, HTML5, and related feature tests can be selected. Once you’ve downloaded your custom script you can add it into your web page using the standard <script> element and you’re ready to start using Modernizr. <script src="Scripts/Modernizr.js" type="text/javascript"></script>   Modernizr and the HTML Element Once you’ve add a script reference to Modernizr in a page it’ll go to work for you immediately. In fact, by adding the script several different CSS classes will be added to the page’s <html> element at runtime. These classes define what features the browser supports and what features it doesn’t support. Features that aren’t supported get a class name of “no-FeatureName”, for example “no-flexbox”. Features that are supported get a CSS class name based on the feature such as “canvas” or “websockets”. An example of classes added when running a page in Chrome is shown next:   <html class=" js flexbox canvas canvastext webgl no-touch geolocation postmessage websqldatabase indexeddb hashchange history draganddrop websockets rgba hsla multiplebgs backgroundsize borderimage borderradius boxshadow textshadow opacity cssanimations csscolumns cssgradients cssreflections csstransforms csstransforms3d csstransitions fontface generatedcontent video audio localstorage sessionstorage webworkers applicationcache svg inlinesvg smil svgclippaths"> Here’s an example of what the <html> element looks like at runtime with Internet Explorer 9:   <html class=" js no-flexbox canvas canvastext no-webgl no-touch geolocation postmessage no-websqldatabase no-indexeddb hashchange no-history draganddrop no-websockets rgba hsla multiplebgs backgroundsize no-borderimage borderradius boxshadow no-textshadow opacity no-cssanimations no-csscolumns no-cssgradients no-cssreflections csstransforms no-csstransforms3d no-csstransitions fontface generatedcontent video audio localstorage sessionstorage no-webworkers no-applicationcache svg inlinesvg smil svgclippaths">   When using Modernizr it’s a common practice to define an <html> element in your page with a no-js class added as shown next:   <html class="no-js">   You’ll see starter projects such as HTML5 Boilerplate (http://html5boilerplate.com) or Initializr (http://initializr.com) follow this approach (see my previous post for more information on HTML5 Boilerplate). By adding the no-js class it’s easy to tell if a browser has JavaScript enabled or not. If JavaScript is disabled then no-js will stay on the <html> element. If JavaScript is enabled, no-js will be removed by Modernizr and a js class will be added along with other classes that define supported/unsupported features. Working with HTML5 and CSS3 Features You can use the CSS classes added to the <html> element directly in your CSS files to determine what style properties to use based upon the features supported by a given browser. For example, the following CSS can be used to render a box shadow for browsers that support that feature and a simple border for browsers that don’t support the feature: .boxshadow #MyContainer { border: none; -webkit-box-shadow: #666 1px 1px 1px; -moz-box-shadow: #666 1px 1px 1px; } .no-boxshadow #MyContainer { border: 2px solid black; }   If a browser supports box-shadows the boxshadow CSS class will be added to the <html> element by Modernizr. It can then be associated with a given element. This example associates the boxshadow class with a div with an id of MyContainer. If the browser doesn’t support box shadows then the no-boxshadow class will be added to the <html> element and it can be used to render a standard border around the div. This provides a great way to leverage new CSS3 features in supported browsers while providing a graceful fallback for older browsers. In addition to using the CSS classes that Modernizr provides on the <html> element, you also use a global Modernizr object that’s created. This object exposes different properties that can be used to detect the availability of specific HTML5 or CSS3 features. For example, the following code can be used to detect canvas and local storage support. You can see that the code is much simpler than the code shown at the beginning of this post. It also has the added benefit of being tested by a large community of web developers around the world running a variety of browsers.   $(document).ready(function () { if (Modernizr.canvas) { //Add canvas code } if (Modernizr.localstorage) { //Add local storage code } }); The global Modernizr object can also be used to test for the presence of CSS3 features. The following code shows how to test support for border-radius and CSS transforms:   $(document).ready(function () { if (Modernizr.borderradius) { $('#MyDiv').addClass('borderRadiusStyle'); } if (Modernizr.csstransforms) { $('#MyDiv').addClass('transformsStyle'); } });   Several other CSS3 feature tests can be performed such as support for opacity, rgba, text-shadow, CSS animations, CSS transitions, multiple backgrounds, and more. A complete list of supported HTML5 and CSS3 tests that Modernizr supports can be found at http://www.modernizr.com/docs.   Loading Scripts using Modernizr In cases where a browser doesn’t support a specific feature you can either provide a graceful fallback or load a shim/polyfill script to fill in missing functionality where appropriate (more information about shims/polyfills can be found at https://github.com/Modernizr/Modernizr/wiki/HTML5-Cross-Browser-Polyfills). Modernizr has a built-in script loader that can be used to test for a feature and then load a script if the feature isn’t available. The script loader is built-into Modernizr and is also available as a standalone yepnope script (http://yepnopejs.com). It’s extremely easy to get started using the script loader and it can really simplify the process of loading scripts based on the availability of a particular browser feature. To load scripts dynamically you can use Modernizr’s load() function which accepts properties defining the feature to test (test property), the script to load if the test succeeds (yep property), the script to load if the test fails (nope property), and a script to load regardless of if the test succeeds or fails (both property). An example of using load() with these properties is show next: Modernizr.load({ test: Modernizr.canvas, yep: 'html5CanvasAvailable.js’, nope: 'excanvas.js’, both: 'myCustomScript.js' }); In this example Modernizr is used to not only load scripts but also to test for the presence of the canvas feature. If the target browser supports the HTML5 canvas then the html5CanvasAvailable.js script will be loaded along with the myCustomScript.js script (use of the yep property in this example is a bit contrived – it was added simply to demonstrate how the property can be used in the load() function). Otherwise, a polyfill script named excanvas.js will be loaded to add missing canvas functionality for Internet Explorer versions prior to 9. Once excanvas.js is loaded the myCustomScript.js script will be loaded. Because Modernizr handles loading scripts, you can also use it in creative ways. For example, you can use it to load local scripts when a 3rd party Content Delivery Network (CDN) such as one provided by Google or Microsoft is unavailable for whatever reason. The Modernizr documentation provides the following example that demonstrates the process for providing a local fallback for jQuery when a CDN is down:   Modernizr.load([ { load: '//ajax.googleapis.com/ajax/libs/jquery/1.6.4/jquery.js', complete: function () { if (!window.jQuery) { Modernizr.load('js/libs/jquery-1.6.4.min.js'); } } }, { // This will wait for the fallback to load and // execute if it needs to. load: 'needs-jQuery.js' } ]); This code attempts to load jQuery from the Google CDN first. Once the script is downloaded (or if it fails) the function associated with complete will be called. The function checks to make sure that the jQuery object is available and if it’s not Modernizr is used to load a local jQuery script. After all of that occurs a script named needs-jQuery.js will be loaded. Conclusion If you’re building applications that use some of the latest and greatest features available in HTML5 and CSS3 then Modernizr is an essential tool. By using it you can reduce the amount of custom code required to test for browser features and provide graceful fallbacks or even load shim/polyfill scripts for older browsers to help fill in missing functionality. 

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• Pluralsight Meet the Author Podcast on HTML5 Canvas Programming

  - by dwahlin

    In the latest installment of Pluralsight’s Meet the Author podcast series, Fritz Onion and I talk about my new course, HTML5 Canvas Fundamentals.  In the interview I describe different canvas technologies covered throughout the course and a sample application at the end of the course that covers how to build a custom business chart from start to finish. Meet the Author:  Dan Wahlin on HTML5 Canvas Fundamentals   Transcript [Fritz] Hi. This is Fritz Onion. I’m here today with Dan Wahlin to talk about his new course HTML5 Canvas Fundamentals. Dan founded the Wahlin Group, which you can find at thewahlingroup.com, which specializes in ASP.NET, jQuery, Silverlight, and SharePoint consulting. He’s a Microsoft Regional Director and has been awarded Microsoft’s MVP for ASP.NET, Connected Systems, and Silverlight. Dan is on the INETA Bureau’s — Speaker’s Bureau, speaks at conferences and user groups around the world, and has written several books on .NET. Thanks for talking to me today, Dan. [Dan] Always good to talk with you, Fritz. [Fritz] So this new course of yours, HTML5 Canvas Fundamentals, I have to say that most of the really snazzy demos I’ve seen with HTML5 have involved Canvas, so I thought it would be a good starting point to chat with you about why we decided to create a course dedicated just to Canvas. If you want to kind of give us that perspective. [Dan] Sure. So, you know, there’s quite a bit of material out there on HTML5 in general, and as people that have done a lot with HTML5 are probably aware, a lot of HTML5 is actually JavaScript centric. You know, a lot of people when they first learn it, think it’s tags, but most of it’s actually JavaScript, and it just so happens that the HTML5 Canvas is one of those things. And so it’s not just, you know, a tag you add and it just magically draws all these things. You mentioned there’s a lot of cool things you can do from games to there’s some really cool multimedia applications out there where they integrate video and audio and all kinds of things into the Canvas, to more business scenarios such as charting and things along those lines. So the reason we made a course specifically on it is, a lot of the material out there touches on it but the Canvas is actually a pretty deep topic. You can do some pretty advanced stuff or easy stuff depending on what your application requirements are, and the API itself, you know, there’s over 30 functions just in the Canvas API and then a whole set of properties that actually go with that as well. So it’s a pretty big topic, and that’s why we created a course specifically tailored towards just the Canvas. [Fritz] Right. And let’s — let me just review the outline briefly here for everyone. So you start off with an introduction to getting started with Canvas, drawing with the HTML5 Canvas, then you talk about manipulating pixels, and you finish up with building a custom data chart. So I really like your example flow here. I think it will appeal to even business developers, right. Even if you’re not into HTML5 for the games or the media capabilities, there’s still something here for everyone I think working with the Canvas. Which leads me to another question, which is, where do you see the Canvas fitting in to kind of your day-to-day developer, people that are working business applications and maybe vanilla websites that aren’t doing kind of cutting edge stuff with interactivity with users? Is there a still a place for the Canvas in those scenarios? [Dan] Yeah, definitely. I think a lot of us — and I include myself here — over the last few years, the focus has generally been, especially if you’re, let’s say, a PHP or ASP.NET or Java type of developer, we’re kind of accustomed to working on the server side, and, you know, we kind of relied on Flash or Silverlight or these other plug-ins for the client side stuff when it was kind of fancy, like charts and graphs and things along those lines. With the what I call massive shift of applications, you know, mainly because of mobile, to more of client side, one of the big benefits I think from a maybe corporate standard way of thinking of things, since we do a lot of work with different corporations, is that, number one, rather than having to have the plug-in, which of course isn’t going to work on iPad and some of these other devices out there that are pretty popular, you can now use a built-in technology that all the modern browsers support, and that includes things like Safari on the iPad and iPhone and the Android tablets and things like that with their browsers, and actually render some really sophisticated charts. Whether you do it by scratch or from scratch or, you know, get a third party type of library involved, it’s just JavaScript. So it downloads fast so it’s good from a performance perspective; and when it comes to what you can render, it’s extremely robust. You can do everything from, you know, your basic circles to polygons or polylines to really advanced gradients as well and even provide some interactivity and animations, and that’s some of the stuff I touch upon in the class. In fact, you mentioned the last part of the outline there is building a custom data chart and that’s kind of gears towards more of the, what I’d call enterprise or corporate type developer. [Fritz] Yeah, that makes sense. And it’s, you know, a lot of the demos I’ve seen with HTML5 focus on more the interactivity and kind of game side of things, but the Canvas is such a diverse element within HTML5 that I can see it being applicable pretty much anywhere. So why don’t we talk a little bit about some of the specifics of what you cover? You talk about drawing and then manipulating pixels. You want to kind of give us the different ways of working with the Canvas and what some of those APIs provide for you? [Dan] Sure. So going all the way back to the start of the outline, we actually started off by showing different demonstrations of the Canvas in action, and we show some fun stuff — multimedia apps and games and things like that — and then also some more business scenarios; and then once you see that, hopefully it kinds of piques your interest and you go, oh, wow, this is actually pretty phenomenal what you can do. So then we start you off with, so how to you actually draw things. Now, there are some libraries out there that will draw things like graphs, but if you want to customize those or just build something you have from scratch, you need to know the basics, such as, you know, how do you draw circles and lines and arcs and Bezier curves and all those fancy types of shapes that a given chart may have on it or that a game may have in it for that matter. So we start off by covering what I call the core API functions; how do you, for instance, fill a rectangle or convert that to a square by setting the height and the width; how do you draw arcs or different types of curves and there’s different types supported such as I mentioned Bezier curves or quadratic curves; and then we also talk about how do you integrate text into it. You might have some images already that are just regular bitmap type images that you want to integrate, you can do that with a Canvas. And you can even sync video into the Canvas, which actually opens up some pretty interesting possibilities for both business and I think just general multimedia apps. Once you kind of get those core functions down for the basic shapes that you need to be able to draw on any type of Canvas, then we go a little deeper into what are the pixels that are there to manipulate. And that’s one of the important things to understand about the HTML5 Canvas, scalable vector graphics is another thing you can use now in the modern browsers; it’s vector based. Canvas is pixel based. And so we talk about how to do gradients, how can you do transforms, you know, how do you scale things or rotate things, which is extremely useful for charts ’cause you might have text that, you know, flips up on its side for a y-axis or something like that. And you can even do direct pixel manipulation. So it’s really, really powerful. If you want to get down to the RGBA level, you can do that, and I show how to do that in the course, and then kind of wrap that section up with some animation fundamentals. [Fritz] Great. Yeah, that’s really powerful stuff for programmatically rendering data to clients and responding to user inputs. Look forward to seeing what everyone’s going to come up with building this stuff. So great. That’s — that’s HTML5 Canvas Fundamentals with Dan Wahlin. Thanks very much, Dan. [Dan] Thanks again. I appreciate it.

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• New Pluralsight Course: HTML5 Canvas Fundamentals

  - by dwahlin

    I just finished up a new course for Pluralsight titled HTML5 Canvas Fundamentals that I had a blast putting together. It’s all about the client and involves a lot of pixel manipulation and graphics creation which is challenging and fun at the same time. The goal of the course is to walk you through the fundamentals, start a gradual jog into the API functions, and then start sprinting as you learn how to build a business chart canvas application from scratch that uses many of the available APIs . It’s fun stuff and very useful in a variety of scenarios including Web (desktop or mobile) and even Windows 8 Metro applications. Here’s a sample video from the course that talks about building a simple bar chart using the HTML5 Canvas:   Additional details about the course are shown next.   HTML5 Canvas Fundamentals The HTML5 Canvas provides a powerful way to render graphics, charts, and other types of visual data without relying on plugins such as Flash or Silverlight. In this course you’ll be introduced to key features available in the canvas API and see how they can be used to render shapes, text, video, images, and more. You’ll also learn how to work with gradients, perform animations, transform shapes, and build a custom charting application from scratch. If you’re looking to learn more about using the HTML5 Canvas in your Web applications then this course will break down the learning curve and give you a great start!    Getting Started with the HTML5 Canvas Introduction HTML5 Canvas Usage Scenarios Demo: Game Demos Demo: Engaging Applications Demo: Charting HTML5 Canvas Fundamentals Hello World Demo Overview of the Canvas API Demo: Canvas API Documentation Summary    Drawing with the HTML5 Canvas Introduction Drawing Rectangles and Ellipses Demo: Simple Bar Chart Demo: Simple Bar Chart with Transforms Demo: Drawing Circles Demo: Using arcTo() Drawing Lines and Paths Demo: Drawing Lines Demo: Simple Line Chart Demo: Using bezierCurveTo() Demo: Using quadraticCurveTo() Drawing Text Demo: Filling, Stroking, and Measuring Text Demo: Using Canvas Transforms with Text Drawing Images Demo: Using Image Functions Drawing Videos Demo: Syncing Video with a Canvas Summary    Manipulating Pixels  Introduction Rendering Gradients Demo: Creating Linear Gradients Demo: Creating Radial Gradients Using Transforms Demo: Getting Started with Transform Functions Demo: Using transform() and and setTransform() Accessing Pixels Demo: Creating Pixels Dynamically Demo: Grayscale Pixels Animation Fundamentals Demo: Getting Started with Animation Demo: Using Gradients, Transforms, and Animations Summary    Building a Custom Data Chart Introduction Creating the CanvasChart Object Creating the CanvasChart Shell Code Rendering Text and Gradients Rendering Data Points Text and Guide Lines Connecting Data Point Lines Rendering Data Points Adding Animation Adding Overlays and Interactivity Summary     Related Courses:  

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• How best to implement HTML5 support for my validation library

  - by Vivin Paliath

  I have created an annotation-based validation library called regula. There seems to be some amount of interest around the framework and the next thing I'd like to do is to support HTML5 validation. Originally I figured that I would check to see if the browser supported the HTML5 validation that has been specified and to either emulate or delegate to built-in regula equivalents. This is trivial for things like required, but once you start getting into the date-validation, it gets tricky (date widgets, localization, etc.). So I have a few options in front of me: Full HTML5 Shim along with widgets (for date stuff etc.): I feel like this is overkill and essentially reinventing the wheel since this is already covered by things like modernizr. Use HTML5 validation if available (either native, or provided by shim; otherwise ignore): What this means is that if HTML5 validation is available (natively or through a shim) I will use it, otherwise I will ignore it. I'm leaning towards the latter since currently if someone wants to use HTML5 validation, they will most probably require a shim since not all browsers support HTML5. Which option do you think is better?

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• error:unknown filesystem grub rescue help

  - by Ridvan Çoban

  I'm trying to install ubuntu on my hdd which doesnt contain any operatin system, mbr or grub. (it has 3 partitions, 1st includes my data on ntfs file system, second is linux swap now, and third ex4 filesystem) Of course i don't want to lose my data on ntfs partition. Anyway i installed ubuntu on ex4 filesystem, selected sda as device for bootloader (not sda1,2 or 2). But i got error Error:unknown filesystem Grub rescue I tried ls command. It gives (hd0) , (hd,msdos1), (hd0,msdos2) and (hd0,msdos3). then tried ls (hd0)/, ls (hd0,1)/, ls (hd0,msdos2)/, ls (hd0,msdos3)/ to find the linux filesystem to boot. But i was unsuccessful. it all gave me unknown filesystem error. Am i missing or something?

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• Rendering Linear Gradients using the HTML5 Canvas

  - by dwahlin

  Related HTML5 Canvas Posts: Getting Started with the HTML5 Canvas Rendering Text with the HTML5 Canvas Creating a Line Chart using the HTML5 Canvas New Pluralsight Course: HTML5 Canvas Fundamentals Gradients are everywhere. They’re used to enhance toolbars or buttons and help add additional flare to a web page when used appropriately. In the past we’ve always had to rely on images to render gradients which works well, but isn’t necessarily the most efficient (although 1 pixel wide images do work well). CSS3 provides a great way to render gradients in modern browsers (see http://www.colorzilla.com/gradient-editor for a nice online gradient generator tool) but it’s not the only option. If you’re working with charts, games, multimedia or other HTML5 Canvas applications you can also use gradients and render them on the client-side without relying on images. In this post I’ll introduce how to use linear gradients and discuss the different functions that can be used to create them.   Creating Linear Gradients Linear gradients can be created using the 2D context’s createLinearGradient function. The function takes the starting x,y coordinates and ending x,y coordinates of the gradient:   createLinearGradient(x1, y1, x2, y2);   By changing the start and end coordinates you can control the direction that the gradient renders. For example, adding the following coordinates causes the gradient to render from left to right since the y value stays at 0 for both points while the x value changes from 0 to 200. var lgrad = ctx.createLinearGradient(0, 0, 200, 0); Here’s an example of how changing the coordinates affects the gradient direction:   Once a linear gradient object has been created you can set color stops using the addColorStop() function. It takes the location where the color should appear in the gradient with 0 being the beginning and 1 being at the end (0.5 would be in the middle) as well as the color to display in the gradient. lgrad.addColorStop(0, 'white'); lgrad.addColorStop(1, 'gray');   An example of combining createLinearGradient() with addColorStop() is shown next:   Using createLinearGradient() var canvas = document.getElementById('myCanvas'); var ctx = canvas.getContext('2d'); var lgrad = ctx.createLinearGradient(0, 0, 200, 0); lgrad.addColorStop(0, 'white'); lgrad.addColorStop(1, 'gray'); ctx.fillStyle = lgrad; ctx.fillRect(0, 0, 200, 200); ctx.strokeRect(0, 0, 200, 200); This code renders a white to gray gradient as shown next: A live example of using createLinearGradient() is shown next. Click the Result tab to see the code in action.   In the next post on the HTML5 Canvas I’ll take a look at radial gradients and how they can be used. In the meantime, if you’re interested in learning more about the HTML5 Canvas and how it can be used in your Web or Windows 8 applications, check out my HTML5 Canvas Fundamentals course from Pluralsight. It has over 4 1/2 hours of canvas goodness packed in it.

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• Rendering Text with the HTML5 Canvas

  - by dwahlin

  In a previous post I walked through the fundamentals of rendering shapes such as squares and circles using the HTML5 Canvas API. In this post I’ll provide a simple example of rendering and rotating text. To render text you can use the fillText() or strokeText() functions which take the text to render as well as the x and y coordinates of where to render it. To rotate text you can use the transform functions available with the HTML5 Canvas such as save(), rotate(), and restore(). To run the live demos that follow click the Result tab in the blue bar of each demo.   Rendering Text This example provides a simple look at how text can be rendered using the HTML5 Canvas. It iterates through a loop, updates the text and font size dynamically, measures the width of the text using the measureText() function, and then calls fillText() to render the text with the desired font size to the screen.   Here’s what the code above renders:   Rotating Text This example shows how text can be rendered and even rotated by using transform functions built into the HTML5 Canvas. The code starts by rendering text the standard way using fillText(). It then saves the state of the canvas performs an x,y coordinate transform (moves to 100, 300 respectively) and then rotates the canvas –90 degrees using the rotate() function. After the text is rendered, the canvas is reverted back to it’s existing state (saved by calling the save() function) by calling the restore() function. An additional line of text is then rendered.   Here’s what the code above renders:   If you’re interested in learning more about the HTML5 Canvas and how it can be used in your Web or Windows 8 applications, check out my HTML5 Canvas Fundamentals course from Pluralsight.

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• Repair ext4 filesystem on USB drive

  - by phineas

  Yet another filesystem question. I wanted to use a USB drive that I hadn't mounted for a month or so and was surprised by the fact Ubuntu was unable to mount it. I looked it up in the disk utility and it said it discovered a device with 17 MB instead of 2 GB. The hardware looks intact, I hope for the best for repairing the ext4 filesystem. I followed the instructions from HOWTO: Repair a broken Ext4 Superblock in Ubuntu, but I wasn't successful. # fsck.ext4 -v /dev/sdb e2fsck 1.42.5 (29-Jul-2012) ext2fs_open2: Bad magic number in super-block fsck.ext4: Superblock invalid, trying backup blocks... fsck.ext4: Bad magic number in super-block while trying to open /dev/sdb The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt, and you might try running e2fsck with an alternate superblock: e2fsck -b 8193 Filesystem blocks are invalid, however when I run the recommended solution to try the alternate superblock, I get the following output: # e2fsck -b 8193 /dev/sdb e2fsck 1.42.5 (29-Jul-2012) e2fsck: Invalid argument while trying to open /dev/sdb plus the same error message as in the last paragraph above. Any ideas how to recover the drive? Thank you very much! Edit: testdisk won't help. I'm still stunned why the tools only discover 17 MB.

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• HTML5-MVC application using VS2010 SP1

  - by nmarun

  This is my first attempt at creating HTML5 pages. VS 2010 allows working with HTML5 now (you just need to make a small change after installing SP1). So my Razor view is now a HTML5 page. I call this application - 5Commerce – (an over-simplified) HTML5 ECommerce site. So here’s the flow of the application: home page renders user enters first and last name, chooses a product and the quantity can enter additional instructions for the order place the order user is then taken to another page showing the order details Off to the details. This is what my page looks in Google Chrome 10 beta (or later) soon after it renders. Here are some of the things to observe on this. Look a little closer and you’ll see a border around the first name textbox – this is ‘autofocus’ in action. I’ve set the autofocus attribute on this textbox. So as soon as the page loads, this control gets focus. 1: <input type="text" autofocus id="firstName" class="inputWidth" data_minlength="" 2: data_maxlength="" placeholder="first name" /> See a partially grayed out ‘last name’ text in the second textbox. This is set using a placeholder attribute (see above). It gets wiped out on-focus and improves the UI visuals in general. The quantity textbox is actually a numerical-only textbox. 1: <input type="number" id="quantity" data_mincount="" class="inputWidth" /> The last line is for additional instructions. This looks like a label but it’s content is editable. Just adding the ‘contenteditable’ attribute to the span allow the user to edit the text inside. 1: <span contenteditable id="additionalInstructions" data_texttype="" class="editableContent">select text and edit </span> All of the above is just plain HTML (no lurking javascript acting in here). Makes it real clean and simple. Going more into the HTML, I see that the _Layout.cshtml already is using some HTML5 content. I created my project before installing SP1, so that was the reason for my surprise. 1: <!DOCTYPE html> This is the doctype declaration in HTML5 and this is supported even by IE6 (just take my word on IE6 now, don’t go install it to test it, especially when MS is doing an IE6 countdown). That’s just amazing and extremely easy to read remember and talk about a few less bytes on every call! I modified the rest of my _Layout.cshtml to the below: 1: <!DOCTYPE html> 2: <html> 3: <head> 4: <title>5Commerce - HTML 5 Ecommerce site</title> 5: <link href="@Url.Content("~/Content/Site.css")" rel="stylesheet" type="text/css" /> 6: <script src="@Url.Content("~/Scripts/jquery-1.4.4.min.js")" type="text/javascript"></script> 7: <script src="@Url.Content("~/Scripts/CustomScripts.js")" type="text/javascript"></script> 8: <script type="text/javascript"> 9: $(document).ready(function () { 10: WireupEvents(); 11: }); 12:</script> 13:  14: </head> 15:  16: <body role="document" class="bodybackground"> 17: <header role="heading"> 18: <h2>5Commerce - HTML 5 Ecommerce site!</h2> 19: </header> 20: <section id="mainForm"> 21: @RenderBody() 22: </section> 23: <footer id="page_footer" role="siteBaseInfo"> 24: <p>&copy; 2011 5Commerce Inc!</p> 25: </footer> 26: </body> 27: </html> I’m sure you’re seeing some of the new tags here. To give a brief intro about them: <header>, <footer>: Marks the header/footer region of a page or section. <section>: A logical grouping of content role attribute: Identifies the responsibility of an element. This attribute can be used by screen readers and can also be filtered through jQuery. SP1 also allows for some intellisense in HTML5. You see the other types of input fields – email, date, datetime, month, url and there are others as well. So once my page loads, i.e., ‘on document ready’, I’m wiring up the events following the principles of unobtrusive javascript. In the snippet below, I’m controlling the behavior of the input controls for specific events. 1: $("#productList").bind('change blur', function () { 2: IsSelectedProductValid(); 3: }); 4:  5: $("#quantity").bind('blur', function () { 6: IsQuantityValid(); 7: }); 8:  9: $("#placeOrderButton").click( 10: function () { 11: if (IsPageValid()) { 12: LoadProducts(); 13: } 14: }); This enables some client-side validation to occur before the data is sent to the server. These validation constraints are obtained through a JSON call to the WCF service and are set to the ‘data_’ attributes of the input controls. Have a look at the ‘GetValidators()’ function below: 1: function GetValidators() { 2: // the post to your webservice or page 3: $.ajax({ 4: type: "GET", //GET or POST or PUT or DELETE verb 5: url: "http://localhost:14805/OrderService.svc/GetValidators", // Location of the service 6: data: "{}", //Data sent to server 7: contentType: "application/json; charset=utf-8", // content type sent to server 8: dataType: "json", //Expected data format from server 9: processdata: true, //True or False 10: success: function (result) {//On Successfull service call 11: if (result.length > 0) { 12: for (i = 0; i < result.length; i++) { 13: if (result[i].PropertyName == "FirstName") { 14: if (result[i].MinLength > 0) { 15: $("#firstName").attr("data_minLength", result[i].MinLength); 16: } 17: if (result[i].MaxLength > 0) { 18: $("#firstName").attr("data_maxLength", result[i].MaxLength); 19: } 20: } 21: else if (result[i].PropertyName == "LastName") { 22: if (result[i].MinLength > 0) { 23: $("#lastName").attr("data_minLength", result[i].MinLength); 24: } 25: if (result[i].MaxLength > 0) { 26: $("#lastName").attr("data_maxLength", result[i].MaxLength); 27: } 28: } 29: else if (result[i].PropertyName == "Quantity") { 30: if (result[i].MinCount > 0) { 31: $("#quantity").attr("data_minCount", result[i].MinCount); 32: } 33: } 34: else if (result[i].PropertyName == "AdditionalInstructions") { 35: if (result[i].TextType.length > 0) { 36: $("#additionalInstructions").attr("data_textType", result[i].TextType); 37: } 38: } 39: } 40: } 41: }, 42: error: function (result) {// When Service call fails 43: alert('Service call failed: ' + result.status + ' ' + result.statusText); 44: } 45: }); 46:  47: //.... 48: } Just before the GetValidators() function runs and sets the validation constraints, this is what the html looks like (seen through the Dev tools of Chrome): After the function executes, you see the values in the ‘data_’  attributes. As and when we enter valid data into these fields, the error messages disappear, since the validation is bound to the blur event of the control. There you see… no error messages (well, the catch here is that once you enter THAT name, all errors disappear automatically). Clicking on ‘Place Order!’ runs the SaveOrder function. You can see the JSON for the order object that is getting constructed and passed to the WCF Service. 1: function SaveOrder() { 2: var addlInstructionsDefaultText = "select text and edit"; 3: var addlInstructions = $("span:first").text(); 4: if(addlInstructions == addlInstructionsDefaultText) 5: { 6: addlInstructions = ''; 7: } 8: var orderJson = { 9: AdditionalInstructions: addlInstructions, 10: Customer: { 11: FirstName: $("#firstName").val(), 12: LastName: $("#lastName").val() 13: }, 14: OrderedProduct: { 15: Id: $("#productList").val(), 16: Quantity: $("#quantity").val() 17: } 18: }; 19:  20: // the post to your webservice or page 21: $.ajax({ 22: type: "POST", //GET or POST or PUT or DELETE verb 23: url: "http://localhost:14805/OrderService.svc/SaveOrder", // Location of the service 24: data: JSON.stringify(orderJson), //Data sent to server 25: contentType: "application/json; charset=utf-8", // content type sent to server 26: dataType: "json", //Expected data format from server 27: processdata: false, //True or False 28: success: function (result) {//On Successfull service call 29: window.location.href = "http://localhost:14805/home/ShowOrderDetail/" + result; 30: }, 31: error: function (request, error) {// When Service call fails 32: alert('Service call failed: ' + request.status + ' ' + request.statusText); 33: } 34: }); 35: } The service saves this order into an XML file and returns the order id (a guid). On success, I redirect to the ShowOrderDetail action method passing the guid. This page will show all the details of the order. Although the back-end weightlifting is done by WCF, I did not show any of that plumbing-work as I wanted to concentrate more on the HTML5 and its associates. However, you can see it all in the source here. I do have one issue with HTML5 and this is an existing issue with HTML4 as well. If you see the snippet above where I’ve declared a textbox for first name, you’ll see the autofocus attribute just dangling by itself. It doesn’t follow the xml syntax of ‘key="value"’ allowing users to continue writing badly-formatted html even in the new version. You’ll see the same issue with the ‘contenteditable’ attribute as well. The work-around is that you can do ‘autofocus=”true”’ and it’ll work fine plus make it well-formatted. But unless the standards enforce this, there will be people (me included) who’ll get by, by just typing the bare minimum! Hoping this will get fixed in the coming version-updates. Source code here. Verdict: I think it’s time for us to embrace the new HTML5. Thank you HTML4 and Welcome HTML5.

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• Will HTML5/JS Eventually Replace All Client Side Languages? [closed]

  - by Shnitzel

  I'm just wondering about the future of it all. IMHO, there are 4 forces that define where technology goes: Microsoft, Apple, Google, Adobe. It looks like in Apple's iPhone/iPad iADs can now be programmed in HTML5. So does that mean HTML5 will eventually replace objective-c? Also, Microsoft has now shifted it's focus from WPF/Silverlight to HTML5 and I assume Visual Studio 2011 will be all about tooling support for HTML5. Because that's what Microsoft do. (Tools). In a few months IE9 the last major browser will support HTML5. Similarly Adobe is getting on the HTML5 bandwagon and allows to export flash content to HTML5 in their latest tools. And we all know how much in bed Google is with html5. Heck, their latest Operating System (Chrome OS) is nothing but a big fat web browser. Apps for Mobile (i.e., iPhone, Android, WM7) are very hard for a company to program especially for many different devices (each with their own language) so I'm assuming this won't last too long. I.e., HTML5 will be the unifying language. Which is somewhat sad for app developers because now users will be able to play the "cool" html5 apps for free on the web and it'll be hard to charge for them. So are strongly-typed languages really doomed, and in the future, say 5-10 years, will client side programming only be in HTML5? Will all of us become javascript programmers? :) Because the signs are sure pointing that way...

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• Html5 Input Validation Presentation

  - by srkirkland

  Last week I gave a presentations to the 2011 UC Davis IT Security Symposium that covered input validation features in HTML5.  I mostly discussed the following three topics: New Html5 Input Types (like <input type=”email” />) Html5 Constraints (like <input type=”text” required maxlength=”8” />) Polyfills The slides only cover part of the story since there are a few “live demos.”  You can find all of the demo code on my github repository https://github.com/srkirkland/ITSecuritySymposium.  You’ll need ASP.NET Mvc 3 installed to run them. The slides are also available in my GitHub repository, but I’ve also added them to slideshare as well because that’s what the cool kids do: http://www.slideshare.net/srkirkland/data-validation-in-web-applications. I believe the presentation was well received and most people learned something, so I just wanted to share.  When loading up the Html5 demo just click on the Html5 tab and go through each example. Enjoy!   [Examples from the Slides and Demos]  

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• No Sound in HTML5 and Google Chrome after update to 13.10

  - by rechengehirn

  After upgrading to Ubuntu 13.10 i have no sound for HTML5 players in Google Chrome Browser. Firefox works. Flash Players are working. No sound on Youtube when using HTML5. No sound on vimeo (They have html5 player as standard). When I open the soundapplication, google doesn't show up when I try to play a html5 video. But it shows up, when playing a Flash Video. Google Chrome Version is: 24.0.1312.52 Installed an updated via ppa: deb http://dl.google.com/linux/chrome/deb/ stable main

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• Unknown filesystem error

  - by Ben

  My computer has (had) a dual boot of Ubuntu Precise and Windows 7. Recently, when I started the computer, grub gave me an error saying "Unknown filesystem", and sent me to grub rescue. I searched for solutions to this, and found this answer: Unknown filesystem error: grub rescue. I followed the instructions there, but they didn't really help: when I restarted the computer, it went straight to Windows without grub intervening at all (so it boots successfully, just not to the OS I want). This is the log from boot-repair. My Ubuntu partition is sda6. Naturally, I'm a little worried, since the log says "unknown filesystem type ''", which to me looks like the partition might be corrupt somehow. From the Ubuntu Live CD, I started gparted and looked at my partitions, and it also told me that my sda6 is an unknown filesystem. So my questions are basically: Can I restore Ubuntu to the way it was? If not, can I at least rescue the data I had on the partition somehow? Again, if I can't restore Ubuntu, how do I clean everything up so that I can reinstall it without too many complications? Another thing I should mention is that yesterday I had a similar problem where the computer told me there was a problem with the hard drive when it was starting, but it fixed itself by running fsck (that time it got past grub, and managed to start Ubuntu). Between that occasion and me having trouble booting the computer today, I have booted it successfully at least twice. Thanks for any help!

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• 3d user experience with HTML5 and Javascript

  - by chako

  I've to build a 3D user experience with HTML5 and any required JS library which provides such functionality. 3D scene consists of a cylindrical pipe and surface. It has 360 degree rotation and can zoom in and out. As user selects a parameter, specific value of that parameter at various depth of pipe in surface should display. I've searched for HTML5 3d and JS libraries and found three.js could help for this.Also found this useful presentation on HTML 3d engine: http://projects.mariusgundersen.net/OnGameStart/#1 .But as this is my first time with HTML5 3d modeling, how should I initiate to build ? What parameters should be considered ? Which tools and libraries would best fit for such requirements ? I would like to create a 3d model using HTML5 and JS 3d engine as shown in the 1st image.

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• Should I refer to browser-based games as HTML5 games or Javascript games?

  - by Bane

  First of all, I know that there are alternatives to both HTML5 and Javascript, but I worded the question so generally ("browser-based") because if I had said "HTML5" or "Javascript" games that would already imply an answer to the question. When writing wiki posts or discussing, I usually call these games "HTML5/Javascript" games. They are written in Javascript, using the new HTML5 technology. What is the proper way to call them: HTML5 or Javascript games? I see that most people opt for HTML5, why?

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• usb drive filesystem?

  - by purbleguy

  So, school is approaching quickly, and one of the things on my supply list is a usb drive. Now I'm asking myself what filesystem to use. After some research, I found ext4 to be the most stable drive filesystem. But, I also found that Windows (The OS used by every computer in my school) can't read ext4 formatted drives without special drivers, and I'm sure the school wouldn't be too happy with me having to install the windows ext4 drivers on every computer I use with my usb. So, my question is, Should I use fat32, one of the ext filesystems (2, 3 or 4 would work) or NTFS, I have an ubuntu laptop, a Mac desktop, and of course the school computers I use are Windows, so which would be the best filesystem for my usb.

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• Learning HTML5 - Sample Sites

  - by Albers

  Part of the challenge with HTML5 is understanding the range of different technologies and finding good samples. The following are some of the sites I have found most useful. IE TestDrive http://ie.microsoft.com/testdrive/ A good set of demos using touch, appcache, IndexDB, etc. Some of these only work with IE10. Be sure to click the "More Demos" link at the bottom for a longer list of Demos in a nicely organized list form. Chrome Experiments http://www.chromeexperiments.com/ Chrome browser-oriented sumbitted sites with a heavy emphasis on display technologies (WebGL & Canvas) Adobe Expressive Web http://beta.theexpressiveweb.com/ Adobe provides a dozen HTML5 & CSS3 samples. I seem to end up playing the "Breakout" style Canvas demo every time I visit the site. Mozilla Demo Studio https://developer.mozilla.org/en-US/demos/tag/tech:html5/ About 100 varied HTML5-related submitted web sites. If you click the "Browse By Technology" button there are other samples for File API, IndexedDB, etc. Introducing HTML5 samples http://html5demos.com/ Specific Tech examples related to the "Introducing HTML5" book by Bruce Lawson & Remy Sharp HTML5 Gallery http://html5gallery.com/ HTML5 Gallery focuses on "real" sites - sites that were not specifically intended to showcase a particular HTML5 feature. The actual use of HTML5 tech can vary from link to link, but it is useful to see real-world uses. FaceBook Developers HTML5 Showcase http://developers.facebook.com/html5/showcase/ A good list of high profile HTML5 applications, games and demos (including the Financial Times, GMail, Kindle web reader, and Pirates Love Daisies). HTML5 Studio http://studio.html5rocks.com/ Another Google site - currently 14 samples of concepts like slideshows, Geolocation, and WebGL using HTML5.

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• filesystem types for partitions

  - by Tim

  I am going to dual-boot install Ubuntu1 10.04 on my laptop with Windows 7. I was wondering what filesystem types (such as ext2, ext3, ext4, ReiserFS and whatever might come into mind) are recommended for various possible partitions (such as /, home, /boot, swap, and others that might come into mind)and why? if ext4 is now stable enough for use for partitions in Ubuntu and Shared partition between Windows and Ubuntu? what journaling Options (writeback, ordered and journal) are recommended for each partition's filesystem? Thanks and regards!

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• Is there a portal dedicated to HTML5 games?

  - by Bane

  Just to get something straight; by "portal", I mean a website that frequently publishes a certain type of games, has a blog, some articles, maybe some tutorials and so on. All of these things are not required (except the game publishing part, of course), for example, I consider Miniclip to be a flash game portal. The reason for defining this term is because I'm not sure if other people use it in this context. I recently (less than a year ago) got into HTML5 game development, nothing serious, just my own small projects that I didn't really show to a lot of people, and that certainly didn't end up somewhere on the web (although, I am planning to make a website for my next game). I am interested in the existence of an online portal where indie devs (or non-indie ones, doesn't really matter that much) can publish their own games, sort of like "by devs for devs", also a place where you can find some simple tutorials on basic HTML5 game development and so on... I doubt something like this exists for several reasons: You can't really commercialize an HTML5 game without a strong server-side and microtransactions The code can be easily copied HTML5 is simply new, and things need time to get their own portals somewhere... If a thing like this does not exist, I think I might get into making one some day...

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• Ubuntu Server Read-Only Filesystem Issue

  - by Scott Deutsch

  We are running a virtual machine server with multiple virtual machines with ubuntu server edition 12.04 and every so often (usually after updates via webmin it seems), the hard-drive turns into read-only filesystem. Only two of the virtual machines get affected by this problem (that I noticed so far). What could be causing this issue? What could we try to fix this problem? Has anyone else had this problem before? If so, what did you do to fix it? If I use Aptitude instead of webmin, it will not turn into into a read-only filesystem. Though this could be a coincidence. Could it be a webmin issue? Thanks. UPDATE 1 Looks like this is not an update/webmin issue at all. How I know this is because one of the virtual servers is a git server and it turned into a read-only filesystem out of the blue today. With this new info provided to you, what should I try? Thanks.

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