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  • Getting snapshot from webcam in Matlab

    - by Harsh
    I have created a simple GUI to preview webcam stream and to get snapshot from it. For this I have created on axes to show video, one push button(pushbutton1) to start preview, one push button(pushbutton2) to get snapshot. Following is the code for these two push buttons. function pushbutton1_Callback(hObject, eventdata, handles) % hObject handle to pushbutton1 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) axes(handles.axes1); vidObj = videoinput('winvideo',1); videoRes = get(vidObj, 'VideoResolution'); numberOfBands = get(vidObj, 'NumberOfBands'); handleToImage = image( zeros([videoRes(2), videoRes(1), numberOfBands], 'uint8') ); preview(vidObj, handleToImage); % --- Executes on button press in pushbutton2. function pushbutton2_Callback(hObject, eventdata, handles) % hObject handle to pushbutton2 (see GCBO) % eventdata reserved - to be defined in a future version of MATLAB % handles structure with handles and user data (see GUIDATA) a=getsnapshot(get(axes,'Children')); imshow(a); In pushbutton2_Callback I am trying to get child of axes ie. vidObj. But this gives me error ??? Undefined function or method 'getsnapshot' for input arguments of type 'double'.. Why is it returing double type instead of child object vidObj? How can I fix it and get snapshot? Is there any other better way? (I just started learning GUI.) Thanks.

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  • JavaScript: Reference a functions local scope as an object

    - by eBusiness
    When I call a function, a local scope is erected for that call. Is there any way to directly reference that scope as an object? Just like window is a reference for the global scope object. Example: function test(foo){ var bar=1 //Now, can I access the object containing foo, bar, arguments and anything //else within the local scope like this: magicIdentifier.bar } Alternately, does anyone have a complete list of what is in the global scope on top of custom variables? Background: I'm trying to get down to a way of completely shifting to global scope from within a function call, the with statement is a joke, call works a little better, but it still breaks for anything declared in function scope but not in global scope, therefore I would declare these few cases in global scope, but that requires me to know what they are. The IE function execScript makes a complete shift, but that only solves the problem for IE. Note: To anyone loading JavaScript dynamically, setTimeout(code,1) is a simple effective hack to achieve global scope, but it will not execute immediately.

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  • Idiomatic ruby for temporary variables within a method

    - by Andrew Grimm
    Within a method, I am using i and j as temporary variables while calculating other variables. What is an idiomatic way of getting rid of i and j once they are no longer needed? Should I use blocks for this purpose? i = positions.first while nucleotide_at_position(i-1) == nucleotide_at_position(i) raise "Assumption violated" if i == 1 i -= 1 end first_nucleotide_position = i j = positions.last while nucleotide_at_position(j+1) == nucleotide_at_position(j) raise "Assumption violated" if j == sequence.length j += 1 end last_nucleotide_position = j Background: I'd like to get rid of i and j once they are no longer needed so that they aren't used by any other code in the method. Gives my code less opportunity to be wrong. I don't know the name of the concept - is it "encapsulation"? The closest concepts I can think of are (warning: links to TV Tropes - do not visit while working) Chekhov'sGun or YouHaveOutlivedYourUsefulness. Another alternative would be to put the code into their own methods, but that may detract from readability.

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  • How can I improve my real-time behavior in multi-threaded app using pthreads and condition variables

    - by WilliamKF
    I have a multi-threaded application that is using pthreads. I have a mutex() lock and condition variables(). There are two threads, one thread is producing data for the second thread, a worker, which is trying to process the produced data in a real time fashion such that one chuck is processed as close to the elapsing of a fixed time period as possible. This works pretty well, however, occasionally when the producer thread releases the condition upon which the worker is waiting, a delay of up to almost a whole second is seen before the worker thread gets control and executes again. I know this because right before the producer releases the condition upon which the worker is waiting, it does a chuck of processing for the worker if it is time to process another chuck, then immediately upon receiving the condition in the worker thread, it also does a chuck of processing if it is time to process another chuck. In this later case, I am seeing that I am late processing the chuck many times. I'd like to eliminate this lost efficiency and do what I can to keep the chucks ticking away as close to possible to the desired frequency. Is there anything I can do to reduce the delay between the release condition from the producer and the detection that that condition is released such that the worker resumes processing? For example, would it help for the producer to call something to force itself to be context switched out? Bottom line is the worker has to wait each time it asks the producer to create work for itself so that the producer can muck with the worker's data structures before telling the worker it is ready to run in parallel again. This period of exclusive access by the producer is meant to be short, but during this period, I am also checking for real-time work to be done by the producer on behalf of the worker while the producer has exclusive access. Somehow my hand off back to running in parallel again results in significant delay occasionally that I would like to avoid. Please suggest how this might be best accomplished.

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  • PHP Scope Resolution Operator Question

    - by anthony
    I'm having trouble with the MyClass::function(); style of calling methods and can't figure out why. Here's an example (I'm using Kohana framework btw): class Test_Core { public $var1 = "lots of testing"; public function output() { $print_out = $this->var1; echo $print_out; } } I try to use the following to call it, but it returns $var1 as undefined: Test::output() However, this works fine: $test = new Test(); $test->output(); I generally use this style of calling objects as opposed to the "new Class" style, but I can't figure out why it doesn't want to work.

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  • Invalid assignment left hand side

    - by JoelM
    I'm getting an invalid assignment left hand side. What I'm trying to do is, to use jscolor http://jscolor.com to define the color of polygons im drawing via Mapbender http://mapbender.org. What I do: Select a polygon by clicking on it, then open the options dialog (seperate window) where I have several options including the color. MyCode: if (isTransactional) {str += "\t\t<tr>\n"; var options = ["insert", "update", "delete", "abort", "pick"]; for (var i = 0 ; i < options.length ; i++) { var onClickText = "this.disabled=true;var result = window.opener.formCorrect(document, '"+featureTypeElementFormId+"');"; onClickText += "if (result.isCorrect) {"; onClickText += "window.opener.dbGeom('"+options[i]+"', "+memberIndex+"); "; // onClickText += "window.close();"; onClickText += "}"; onClickText += "else {"; onClickText += "alert(result.errorMessage);this.disabled=false;" onClickText += "}"; if (options[i] == "insert" && hasGeometryColumn && (!fid || showSaveButtonForExistingGeometries)) { str += "\t\t\t<td><input type='button' name='saveButton' value='"+msgObj.buttonLabelSaveGeometry+"' onclick=\""+onClickText+"\" /></td>\n"; } if (!featureTypeMismatch && fid) { if (options[i] == "update" && hasGeometryColumn) { str += "\t\t\t<td><input type='button' name='updateButton' value='"+msgObj.buttonLabelUpdateGeometry+"' onclick=\""+onClickText+"\"/></td>\n"; } if (options[i] == "delete"){ var deleteOnClickText = "var deltrans = confirm('"+msgObj.messageConfirmDeleteGeomFromDb+"');"; deleteOnClickText += "if (deltrans){"; deleteOnClickText += onClickText + "}"; str += "\t\t\t<td><input type='button' name='deleteButton' value='"+msgObj.buttonLabelDeleteGeometry+"' onclick=\""+deleteOnClickText+"\"/></td>\n"; }} if (options[i] == "abort") { str += "\t\t\t<td><input type='button' name='abortButton' value='"+msgObj.buttonLabelAbort+"' onclick=\"window.close();\" /></td>\n"; } if (options[i] == "pick") { var color; str += "<td><input class='color' name='color' id='cPick' onchange="+color+"></td>"; str += "<td><input type='text' id='text' value="+color+"></td>"; //color = document.getElementById('cPick').value; //var color2 = color; //alert(color2); } }str += "\t\t</tr>\n";}str += "\t</table>\n";str += "<input type='hidden' id='fid' value='"+fid+"'>"; //str += "<input type='text' name='mb_wfs_conf'>"; str += "</form>\n";}return str;} The Application: It is a Mapbender application to display maps and draw on it. You can draw points, lines and polygons also merge and split them. You can also select the polygons that you have drawn to alter them. Using: PHP, JavaScript, HTML, CSS, Mapbender, jQuery, Geoserver, PostgreSQL, WMS, WFS-T Sorry guys, but I think I'm wasting your time. Will ask this question in GIS specified Q&A. Thank you for the input. Greetings Joël

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  • c declaring variables in blocks

    - by anon
    I know that in C++, I can declare variables pretty much everywhere. I recall once reading that in C, variables must be declared at the top of a function i.e. the following is invalid: void foo() { int good; if (...) { int bad; } } In the above code, is the declaraing of the bad varaible legal by C standards, or only legal due to a gcc extension? Thanks!

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  • c declaraing varibles in blocks

    - by anon
    I know that in C++, I can declare variables pretty much everywhere. I recall once reading that in C, variables must be declared at the top of a function i.e. the following is invalid: void foo() { int good; if (...) { int bad; } } In the above code, is the declaraing of the bad varaible legal by C standards, or only legal due to a gcc extension? Thanks!

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  • Where does "foo" come from in coding examples? [closed]

    - by ThePower
    Possible Duplicates: Using “Foo” and “Bar” in examples To foo bar, or not to foo bar: that is the question. Possible Duplicates: Using "Foo" and "Bar" in examples To foo bar, or not to foo bar: that is the question. Bit of a general question here, but it's something I would like to know! Whenever I am looking for resolutions to my C# problems online, I always come across "foo" being used as an example. Does this represent anything or is it just one of those unexplained catchy object names, used by many people in examples?

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  • How do i fix this JS scope in GM_xmlhttpRequest

    - by acidzombie24
    When i run this code alert 2 shows 6 different href links. alert 3 shows the last href 6 times. How do i make it use the same object (linkdom aka thelink) as alert 2. NOTE: This is in a greasemonkey script { var linkdom = thelink; alert('2' + linkdom.getAttribute("href")); GM_xmlhttpRequest({ method: 'GET', url: href, onload: function(resp){ //... alert('3' + linkdom.getAttribute("href")); } }); //... }

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  • How can I determine a file extension given a file path in LaTeX?

    - by Frank
    I am attempting to write a LaTeX package which leverages the minted package's \inputminted command. My \mycommand command takes two parameters, the first being a path to a file, and I want to pass the file's extension to the \inputminted command: \newcommand\mycommand[2]{ \inputminted{#1}{...} } Note that the above won't work since the full path is passed to \inputminted. Example: \mycommand{/path/to/Test.java}{blah} should invoke \inputminted{java}{...}

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  • How can I return a value from GM_xmlhttprequest?

    - by GeoffreyF67
    I have this code here: var infiltrationResult; while(thisOption) { var trNode = document.createElement('tr'); var tdNode = document.createElement('td'); var hrefNode = document.createElement('a'); infPlanetID = thisOption.getAttribute('value'); var myURL = "http://www.hyperiums.com/servlet/Planetinf?securitylevel=90&newinfiltr=New+infiltration&planetid=" + PlanetID + "&infplanetid=" + infPlanetID; GM_xmlhttpRequest({ method: 'GET', url: myURL, headers: { 'User-agent': 'Mozilla/4.0 (compatible) Greasemonkey', 'Accept': 'application/atom+xml,application/xml,text/xml', }, onload: function(responseDetails) { if (responseDetails.responseText.match(/<b>Invalid order<\/td><\/tr><tr><td><BR><center><font color=#AAAA77 face=verdana,arial size=2>The target planet is blocking all infiltrations[\s\S]<BR><BR>/im)) { // Successful match infiltrationResult = 'Invalid Order'; } else { // Match attempt failed infiltrationResult = 'Infiltration Successfully Created'; } } }); When I add alert(infiltrationResult); right after it is assigned, I correctly see the string. However, after the function has exited, I have try the same alert and I get: undefined Any ideas what I'm doing wrong? I'm guessing it's some simple silly javascript synxtax I'm missing here :) G-Man

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  • Can't add object to Array in jQuery's getJSON data function (scope issue)

    - by seo20
    I have a person object and wants to store it into a global ArrayCollection I have made. Works great in normal scope: var s = new ArrayCollection(); s.add(new person("Knud", "Mikkelsen", 35)); The problem is when I want to add people inside my jQuery function "mainFunction". I can't seem to get it right. I know it's something to do with scope and I have to wrap something in functions like in my ArrayCollection. Please help me - thanks a lot. function ArrayCollection() { var myArray = new Array; return { empty: function () { myArray.splice(0, myArray.length); }, add: function (myElement) { myArray.push(myElement); }, getAll: function () { return myArray; } } } function person(firstName, lastName, age) { this.firstName = firstName; this.lastName = lastName; this.age = parseInt(parseFloat(age)); } function mainFunction() { //.... var s = new ArrayCollection(); s.add(new person("Knud", "Mikkelsen", 35)); $.getJSON(url, function (data) { for (var x = 0; x < data.length; x++) { var myPerson = new person(data[x].FirstName.toString(), data[x].LastName.toString(), data[x].Age.toString()); s.add(myPerson); } }); alert(drawArray(s.getAll())); } function drawArray(myArray) { var v = ""; for (var i = 0; i < myArray.length; i++) { v += myArray[i].firstName + " " + myArray[i].lastName + " (" + myArray[i].age + ")\n"; } return v; }

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  • [Iphone-Dev] Assigning values : difference between properties and class variables ?

    - by gotye
    Hey guys, I noticed that I rarely use properties, due to the fact that I rarely need to access my object's variables outside my class ;) So I usually do : NSMutableArray *myArray; // not a property ! My question is : even if i don't declare myArray as a property, does iphone make a retain anyway if I do myArray = arrayPassedToMe; I think so but I just wanted to confirm ;) Any thoughts welcome ! Gotye

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  • Java array assignment (multiple values)

    - by Danny King
    Hello, I have a Java array defined already e.g. float[] values = new float[3]; I would like to do something like this further on in the code: values = {0.1f, 0.2f, 0.3f}; But that gives me a compile error. Is there a nicer way to define multiple values at once, rather than doing this?: values[0] = 0.1f; values[1] = 0.2f; values[2] = 0.3f; Thanks!

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  • Working with strings in C++

    - by Elliot Bonneville
    Hi. I'm working with strings in C++. I recently came across a problem when entering strings. I'm using cin >> string; to get my string as user input. When the user enters a space into the string, the next input is automatically filled out with the remaining letters, or sometimes left blank. As the next input string is often an integer, this will result in an unpleasant bug. What's a good fix for this?

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  • Changing variables outside of Scope C#

    - by sam
    Hi, I'm a beginner C# programmer, and to improve my skills I decided to give Project Euler a try. The first problem on the site asks you to find the sum of all the multiples of 3 and 5 under 1000. Since I'm essentially doing the same thing twice, I made a method to multiply a base number incrementally, and add the sum of all the answers togethor. public static int SumOfMultiplication(int Base, int limit) { bool Escape = false; for (int mult = 1; Escape == true; mult++) { int Number = 0; int iSum = 0; Number = Base * mult; if (Number > limit) return iSum; else iSum = iSum + Number; } regardless of what I put in for both parameters, it ALWAYS returns zero. I'm 99% sure it has something to do with the scope of the variables, but I have no clue how to fix it. All help is appreciated. Thanks in advance, Sam

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  • c++ function scope

    - by Myx
    I have a main function in A.cpp which has the following relevant two lines of code: B definition(input_file); definition.Print(); In B.h I have the following relevant lines of code: class B { public: // Constructors B(void); B(const char *filename); ~B(void); // File input int ParseLSFile(const char *filename); // Debugging void Print(void); // Data int var1; double var2; vector<char* > var3; map<char*, vector<char* > > var4; } In B.cpp, I have the following function signatures (sorry for being redundant): B::B(void) : var1(-1), var2(numeric_limits<double>::infinity()) { } B::B(const char *filename) { B *def = new B(); def->ParseLSFile(filename); } B::~B(void) { // Free memory for var3 and var 4 } int B::ParseLSFile(const char *filename) { // assign var1, var2, var3, and var4 values } void B::Print(void) { // print contents of var1, var2, var3, and var4 to stdout } So when I call Print() from within B::ParseLSFile(...), then the contents of my structures print correctly to stdout. However, when I call definition.Print() from A.cpp, my structures are empty or contain garbage. Can anyone recommend the correct way to initialize/pass my structures so that I can access them outside of the scope of my function definition? Thanks.

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  • C++ this as thread parameter, variables unavailable

    - by brecht
    I have three classes: class Rtss_Generator { int mv_transfersize; } class Rtss_GenSine : Rtss_Generator class Rtss_GenSineRpm : Rtss_GenSine Rtss_GenSine creates a thread in his constructer, it is started immediatly and the threadfunction is off-course declared static, waiting for an event to start calculating. the problem: all the variables that are accessed through the gen-pointer are 0, but it does not fail. Also, this-address in the constructer and the gen-pointer-address in the thread are the same, so the pointer is ok. this code is created and compile in visual studio 6.0 service pack 2003 ORIGINAL CODE no thread Rtss_GenSine::getNextData() { //[CALCULATION] //mv_transferSize is accessible and has ALWAYS value 1600 which is ok } NEW CODE Rtss_GenSine::Rtss_GenSine() { createThread(NULL, threadFunction, (LPVOID) this,0,0); } Rtss_GenSine::getNextData() { SetEvent(startCalculating); WaitForSingleObject(stoppedCalculaing, INFINITE); } DWORD Rtss_GenSine::threadFunction(LPVOID pParam) { Rtss_GenSine* gen = (Rtss_GenSine*) pParam; while(runThread) { WaitForSingleObject(startCalculating, INFINITE); ResetEvent(startCalculating) //[CALCULATION] //gen->mv_transferSize ---> it does not fail, but is always zero //all variables accessed via the gen-pointer are 0 setEvent(stoppedCalculaing) } }

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