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  • Black Magic in Grails Data Binding!?

    - by Tiago Alves
    As described in http://n4.nabble.com/Grails-Data-Binding-for-One-To-Many-Relationships-with-REST-tp1754571p1754571.html i'm trying to automatically bind my REST data. I understand now that for one-to-many associations the map that is required for the data binding must have a list of ids of the many side such as: [propName: propValue, manyAssoc: [1, 2]] However, I'm getting this exception Executing action [save] of controller [com.example.DomainName] caused exception: org.springframework.orm.hibernate3.HibernateSystemException: IllegalArgumentException occurred calling getter of com.example.DomainName.id; nested exception is org.hibernate.PropertyAccessException: IllegalArgumentException occurred calling getter of com.example.DomainName.id However, even weirder is the update action that is generated for the controller. There we have the databinding like this: domainObjectInstance.properties = params['domainObject'] But, and this is the really weird thing, params['domainObject'] is null! It is null because all the domainObject fields are passed directly in the params map itself. If I change the above line to domainObjectInstance.properties = null the domainObject is still updated! Why is this happening and more important, how can I bind my incoming XML automatically if it comes in this format (the problem is the one-to-many associations): <product> <name>Table</name> <brand id="1" /> <categories> <category id="1" /> <category id="2" /> </categories> </product>

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  • ByPassing Google App Engine SDK to allow black listed classes

    - by ivanceras
    Is there a way to circumbent google app engine sdk to allow the usage of classes that are not present in the GAE JRE white list? I know the app that I would be building will not run in appspot, but at least in my development server, I need to access a postgresql database(java.net.socket.*) and generate some files(java.io.FileWriter) in my development server.

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  • Interval tree algorithm that supports merging of intervals with no overlap

    - by Dave Griffiths
    I'm looking for an interval tree algorithm similar to the red-black interval tree in CLR but that supports merging of intervals by default so that there are never any overlapping intervals. In other words if you had a tree containing two intervals [2,3] and [5,6] and you added the interval [4,4], the result would be a tree containing just one interval [2,6]. Thanks Update: the use case I'm considering is calculating transitive closure. Interval sets are used to store the successor sets because they have been found to be quite compact. But if you represent interval sets just as a linked list I have found that in some situations they can become quite large and hence so does the time required to find the insertion point. Hence my interest in interval trees. Also there may be quite a lot of merging one tree with another (i.e. a set OR operation) - if both trees are large then it may be better to create a new tree using inorder walks of both trees rather than repeated insertions of each interval.

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  • Black screen while booting, after installing installing AMD Catalyst™ 12.8 Proprietary Linux x86 Display Driver on HP pavilion dm4

    - by Megharaj
    HP Pavilion dm4 with configuration as shown below cpu intel Core i5 2.26 GHz RAM 4.0 GB Graphics processor 512MB ATI Mobility Radeon(TM) HD 5450 switchable graphics [HDMI, VGA]. I installed ubuntu 10.04 ( without AMD graphics driver) it was working fine, but when I installed AMD graphics drivers AMD Catalyst™ 12.8 Proprietary Linux x86 Display Driver, than the problem started from then When I boot I was get black screen. Than I thought to upgrade from ubuntu 10.04 to 12.04 using the bootable pen drive but was getting black screen than read on some forums that was because of the switchable graphics, than upgraded ubuntu 12.04 by setting to "nomodeset". It was working, again thought to install graphics driver AMD Catalyst™ 12.8 Proprietary Linux x86 Display Driver, again after installing this, when I boot I am getting blank scree . Can anyone help me to inatall ubuntu 12.04 along with AMD Catalyst™ 12.8 Proprietary Linux x86 Display Driver. Any help is highly appreciated.

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  • Ubuntu 13.04 boot into black screen, even after installing nvidia drivers, fail at: "Starting Reload cups, upon starting avahi-daemon..."

    - by Elad92
    I got a new machine with i7 4770k and gefore gtx660. I installed windows and then installed Ubuntu 13.04. In the installation everything went well, after the installation I again boot from the USB and choose try ubuntu, and installed boot-repair because windows automatically boot with no option for ubuntu. After I repaired the boot, I restarted and got into grub, when I chose Ubuntu I got message saying I'm running on low graphics mode and when I pressed ok the screen turned off. I couldn't do anything so I restarted and after reading this post: My computer boots to a black screen, what options do I have to fix it? I got into recovery, selected dpkg and repaired packages. Then I rebooted, and tried to press 'e' and change quiet splash to no splash and nomodeset but unfortunately both of them didn't work, and not the screen didn't get turned off, but I just saw a blank screen. So I rebooted again, entered the recovery, and this time I went to the root shell, and tried to install nvidia drivers from this guide here: http://www.howopensource.com/2012/10/install-nvidia-geforce-driver-in-ubuntu-12-10-12-04-using-ppa/ I rebooted and got the same black screen again (the screen didn't go off, just saw a blank screen). In the grub I see that the kernel is 3.8.0-25. I also checked that the usb files are not corrupted using the check CD from the ubuntu installation screen. I'm really frustrated, I don't know what else can I do. (If someone also knows how can I connect to wifi using the root shell it will be very appreciated, because when I choose the 'enable networking' it again booting me to a black screen. Thanks Edit After digging more, I again boot with nomodeset and saw where is it failing, this is the lines I saw: * Starting Reload cups, upon starting avahi-daemon to make sure remote queues are populated [OK] * Starting Reload cups, upon starting avahi-daemon to make sure remote queues are populated [fail] I searched for it in google and this is the closest result I got: http://ubuntuforums.org/showthread.php?t=2144261 i didn't find any way to solve it in the internet, from what I understand this is a problem with 13.04. If someone knows how to fix it I will be very grateful. Thanks Edit 2 - 23.6.13 As Mitch suggested, I disabled the avahi-daemon, and when I boot in nomodeset I get the following error: What else can be the problem?

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  • SEO - Delimiter character for page title

    - by cept0
    I have noticed a few oddities recently with the titles of web pages in SERPs. However, it seems there are several main conventions: Contact Page - Joe Schmoe's Awesome Site // &#045; Hyphen Contact Page — Joe Schmoe's Awesome Site // &mdash; Em dash Contact Page | Joe Schmoe's Awesome Site // &#x007C; Vertical bar Contact Page « Joe Schmoe's Awesome Site // &laquo; Left double angle quotes Is there any reason to use one over the other?

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  • ????????·???

    - by katsumii
    ???????????????????? ?????5????????????????????? ?????????K???????????????SQL?????Celko?????????????????????????????????????????Joe Celko - Wikipedia, the free encyclopediaHe has participated on the ANSI X3H2 Database Standards Committee, and helped write the SQL-89 and SQL-92 standards.???NoSQL????????????Joe Celko's Complete Guide to NoSQL: What Every SQL Professional Needs to Know about Non-Relational Databases: Joe Celko: 9780124071926: Amazon.com: BooksPublication Date: October 31, 2013???????????????????3??????????Amazon.co.jp: ???·????????????SQL ?4? ???·????Joe Celko? ??? (2013/5/24)  

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  • Craftsmanship is ALL that Matters

    - by Wayne Molina
    Today, I'm going to talk about a touchy subject: the notion of working in a company that doesn't use the prescribed "best practices" in its software development endeavours.  Over the years I have, using a variety of pseudonyms, asked this question on popular programming forums.  Although I always add in some minor variation of the story to avoid suspicion that it's the same person posting, the crux of the tale remains the same: A Programmer’s Tale A junior software developer has just started a new job at an average company, creating average line-of-business applications for internal use (the most typical scenario programmers find themselves in).  This hypothetical newbie has spent a lot of time reading up on the "theory" of software development, devouring books, blogs and screencasts from well-known and respected software developers in the community in order to broaden his knowledge and "do what the pros do".  He begins his new job, eager to apply what he's learned on a real-world project only to discover that his new teammates doesn't use any of those concepts and techniques.  They hack their way through development, or in a best-case scenario use some homebrew, thrown-together semblance of a framework for their applications that follows not one of the best practices suggested by the “elite” in the software community - things like TDD (TDD as a "best practice" is the only subjective part of this post, but it's included here due to a very large following of respected developers who consider it one), the SOLID principles, well-known and venerable tools, even version control in a worst case and truly nightmarish scenario.  Our protagonist is frustrated that he isn't doing things the "proper" way - a way he's spent personal time digesting and learning about and, more importantly, a way that some of the top developers in the industry advocate - and turns to a forum to ask the advice of his peers. Invariably the answer I, in the guise of the concerned newbie, will receive is that A) I don't know anything and should just shut my mouth and sling code the bad way like everybody else on the team, and B) These "best practices" are fade or a joke, and the only thing that matters is shipping software to your customers. I am here today to say that anyone who says this, or anything like it, is not only full of crap but indicative of exactly the type of “developer” that has helped to give our industry a bad name.  Here is why: One Who Knows Nothing, Understands Nothing On one hand, you have the cognoscenti of the .NET development world.  Guys like James Avery, Jeremy Miller, Ayende Rahien and Rob Conery; all well-respected and noted programmers that are pretty much our version of celebrities.  These guys write blogs, books, and post videos outlining the "correct" way of writing software to make sure it not only works but is maintainable and extensible and a joy to work with.  They tout the virtues of the SOLID principles, or of using TDD/BDD, or using a mature ORM like NHibernate, Subsonic or even Entity Framework. On the other hand, you have Joe Everyman, Lead Software Developer at Initrode Corporation - in our hypothetical story Joe is the junior developer's new boss.  Joe's been with Initrode for 10 years, starting as the company’s very first programmer and over the years building up a little fiefdom of his own until at the present he’s in charge of all Initrode’s software development.  Joe writes code the same way he always has, without bothering to learn much, if anything.  He looked at NHibernate once and found it was "too hard", so he uses a primitive implementation of the TableDataGateway pattern as a wrapper around SqlClient.SqlConnection and SqlClient.SqlCommand instead of an actual ORM (or, in a better case scenario, has created his own ORM); the thought of using LINQ or Entity Framework or really anything other than his own hastily homebrew solution has never occurred to him.  He doesn't understand TDD and considers “testing” to be using the .NET debugger to step through code, or simply loading up an app and entering some values to see if it works.  He doesn't really understand SOLID, and he doesn't care to.  He's worked as a programmer for years, and that's all that counts.  Right?  WRONG. Who would you rather trust?  Someone with years of experience and who writes books, creates well-known software and is akin to a celebrity, or someone with no credibility outside their own minute environment who throws around their clout and company seniority as the "proof" of their ability?  Joe Everyman may have years of experience at Initrode as a programmer, and says to do things "his way" but someone like Jeremy Miller or Ayende Rahien have years of experience at companies just like Initrode, THEY know ten times more than Joe Everyman knows or could ever hope to know, and THEY say to do things "this way". Here's another way of thinking about it: If you wanted to get into politics and needed advice on the best way to do it, would you rather listen to the mayor of Hicktown, USA or Barack Obama?  One is a small-time nobody while the other is very well-known and, as such, would probably have much more accurate and beneficial advice. NOTE: The selection of Barack Obama as an example in no way, shape, or form suggests a political affiliation or political bent to this post or blog, and no political innuendo should be mistakenly read from it; the intent was merely to compare a small-time persona with a well-known persona in a non-software field.  Feel free to replace the name "Barack Obama" with any well-known Congressman, Senator or US President of your choice. DIY Considered Harmful I will say right now that the homebrew development environment is the WORST one for an aspiring programmer, because it relies on nothing outside it's own little box - no useful skill outside of the small pond.  If you are forced to use some half-baked, homebrew ORM created by your Director of Software, you are not learning anything valuable you can take with you in the future; now, if you plan to stay at Initrode for 10 years like Joe Everyman, this is fine and dandy.  However if, like most of us, you want to advance your career outside a very narrow space you will do more harm than good by sticking it out in an environment where you, to be frank, know better than everybody else because you are aware of alternative and, in almost most cases, better tools for the job.  A junior developer who understands why the SOLID principles are good to follow, or why TDD is beneficial, or who knows that it's better to use NHibernate/Subsonic/EF/LINQ/well-known ORM versus some in-house one knows better than a senior developer with 20 years experience who doesn't understand any of that, plain and simple.  Anyone who disagrees is either a liar, or someone who, just like Joe Everyman, Lead Developer, relies on seniority and tenure rather than adapting their knowledge as things evolve. In many cases, the Joe Everymans of the world act this way out of fear - they cannot possibly fathom that a “junior” could know more than them; after all, they’ve spent 10 or more years in the same company, doing the same job, cranking out the same shoddy software.  And here comes a newbie who hasn’t spent 10+ years doing the same things, with a fresh and often radical take on the craft, and Joe Everyman is afraid he might have to put some real effort into his career again instead of just pointing to his 10 years of service at Initrode as “proof” that he’s good, or that he might have to learn something new to improve; in most cases the problem is Joe Everyman, and by extension Initrode itself, has a mentality of just being “good enough”, and mediocrity is the rule of the day. A Thorn Bush is No Place for a Phoenix My advice is that if you work on a team where they don't use the best practices that some of the most famous developers in our field say is the "right" way to do things (and have legions of people who agree), and YOU are aware of these practices and can see why they work, then LEAVE the company.  Find a company where they DO care about quality, and craftsmanship, otherwise you will never be happy.  There is no point in "dumbing" yourself down to the level of your co-workers and slinging code without care to craftsmanship.  In 95% of these situations there will be no point in bringing it to the attention of Joe Everyman because he won't listen; he might even get upset that someone is trying to "upstage" him and fire the newbie, and replace someone with loads of untapped potential with a drone that will just nod affirmatively and grind out the tasks assigned without question. Find a company that has people smart enough to listen to the "best and brightest", and be happy.  Do not, I repeat, DO NOT waste away in a job working for ignorant people.  At the end of the day software development IS a craft, and a level of craftsmanship is REQUIRED for any serious professional.  When you have knowledgeable people with the credibility to back it up saying one thing, and small-time people who are, to put it bluntly, nobodies in the field saying and doing something totally different because they can't comprehend it, leave the nobodies to their own devices to fade into obscurity.  Work for a company that uses REAL software engineering techniques and really cares about craftsmanship.  The biggest issue affecting our career, and the reason software development has never been the respected, white-collar career it was meant to be, is because hacks and charlatans can pass themselves off as professional programmers without following a lick of good advice from programmers much better at the craft than they are.  These modern day snake-oil salesmen entrench themselves in companies by hoodwinking non-technical businesspeople and customers with their shoddy wares, end up in senior/lead/executive positions, and push their lack of knowledge on everybody unfortunate enough to work with/for/under them, crushing any dissent or voices of reason and change under their tyrannical heel and leaving behind a trail of dismayed and, often, unemployed junior developers who were made examples of to keep up the facade and avoid the shadow of doubt being cast upon them. To sum this up another way: If you surround yourself with learned people, you will learn.  Surround yourself with ignorant people who can't, as the saying goes, see the forest through the trees, and you'll learn nothing of any real value.  There is more to software development than just writing code, and the end goal should not be just "shipping software", it should be shipping software that is extensible, maintainable, and above all else software whose creation has broadened your knowledge in some capacity, even if a minor one.  An eager newbie who knows theory and thirsts for knowledge can easily be moulded and taught the advanced topics, but the same can't be said of someone who only cares about the finish line.  This industry needs more people espousing the benefits of software craftsmanship and proper software engineering techniques, and less Joe Everymans who are unwilling to adapt or foster new ways of thinking. Conclusion - I Cast “Protection from Fire” I am fairly certain this post will spark some controversy and might even invite the flames.  Please keep in mind these are opinions and nothing more.  A little healthy rant and subsequent flamewar can be good for the soul once in a while.  To paraphrase The Godfather: It helps to get rid of the bad blood.

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  • Ubuntu 13.10 AMD/ATI proprietary driver slow boot time, black screen after logging in and lengthy login/logout delays

    - by NahsiN
    Ubuntu 13.10 is causing me major headaches with my AMD/ATI HD 5770 GPU. Below is a list of problems I am currently encountering. 1) The boot time is extended by at least 25s after installing catalyst 13.4. Using open source radeon drivers, my boot time till the login screen is ~10s. With catalyst 13.4 installed, the boot time increases to ~35s. This was not the case in Ubuntu 13.04, 12.10 or 12.04. I have done the driver installation manually (instructions from wiki.cchtml.com) and using software center and there is no difference. I have not tried the catalyst 13.8 beta driver. 2) After manual installation of catalyst 13.4, I get stuck at a black screen after logging in. I have to purge fglrx to resolve the problem. I tried sudo amdconfig --initial -f but it didn't help. 3) The delay between logging in and unity being displayed is ~10-15s for BOTH open source and proprietary drivers. During the delay, it's just a black screen. Whenever I logout, there is again a ~10-15s delay with the login screen appearing stuck before lightdm allows me to enter my password again. This is ridiculous! Yes, I could stick with open source radeon drivers but I would like to install Steam and play my Valve collection on the machine. Is anybody else encountering similar issues?

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  • Ubuntu 11.10 loads from live usb fine, but boots to black screen from harddrive. Why?

    - by Estel
    A few days ago I had a hard drive failure, which was running Windows XP (32-bit) just fine. The second hard drive in my computer held a few unimportant files, so I formatted it in the Ubuntu setup and installed 11.10 without a hitch. I had been using it for about a week, but decided to install Windows 7 (64-bit) in order to utilize Networking with my home server (running Windows Server 2000). My system is 64-bit based, and thus I had no problems installing other than a basic RAM error that required me to remove my RAM down to a single stick. I played with the settings in Windows 7 for around an hour before I shut down. After reinstalling the RAM, Windows 7 would not boot. In this, I then assumed that something about my system was rejecting Win7 and I reinstalled Ubuntu. However, now Ubuntu (11.10) boots into black screen, and I've already attempted activating the grub menu with the shift key, and following steps listed here: https://wiki.ubuntu.com/X/Troubleshooting/BlankScreen but nothing seems to work. I've reinstalled twice now, with the same result each time. Now, the very odd part about this whole scenario is that the USB I installed from has no problems booting as a live USB. This puzzles me greatly, because the hard drive boots straight to black screen and the live USB loads normally. At this point, my only theory is that the boot sector of the hard disk was somehow corrupted with Win7, and that Ubuntu was unable to completely write through. I used Darik's Boot n Nuke to wipe the drive, but was met with an error, this also puzzles me because the hard disk has no promblems reading or writing. Any suggestions/comments are appreciated. If you have a theory, I will be more than happy to oblige. Additional information: Intel Core2 Duo e6400 2.13GHz nVidia GeForce 7-series (7900 GS) 4 GB DDR2 333MHz (2x 2GB) Dell XPS 410 BIOS Revision 2.5.3

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  • Advice on database design / SQL for retrieving data with chronological order

    - by Remnant
    I am creating a database that will help keep track of which employees have been on a certain training course. I would like to get some guidance on the best way to design the database. Specifically, each employee must attend the training course each year and my database needs to keep a history of all the dates on which they have attend the course in the past. The end user will use the software as a planning tool to help them book future course dates for employees. When they select a given employee they will see: (a) Last attendance date (b) Projected future attendance date(i.e. last attendance date + 1 calendar year) In terms of my database, any given employee may have multiple past course attendance dates: EmpName AttandanceDate Joe Bloggs 1st Jan 2007 Joe Bloggs 4th Jan 2008 Joe Bloggs 3rd Jan 2009 Joe Bloggs 8th Jan 2010 My question is what is the best way to set up the database to make it easy to retrieve the most recent course attendance date? In the example above, the most recent would be 8th Jan 2010. Is there a good way to use SQL to sort by date and pick the MAX date? My other idea was to add a column called ‘MostRecent’ and just set this to TRUE. EmpName AttandanceDate MostRecent Joe Bloggs 1st Jan 2007 False Joe Bloggs 4th Jan 2008 False Joe Bloggs 3rd Jan 2009 False Joe Bloggs 8th Jan 2010 True I wondered if this would simplify the SQL i.e. SELECT Joe Bloggs WHERE MostRecent = ‘TRUE’ Also, when the user updates a given employee’s attendance record (i.e. with latest attendance date) I could use SQL to: Search for the employee and set the MostRecent value to FALSE Add a new record with MostRecent set to TRUE? Would anybody recommended either method over the other? Or do you have a completely different way of solving this problem?

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  • Permission issues causes Unity Segmentation fault

    - by Dj Gilcrease
    I upgraded from 13.04 to 13.10 and I can boot to the unity-greeter and login just fine, but after login I just get a black screen with a cursor. I have tried following http://help.ubuntu.com/community/BinaryDriverHowto/ATI http://help.ubuntu.com/community/RadeonDriver and the manual install of the downloaded AMD drivers. All have the same affect. Also I have read Black screen after login with cursor I get a black screen after logging in ubuntu 13.04 black screen after login Ubuntu 13.10 - Black screen after login session Ubuntu 13.04 - Black screen with unresponsive cursor Upgrade to Ubuntu 13.04 Problem - Boots into Blank Black Screen All of which were no further help then the two support articles about ATI drivers So I switched back to the default drivers and went a little further into debugging, when I do ctrl+alt+F1 and login and try unity --debug > unity_start.log then ctrl+alt+F8 the screen stays black with a cursor and when I switch back ctrl+alt+F1 the contents of the log output are http://pastebin.com/rdQG4Hb0 However when I try sudo unity --debug > unity_start_root.log then ctrl+alt+F8, unity starts and the output of the log is http://pastebin.com/Yv4RD2j7 The fact that it starts as root tells be it is either a permissions issue of some required file or there is some setting that is specific to my user that is causing the SIGSEGV. So to narrow this down I activated the guest account and tried to login and got the same black screens with only a mouse cursor, so this tells me that it is not a configuration issue, but a permissions issue, so how do I narrow down which file has the wrong permissions? Also is there anything further that may help debug this issue? Ok after a few more hours of googling I found that if I add myself to the video group I can login and see the desktop, but there are lots of other permission related issues, so I am thinking something went wonky with PolicyKit during the upgrade, is there a way to reset PolicyKit settings for a user?

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  • Dell xps l502 optimus ... stuck at black screen after installing bumblebee

    - by Abdul Azzawi
    I am facing a problem after installing bumblebee when I try to start ubuntu normally the device get stuck on a black screen Can any one help me with the right configuration for the graphic card ... All i need is to run with full desktop effects currently even compizconfig effects arent working Also what should I have in the blacklist or is it correct the way bumblebee does it Running ubuntu Natty 11.04 32 bit Thanks

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  • How to remove the black bar at the top of my screen?

    - by Casper Li
    The display area is not fit to my monitor(1440x900) and there is a black bar at the top of my screen. The bottom of the display area can't be displayed. How can I deal with this problem? Moreover, I don't know how to install my display card's driver(MSI R4770 Cyclone). Do I need to install it? Here are some related pictures : My monitor My monitor Displays xrandr Thank you for your attention

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  • Why does terminal prompt text becomes black when connecting to Ubuntu with Nomachine NX client?

    - by David B
    I'm using Nomachine NX client for Windows to remotely connect to my Ubuntu. Every now and then I experience a strange phenomena: the text in the prompt of all open terminal windows becomes black, so it can't be viewed over the black background. Typed commands are also black, but the results are in normal colors. So I can run stuff, but can't see what I'm typing... After I close all open terminal windows and start a new terminal window, everything goes back to normal. This is rerally annoying and happens quite often. Any idea why?

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  • Actionscript 3: How to remove all black pixels from BitmapData ?

    - by Adnan Doric
    Hello, Let say I have a BitmapData with different pixels representing an object, and some black pixels around it that I want to remove. I would like to obtain a new BitmapData, with width and height of the object represented by non-black pixels. For example, let say I have a BitmapData 400x400px, but the object represented by non-black pixels occupies the rect: x=100, y=100, width=200, height=200. I want to get new BitmapData representing that rect, all black pixels should be removed. Any idea on how to do this please ?

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  • How can I request an image and return it as black and white in rails?

    - by NotDan
    I'd like to have an image and a combo box with 2 options: color, and black and white. When the combo box selection changes, I'd like to return the image as black and white and have this done dynamically on the server (so I don't have to store the black and white image on the server). I was thinking I could point the img tag at a url like "/images/blackandwhite/120" where 120 is the image id of the color picture, and have it dynamically turn the image to black and white and return the image data to the browser. Is this possible? How would I do this?

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  • How to make my robot move in a rectangular path along the black tape?

    - by Sahat
    I am working on a robot, it's part of the summer robotics workshop in our college. We are using C-STAMP micro controllers by A-WIT. I was able to make it move, turn left, turn right, move backward. I have even managed to make it go along the black tape using a contrast sensor. I send the robot at 30-45 degrees toward the black tape on the table and it aligns itself and starts to move along the black tape. It jerks a little, probably due to my programming logic below, it's running a while loop and constantly checking if statements, so it ends up trying to turn left and right every few milliseconds, which explains the jerking part. But it's okay, it works, not as smooth as I want it to work but it works! Problem is that I can't make my robot go into a rectangular path of the black tape. As soon as it reaches the corner it just keeps going straight instead of making a left/right turn. Here's my attempt. The following code is just part of the code. My 2 sensors are located right underneath the robot, next to the front wheel, almost at the floor level. It has "index" value ranging from 0 to 8. I believe it's 8 when you have a lot of light coming into the sensor , and 0 when it's nearly pitch black. So when the robot moves into the black-tape-zone, the index value drops, and based on that I have an if-statement telling my robot to either turn left or right. To avoid confusion I didn't post the entire source code, but only the logical part responsible for the movement of my robot along the black tape. while(1) { // don't worry about these. // 10 and 9 represent Sensor's PIN location on the motherboard V = ANALOGIN(10, 1, 0, 0, 0); V2 = ANALOGIN(9, 1, 0, 0, 0); // i got this "formula" from the example in my Manual. // V stands for voltage of the sensor. // it gives me the index value of the sensor. 0 = darkest, 8 = lightest. index = ((-(V - 5) / 5) * 8 + 0.5); index2 = ((-(V2 - 5) / 5) * 8 + 0.5); // i've tweaked the position of the sensors so index > 7 is just right number. // the robot will move anywhere on the table just fine with index > 7. // as soon as it drops to or below 7 (i.e. finds black tape), the robot will // either turn left or right and then go forward. // lp & rp represent left-wheel pin and right-wheel pin, 1 means run forever. // if i change it from 1 to 100, it will go forward for 100ms. if (index > 7 && index2 > 7) goForward(lp, rp, 1); if (index <= 7) { turnLeft(lp, rp, 1); goForward(lp, rp, 1); // this is the tricky part. i've added this code last minute // trying to make my robot turn, but i didn't work. if (index > 4) { turnLeft(lp, rp, 1); goForward(lp, rp, 1); } } else if (index2 <= 7) { turnRight(lp, rp, 1); goForward(lp, rp, 1); // this is also the last minute addition. it's same code as above // but it's for the 2nd sensor. if (index2 > 4) { turnRight(lp, rp, 1); goForward(lp, rp, 1); } } I've spent the entire day trying to figure it out. I've pretty much exhausted all avenues. Asking for the solution on stackoverflow is my very last option now. Thanks in advance! If you have any questions about the code, let me know, but comments should be self-explanatory.

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  • Why when i rotate the image black borders appear? PHP GD

    - by EAGhost
    This code generates two images using GD and rotates one of them. When I rotate the image black borders begin to appear. Anyone have an idea of how to resolve this? imagefilledrectangle($im, 0, 0, 300, 400, $black); imagefilledrectangle($im, 1, 1, 298, 398, $grey); imagefilledrectangle($im, 49, 69, 251, 271, $black); imagefilledrectangle($im, 50, 70, 250, 270, $white); imagefttext($im, 13, 0, 90, 30, $black, $font_file, "Wind Direcction"); $source=imagecreatetruecolor(100, 100); imagefilledrectangle($source, 0, 0, 100, 100, $white); $values = array( 20, 30, // Point 1 (x, y) 50, 0, 80, 30, 65, 30, 65, 100, 35, 100, 35, 30 // Point 7 (x, y) ); imagefilledpolygon($source, $values, 7, $black1); $asd=imagerotate($source, $rotate, 0); imagecolortransparent($asd, $black); imageantialias($asd, true); $insert_x = imagesx($asd); $insert_y = imagesy($asd); if($rotate==0 || $rotate==90 || $rotate==180 || $rotate==270){ imagecopymerge ( $im , $asd , 100 , 130 , 0 , 0 , $insert_x , $insert_y , 100 ); } if($rotate==45 || $rotate==135 || $rotate==225 || $rotate==315){ imagecopymerge ( $im , $asd , 85 , 110 , 0 , 0 , $insert_x , $insert_y , 100 ); } imageantialias($im, true); header('Content-Type: image/png'); imagepng($im); imagedestroy($im); ?

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  • When attempting to install ubuntu 12.04 from CD, I am stuck on black streen with "loading bootlogo..."

    - by Jessica K
    I downloaded Ubuntu 12.04 to my desktop and burned to a CD using Infra Recorder and instructions on ubuntu website. Restarted PC to boot from CD receive black screen with "Loading bootlogo..." then nothing happens and I have to restart with windows. The CD seems to be correct. Folders include .disk, boot, casper, dists, install, isolinux, pics, pool, preseed, autorun file, md5sum text file, readme.diskdefines file, wubi app. System Information Operating System: Windows Vista™ Home Premium (6.0, Build 6002) Service Pack 2 (6002.vistasp2_gdr.120824-0336) System Manufacturer: TOSHIBA System Model: Satellite L305 BIOS: Default System BIOS Processor: Intel(R) Pentium(R) Dual CPU T2390 @ 1.86GHz (2 CPUs), ~1.9GHz Memory: 3062MB RAM Page File: 1553MB used, 4772MB available Windows Dir: C:\Windows DirectX Version: DirectX 11 DX Setup Parameters: Not found DxDiag Version: 7.00.6002.18107 32bit Unicode Drive: D: Model: PIONEER DVD-RW DVRKD08L ATA Device Driver: c:\windows\system32\drivers\cdrom.sys, 6.00.6002.18005 (English), 4/11/2009 00:39:17, 67072 bytes

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  • bxslider and sproutvideo on iPad: video is just a black box when returning to slide [on hold]

    - by hm.
    I use sproutvideo inside of bxslider. I teste it well on chrome and firefox. On the iPad I have the following issue: I have the video in the forst screen and it loads fine, the slider stops when the video is running and when i switch to another slide and come back the video is still running. On the iPad, the video starts also, but when I go to anoter slide and back, the video disappears and I only see a black box. Any ideas what can be wrong?

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  • Installing Ubuntu 64bit on Acer netbook causes black screen.

    - by big-marc
    Trying to install Ubuntu on an external usb 3 500 Gb hard-drive. I am using an Acer netbook. the specs are: amd c-60 1ghz with 4 Gb ram. I have a 64 bits windows 7 no2 installed. I downloaded the ubuntu-12.04.1-alternate-amd64 ISO and used the universal usb installer to install the Ubuntu When I reboot on the external hard drive, I have the language selection, then the menu...I choose to install...and I get a black flickering screen. and nothing more. Any suggestion?

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