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  • WPF Dispatcher {"The calling thread cannot access this object because a different thread owns it."}

    - by user359446
    first I need to say that I´m noob with WPF and C#. Application: Create Mandelbrot Image (GUI) My disptacher works perfektly this this case: private void progressBarRefresh(){ while ((con.Progress) < 99) { progressBar1.Dispatcher.Invoke(DispatcherPriority.Send, new Action(delegate { progressBar1.Value = con.Progress; } )); } } I get the Message (Title) when tring to do this with the below code: bmp = BitmapSource.Create(width, height, 96, 96, pf, null, rawImage, stride); this.Dispatcher.Invoke(DispatcherPriority.Send, new Action(delegate { img.Source = bmp; ViewBox.Child = img; //vllt am schluss } )); I will try to explain how my program works. I created a new Thread (because GUI dont response) for the calculation of the pixels and the colors. In this Thread(Mehtod) I´m using the Dispatcher to Refresh my Image in the ViewBox after the calculations are ready. When I´m dont put the calculation in a seperate Thread then I can refresh or build my Image.

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  • GLOBAL problem with javascript

    - by Syom
    There is some problem, i can't understand anyway. look at this code please <script type="text/javascript"> function math(x) { var y; y = x*10; alert(y); } </script> <input type="button" onclick="math(0.011)"> What must be alerted after i click on button? i think 0.11, but no, it alerts 0.10999999999999999 explain please this behavior. thanks in advance

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  • Single HTML Table from multiple MySQL tables

    - by David Chouinard
    Hi! I've been struggling for a while with this one; I'll try to explain it here as simply as possible. Consider this MySQL table: +----------+-----------+---------+--------+ |status_id |session_id |pilot_id |present | +----------+-----------+---------+--------+ |1 |61 |901 |1 | |2 |63 |901 |1 | |3 |62 |901 |0 | |4 |62 |902 |1 | |5 |63 |903 |1 | +----------+-----------+---------+--------+ Both session_id and pilot_id are foreign keys making reference to a primary key in another table. The same pilot_id can be associated with different session_id, but every pilot_id-session_id combination is unique. I need to make an HTML table (in PHP) that would display the data like this: +----------+---------+---------+---------+ | |61 |62 |63 | +----------+---------+---------+---------+ |901 |X | |X | |902 | |X | | |903 | | |X | +----------+---------+---------+---------+ Hence, rows are pilot_id and columns are session_id. When a pilot_id-session_id combination has a present value of 1, the corresponding cell should be checked. (ie. when the row-combination is zero or the combination does not exist in the MySQL table, nothing should appear in the HTML table) Phew. Any ideas? Thanks!

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  • How to optimise MySQL query containing a subquery?

    - by aidan
    I have two tables, House and Person. For any row in House, there can be 0, 1 or many corresponding rows in Person. But, of those people, a maximum of one will have a status of "ACTIVE", the others will all have a status of "CANCELLED". e.g. SELECT * FROM House LEFT JOIN Person ON House.ID = Person.HouseID House.ID | Person.ID | Person.Status 1 | 1 | CANCELLED 1 | 2 | CANCELLED 1 | 3 | ACTIVE 2 | 1 | ACTIVE 3 | NULL | NULL 4 | 4 | CANCELLED I want to filter out the cancelled rows, and get something like this: House.ID | Person.ID | Person.Status 1 | 3 | ACTIVE 2 | 1 | ACTIVE 3 | NULL | NULL 4 | NULL | NULL I've achieved this with the following sub select: SELECT * FROM House LEFT JOIN ( SELECT * FROM Person WHERE Person.Status != "CANCELLED" ) Person ON House.ID = Person.HouseID ...which works, but breaks all the indexes. Is there a better solution that doesn't? I'm using MySQL and all relevant columns are indexed. EXPLAIN lists nothing in possible_keys. Thanks.

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  • Haskell: What is the difference between $ (dollar) and $! (dollar exclamation point)

    - by Jelle Fresen
    Can anybody explain the difference in Haskell between the operators ($) and ($!) (dollar sign vs dollar sign exclamation point)? I haven't seen the use of $! anywhere so far, but while browsing through the Haskell reference on www.zvon.org, I noticed its existence and that it has the exact same definition as $. When trying some simple statements in a Haskell interpreter (ghci), I couldn't find any difference, nor could I find any reference to the operator in the top listed tutorials when googling for haskell tutorial. So, just out of curiosity, what is the difference, if at all?

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  • Why are the contents of my UITableViewCell disappearing?

    - by barfoon
    Hey everyone, I am learning about using the checkmark cell accessory and am wondering why the contents of my cell is disappearing when toggling it. Here is my code: + (void) toggleCheckmarkedCell:(UITableViewCell *)cell { if (cell.accessoryType == UITableViewCellAccessoryNone) cell.accessoryType = UITableViewCellAccessoryCheckmark; else cell.accessoryType = UITableViewCellAccessoryNone; } And here is didSelectRowAtIndexPath: UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath]; [cell setSelectionStyle:UITableViewCellSelectionStyleNone]; [RootViewController toggleCheckmarkedCell:cell]; The checkmark is toggling on/off and is visible but the main contents of the cell disappears. Can anyone explain why this is happening? Thank you,

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  • Service design or access to another process

    - by hotyi
    I have a cache service,it's works as .net remoting, i want to create another windows service to clean up the that cache service by transfer the objects from cache to files. because they are in separate process, is their any way i could access that cache service or do i have to expose a method from the cache service to do that clean up work? the "clean up" means i want to serialize the object from Cache to file and these saved file will be used for further process. let me explain this application more detail. the application is mainly a log service to log all the coming request and these request will be saved to db for further data mining. we have 2 design for this log system 1) use MSMQ, but seems it's performance is not good enough, we don't use it. 2) we design a cache service, each request will be saved into the cache, and we need another function to clean up the cache by serialize the object to file.

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  • What exactly is a Monad?

    - by WeNeedAnswers
    Can someone please explain to me what a Monad is. I think I grasp Monoids and I grasp that they basically control the input of state into a system. I just look at the text in Haskell and glaze over. A simple example in python would be great. My current understanding is that a Monoid is a procedural piece of code that needs to be read from top to bottom in sequence with the output being the input for the function. I think that I may even got that wrong, but hey I am here to learn.

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  • tomcat 6 - Cluster / BackupManager

    - by Kevin
    Hi, I have a question regarding Clustering (session replication/failover) in tomcat 6 using BackupManager. Reason I chose BackupManager, is because it replicates the session to only one other server. I am going to run through the example below to try and explain my question. I have 6 nodes setup in a tomcat 6 cluster with BackupManager. The front end is one Apache server using mod_jk with sticky session enabled Each node has 1 session each. node1 has a session from client1 node2 has a session from client2 .. .. Now lets say node1 goes down ; assuming node2 is the backup, node2 now has two sessions (for client2 and client1) The next time client1 makes a request, what exactly happens ? Does Apache "know" that node1 is down and does it send the request directly to node2 ? =OR= does it try each of the 6 instances and find out the hard way who the backup is ?

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  • Having an online highscore leaderboard for a Flash game

    - by Marco Fox
    Why, hello there. I'm trying to develop a simple Flash game using Actionscript 2 (I know its a bit dated, but its a simple project that doesen't benefict much from AS3), and I came up with an ideia of implementing an online leaderboard that records and shows the highscore of the player. This isn't anything too complicated, but I seem to be having problem finding resources online that explain how I should implement this. All I want is a call, probably to a PHP/MySQL database that records the player's name (which will be recorded via a input window) and its current score. It would also have to show the best all time scores, by order. I should remind you that I am working on a Actionscript 2 so Actionscript 3 solutions are probably not going to work. Can anyone out there help me out here? Did any of you already been through this?

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  • Why is the destructor called when the CPython garbage collector is disabled?

    - by Frederik
    I'm trying to understand the internals of the CPython garbage collector, specifically when the destructor is called. So far, the behavior is intuitive, but the following case trips me up: Disable the GC. Create an object, then remove a reference to it. The object is destroyed and the __del__ method is called. I thought this would only happen if the garbage collector was enabled. Can someone explain why this happens? Is there a way to defer calling the destructor? import gc import unittest _destroyed = False class MyClass(object): def __del__(self): global _destroyed _destroyed = True class GarbageCollectionTest(unittest.TestCase): def testExplicitGarbageCollection(self): gc.disable() ref = MyClass() ref = None # The next test fails. # The object is automatically destroyed even with the collector turned off. self.assertFalse(_destroyed) gc.collect() self.assertTrue(_destroyed) if __name__=='__main__': unittest.main() Disclaimer: this code is not meant for production -- I've already noted that this is very implementation-specific and does not work on Jython.

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  • Static and overriding in Java

    - by Abhishek Jain
    public class B { static int i =1; public static int multiply(int a,int b) { return i; } public int multiply1(int a,int b) { return i; } public static void main(String args[]) { B b = new A(); System.out.println(b.multiply(5,2)); System.out.println(b.multiply1(5,2)); } } class A extends B { static int i =8; public static int multiply(int a,int b) { return 5*i; } public int multiply1(int a,int b) { return 5*i; } } Output: 1 40 Why is it so? Please explain.

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  • 2-Version software: Best VCS approach?

    - by Tom R
    I suppose I'd better explain my situation: I'm in the process of developing some software, and I'm at the stage where I'd like to split my project into two branches which differ in features. It so happens that this application is an Android application which I will be deploying on the Market, which has the constraint that every app must have a unique package identifier (sensible, no?). My current approach has been to clone the git repo of my original project, but this causes issues with package names. I want the system to be robust enough so that a bugfix/new feature on one branch will merge into another branch, but only when I want it to. Does anyone have any suggestions?

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  • Issue with UITextView in an animation block

    - by collin
    I'm having an issue with a UITextView inside another UIView whose frame is manipulated in an animation block when the keyboard displays. During the animation block the UIView scales beautifully and as expected, but the UITextView jumps out of it's superview(the UIView being animated) at the start of the animation. By the end of the animation, the UITextView ends up in the right place... what gives? Can anybody explain why the UITextView is jumping out of it's container view at the start of the animation? Thanks in advance.

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  • Python Imaging: YCbCr problems

    - by daver
    Hi, I'm doing some image processing in Python using PIL, I need to extract the luminance layer from a series of images, and do some processing on that using numpy, then put the edited luminance layer back into the image and save it. The problem is, I can't seem to get any meaningful representation of my Image in a YCbCr format, or at least I don't understand what PIL is giving me in YCbCr. PIL documentation claims YCbCr format gives three channels, but when I grab the data out of the image using np.asarray, I get 4 channels. Ok, so I figure one must be alpha. Here is some code I'm using to test this process: import Image as im import numpy as np pengIm = im.open("Data\\Test\\Penguins.bmp") yIm = pengIm.convert("YCbCr") testIm = np.asarray(yIm) grey = testIm[:,:,0] grey = grey.astype('uint8') greyIm = im.fromarray(grey, "L") greyIm.save("Data\\Test\\grey.bmp") I'm expecting a greyscale version of my image, but what I get is this jumbled up mess: http://i.imgur.com/zlhIh.png Can anybody explain to me where I'm going wrong? The same code in matlab works exactly as I expect.

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  • jQuery .val Enigma between two input boxes

    - by Matt
    I'm trying to get it so that if I move a red div-square around the screen using jQuery UI and jQuery, then an input field updates with the position of the div. I got that working with a simple .val. But, it's hard to explain why, but I need to make it so that when I move the square, it updates my input box, and when the input box value is changed, another input box reflects the new value of the old input box. Do I make any sense, coz I'm confusing myself :). I made a jsfiddle, so perhaps it'll make more sense there. If you move the red square, then the input box directly above it updates, but the input box above that does not, even though it is programmed to reflect the value of the input box below itself. P.S. Is this specific to only jQuery, or is this problem present in all of JavaScript. Thanks! http://jsfiddle.net/xmCsq/27/

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  • Specific 'boot file' definition

    - by Jazz
    Hey, I have been given a general explanation of how a computer boots up. However a very loose definition to the term 'boot file' was given. Could someone explain 'boot file' to me in a very simple but concise manner? I have read about the POST, the clearing of registers, BIOS in the CMOS, etc. What I understand is that the boot file is different to the boot program. the boot program gets the system ready to accept an OS while the boot file contains some of the parameters by which the system will operate. The boot program is stored on ROM and the boot file isnt? cheers, jazz

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  • JTable custom cell renderer to create row header

    - by hhj
    Can somebody please explain how I would create row headers? I already have the data and header texts set in the JTable: all I want to know is how I can use a cell renderer to take that first column (i.e. the row header column) and make it look like the column headers (i.e. the first row). Right now its background is white, so it looks like regular data. I want it to appear gray (or non-opaque I guess??). Oh and it should also not be selectable. Thanks.

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  • Why is this not a bug in qmail?

    - by jemfinch
    I was reading DJB's "Some thoughts on security after ten years of Qmail 1.0" and he listed this function for moving a file descriptor: int fd_move(to,from) int to; int from; { if (to == from) return 0; if (fd_copy(to,from) == -1) return -1; close(from); return 0; } It occurred to me that this code does not check the return value of close, so I read the man page for close(2), and it seems it can fail with EINTR, in which case the appropriate behavior would seem to be to call close again with the same argument. Since this code was written by someone with far more experience than I in both C and UNIX, and additionally has stood unchanged in qmail for over a decade, I assume there must be some nuance that I'm missing that makes this code correct. Can anyone explain that nuance to me?

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  • killall httpd for sleep process

    - by user172697
    Hello guys this shell explain the issue , after executing the .sh file halt and nothing happen , any clue where is my mistake its kill httpd if there is more than 10 sleep process and start the httpd with zero sleep process #!/bin/bash #this means loop forever while [ 1 ]; do HTTP=`ps auwxf | grep httpd | grep -v grep | wc -l`; #the above line counts the number of httpd processes found running #and the following line says if there were less then 10 found running if [ $[HTTP] -lt 10 ]; then killall -9 httpd; #inside the if now, so there are less then 10, kill them all and wait 1 second sleep 1; #start apache /etc/init.d/httpd start; fi; #all done, sleep for ten seconds before we loop again sleep 10;done

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  • TypeError: Python thinks that I passed a function 2 arguments but I only passed it 1

    - by slhck
    I work on something in Seattle Repy which is a restricted subset of Python. Anyway, I wanted to implement my own Queue that derives from a list: class Queue(list): job_count = 0 def __init__(self): list.__init__(self) def appendleft(item): item.creation_time = getruntime() item.current_count = self.job_count self.insert(0, item) def pop(): item = self.pop() item.pop_time = getruntime() return item Now I call this in my main server, where I use my own Job class to pass Jobs to the Queue: mycontext['queue'] = Queue() # ... job = Job(str(ip), message) mycontext['queue'].appendleft(job) The last line raises the following exception: Exception (with type 'exceptions.TypeError'): appendleft() takes exactly 1 argument (2 given) I'm relatively new to Python, so could anyone explain to me why it would think that I gave appendleft() two arguments when there obviously was only one?

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  • Google Street View API v3 : how can I avoid having "fish-eye" effect on Firefox?

    - by Benj
    I'm using google maps API V3 and I'm having trouble displaying correctly the street view within Firefox. I always get the "fish-eye" view (does not happen with Google chrome). So I assumed that the problem came from Firefox. I took a look to the street view options but found nothing. I would like to know if there is an option to have a flatten street view or if it is because Firefox does not support this kind of feature. If someone could explain it to me, I would be grateful. Below, what it looks in Firefox : And what it looks in Chrome :

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  • Creating combinations that have no more one intersecting element

    - by khuss
    I am looking to create a special type of combination in which no two sets have more than one intersecting element. Let me explain with an example: Let us say we have 9 letter set that contains A, B, C, D, E, F, G, H, and I If you create the standard non-repeating combinations of three letters you will have 9C3 sets. These will contain sets like ABC, ABD, BCD, etc. I am looking to create sets that have at the most only 1 common letter. So in this example, we will get following sets: ABC, ADG, AEI, AFH, BEH, BFG, BDI, CFI, CDH, CEG, DEF, and GHI - note that if you take any two sets there are no more than 1 repeating letter. What would be a good way to generate such sets? It should be scalable solution so that I can do it for a set of 1000 letters, with sub set size of 4. Any help is highly appreciated. Thanks

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  • Socket ping-pong performance

    - by Kamil_H
    I have written two simple programs (tried it in C++ and C#). This is pseudo code: -------- Client --------------- for(int i = 0; i < 200.000; i++) { socket_send("ping") socket_receive(buff) } --------- Server ------------- while(1) { socket_receive(buff) socket_send("pong") } I tried it on Windows. Execution time of client is about 45 seconds. Can somebody explain me why this takes so long? I understand that if there were real network connection between client and server the time of one 'ping-pong' would be: generate_ping + send_via_network + generate_pong + send_via_network but here everything is done in 'local' mode. Is there any way to make this inter process ping-pong faster using network sockets (I'm not asking about shared memory for example :) )

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  • ajax parameter to send correctly a variable to a specified url

    - by kawtousse
    I am trying to send data to a servlet from a js file but the servlet never received the parameter. so this is what I have: function showProject(prj) { xmlhttp=GetXmlHttpObject(); if (xmlhttp==null) { alert ("Browser does not support HTTP Request"); return; } var url="ServletxmlGenerator"; idprj = prj.options[prj.selectedIndex].value; //alert(idprj); url=url+"?idprj="+idprj; xmlhttp.onreadystatechange=stateChanged; xmlhttp.open("GET",url,true); xmlhttp.send(null); } and to capture th request it is with: public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String projectcode=request.getParameter("idprj"); System.out.println("++++projectCode:=" +projectcode); the output is like: ++++projectCode:=null Can any one explain it to me it seems to be correct but i didnot find the error.Thinks

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