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• Communities - The importance of exchange and discussion

  Communication with your environment is an essential part of everyone's life. And it doesn't matter whether you are actually living in a rural area in the middle of nowhere, within the pulsating heart of a big city, or in my case on a wonderful island in the Indian Ocean. The ability to exchange your thoughts, your experience and your worries with another person helps you to get different points of view and new ideas on how to resolve an issue you might be confronted with. Benefits of community work What happens to be common sense in your daily life, also applies to your work environment. Working in IT, or ICT as it is called in Mauritius, requires a lot of reading and learning. Not only during your lectures at the university but with your colleagues in a project assignment and hopefully with 'unknown' pals in the universe of online communities. At least I can say that I learned quite a lot from other developers code, their responses in various forums, their numerous blog articles, and while attending local user group meetings. When I started to work as a professional software developer (or engineer some may say) years ago I immediately checked the existence of communities on the programming language, the database technology and other vital information on software development in general. Luckily, it wasn't too difficult to find. My employer had a subscription of the monthly magazines and newsletters of a national organisation which also run the biggest forum in that area. Getting in touch with other developers and reading their common problems but also solutions was a huge benefit to my growth. Image courtesy of Michael Kappel (CC BY-NC 2.0) Active participation and regular contribution to this community gave me some nice advantages, too. Within three years I was listed as a conference speaker at the annual developer's conference and provided several sessions on different topics during consecutive years. Back in 2004, I took over the responsibility and management of the monthly meetings of a regional user group, and organised it for more than two years. Furthermore, I was invited to the newly-founded community program of Microsoft Germany (Community Leader/Insider Program - CLIP). My website on Active FoxPro Pages was nominated in the second batch of online communities. Due to my community work and providing advice to others, I had the honour to be awarded as Microsoft Most Valuable Professional (MVP) - Visual Developer for Visual FoxPro in the years 2006 and 2007. It was a great experience to meet with other like-minded people and I'm really grateful for that. Just in case, more details are listed in my Curriculum Vitae. But this all changed when I moved to Mauritius... Cyber island Mauritius? During the first months in Mauritius I was way too busy to think about community activities at all. First of all, there was the new company that had to be set up, the new staff had to be trained and of course the communication work-flows and so on with the project managers back in Germany had to be sorted out, too. Second, I had to get a grip of my private matters like getting the basics for my new household or exploring the neighbourhood, and last but not least I needed a break from the hectic and intensive work prior to my departure. As soon as the sea literally calmed down, I started to have conversations with my colleagues about communities and user groups. Sadly, it turned out that there were none, or at least no one was aware of any at that time. Oh oh, what did I do? Anyway, having this kind of background and very positive experience with off-line and on-line activities I decided for myself that some day I'm going to found a community in Mauritius for all kind of IT/ICT-related fields. The main focus might be on software development but not on a certain technology or methodology. It was clear to me that it should be an open infrastructure and anyone is welcome to join, to experience, to share and to contribute if they would like to. That was the idea at that time... Ok, fast-forward to recent events. At the end of October 2012 I was invited to an event called Open Days organised by Microsoft Indian Ocean Islands together with other local partners and resellers. There I got in touch with local Technical Evangelist Arnaud Meslier and we had a good conversation on communities during the breaks. Eventually, I left a good impression on him, as we are having chats on Facebook or Skype irregularly. Well, seeing that my personal and professional surroundings have been settled and running smooth, having that great exchange and contact with Microsoft IOI (again), and being really eager to re-animate my intentions from 2007, I recently founded a new community: Mauritius Software Craftsmanship Community - #MSCC It took me a while to settle down with the name but it was obvious that the community should not be attached to one single technology, like ie. .NET user group, Oracle developers, or Joomla friends (these are fictitious names). There are several other reasons why I came up with 'Craftsmanship' as the core topic of this community. The expression of 'engineering' didn't feel right with the fields covered. Software development in all kind of facets is a craft, and therefore demands a lot of practice but also guidance from more experienced developers. It also includes the process of designing, modelling and drafting the ideas. Has to deal with various types of tests and test methodologies, and of course should be focused on flexible and agile ways of acting. In order to meet and to excel a customer's request for a solution. Next, I was looking for an easy way to handle the organisation of events and meeting appointments. Using all kind of social media platforms like Google+, LinkedIn, Facebook, Xing, etc. I was never really confident about their features of event handling. More by chance I stumbled upon Meetup.com and in combination with the other entities (G+ Communities, FB Pages or in Groups) I am looking forward to advertise and manage all future activities here: Mauritius Software Craftsmanship Community This is a community for those who care and are proud of what they do. For those developers, regardless how experienced they are, who want to improve and master their craft. This is a community for those who believe that being average is just not good enough. I know, there are not many 'craftsmen' yet but it's a start... Let's see how it looks like by the end of the year. There are free smartphone apps for Android and iOS from Meetup.com that allow you to keep track of meetings and to stay informed on latest updates. And last but not least, there will be a Trello workspace to collect and share ideas and provide downloads of slides, etc. Sharing is caring! As mentioned, the #MSCC is present in various social media networks in order to cover as many people as possible here in Mauritius. Following is an overview of the current networks: Twitter - Latest updates and quickies Google+ - Community channel Facebook - Community Page LinkedIn - Community Group Trello - Collaboration workspace to share and develop ideas Hopefully, this covers the majority of computer-related people in Mauritius. Please spread the word about the #MSCC between your colleagues, your friends and other interested 'geeks'. Your future looks bright Running and participating in a user group or any kind of community usually provides quite a number of advantages for anyone. On the one side it is very joyful for me to organise appointments and get in touch with people that might be interested to present a little demo of their projects or their recent problems they had to tackle down, and on the other side there are lots of companies that have various support programs or sponsorships especially tailored for user groups. At the moment, I already have a couple of gimmicks that I would like to hand out in small contests or raffles during one of the upcoming meetings, and as said, companies provide all kind of goodies, books free of charge, or sometimes even licenses for communities. Meeting other software developers or IT guys also opens up your point of view on the local market and there might be interesting projects or job offers available, too. A community like the Mauritius Software Craftsmanship Community is great for freelancers, self-employed, students and of course employees. Meetings will be organised on a regular basis, and I'm open to all kind of suggestions from you. Please leave a comment here in blog or join the conversations in the above mentioned social networks. Let's get this community up and running, my fellow Mauritians!

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• Which of these algorithms is best for my goal?

  - by JonathonG

  I have created a program that restricts the mouse to a certain region based on a black/white bitmap. The program is 100% functional as-is, but uses an inaccurate, albeit fast, algorithm for repositioning the mouse when it strays outside the area. Currently, when the mouse moves outside the area, basically what happens is this: A line is drawn between a pre-defined static point inside the region and the mouse's new position. The point where that line intersects the edge of the allowed area is found. The mouse is moved to that point. This works, but only works perfectly for a perfect circle with the pre-defined point set in the exact center. Unfortunately, this will never be the case. The application will be used with a variety of rectangles and irregular, amorphous shapes. On such shapes, the point where the line drawn intersects the edge will usually not be the closest point on the shape to the mouse. I need to create a new algorithm that finds the closest point to the mouse's new position on the edge of the allowed area. I have several ideas about this, but I am not sure of their validity, in that they may have far too much overhead. While I am not asking for code, it might help to know that I am using Objective C / Cocoa, developing for OS X, as I feel the language being used might affect the efficiency of potential methods. My ideas are: Using a bit of trigonometry to project lines would work, but that would require some kind of intense algorithm to test every point on every line until it found the edge of the region... That seems too resource intensive since there could be something like 200 lines that would have each have to have as many as 200 pixels checked for black/white.... Using something like an A* pathing algorithm to find the shortest path to a black pixel; however, A* seems resource intensive, even though I could probably restrict it to only checking roughly in one direction. It also seems like it will take more time and effort than I have available to spend on this small portion of the much larger project I am working on, correct me if I am wrong and it would not be a significant amount of code (100 lines or around there). Mapping the border of the region before the application begins running the event tap loop. I think I could accomplish this by using my current line-based algorithm to find an edge point and then initiating an algorithm that checks all 8 pixels around that pixel, finds the next border pixel in one direction, and continues to do this until it comes back to the starting pixel. I could then store that data in an array to be used for the entire duration of the program, and have the mouse re-positioning method check the array for the closest pixel on the border to the mouse target position. That last method would presumably execute it's initial border mapping fairly quickly. (It would only have to map between 2,000 and 8,000 pixels, which means 8,000 to 64,000 checked, and I could even permanently store the data to make launching faster.) However, I am uncertain as to how much overhead it would take to scan through that array for the shortest distance for every single mouse move event... I suppose there could be a shortcut to restrict the number of elements in the array that will be checked to a variable number starting with the intersecting point on the line (from my original algorithm), and raise/lower that number to experiment with the overhead/accuracy tradeoff. Please let me know if I am over thinking this and there is an easier way that will work just fine, or which of these methods would be able to execute something like 30 times per second to keep mouse movement smooth, or if you have a better/faster method. I've posted relevant parts of my code below for reference, and included an example of what the area might look like. (I check for color value against a loaded bitmap that is black/white.) // // This part of my code runs every single time the mouse moves. // CGPoint point = CGEventGetLocation(event); float tX = point.x; float tY = point.y; if( is_in_area(tX,tY, mouse_mask)){ // target is inside O.K. area, do nothing }else{ CGPoint target; //point inside restricted region: float iX = 600; // inside x float iY = 500; // inside y // delta to midpoint between iX,iY and tX,tY float dX; float dY; float accuracy = .5; //accuracy to loop until reached do { dX = (tX-iX)/2; dY = (tY-iY)/2; if(is_in_area((tX-dX),(tY-dY),mouse_mask)){ iX += dX; iY += dY; } else { tX -= dX; tY -= dY; } } while (abs(dX)>accuracy || abs(dY)>accuracy); target = CGPointMake(roundf(tX), roundf(tY)); CGDisplayMoveCursorToPoint(CGMainDisplayID(),target); } Here is "is_in_area(int x, int y)" : bool is_in_area(NSInteger x, NSInteger y, NSBitmapImageRep *mouse_mask){ NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; NSUInteger pixel[4]; [mouse_mask getPixel:pixel atX:x y:y]; if(pixel[0]!= 0){ [pool release]; return false; } [pool release]; return true; }

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• Feedback on meeting of the Linux User Group of Mauritius

  Once upon a time in a country far far away... Okay, actually it's not that bad but it has been a while since the last meeting of the Linux User Group of Mauritius (LUGM). There have been plans in the past but it never really happened. Finally, Selven took the opportunity and organised a new meetup with low administrative overhead, proper scheduling on alternative dates and a small attendee's survey on the preferred option. All the pre-work was nicely executed. First, I wasn't sure whether it would be possible to attend. Luckily I got some additional information, like children should come, too, and I was sold to this community gathering. According to other long-term members of the LUGM it was the first time 'ever' that a gathering was organised outside of Quatre Bornes, and I have to admit it was great! LUGM - user group meeting on the 15.06.2013 in L'Escalier Quick overview of Linux & the LUGM With a little bit of delay the LUGM meeting officially started with a quick overview and introduction to Linux presented by Avinash. During the session he told the audience that there had been quite some activity over the island some years ago but unfortunately it had been quiet during recent times. Of course, we also spoke about the acknowledged world dominance of Linux - thanks to Android - and the interesting possibilities for countries like Mauritius. It is known that a couple of public institutions have there back-end infrastructure running on Red Hat Linux systems but the presence on the desktop is still very low. Users are simply hanging on to Windows XP and older versions of Microsoft Office. Following the introduction of the LUGM Ajay joined into the session and it quickly changed into a panel discussion with lots of interesting questions and answers, sharing of first-hand experience either on the job or in private use of Linux, and a couple of ideas about how the LUGM could promote Linux a bit more in Mauritius. It was great to get an insight into other attendee's opinion and activities. Especially taking into consideration that I'm already using Linux since around 1996/97. Frankly speaking, I bought a SuSE 4.x distribution back in those days because I couldn't achieve certain tasks on Windows NT 4.0 without spending a fortune. OpenELEC Mediacenter Next, Selven gave us decent introduction on OpenELEC: Open Embedded Linux Entertainment Center (OpenELEC) is a small Linux distribution built from scratch as a platform to turn your computer into an XBMC media center. OpenELEC is designed to make your system boot fast, and the install is so easy that anyone can turn a blank PC into a media machine in less than 15 minutes. I didn't know about it until this presentation. In the past, I was mainly attached to Video Disk Recorder (VDR) as it allows the use of satellite receiver cards very easily. Hm, somehow I'm still missing my precious HTPC that I had to leave back in Germany years ago. It was great piece of hardware and software; self-built PC in a standard HiFi-sized (43cm) black desktop casing with 2 full-featured Hauppauge DVB-s cards, an old-fashioned Voodoo graphics card, WiFi card, Pioneer slot-in DVD drive, and fully remote controlled via infra-red thanks to Debian, VDR and LIRC. With EP Guide, scheduled recordings and general multimedia centre it offered all the necessary comfort in the living room, besides a Nintendo game console; actually a GameCube at that time... But I have to admit that putting OpenELEC on a Raspberry Pi would be a cool DIY project in the near future. LUGM - our next generation of linux users (15.06.2013) Project Evil Genius (PEG) Don't be scared of the paragraph header. Ish gave us a cool explanation why he named it PEG - Project Evil Genius; it's because of the time of the day when he was scripting down his ideas to be able to build, package and provide software applications to various Linux distributions. The main influence came from openSuSE but the platform didn't cater for his needs and ideas, so he started to work out something on his own. During his passionate session he also talked about the amazing experience he had due to other Linux users from all over the world. During the next couple of days Ish promised to put his script to GitHub... Looking forward to that. Check out Ish's personal blog over at hacklog.in. Highly recommended to read. Why India? Simply because the registration fees per year for an Indian domain are approximately 20 times less than for a Mauritian domain (.mu). Exploring the beach of L'Escalier af the meeting 'After-party' at the beach of L'Escalier Puh, after such interesting sessions, ideas around Linux and good conversation during the breaks and over lunch it was time for a little break-out. Selven suggested that we all should head down to the beach of L'Escalier and get some impressions of nature down here in the south of the island. Talking about 'beach' ;-) - absolutely not comparable to the white-sanded ones here in Flic en Flac... There are no lagoons down at the south coast of Mauriitus, and watching the breaking waves is a different experience and joy after all. Unfortunately, I was a little bit worried about the thoughtless littering at such a remote location. You have to drive on natural paths through the sugar cane fields and I was really shocked by the amount of rubbish lying around almost everywhere. Sad, really sad and it concurs with Yasir's recent article on the same topic. Resumé & outlook It was a great event. I met with new people, had some good conversations, and even my children enjoyed themselves the whole day. The location was well-chosen, enough space for each and everyone, parking spaces and even a playground for the children. Also, a big "Thank You" to Selven and his helpers for the organisation and preparation of lunch. I'm kind of sure that this was an exceptional meeting of LUGM and I'm really looking forward to the next gathering of Linux geeks. Hopefully, soon. All images are courtesy of Avinash Meetoo. More pictures are available on Flickr.

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• Retrieving recent tweets using LINQ

  - by brian_ritchie

  There are a few different APIs for accessing Twitter from .NET.  In this example, I'll use linq2twitter.  Other APIs can be found on Twitter's development site. First off, we'll use the LINQ provider to pull in the recent tweets. .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: public static Status[] GetLatestTweets(string screenName, int numTweets) 2: { 3: try 4: { 5: var twitterCtx = new LinqToTwitter.TwitterContext(); 6: var list = from tweet in twitterCtx.Status 7: where tweet.Type == StatusType.User && 8: tweet.ScreenName == screenName 9: orderby tweet.CreatedAt descending 10: select tweet; 11: // using Take() on array because it was failing against the provider 12: var recentTweets = list.ToArray().Take(numTweets).ToArray(); 13: return recentTweets; 14: } 15: catch 16: { 17: return new Status[0]; 18: } 19: } Once they have been retrieved, they would be placed inside an MVC model. Next, the tweets need to be formatted for display. I've defined an extension method to aid with date formatting: .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: public static class DateTimeExtension 2: { 3: public static string ToAgo(this DateTime date2) 4: { 5: DateTime date1 = DateTime.Now; 6: if (DateTime.Compare(date1, date2) >= 0) 7: { 8: TimeSpan ts = date1.Subtract(date2); 9: if (ts.TotalDays >= 1) 10: return string.Format("{0} days", (int)ts.TotalDays); 11: else if (ts.Hours > 2) 12: return string.Format("{0} hours", ts.Hours); 13: else if (ts.Hours > 0) 14: return string.Format("{0} hours, {1} minutes", 15: ts.Hours, ts.Minutes); 16: else if (ts.Minutes > 5) 17: return string.Format("{0} minutes", ts.Minutes); 18: else if (ts.Minutes > 0) 19: return string.Format("{0} mintutes, {1} seconds", 20: ts.Minutes, ts.Seconds); 21: else 22: return string.Format("{0} seconds", ts.Seconds); 23: } 24: else 25: return "Not valid"; 26: } 27: } Finally, here is the piece of the view used to render the tweets. .csharpcode, .csharpcode pre { font-size: small; color: black; font-family: Consolas, "Courier New", Courier, Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } 1: <ul class="tweets"> 2: <% 3: foreach (var tweet in Model.Tweets) 4: { 5: %> 6: <li class="tweets"> 7: <span class="tweetTime"><%=tweet.CreatedAt.ToAgo() %> ago</span>: 8: <%=tweet.Text%> 9: </li> 10: <%} %> 11: </ul>  

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• .NET HTML Sanitation for rich HTML Input

  - by Rick Strahl

  Recently I was working on updating a legacy application to MVC 4 that included free form text input. When I set up the new site my initial approach was to not allow any rich HTML input, only simple text formatting that would respect a few simple HTML commands for bold, lists etc. and automatically handles line break processing for new lines and paragraphs. This is typical for what I do with most multi-line text input in my apps and it works very well with very little development effort involved. Then the client sprung another note: Oh by the way we have a bunch of customers (real estate agents) who need to post complete HTML documents. Oh uh! There goes the simple theory. After some discussion and pleading on my part (<snicker>) to try and avoid this type of raw HTML input because of potential XSS issues, the client decided to go ahead and allow raw HTML input anyway. There has been lots of discussions on this subject on StackOverFlow (and here and here) but to after reading through some of the solutions I didn't really find anything that would work even closely for what I needed. Specifically we need to be able to allow just about any HTML markup, with the exception of script code. Remote CSS and Images need to be loaded, links need to work and so. While the 'legit' HTML posted by these agents is basic in nature it does span most of the full gamut of HTML (4). Most of the solutions XSS prevention/sanitizer solutions I found were way to aggressive and rendered the posted output unusable mostly because they tend to strip any externally loaded content. In short I needed a custom solution. I thought the best solution to this would be to use an HTML parser - in this case the Html Agility Pack - and then to run through all the HTML markup provided and remove any of the blacklisted tags and a number of attributes that are prone to JavaScript injection. There's much discussion on whether to use blacklists vs. whitelists in the discussions mentioned above, but I found that whitelists can make sense in simple scenarios where you might allow manual HTML input, but when you need to allow a larger array of HTML functionality a blacklist is probably easier to manage as the vast majority of elements and attributes could be allowed. Also white listing gets a bit more complex with HTML5 and the new proliferation of new HTML tags and most new tags generally don't affect XSS issues directly. Pure whitelisting based on elements and attributes also doesn't capture many edge cases (see some of the XSS cheat sheets listed below) so even with a white list, custom logic is still required to handle many of those edge cases. The Microsoft Web Protection Library (AntiXSS) My first thought was to check out the Microsoft AntiXSS library. Microsoft has an HTML Encoding and Sanitation library in the Microsoft Web Protection Library (formerly AntiXSS Library) on CodePlex, which provides stricter functions for whitelist encoding and sanitation. Initially I thought the Sanitation class and its static members would do the trick for me,but I found that this library is way too restrictive for my needs. Specifically the Sanitation class strips out images and links which rendered the full HTML from our real estate clients completely useless. I didn't spend much time with it, but apparently I'm not alone if feeling this library is not really useful without some way to configure operation. To give you an example of what didn't work for me with the library here's a small and simple HTML fragment that includes script, img and anchor tags. I would expect the script to be stripped and everything else to be left intact. Here's the original HTML:var value = "<b>Here</b> <script>alert('hello')</script> we go. Visit the " + "<a href='http://west-wind.com'>West Wind</a> site. " + "<img src='http://west-wind.com/images/new.gif' /> " ; and the code to sanitize it with the AntiXSS Sanitize class:@Html.Raw(Microsoft.Security.Application.Sanitizer.GetSafeHtmlFragment(value)) This produced a not so useful sanitized string: Here we go. Visit the <a>West Wind</a> site. While it removed the <script> tag (good) it also removed the href from the link and the image tag altogether (bad). In some situations this might be useful, but for most tasks I doubt this is the desired behavior. While links can contain javascript: references and images can 'broadcast' information to a server, without configuration to tell the library what to restrict this becomes useless to me. I couldn't find any way to customize the white list, nor is there code available in this 'open source' library on CodePlex. Using Html Agility Pack for HTML Parsing The WPL library wasn't going to cut it. After doing a bit of research I decided the best approach for a custom solution would be to use an HTML parser and inspect the HTML fragment/document I'm trying to import. I've used the HTML Agility Pack before for a number of apps where I needed an HTML parser without requiring an instance of a full browser like the Internet Explorer Application object which is inadequate in Web apps. In case you haven't checked out the Html Agility Pack before, it's a powerful HTML parser library that you can use from your .NET code. It provides a simple, parsable HTML DOM model to full HTML documents or HTML fragments that let you walk through each of the elements in your document. If you've used the HTML or XML DOM in a browser before you'll feel right at home with the Agility Pack. Blacklist based HTML Parsing to strip XSS Code For my purposes of HTML sanitation, the process involved is to walk the HTML document one element at a time and then check each element and attribute against a blacklist. There's quite a bit of argument of what's better: A whitelist of allowed items or a blacklist of denied items. While whitelists tend to be more secure, they also require a lot more configuration. In the case of HTML5 a whitelist could be very extensive. For what I need, I only want to ensure that no JavaScript is executed, so a blacklist includes the obvious <script> tag plus any tag that allows loading of external content including <iframe>, <object>, <embed> and <link> etc. <form>  is also excluded to avoid posting content to a different location. I also disallow <head> and <meta> tags in particular for my case, since I'm only allowing posting of HTML fragments. There is also some internal logic to exclude some attributes or attributes that include references to JavaScript or CSS expressions. The default tag blacklist reflects my use case, but is customizable and can be added to. Here's my HtmlSanitizer implementation:using System.Collections.Generic; using System.IO; using System.Xml; using HtmlAgilityPack; namespace Westwind.Web.Utilities { public class HtmlSanitizer { public HashSet<string> BlackList = new HashSet<string>() { { "script" }, { "iframe" }, { "form" }, { "object" }, { "embed" }, { "link" }, { "head" }, { "meta" } }; /// <summary> /// Cleans up an HTML string and removes HTML tags in blacklist /// </summary> /// <param name="html"></param> /// <returns></returns> public static string SanitizeHtml(string html, params string[] blackList) { var sanitizer = new HtmlSanitizer(); if (blackList != null && blackList.Length > 0) { sanitizer.BlackList.Clear(); foreach (string item in blackList) sanitizer.BlackList.Add(item); } return sanitizer.Sanitize(html); } /// <summary> /// Cleans up an HTML string by removing elements /// on the blacklist and all elements that start /// with onXXX . /// </summary> /// <param name="html"></param> /// <returns></returns> public string Sanitize(string html) { var doc = new HtmlDocument(); doc.LoadHtml(html); SanitizeHtmlNode(doc.DocumentNode); //return doc.DocumentNode.WriteTo(); string output = null; // Use an XmlTextWriter to create self-closing tags using (StringWriter sw = new StringWriter()) { XmlWriter writer = new XmlTextWriter(sw); doc.DocumentNode.WriteTo(writer); output = sw.ToString(); // strip off XML doc header if (!string.IsNullOrEmpty(output)) { int at = output.IndexOf("?>"); output = output.Substring(at + 2); } writer.Close(); } doc = null; return output; } private void SanitizeHtmlNode(HtmlNode node) { if (node.NodeType == HtmlNodeType.Element) { // check for blacklist items and remove if (BlackList.Contains(node.Name)) { node.Remove(); return; } // remove CSS Expressions and embedded script links if (node.Name == "style") { if (string.IsNullOrEmpty(node.InnerText)) { if (node.InnerHtml.Contains("expression") || node.InnerHtml.Contains("javascript:")) node.ParentNode.RemoveChild(node); } } // remove script attributes if (node.HasAttributes) { for (int i = node.Attributes.Count - 1; i >= 0; i--) { HtmlAttribute currentAttribute = node.Attributes[i]; var attr = currentAttribute.Name.ToLower(); var val = currentAttribute.Value.ToLower(); span style="background: white; color: green">// remove event handlers if (attr.StartsWith("on")) node.Attributes.Remove(currentAttribute); // remove script links else if ( //(attr == "href" || attr== "src" || attr == "dynsrc" || attr == "lowsrc") && val != null && val.Contains("javascript:")) node.Attributes.Remove(currentAttribute); // Remove CSS Expressions else if (attr == "style" && val != null && val.Contains("expression") || val.Contains("javascript:") || val.Contains("vbscript:")) node.Attributes.Remove(currentAttribute); } } } // Look through child nodes recursively if (node.HasChildNodes) { for (int i = node.ChildNodes.Count - 1; i >= 0; i--) { SanitizeHtmlNode(node.ChildNodes[i]); } } } } } Please note: Use this as a starting point only for your own parsing and review the code for your specific use case! If your needs are less lenient than mine were you can you can make this much stricter by not allowing src and href attributes or CSS links if your HTML doesn't allow it. You can also check links for external URLs and disallow those - lots of options.  The code is simple enough to make it easy to extend to fit your use cases more specifically. It's also quite easy to make this code work using a WhiteList approach if you want to go that route. The code above is semi-generic for allowing full featured HTML fragments that only disallow script related content. The Sanitize method walks through each node of the document and then recursively drills into all of its children until the entire document has been traversed. Note that the code here uses an XmlTextWriter to write output - this is done to preserve XHTML style self-closing tags which are otherwise left as non-self-closing tags. The sanitizer code scans for blacklist elements and removes those elements not allowed. Note that the blacklist is configurable either in the instance class as a property or in the static method via the string parameter list. Additionally the code goes through each element's attributes and looks for a host of rules gleaned from some of the XSS cheat sheets listed at the end of the post. Clearly there are a lot more XSS vulnerabilities, but a lot of them apply to ancient browsers (IE6 and versions of Netscape) - many of these glaring holes (like CSS expressions - WTF IE?) have been removed in modern browsers. What a Pain To be honest this is NOT a piece of code that I wanted to write. I think building anything related to XSS is better left to people who have far more knowledge of the topic than I do. Unfortunately, I was unable to find a tool that worked even closely for me, or even provided a working base. For the project I was working on I had no choice and I'm sharing the code here merely as a base line to start with and potentially expand on for specific needs. It's sad that Microsoft Web Protection Library is currently such a train wreck - this is really something that should come from Microsoft as the systems vendor or possibly a third party that provides security tools. Luckily for my application we are dealing with a authenticated and validated users so the user base is fairly well known, and relatively small - this is not a wide open Internet application that's directly public facing. As I mentioned earlier in the post, if I had my way I would simply not allow this type of raw HTML input in the first place, and instead rely on a more controlled HTML input mechanism like MarkDown or even a good HTML Edit control that can provide some limits on what types of input are allowed. Alas in this case I was overridden and we had to go forward and allow *any* raw HTML posted. Sometimes I really feel sad that it's come this far - how many good applications and tools have been thwarted by fear of XSS (or worse) attacks? So many things that could be done *if* we had a more secure browser experience and didn't have to deal with every little script twerp trying to hack into Web pages and obscure browser bugs. So much time wasted building secure apps, so much time wasted by others trying to hack apps… We're a funny species - no other species manages to waste as much time, effort and resources as we humans do :-) Resources Code on GitHub Html Agility Pack XSS Cheat Sheet XSS Prevention Cheat Sheet Microsoft Web Protection Library (AntiXss) StackOverflow Links: http://stackoverflow.com/questions/341872/html-sanitizer-for-net http://blog.stackoverflow.com/2008/06/safe-html-and-xss/ http://code.google.com/p/subsonicforums/source/browse/trunk/SubSonic.Forums.Data/HtmlScrubber.cs?r=61© Rick Strahl, West Wind Technologies, 2005-2012Posted in Security  HTML  ASP.NET  JavaScript   Tweet !function(d,s,id){var js,fjs=d.getElementsByTagName(s)[0];if(!d.getElementById(id)){js=d.createElement(s);js.id=id;js.src="//platform.twitter.com/widgets.js";fjs.parentNode.insertBefore(js,fjs);}}(document,"script","twitter-wjs"); (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();

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• XNA 3D model collision is inaccurate

  - by Daniel Lopez

  I am creating a classic game in 3d that deals with asteriods and you have to shoot them and avoid being hit from them. I can generate the asteroids just fine and the ship can shoot bullets just fine. But the asteroids always hit the ship even it doesn't look they are even close. I know 2D collision very well but not 3D so can someone please shed some light to my problem. Thanks in advance. Code For ModelRenderer: using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace _3D_Asteroids { class ModelRenderer { private float aspectratio; private Model model; private Vector3 camerapos; private Vector3 modelpos; private Matrix rotationy; float radiansy = 0; private bool isalive; public ModelRenderer(Model m, float AspectRatio, Vector3 initial_pos, Vector3 initialcamerapos) { isalive = true; model = m; if (model.Meshes.Count == 0) { throw new Exception("Invalid model because it contains zero meshes!"); } modelpos = initial_pos; camerapos = initialcamerapos; aspectratio = AspectRatio; return; } public float RadiusOfSphere { get { return model.Meshes[0].BoundingSphere.Radius; } } public BoundingBox BoxBounds { get { return BoundingBox.CreateFromSphere(model.Meshes[0].BoundingSphere); } } public BoundingSphere SphereBounds { get { return model.Meshes[0].BoundingSphere; } } public Vector3 CameraPosition { set { camerapos = value; } get { return camerapos; } } public bool IsAlive { get { return isalive; } } public Vector3 ModelPosition { set { modelpos = value; } get { return modelpos; } } public void RotateY(float radians) { radiansy += radians; rotationy = Matrix.CreateRotationY(radiansy); } public Matrix RotationY { set { rotationy = value; } get { return rotationy; } } public float AspectRatio { set { aspectratio = value; } get { return aspectratio; } } public void Kill() { isalive = false; } public void Draw(float scale) { Matrix world; if (rotationy == new Matrix(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)) { world = Matrix.CreateScale(scale) * Matrix.CreateTranslation(modelpos); } else { world = rotationy * Matrix.CreateScale(scale) * Matrix.CreateTranslation(modelpos); } Matrix view = Matrix.CreateLookAt(camerapos, Vector3.Zero, Vector3.Up); Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), this.AspectRatio, 1f, 100000f); foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.World = world; effect.View = view; effect.Projection = projection; } mesh.Draw(); } } public void Draw() { Matrix world; if (rotationy == new Matrix(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)) { world = Matrix.CreateTranslation(modelpos); } else { world = rotationy * Matrix.CreateTranslation(modelpos); } Matrix view = Matrix.CreateLookAt(camerapos, Vector3.Zero, Vector3.Up); Matrix projection = Matrix.CreatePerspectiveFieldOfView(MathHelper.ToRadians(45.0f), this.AspectRatio, 1f, 100000f); foreach (ModelMesh mesh in model.Meshes) { foreach (BasicEffect effect in mesh.Effects) { effect.World = world; effect.View = view; effect.Projection = projection; } mesh.Draw(); } } } Code For Game1: using System; using System.Collections.Generic; using System.Linq; using Microsoft.Xna.Framework; using Microsoft.Xna.Framework.Audio; using Microsoft.Xna.Framework.Content; using Microsoft.Xna.Framework.GamerServices; using Microsoft.Xna.Framework.Graphics; using Microsoft.Xna.Framework.Input; using Microsoft.Xna.Framework.Media; namespace _3D_Asteroids { /// <summary> /// This is the main type for your game /// </summary> public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; int score = 0, lives = 5; SpriteBatch spriteBatch; GameState gstate = GameState.OnMenuScreen; Menu menu = new Menu(Color.Yellow, Color.White); SpriteFont font; Texture2D background; ModelRenderer ship; Model b, a; List<ModelRenderer> bullets = new List<ModelRenderer>(); List<ModelRenderer> asteriods = new List<ModelRenderer>(); float time = 0.0f; int framecount = 0; SoundEffect effect; public Game1() { graphics = new GraphicsDeviceManager(this); graphics.PreferredBackBufferWidth = 1280; graphics.PreferredBackBufferHeight = 796; graphics.ApplyChanges(); Content.RootDirectory = "Content"; } /// <summary> /// Allows the game to perform any initialization it needs to before starting to run. /// This is where it can query for any required services and load any non-graphic /// related content. Calling base.Initialize will enumerate through any components /// and initialize them as well. /// </summary> protected override void Initialize() { // TODO: Add your initialization logic here base.Initialize(); } /// <summary> /// LoadContent will be called once per game and is the place to load /// all of your content. /// </summary> protected override void LoadContent() { // Create a new SpriteBatch, which can be used to draw textures. spriteBatch = new SpriteBatch(GraphicsDevice); font = Content.Load<SpriteFont>("Fonts\\Lucida Console"); background = Content.Load<Texture2D>("Textures\\B1_stars"); Model p1 = Content.Load<Model>("Models\\p1_wedge"); b = Content.Load<Model>("Models\\pea_proj"); a = Content.Load<Model>("Models\\asteroid1"); effect = Content.Load<SoundEffect>("Audio\\tx0_fire1"); ship = new ModelRenderer(p1, GraphicsDevice.Viewport.AspectRatio, new Vector3(0, 0, 0), new Vector3(0, 0, 9000)); } /// <summary> /// UnloadContent will be called once per game and is the place to unload /// all content. /// </summary> protected override void UnloadContent() { } /// <summary> /// Allows the game to run logic such as updating the world, /// checking for collisions, gathering input, and playing audio. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Update(GameTime gameTime) { KeyboardState state = Keyboard.GetState(PlayerIndex.One); switch (gstate) { case GameState.OnMenuScreen: { if (state.IsKeyDown(Keys.Enter)) { switch (menu.SelectedChoice) { case MenuChoices.Play: { gstate = GameState.GameStarted; break; } case MenuChoices.Exit: { this.Exit(); break; } } } if (state.IsKeyDown(Keys.Down)) { menu.MoveSelectedMenuChoiceDown(gameTime); } else if(state.IsKeyDown(Keys.Up)) { menu.MoveSelectedMenuChoiceUp(gameTime); } else { menu.KeysReleased(); } break; } case GameState.GameStarted: { foreach (ModelRenderer bullet in bullets) { if (bullet.ModelPosition.X < (ship.ModelPosition.X + 4000) && bullet.ModelPosition.Z < (ship.ModelPosition.X + 4000) && bullet.ModelPosition.X > (ship.ModelPosition.Z - 4000) && bullet.ModelPosition.Z > (ship.ModelPosition.Z - 4000)) { bullet.ModelPosition += (bullet.RotationY.Forward * 120); } else if (collidedwithasteriod(bullet)) { bullet.Kill(); } else { bullet.Kill(); } } foreach (ModelRenderer asteroid in asteriods) { if (ship.SphereBounds.Intersects(asteroid.BoxBounds)) { lives -= 1; asteroid.Kill(); // This always hits no matter where the ship goes. } else { asteroid.ModelPosition -= (asteroid.RotationY.Forward * 50); } } for (int index = 0; index < asteriods.Count; index++) { if (asteriods[index].IsAlive == false) { asteriods.RemoveAt(index); } } for (int index = 0; index < bullets.Count; index++) { if (bullets[index].IsAlive == false) { bullets.RemoveAt(index); } } if (state.IsKeyDown(Keys.Left)) { ship.RotateY(0.1f); if (state.IsKeyDown(Keys.Space)) { if (time < 17) { firebullet(); //effect.Play(); } } else { time = 0; } } else if (state.IsKeyDown(Keys.Right)) { ship.RotateY(-0.1f); if (state.IsKeyDown(Keys.Space)) { if (time < 17) { firebullet(); //effect.Play(); } } else { time = 0; } } else if (state.IsKeyDown(Keys.Up)) { ship.ModelPosition += (ship.RotationY.Forward * 50); if (state.IsKeyDown(Keys.Space)) { if (time < 17) { firebullet(); //effect.Play(); } } else { time = 0; } } else if (state.IsKeyDown(Keys.Space)) { time += gameTime.ElapsedGameTime.Milliseconds; if (time < 17) { firebullet(); //effect.Play(); } } else { time = 0.0f; } if ((framecount % 60) == 0) { createasteroid(); framecount = 0; } framecount++; break; } } base.Update(gameTime); } void firebullet() { if (bullets.Count < 3) { ModelRenderer bullet = new ModelRenderer(b, GraphicsDevice.Viewport.AspectRatio, ship.ModelPosition, new Vector3(0, 0, 9000)); bullet.RotationY = ship.RotationY; bullets.Add(bullet); } } void createasteroid() { if (asteriods.Count < 2) { Random random = new Random(); float z = random.Next(-13000, -11000); float x = random.Next(-9000, -8000); Random random2 = new Random(); int degrees = random.Next(0, 45); float radians = MathHelper.ToRadians(degrees); ModelRenderer asteroid = new ModelRenderer(a, GraphicsDevice.Viewport.AspectRatio, new Vector3(x, 0, z), new Vector3(0,0, 9000)); asteroid.RotateY(radians); asteriods.Add(asteroid); } } /// <summary> /// This is called when the game should draw itself. /// </summary> /// <param name="gameTime">Provides a snapshot of timing values.</param> protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue); switch (gstate) { case GameState.OnMenuScreen: { spriteBatch.Begin(); spriteBatch.Draw(background, Vector2.Zero, Color.White); menu.DrawMenu(ref spriteBatch, font, new Vector2(GraphicsDevice.Viewport.Width / 2, GraphicsDevice.Viewport.Height / 2) - new Vector2(50f), 100f); spriteBatch.End(); break; } case GameState.GameStarted: { spriteBatch.Begin(); spriteBatch.Draw(background, Vector2.Zero, Color.White); spriteBatch.DrawString(font, "Score: " + score.ToString() + "\nLives: " + lives.ToString(), Vector2.Zero, Color.White); spriteBatch.End(); ship.Draw(); foreach (ModelRenderer bullet in bullets) { bullet.Draw(); } foreach (ModelRenderer asteroid in asteriods) { asteroid.Draw(0.1f); } break; } } base.Draw(gameTime); } bool collidedwithasteriod(ModelRenderer bullet) { foreach (ModelRenderer asteroid in asteriods) { if (bullet.SphereBounds.Intersects(asteroid.BoxBounds)) { score += 10; asteroid.Kill(); return true; } } return false; } } } }

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• Error Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException [migrated]

  - by user134212

  I'm new here. I'm learning how to program on java and I have a problem with my code. I really have no clue why my code is not working. I think my mistake may be here, but I'm not quite sure. m3 = new Matriz(ren2,col2); btSumar.addActionListener(new ActionListener() { Matriz m3;//(ren2,col2); public void actionPerformed(ActionEvent e) { m3 = new Matriz(ren2,col2); if(ventanaAbierta==true) { try { crearMat.SUMA(m1,m2); } catch(Exception nul) { System.out.println(nul); } } else { JOptionPane.showMessageDialog(null,"Ya se realizo la suma"); } } }); My Complete code import java.awt.*; import javax.swing.*; import javax.swing.BorderFactory; import javax.swing.border.Border; import java.awt.event.*; import java.awt.*; import java.io.*; import java.util.*; public class Practica2 { private int opcion,ren2,col2; private JFrame ventana,ventanaPrintMatriz; private JPanel panel,panel2; private Border borderRed2,borderBlue2,borderGreen2,borderGreen4; private Color red,green,blue,white,black; private Font Verdana14,ArialBlack18; private JLabel labelTitulo; public JButton btSalir,btSumar,btRestar,btMultiplica,btTranspuesta,btCrear; private ImageIcon suma,resta,multi,crear,salir,trans; private boolean ventanaAbierta = false; private static ValidacionesMatrices valida; private static Operaciones operacion; private static Matriz m1,m2,m3; private static ImprimirMatriz printMat; public Practica2() { panel = new JPanel(); panel.setLayout(null); ventana = new JFrame("Operaciones con Matrices"); ventana.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); ventana.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { //Sale del programa System.exit(0); } }); ventana.setContentPane(panel); ventana.setVisible(true); ventana.setResizable(false); ventana.setBounds(150,150,300,380); //ventana.setBounds(0,0,650,650); } public void inicializarComponentes() { panel2 = new JPanel(); panel2.setLayout(null); labelTitulo = new JLabel("Practica #2"); suma = new ImageIcon("suma1.png"); resta = new ImageIcon("resta1.png"); multi = new ImageIcon("multi1.png"); trans = new ImageIcon("trans2.png"); crear = new ImageIcon("crear1.png"); salir = new ImageIcon("salir1.png"); btTranspuesta = new JButton("Transpuesta",trans); btMultiplica = new JButton("Multiplica",multi); btRestar = new JButton("Restar",resta); btSumar = new JButton("Sumar",suma); btCrear = new JButton("Crear",crear); btSalir = new JButton("Salir",salir); //Tipo de letra ArialBlack18 = new Font("Arial Black",Font.BOLD,18); //Color green = new Color(0,255,0); //Formato labelTitulo labelTitulo.setBounds(80,-60,200,150); labelTitulo.setFont(ArialBlack18); labelTitulo.setForeground(blue); labelTitulo.setVisible(true); //Formato de CrearMatriz btCrear.setBounds(80,50,130,30); btCrear.setToolTipText("Crea una matriz"); //Formato de Muliplica btMultiplica.setBounds(80,100,130,30); btMultiplica.setToolTipText("Mat[A] * Mat[B]"); //Formato de botonRestar btRestar.setBounds(80,150,130,30); btRestar.setToolTipText("Mat[A] - Mat[B]"); //Formato del botonSumar btSumar.setBounds(80,200,130,30); btSumar.setToolTipText("Mat[A] + Mat[B]"); //Formato de Transpuesta btTranspuesta.setBounds(80,250,130,30); btTranspuesta.setToolTipText("Mat[A]^-1"); //Formato del botonSalir btSalir.setBounds(80,300,130,30); //Agregando componentes al panel1 panel2.add(labelTitulo); panel2.add(btMultiplica); panel2.add(btCrear); panel2.add(btRestar); panel2.add(btSumar); panel2.add(btSalir); panel2.add(btTranspuesta); //Formato panel2 panel2.setBackground(green); panel2.setVisible(true); panel2.setBounds(0,0,300,380); //Argregamos componentes al panelPrincipal= panel.add(panel2); //BotonCrear btCrear.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) //throws IOException { if(ventanaAbierta==false) { ventanaAbierta=true; new CrearMatriz(); } else { JOptionPane.showMessageDialog(null,"Ya se crearon las Matrices"); } } }); m3 = new Matriz(ren2,col2); btSumar.addActionListener(new ActionListener() { Matriz m3;//(ren2,col2); public void actionPerformed(ActionEvent e) { m3 = new Matriz(ren2,col2); if(ventanaAbierta==true) { try { crearMat.SUMA(m1,m2); } catch(Exception nul) { System.out.println(nul); } } else { JOptionPane.showMessageDialog(null,"Ya se realizo la suma"); } } }); //BotonSalir btSalir.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { System.exit(0); } }); panel.setVisible(true); panel.setBounds(0,0,350,380); } class VentanaMatriz { private JFrame ventana; private JPanel panel; private JTextArea textArea1,textArea2; private JLabel mat1,mat2; private JTextField textField1; public VentanaMatriz() { panel = new JPanel(); panel.setLayout(null); ventana = new JFrame("Creacion de Matrices"); ventana.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { ventana.dispose(); } }); ventana.setContentPane(panel); ventana.setVisible(true); ventana.setResizable(false); ventana.setBounds(200,100,850,420); } public void inicializarComponentes() { //Colores black = new Color(0,0,0); white = new Color(255,255,255); blue = new Color(0,0,255); green = new Color(0,255,0); red = new Color(255,0,0); //Tipo de letra Verdana14 = new Font("Verdana",Font.BOLD,14); //Tipos de borde borderRed2 = BorderFactory.createLineBorder(red,2); borderBlue2 = BorderFactory.createLineBorder(blue,2); borderGreen2 = BorderFactory.createLineBorder(green,2); borderGreen4 = BorderFactory.createLineBorder(green,4); //Agregando componentes al panel1 panel.add(mat1); panel.add(textArea1); panel.add(mat2); panel.add(textArea2); //Formato panel2 panel.setBackground(blue); panel.setVisible(true); panel.setBounds(0,0,850,420); } } class CrearMatriz { public int col1,re1,ren2,col2; public Matriz m1,m2,m3; public CrearMatriz() { int col1,ren1,ren2,col2; ren2 = Integer.parseInt(JOptionPane.showInputDialog("Numero de Renglones Matriz A: ")); col2 = Integer.parseInt(JOptionPane.showInputDialog("Numero de Columnas Matriz A: ")); final Matriz m1= new Matriz(ren2,col2); ren2 = Integer.parseInt(JOptionPane.showInputDialog("Numero de Renglones Matriz B: ")); col2 = Integer.parseInt(JOptionPane.showInputDialog("Numero de Columnas Matriz B: ")); final Matriz m2= new Matriz(ren2,col2); m3 = new Matriz(ren2,col2); m1.llenarMatriz(); m2.llenarMatriz(); m1.printMat(); m2.printMat(); } public void SUMA(Matriz m1,Matriz m2) { Matriz m3; if(ventanaAbierta==false) { m3 = new Matriz(ren2,col2); if(valida.validaSumayResta(m1,m2)) { m3 = operacion.sumaMat(m1,m2); JOptionPane.showMessageDialog(null,"La suma es = "); m3.imprimeMatriz(); } else { JOptionPane.showMessageDialog(null,"No es posible hacer la suma"); } } } public void RESTA() { } //btSumar = new JButton("Sumar",suma); //BotonSumar //Mostrar matriz 1 y 2 // System.out.println("\n\n\nMatriz 1="); // m1.imprimeMatriz(); // System.out.println("\nMatriz 2="); //Poner en botones /* if(valida.validaSumayResta(m1,m2)) { m3 = operacion.sumaMat(m1,m2); JOptionPane.showMessageDialog(null,"La suma es = "); m3.imprimeMatriz(); } else { JOptionPane.showMessageDialog(null,"No es posible hacer la suma"); } if(valida.validaSumayResta(m1,m2)) { m3=operacion.restaMat(m1,m2); JOptionPane.showMessageDialog(null,"La resta es = "); m3.imprimeMatriz(); } else { JOptionPane.showMessageDialog(null,"No es posible hacer la resta"); } if(valida.validaMultiplicacion(m1,m2)){ m3=operacion.multiplicaMat(m1,m2); JOptionPane.showMessageDialog(null,"La multiplicacion es = "); m3.imprimeMatriz(); } else { JOptionPane.showMessageDialog(null,"No es posible hacer la multiplicacion"); } JOptionPane.showMessageDialog(null,"La multiplicacion es = "); m1=operacion.transpuesta(m1); m2=operacion.transpuesta(m2); */ } class Matriz { public JTextField matriz; //public JTextArea texto; private JFrame ventanaPrintMatriz; private JPanel panel2; int ren; int col; int pos[][]; public Matriz(int ren1, int col1) { ren = ren1; col = col1; pos = new int [ren][col];/*una matriz de enteros de renglon por columan*/ } public void llenarMatriz() { for(int i=0;i<ren;i++) for(int j=0;j<col;j++) pos[i][j]=(int) (Math.random()*10);/*la posicion i y j crea un entero random*/ } /*vuelve a recorrer los espacio de i y j*/ } //Esta clase era un metodo de CrearMatriz class ImprimirMatriz { public void ImprimirMatriz() { panel2 = new JPanel(); panel2.setLayout(null); ventanaPrintMatriz = new JFrame("Matriz"); ventana.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent e) { //Practica2.ventanaAbierta=false; ventana.dispose(); } }); int i,j; int x=0,y=0; borderRed2 = BorderFactory.createLineBorder(red,2); white = new Color(255,255,255); red = new Color(255,0,0); black = new Color(0,0,0); blue = new Color(0,0,255); for(i=0;i<ren;i++) { for(j=0;j<col;j++) { matriz = new JTextField(" "+pos[i][j]); matriz.setBorder(borderRed2); matriz.setForeground(white); matriz.setBounds(x+25,y+25,25,25); matriz.setBackground(black); matriz.setEditable(false); matriz.setVisible(true); //Se incrementa la coordenada en X //para el siguiente Textfield no se encime x=x+35; //Agregamos el textField al panel panel2.add(matriz); } //Regreso las cordenadas de X a 0 para que el //siguiente renglon empieze en donde mismo x=0; //Incremento las coordenada Y para que se brinque //de linea y=y+35; } //Formato panel2 panel2.setBounds(150,150,350,380); panel2.setBackground(blue); //panel2.setEditable(false); panel2.setVisible(true); //Formato de Ventana ventanaPrintMatriz.setContentPane(panel2); ventanaPrintMatriz.setBounds(150,150,350,380); ventanaPrintMatriz.setResizable(false); ventanaPrintMatriz.setVisible(true); } } class Operaciones { public Matriz sumaMat(Matriz m1, Matriz m2) { Matriz m3; m3 = new Matriz(m1.ren, m1.col); for(int i=0;i<m1.col;i++) for(int j=0;j<m1.ren;j++) m3.pos[i][j]=m1.pos[i][j]+m2.pos[i][j]; return m3; } public Matriz restaMat(Matriz m1, Matriz m2) { Matriz m3; m3 = new Matriz(m1.ren, m1.col); for(int i=0;i<m1.col;i++) for(int j=0;j<m1.ren;j++) m3.pos[i][j]=m1.pos[i][j]-m2.pos[i][j]; return m3; } public Matriz multiplicaMat(Matriz m1, Matriz m2) { Matriz m3; m3 = new Matriz(m1.ren, m2.col); for(int i=0;i<m1.ren;i++) for(int j=0;j<m2.col;j++) { m3.pos[i][j]=0; for(int k=0;k<m1.col;k++) m3.pos[i][j]+=(m1.pos[i][k]*m2.pos[k][j]); } return m3; } public Matriz transpuesta(Matriz m1) { Matriz m3=new Matriz(m1.col,m1.ren); for(int i=0;i<m1.col;i++) for(int j=0;j<m1.ren;j++) m3.pos[i][j]=m1.pos[j][i]; return m3; } } class ValidacionesMatrices { public boolean validaSumayResta(Matriz m1, Matriz m2) { if((m1.ren==m2.ren) && (m1.col==m2.col)) return true; else return false; } public boolean validaMultiplicacion(Matriz m1, Matriz m2) { if(((m1.ren==m2.ren) && (m1.col==m2.col)) || (m1.col==m2.ren)) return true; else return false; } } public static void main(String[] args) { Practica2 practica2 = new Practica2(); practica2.inicializarComponentes(); } } Exc

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• How can I assert from Python C code?

  - by Joe

  I'm writing a Python class in C and I want to put assertions in my debug code. assert.h suits me fine. This only gets put in debug compiles so there's no chance of an assert failure impacting a user of the Python code*. I'm trying to divide my 'library' code (which should be separate to the code linked against Python) so I can use it from other C code. My Python methods are therefore thinnish wrappers around my pure-C code. So I can't do this in my 'library' code: if (black == white) { PyErr_SetString(PyExc_RuntimeError, "Remap failed"); } because this pollutes my pure-C code with Python. It's also far uglier than a simple assert(black != white); I believe that the Distutils compiler always sets NDEBUG, which means I can't use assert.h even in debug builds. Mac OS and Linux. Help! *one argument I've heard against asserting in C code called from Python.

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• Can't change background for UIWebView in iPhone SDK

  - by leon

  Hi, Is there a way to change background color for UIWebView? None of the colors set in IB effect UIWebView behavior: before acctual content is loaded it shows as up as white (causing a white flash between the moment it is loaded and content is rendered). Setting background color programmatically does not do anything either. Here is code: @interface Web_ViewViewController : UIViewController { UIWebView *web; } @property (nonatomic, retain) IBOutlet UIWebView *web; @end .... (void)viewDidLoad { super viewDidLoad; web.backgroundColor = UIColor blueColor; NSURL *clUrl = NSURL URLWithString:@"http://www.apple.com" ; NSURLRequest *req = NSURLRequest requestWithURL:clUrl; web loadRequest:req; } thanks

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• css nth-child(2n+1) repaint css after filtering out list items

  - by Michael

  I have a list of 20+ items. The background-color changes using the :nth-child(2n+1) selector. (ie. even item black, odd item white). When I click a button to filter out specific items using the jQuery Isotope plugin it adds a .isotope-hidden class to the items I want to filter out, which changes the position of the list item to 0,0 and opacity to 0. When this happens the remaining items are left with the original black/white background-colors, which are now no longer in order. Does anyone know a way to "repaint' the css using the :nth-child(2n+1) selector on the items that do not contain the .isotope-hidden class. I tried #element tr:not(.isotope-hidden):nth-child(2n+1) with no avail. Any help would be appreciated. Thank you.

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• Overlay WriteableBitmap with color

  - by rajenk

  I'm trying to overlay a WriteableBitmap with a certain color in Silverlight. I have a black and white base image, which I'm using to create smaller WriteableBitmap images for a new composite image and I want to overlay either the black or white part of the source image cut-out with a certain color before adding it to the composite image. What I'm doing now is: var cutOut = new WriteableBitmap(8, 14); /* cut out the image here */ cutOut.Render(sourceImage, transform); // sourceImage is the base image cutOutImage.Source = cutOut; // cutOutImage is an Image element in XAML compositeImage.Render(cutOutImage, transform2); // compositeImage is the final WriteableBitmap that is shown on screen I tried the methods on http://blogs.silverarcade.com/silverlight-games-101/15/silverlight-blitting-and-blending-with-silverlights-writeablebitmap/ and using the extension methods from hxxp://writeablebitmapex.codeplex.com/, but I cannot seem to get a color overlay on the cutOut image before rendering it to the compositeImage. Does anyone know of a good method to do this? Thanks in advance.

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• IE GIF/PNG Transparency issue with jQuery

  - by Andrew

  Ok, this is pretty weird... Here's the page in question: http://s289116086.onlinehome.us/lawjournaltv/index.php The main blue callout background was originally a PNG, but when I applied some jQuery trickery to it (click the numbers in the top right to see what I mean), an ugly white border appeared where the transparency should be. See this screenshot from IE8: http://skitch.com/darkdriving/n62bu/windows-xp-professional I figured I could sacrifice the quality/flexibility of a PNG and just resaved each of the backgrounds as GIFs and set the matte color to white (for now). Well, I was proven wrong because IE is treating the GIF transparency the same as the original PNGs. I've read here that the issue with PNGs, Javascript, and IE has something to do with multiple filters can't be applied to one image, but shouldn't GIFs be exempt from this because they lack the Alpha Channel? Is there any way to make this page look similar in IE to Firefox or Webkit browsers? Thanks in advance!

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• Rails, searchlogic choose categories with checkboxes

  - by atmorell

  Hello, I am useing searchlogic to search some paintings. Each painting belong to a single category. What I would like to do is add multiple checkboxes to my search form, so that users can mark multiple categories. (joined with or) Is this possible with searchlogic? The query I am looking for is something like this: SELECT * FROM paintings WHERE category LIKE "white" OR category LIKE "red"... f.check_box :category (white) f.check_box :category (black) f.check_box :category (red) f.check_box :category (green) etc.

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• How to get transparent corner using jquery corner plugin

  - by metal-gear-solid

  http://jquery.malsup.com/corner/ I tried but it fills color at corners in place of white i need transparent corner with 0 opacity.

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• Applying atyle sheets in pyqt

  - by Jebagnanadas

  Hello all, If i apply a property to a parent widget it is automatically applied for child widgets too.. Is there any way of preventing this?? For example if i set background color as white in a dialog the button,combo boxes and scroll bars looks white as it lacks it native look(have to say it's unpleasant & ugly).. Is there any way that i can apply the stylesheets only to a parent widget not to it's children??? Experts help please..

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• Silverlight 4 Setting background color of textbox on focus

  - by Sean Riedel

  I am trying to set the background color of a Textbox to white on focus using a Style. My enabled Textbox has a Linear Gradient background by default: <Setter Property="Background"> <Setter.Value> <LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1"> <GradientStop Color="#e8e8e8" Offset="0.0" /> <GradientStop Color="#f3f3f3" Offset="0.25" /> <GradientStop Color="#f4f4f4" Offset="0.75" /> <GradientStop Color="#f4f4f4" Offset="1.0" /> </LinearGradientBrush> </Setter.Value> </Setter> I have a focus visual state defined: <VisualStateGroup x:Name="FocusStates"> <VisualState x:Name="Focused"> <Storyboard> <DoubleAnimation Storyboard.TargetName="FocusVisualElement" Storyboard.TargetProperty="Opacity" To="1" Duration="0"/> </Storyboard> </VisualState> Here is the rest of the Control Template: <Border x:Name="Border" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="1" Opacity="1" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}"> <Grid> <Border x:Name="ReadOnlyVisualElement" Opacity="0" Background="#5EC9C9C9"/> <Border x:Name="MouseOverBorder" BorderThickness="1" BorderBrush="Transparent"> <ScrollViewer x:Name="ContentElement" Padding="{TemplateBinding Padding}" BorderThickness="0" IsTabStop="False"/> </Border> </Grid> </Border> <Border x:Name="DisabledVisualElement" Background="#A5D7D7D7" BorderBrush="#A5D7D7D7" BorderThickness="{TemplateBinding BorderThickness}" Opacity="0" IsHitTestVisible="False"/> <Border x:Name="FocusVisualElement" Background="#A5ffffff" BorderBrush="#FF72c1ec" BorderThickness="{TemplateBinding BorderThickness}" Margin="1" Opacity="0" IsHitTestVisible="False"/> On the last Border tag is where I am trying to set the background to white (#ffffff). Right now I have the opacity at A5 which does turn the background white, however it also starts to obscure the text in the box. Any higher opacity makes the text invisible so I am pretty sure that setting the background of that border is not the right way to do this. Can I set the Background color of the ContentElement somehow through a StoryBoard? Thanks.

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• Code editor skins?

  - by Khalspi

  This is a kind of unorthodox question. Frankly, I won't lie to you. I am new to programming and am planning to improve myself. I enjoy coding but I need something to keep me going during the down times, so my question is: Is there such a thing as a code editor skin? A compiler skin? For example, you have the Command Prompt, it has a black background with white writing, it seems geeky, exactly what I want. I want a compiler that looks like command prompt...black with white writing (or green) or still has color coding (some compilers change color of text based on command). Yes, this is mainly for boasting, but I don't want to show someone something that basically looks like a text editor, I just want something that looks a little cooler. P.S (This question may seem a little unnecessary, it is because it is my first question, I'd like to warm up to this community before I start asking some real questions about code.)

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• putpixel with pyglet

  - by pts

  I'm new to pyglet. I'd like to change a pixel from black to white at each on_draw iteration. So after 1000 iterations, there should be exactly 1000 white pixels in the window. However, I'd like to avoid calling 1000 draw operations in on_draw for that. So I'd like to create an image, do an RGB putpixel on the image, and blit the image to the screen. How can I do that? The pyglet documentation, the examples and the source code aren't too helpful on this.

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• composite colors : CALayer and blend mode on iPhone

  - by Ali

  I'm trying to use core image on the iphone. I'm able to composite my colors using quartz to draw an uiview, but i want to separate each component into CALayer (UIview consume more resources). So i have a white mask i want to use to filter a background bitmap, and i want to try diffrent blending mode. UNfortunately, the layers are only "adding" their colors. Here is my code : @implementation WhiteLayerHelper - (void)drawLayer:(CALayer *)theLayer inContext:(CGContextRef)myContext { // draw a white overlay, with special blending and alpha values, so that the saturation can be animated CGContextSetBlendMode(myContext,kCGBlendModeSaturation); CGContextSetRGBFillColor(myContext,1.0,1.0,1.0,0.9); CGContextFillRect(myContext,[UIScreen mainScreen].bounds); } @end And here is the main view drawrect code, where i use my CALayer : - (void)drawRect:(CGRect)rect { //get the drawing context CGContextRef myContext = UIGraphicsGetCurrentContext(); // draw the background [self fillContext:myContext withBounds:m_overlayRect withImage:m_currentImage]; [whiteLayer renderInContext:myContext]; } Is there something wrong ?

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• How to specify behavior of Java BufferedImage resize: need min for pixel rows instead of averaging

  - by tucuxi

  I would like to resize a Java BufferedImage, making it smaller vertically but without using any type of averaging, so that if a pixel-row is "blank" (white) in the source image, there will be a white pixel-row in the corresponding position of the destination image: the "min" operation. The default algorithms (specified in getScaledInstance) do not allow me a fine-grained enough control. I would like to implement the following logic: for each pixel row in the w-pixels wide destination image, d = pixel[w] find the corresponding j pixel rows of the source image, s[][] = pixel[j][w] write the new line of pixels, so that d[i] = min(s[j][i]) over all j, i I have been reading on RescaleOp, but have not figured out how to implement this functionality -- it is admittedly a weird type of scaling. Can anyone provide me pointers on how to do this? In the worse case, I figure I can just reserve the destination ImageBuffer and copy the pixels following the pseudocode, but I was wondering if there is better way.

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• Eclipse: Subclipse "Edit Conflicts"

  - by Wilco

  I have found that when using Subclipse to edit conflicts, all my syntax color settings are preserved except for the background color, which is reset to the standard white. Using my particular color scheme makes it almost impossible to read any of the text when stuck with a white background. Is there anywhere I can change this default background color? There doesn't seem to be any way to do this from the preferences window, but perhaps there is a config file somewhere I could edit? Any help would be very much appreciated (my eyes will thank you too)!

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• Strange padding/margin when using UIWebView

  - by Nicsoft

  Hello, I am creating an app that is having a UIWebView which contains an advert. The size of the view is the same as the advert (image) itself. Still, there is a white margin/padding of some kind above and to the left of the image, inside the UIWebView. Check out the linked image: Also, I did link to the actual advert itself, you can check out the image loaded and view the source code there: Link to advert Any idea how I should remove the white padding? Thanks in advance!

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• Masking a Drawable/Bitmap on Android

  - by Joshua Rodgers

  I'm currently looking for a way to use a black and white bitmap to mask the alpha channel of another bitmap or Drawable on Android. I'm curious as to what the best way to do this is. I certainly have a couple of ideas for how to do this, but they are not optimal. I need to be able to apply a new mask to the image every so often (the black and white bitmap will change every few seconds). Any feedback on how to achieve this would be greatly appreciated.

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• Save a 32-bit Bitmap as 1-bit .bmp file in C#

  - by Dmi

  What is the easiest way to convert and save a 32-bit Bitmap to a 1-bit (black/white) .bmp file in C#?

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• Changing color of the titlebar, background and text of MFMailComposeViewController

  - by iSharreth

  I am sending email from my iPhone application. Everything working fine, but I want to change the color of the title bar that appears from blue to black and the background color from white to black. Also, all the text to white color. What should I do? Anyone please help! I used the below code: (IBAction)sendMail{ MFMailComposeViewController *mailComposer = [[MFMailComposeViewController alloc]init]; mailComposer.mailComposeDelegate = self; if([MFMailComposeViewController canSendMail]){ [mailComposer setToRecipients: [NSArray arrayWithObjects:@"[email protected]",nil]]; [mailComposer setSubject: nil]; [mailComposer setMessageBody: nil isHTML:NO]; [self presentModalViewController:mailComposer animated: YES]; }

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