c++

get metadata from jpg, dng and arw raw files

I was wondering if anyone new how to get access the metadata (the date in particular) from jpg, arw and dng files. I've recently lost the folder structure after a merge operation gone-bad and would like to rename the recovered files according to the metadata. I'm planning on creating a little C++ app to dig into each file and get the m...

QGraphicsItem doesn't receive mouse hover events

I have a class derived from QGraphicsView, which contains QGraphicsItem-derived elements. I want these elements to change color whenever the mouse cursor hovers over them, so I implemented hoverEnterEvent (and hoverLeaveEvent): void MyGraphicsItem::hoverEnterEvent(QGraphicsSceneHoverEvent* event) { update (boundingRect()); } Howe...

Templated derived class in CRTP (Curiously Recurring Template Pattern)

Hi, I have a use of the CRTP that doesn't compile with g++ 4.2.1, perhaps because the derived class is itself a template? Does anyone know why this doesn't work or, better yet, how to make it work? Sample code and the compiler error are below. Source: foo.C #include <iostream> using namespace std; template<typename X, typename D> str...

what functions are called when passing value to function

In C++, if an object of a class is passed as a parameter into a function, the copy constructor of the class will be called. I was wondering if the object is of nonclass type, what function will be called? Similarly in C, what function is called when passing values or address of variables into a function? Thanks and regards! ...

Must parameter of assignment operator be reference?

When overloading assignment operator of a class in C++, must its parameter be reference? For example, class MyClass { public: ... MyClass & operator=(const MyClass &rhs); ... } Can it be class MyClass { public: ... MyClass & operator=(const MyClass rhs); ... } ? Thanks! ...

How to treat RAM data as if it was a real file?

So I have some temp data in my program (in RAM). I want to somehow make it seem as it is a file (for example for sending it into another program which takes a file link as argument)? Is it possible? How to do such thing? ...

How to encode series of images into H264 using x264 API? (C/C++)

How to encode RBG images into H264 frames (Keyframe + some dependent frames)? So I created some images how to turn them into H264 now? ...

C++: Chr() and unichr() equivalent?

I could have sworn I used a chr() function 40 minutes ago but can't find the file. I know it can go up to 256 so I use this: std::string chars = ""; chars += (char) 42; //etc So that's alright, but I really want to access unicode characters. Can I do (w_char) 512? Or maybe something just like the unichr() function in python, I just ca...

Problem with cvCreateVideoWriter in OpenCv. Again )

I know, that the issue had been widely discussed before, but after 5 hours of inefficient googling I guess I deserve to ask :) By the way, all such problems concerned earlier versions of OpenCV, so.. I've compiled fresh OpenCV 2.1. from source under Ubuntu 9.10. It works fine except of cvCreateVideoWriter, which returns null to the fo...

Using custom Qt subclasses in Python

First off: I'm new to both Qt and SWIG. Currently reading documentation for both of these, but this is a time consuming task, so I'm looking for some spoilers. It's good to know up-front whether something just won't work. I'm attempting to formulate a modular architecture for some in-house software. The core components are in C++ and e...

How to determine if std::chrono::monotonic_clock is available?

C++0x N3092 states that monotonic_clock is optional: 20.10.5.2 Class monotonic_clock [time.clock.monotonic] Objects of class monotonic_clock represent clocks for which values of time_point never decrease as physical time advances. monotonic_clock may be a synonym for system_clock if system_clock::is_monotonic is true. The c...

C++ templates error: instantiated from 'void TestClass::testMethod(T, std::map) [with T = SomeClass]

Hello there, I've some problem in my code I cannot deal with: #ifndef TESTCLASS_H_ #define TESTCLASS_H_ #include <map> using namespace std; template <typename T> class TestClass { public: TestClass(){}; virtual ~TestClass(){}; void testMethod(T b,std::map<T,int> m); }; template <typename T> void TestClass<T>::testMethod(T b,st...

Why do structures need to be told how big they are?

I've noticed that in c/c++ a lot of Win32 API structs need to be told how big they are. i.e someStruct.pbFormat = sizeof(SomeStruct) Why is this the case? Is it just for legacy reasons? Also any idea what "pb" stands for too? EDIT: oops, yeah I meant "cbFormat" ...

Writing a managed wrapper for unmanaged (C++) code - custom types/structs

faacEncConfigurationPtr FAACAPI faacEncGetCurrentConfiguration( faacEncHandle hEncoder); I'm trying to come up with a simple wrapper for this C++ library; I've never done more than very simple p/invoke interop before - like one function call with primitive arguments. So, given the above C++ function, for example, what should I ...

Why is this c++ string concatenation missing a space?

I am working with c++ strings, and am a beginner at programming. I am expecting: 99 Red Balloons But I am receiving: 99 RedBalloons Why is that? #include <string> #include <iostream> using namespace std; int main() { string text = "9"; string term( "9 "); string info = "Toys"; string color; char hue[4] = {'R','e...

What does (void**) mean in C?

I would look this up, but honestly I wouldn't know where to start because I don't know what it is called. I've seen variables passed to functions like this: myFunction((void**)&variable); Which confuses the heck out of me cause all of those look familiar to me; I've just never seen them put together like that before. What does it mea...

Monitoring GPS Coordinates

I need to monitor GPS Coordinates changes at every 15 min and take action based on that. as per bada developer guide report "only one application allowed to run at a time if another application try to run first one is closed" .so that how do i monitor GPS coordinates without interruption from other applications. how do i keep my applic...

sorting names in a linked list

Hi there, I'm trying to sort names into alphabetical order inside a linked list but am getting a run time error. what have I done wrong here? #include <iostream> #include <string> using namespace std; struct node{ string name; node *next; }; node *A; void addnode(node *&listpointer,string newname){ node *temp; temp = ...

Prevent monitor from powering on

I'm turning off the monitor using SendMessage(HWND_BROUADCART, WM_SYSCOMMAND, SC_MONITORRPOWER, 2). That works, but the monitor turns back on when someone touches the keyboard or mouse. I tried to get rid of this using the DevicePowerSetDeviceState function with DEVICEPOWER_CLEAR_WAKEENABLED for the keyboard and mouse: it returns no err...

Echo cancellation

Can any of you suggest a good and stable echo cancelation package (gnu or not) to be linked with my videoconference application (C/C++) (Windows / Linux / MacOSX) ? My application should be freeware, so i do not want to pay for each user who download the app. ...