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  • Generic transparent Qt widget that can catch clicks?

    - by Pieter
    I've figured out how to use QPainter to draw rectangles. Now I want to have a drawing area where if the user clicks, a 1x1 rectangle is drawn where the mouse pointer is. To accomplish this, I assume I need a transparent Qt widget that supports the clicked() signal. How do I make such a transparent widget? Or is there something else I can use? Perhaps I can only use the window's clicked() signal?

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  • An interview question

    - by maddy
    Hi, The questions shown below is an interview question Q)You are given have a datatype, say X in C. The requirement is to get the size of the datatype, without declaring a variable or a pointer variable of that type, And, of course without using sizeof operator ! I am not sure if this question was asked before in SO. Thanks and regards Maddy

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  • Get specific process memory space

    - by Saul Rennison
    Hi, I have a pointer (void *) to a function and I want to know which process this function belongs to. I have no idea which way to go about it, but I think it's possible by using some form of VirtualQuery trickery. Any help would be appreciated. Thanks in advance,

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  • Moving a unit precisely along a path in x,y coordinates

    - by Adam Eberbach
    I am playing around with a strategy game where squads move around a map. Each turn a certain amount of movement is allocated to a squad and if the squad has a destination the points are applied each turn until the destination is reached. Actual distance is used so if a squad moves one position in the x or y direction it uses one point, but moving diagonally takes ~1.4 points. The squad maintains actual position as float which is then rounded to allow drawing the position on the map. The path is described by touching the squad and dragging to the end position then lifting the pen or finger. (I'm doing this on an iPhone now but Android/Qt/Windows Mobile would work the same) As the pointer moves x, y points are recorded so that the squad gains a list of intermediate destinations on the way to the final destination. I'm finding that the destinations are not evenly spaced but can be further apart depending on the speed of the pointer movement. Following the path is important because obstacles or terrain matter in this game. I'm not trying to remake Flight Control but that's a similar mechanic. Here's what I've been doing, but it just seems too complicated (pseudocode): getDestination() { - self.nextDestination = remove_from_array(destinations) - self.gradient = delta y to destination / delta x to destination - self.angle = atan(self.gradient) - self.cosAngle = cos(self.angle) - self.sinAngle = sin(self.angle) } move() { - get movement allocation for this turn - if self.nextDestination not valid - - getNextDestination() - while(nextDestination valid) && (movement allocation remains) { - - find xStep and yStep using movement allocation and sinAngle/cosAngle calculated for current self.nextDestination - - if current position + xStep crosses the destination - - - find x movement remaining after self.nextDestination reached - - - calculate remaining direct path movement allocation (xStep remaining / cosAngle) - - - make self.position equal to self.nextDestination - - else - - - apply xStep and yStep to current position - } - round squad's float coordinates to integer screen coordinates - draw squad image on map } That's simplified of course, stuff like sign needs to be tweaked to ensure movement is in the right direction. If trig is the best way to do it then lookup tables can be used or maybe it doesn't matter on modern devices like it used to. Suggestions for a better way to do it? an update - iPhone has zero issues with trig and tracking tens of positions and tracks implemented as described above and it draws in floats anyway. The Bresenham method is more efficient, trig is more precise. If I was to use integer Bresenham I would want to multiply by ten or so to maintain a little more positional accuracy to benefit collisions/terrain detection.

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  • Pointers to threads

    - by viswanathan
    Suppose i have pointer to a thread like this CWinThread *m_pThread = AfxBeginThread(StartThread, this, THREAD_PRIORITY_NORMAL, 0, 0); Now in my StartThread function assume i did all operations and the function returned like this UINT CClassThread::StartThread(LPVOID pVoid) { return true; } Will my m_pThread be invalid when the return statement is executed?

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  • Creating a console in Java

    - by DeadMG
    When I try to use java.lang.System.console(), I get a null pointer. I can still write to out and read from in, but this only works when I run straight from my IDE. When I run the .jar file directly, nothing happens. How can I create a console like I'd see using std::cout for use in Java?

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  • Java app makes screen display unresponsive after 10 minutes of user idle time

    - by Ross
    I've written a Java app that allows users to script mouse/keyboard input (JMacro, link not important, only for the curious). I personally use the application to automate character actions in an online game overnight while I sleep. Unfortunately, I keep coming back to the computer in the morning to find it unresponsive. Upon further testing, I'm finding that my application causes the computer to become unresponsive after about 10 minutes of user idle time (even if the application itself it simulating user activity). I can't seem to pin-point the issue, so I'm hoping somebody else might have a suggestion of where to look or what might be causing the issue. The relevant symptoms and characteristics: Unresponsiveness occurs after user is idle for 10 minutes User can still move the mouse pointer around the screen Everything but the mouse appears frozen... mouse clicks have no effect and no applications update their displays, including the Windows 7 desktop I left the task manager up along the with the app overnight so I could see the last task manager image before the screen freezes... the Java app is at normal CPU/Memory usage and total CPU usage is only ~1% After moving the mouse (in other words, the user comes back from being idle), the screen image starts updating again within 30 minutes (this is very hit and miss... sometimes 10 minutes, sometimes no results after two hours) User can CTRL-ALT-DEL to get to Windows 7's CTRL-ALT-DEL screen (after a 30 second pause). User is still able to move mouse pointer, but clicking any of the button options causes the screen to appear to freeze again On some very rare occasions, the system never freezes, and I come back to it in the morning with full responsiveness The Java app automatically stops input scripting in the middle of the night, so Windows 7 detects "real" idleness and turns the monitors into Standby mode... which they successfully come out of upon manually moving the mouse in the morning when I wake up, even though the desktop display still appears frozen Given the symptoms and characteristics of the issue, it's as if the Java app is causing the desktop display of the logged in user to stop updating, including any running applications. Programming concepts and Java packages used: Multi-threading Standard out and err are rerouted to a javax.swing.JTextArea The application uses a Swing GUI awt.Robot (very heavily used) awt.PointerInfo awt.MouseInfo System Specs: Windows 7 Professional Java 1.6.0 u17 In conclusion, I should stress that I'm not looking for any specific solutions, as I'm not asking a very specific question. I'm just wondering if anybody has run into a similar problem when using the Java libraries that I'm using. I would also gladly appreciate any suggestions for things to try to attempt to further pinpoint what is causing my problem. Thanks! Ross PS, I'll post an update/answer if I manage to stumble across anything else while I continue to debug this.

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  • Are there any good books to learn C++ if you already know Java and C#

    - by JF LR
    Hi, I would like to know if you have any good books that teach C++ programming without repeating basic stuff. In fact, I already well know Java and C#. I also have a basic knowledge in C and assembly, so I understand a little bit pointer arithmetic, manual memory management and heap based allocation. I was looking at O'Reilly's C++ in a Nutshell and was also wondering if this book would be a good choice. Thank you

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  • Array performance question

    - by Konrad
    I am very familiar with STL vector (and other container) performance guarantees, however I can't seem to find anything concrete about plain arrays. Are pointer arithmetic and [] methods constant or linear time?

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  • return an address of a double

    - by bks
    i'm having an issue understanding why the following works: void doubleAddr(double* source, double** dest) { *dest = source; } i get a pointer to a double and want to change the double that dest points to: //usage: int main() { double* num; double* dest; doubleAddr(num, &dest); return 0; } thanks in advance

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  • Cocoa equivalent of diskEvt/kEventClassVolume?

    - by tewha
    We have a drop-down menu of volumes in our UI, and I'd like to update it when a new disk is mounted. In the Classic days, this would involve watching for a diskEvt event. In Carbon, I think this was kEventClassVolume. What's the Cocoa equivalent? (A pointer into Apple's documentation on this would satisfy the question. I've been unable to find anything!)

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  • C question on functions

    - by benjamin button
    some times i see that functions are defined as below: read_dir(dir) char *dir; { DIR * dirp; struct dirent *d; /* open directory */ dirp = opendir(dir); ......... so on here what is the importance of the statement char *dir; what is the intension behind declaring the pointer soon after the function name and then starting the function body.

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  • Setting clustered index in nhibernate

    - by SolBadguy
    Hi. I'm trying to define a property that is not the id as a clustered index in nhibernate, yet I've found no way of doing this. Could anyone give me a pointer of how this is done, or it is something not currently available in nhibernate? Thanks in advance

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  • Does the openssl command line do key strengthening?

    - by chotchki
    If I run the openssl command line in hmac mode (as below), is the key used for the hmac used directly or is it hashed before using it as the key? echo "foo" | openssl dgst -sha256 -binary -hmac "test" | openssl base64 Similarly, when encrypting a file with openssl (as below)is the pass phrase hashed with the salt? (If so how is it done? A pointer to the right source file would be even better.) openssl enc -salt

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  • Ocamlrun.lib Not Found For Linking

    - by Onorio Catenacci
    Hi all, Trying to build the OCaml Win32 API binaries for OCaml 3.11.0 on Win 7 and I consistently get a message when I try nmake dynamic: 'cannot open input file "ocamlrun.lib"'. My google skills seem to be failing me--is there something I need to do to get this .lib file? It doesn't seem to be part of the libraries which are included in the OCaml binary distribution for Windows. Can anyone give me a pointer in the right direction?

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  • div refresh without click of the button

    - by fusion
    how do i make the div refresh, say after 10 secs and execute the run_query() function without clicking on the button? <script src="scripts/ajax.js" type="text/javascript"></script> <div id="quote"><strong>Quote of the Day</strong></div> <div><a style="cursor:pointer" onclick="run_query()">Next quote …</a></div>

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