I have developed an OCR application on Windows using OpenCV and Tesseract. Now all I want to do is to write same application over Linux (Ubuntu 12.10) in C++. And I don't have any experience in Linux development. I don't know where to start. All I want is developing environment in which I would able to link these two libraries OpenCV and Tesseract.
Please suggest me. I have tried searching Google but failed. Maybe I am not searching with good keywords. As I am totally new in Linux
First make sure that you compiled OpenCV on your system, as OpenCV's linux bundle hasn't got pre-compiled libs (unlike Windows bundle). Follow this tutorial.
For a starting point, build up Eclipse as IDE and follow this tutorial. It shouldn't be so hard to adopt if you already used Visual Studio (MSVC Windows compiler).
Later on, it would be wise to learn about gcc (official linux compiler for your c++ code) and its syntax, and maybe together with CMake. Because learning the terminal and g++ syntax suddenly accelerates the development process. Linux has got many opportunities for a developer, such as pkg-config, which links all the libs and headers automatically (well, almost). You can also go for learning CMake for cross platform development and let it use "gcc" by default; example here.
Also note that, using cygwin, you can actually compile & build linux binaries on a Windows platform. For the opposite; check MinGW.
Good luck.
EDIT: other cross platform solutions
VisualGDB
Qt
Related
I've got a C++ VS2013 solution with 3 projects, using OpenCV 2.4.10, easylogging++ and Dlib libraries. The problem is that our client is now migrating to Linux (Ubuntu Server). I've looked into Cygwin and MinGW and a few questions here on stackoverflow, but I'm still lost as to where I should start. I need this done as soon as possible, so the simpler solution would be best. I really appreciate any help you can provide.
I recommend using cmake build system on ubuntu. Using Opencv and easylogging on ubuntu out of the box could be a matter of minutes. dlib's website also mentions a simple cmake building steps that works on ubuntu.
After you get your libraries up and running, build your code and see if there are any system-dependent functions then google how to standardize them across systems. If your code is already standardized it should run right then and there.
You can then ask about any specific issues you meet on the way.
I've got some experience in programming for Windows environment but I need to develop a "Kiosk" (I've heard that this is the right name) on a BeagleBone Black. I'm totally new to Linux and also new to the tools I'm going to use. Until the last couple of months, I developed with VB6 and C++Builder only.
Right now I have Eclipse, MinGW and wxWidgets working on my Windowns 7 64-bits PC, and the BeagleBone Black booting a Debian 7.8 with LXDE.
I need to setup a tool-chain to compile for the BeagleBone Black. I tried really hard and have read at least hundred pages, but still I've not figured it out.
From This Site I've learnt that it's possible to compile for Linux from Windows, which could be the perfect solution. If not possible, I already have a Virtual Machine running Ubuntu (but I can change it if needed) ready for Eclipse and other stuff installation.
I'm still lost about what tool-chain to use/build with. This site seems to have already built a tool-chain, but there's no indication to where to go from there. I understand that I should now compile the wxWidgets with this tools, but I'm unsure and also I don't want to mess-up my current working setup in Windows 'cause I missed a switch or a path.
I see how this question was asked more than one time, but I didn't find one that is up-to-date so I'm asking it again.
How to make a tool-chain to compile a GUI application, from Windows using Eclipse, MinGW and wxWidget for a BeagleBone Black running Debian and LXDE?
You need a compiler that runs on Windows and produces binaries for the target platform (Debian arm).
You need a SDK (headers, libs) for the target platform.
The MinGW-64w wiki describes how to build MinGW cross-compiler and build environment.
You can also look at SO: C++ cross-compiler from Windows to Linux.
Another technique is Canadian Cross, like Google makes its Android NDK for Windows host. At first you should setup Linux build machine. Then build GCC and binutils that will run on Windows machine and will produce binaries for Debian arm. Then copy built toolchain to Windows Cygwin or MSYS environment.
My experience with C++, GCC, MinGW and Cygwin is very limited. However, I already tested it and realized that Cygwin is not the ideal solution for what I am trying to do. Even though a GTK+ program with GTKWebkit works fine on Cygwin, it's not that great in terms of packaging the final project to a single .exe. The dependency on the cywin1.dll, etc... is a deal breaker.
I tested MinGW and it works flawlessly for a standard GTK only application in Windows. And the file size is great!
I tested a standard GCC compiler to compile a GTK & WebKitGtk application on Mac and it worked flawlessly.
But in the windows world where I am getting confused with GTK and WebkitGTK. What I want to do is compile a sample WebkitGTK application on Windows using MinGW. So, all the required libraries are statically linked and has a single .exe.
What are my choices? How do I actually build WebsiteGTK on Windows? Please give me the tools and as much details as you can.
FYI, QtWebkit is not going to cut it. Their licensing terms are not that commercial friendly.
I never did get WebKitGtk to compile on Windows. I think I could have got it to work using cygwin, but that's a non-starter for the project I'm working on.
I ended up using Chromium Embedded Framework instead: https://code.google.com/p/chromiumembedded/. It has clear instructions and sample apps for Mac, Linux, Windows, and mobile.
Here someone says that the easiest way to do that it's to cross-compile from virtual machine. Actually, there is binary there.
He uses OpenSUSE booted through VirtualBox. Then, using osc tool, get the mingw32-webkitgtk from windows:mingw:win32 and build it with osc.
I'm working on a program which uses autotools for its build system and compiles fine on linux. To build for windows I'm trying to get a mingw cross-compiler working for windows. Now when I compile on linux and move to windows of course I am missing some dll's that are not installed by default on windows. This leads to missing dll errors. I cannot statically link my program due to restrictions in the LGPL.
So my question is what is the correct way to cross compile in this situation? I feel like I need to wrap my exe in a installer which automatically resolves and installs the dll dependencies for windows but I haven't been able to locate something explaining how to do this. Basically I'm thinking of yum/apt-get for windows. How do I manage dll dependencies on windows? I'm a linux guy, not a windows guy, so please bear with me.
Probably the easiest thing would be if you could move your development to a Windows machine. But short of that, you could install Windows-Mingw on your Linux machine using Wine. (IIRC winetricks has even a target for this) That way you get a "feel" for the issues on windows. An alternative could be Windows in a virtual machine, but Wine should be ok for a development environment.
I also strongly suggest that you install Microsoft Visual C++. The express versions will do fine. There are a number of tools coming with MSVC++ that can make your life a lot easier, like dll-dependency checker etc. An additional excellent source of information are the Sysinternals tools from Mark Russinovich and his blog.
I have some question about cygwin :
Can I use Cygwin develop socket based code?
Does Cygwin have read() and write() functions that work with file descriptors?
Can I use Pthread library in Cygwin?
Does code that compiles in Cygwin also
compile in Linux without any change or with little change?
Will an executable file that built by
Cygwin run in Linux ?
Why does Cygwin not need the linker
option -lpthread when I use pthread library?
why in #include <iostream> don't I need to use using namespace std; ?
Can I work with QT in Cygwin? If so,How?
Can I boot my Linux in other
partition with Cygwin and use it?
Can I access the other partition
that is EXT3 in Cygwin?
On 1:
Yes. Socket libraries are shipped with Cygwin - many socket based apps such as web servers are included in the base distribution.
On 2:
Yes. I think all of the 'section 2 and 3' system calls in the GNU C runtime and library are implemented by the cygwin runtume. You can check this in the man pages that come with Cygwin. A list of system calls and std lib calls implementd by Cygwin can be found here.
On 3: Yes. Pthread is included in Cygwin. The list referred to in the link above mentions pthreads as well.
On 4: Anything built against GNU libraries should work with little or no change between Cygwin and Linux (assuming there are no dependencies missing on Cygwin). Depending on CPU architecture you may have to worry about word alignment, endianness and other architecture-specific porting issues, but if you're targeting Windows and Linux on Intel your code would have few if any porting issues arising from CPU architecture.
On 5: Cygwin will build a program against its own shared libraries by default but GCC can cross-compile to target other platforms. You could (in theory) set GCC up to cross-compile to any target supported by the compiler. There are plenty of resources on the web about cross-compiling with GCC, and I don't think the process will be materially different on Cygwin.
Note that Cygwin binaries will not run on Linux - or Vice-versa. You will still need separate builds for both.
On 6: Not sure - at a guess it's included in the standard runtime, perhaps because it was necessary to wrap the Win32 threading API for some reason.
On 7: Don't know - it's probably the same on g++ on all platforms. Apparently a compiler bug. Dan Moulding's Answer covers this in more detail.
On 8: Yes. IIRC QT is available in the standard builds and it will certainly compile on Cygwin. As with Linux/Unix, QT on Cygwin uses an X11 backend so you will need to have an X server such as XMing running.
In order to avoid the dependency on an X server you may want to build QT apps against the Win32 API,. It is possible to do this with MinGW, which is a set of header files and libraries to build native Win32 apps with GCC. MinGW can be used from within a Cygwin environment (an example of GCC on Cygwin cross-compiling to a non-Cygwin target) and the installer from cygwin.com gives you the option of installing it.
MinGW is quite mature; it has all of the 'usual suspects' - libraries and header files you would expect to find on a Unix/Linux GCC development environment and is very stable. It
is often the tool of choice for building Win32 ports of open-source software because it is (a) free, (b) supports the libraries used by the software and (c) uses GCC so it is not affected by dialectic variations between MSVC and GCC.
However, these dialectic variations in the language and available libraries (for example MSVC doesn't come with an implementation of getopt) mean that porting programs between MinGW and MSVC can be quite fiddly. My experience - admittedly not terribly extensive as I've only done this a few times - is that porting applications between MinGW32 and Linux is easier than porting between MinGW and MSVC. Obviously apps with non-portable dependencies such as Win32 specific API usage would require the dependent components to be re-written for the new platform but you'll have far fewer problems with differences in the standard libs, header files and language dialect.
QT does a fairly good job of providing a platform abstraction layer. It provides APIs for database access, threading, I/O and many other services as well as the GUI. Using the QT APIs where possible should help with portability and the Unix/Linux flavoured libraries that come with MinGW mean that it might give you a good platform for making applications that will port between Win32 and Linux with relatively little platform dependent code.
EDIT: The qt development packages in Cygwin are:
qt4: Qt application framework (source)
qt4-devel-tools: Qt4 Assistant, Designer, and Linguist
qt4-doc: Qt4 API documentation
qt4-qtconfig: Qt4 desktop configuration app
qt4-qtdemo: Qt4 demos and examples
You'll probably also need gcc4-g++ and some other bits and pieces. This listing on the cygwin web site has a list of the packages.
"Yes" to all of those except 5. You'll have to build your executables separately for Linux, but that should be straightforward since the answer to 4 is "yes".
Make sure you install all the development headers you need on both platforms.
Yes, Yes, Yes, Yes (if you write it carefully and don't use anything specific to cygwin), No.
On 5: it may be possible to cross-compile from Cygwin to Linux, I really don't know. If it is, then technically some executables "built by Cygwin" would run on Linux. But Cygwin executables won't run on Linux.
1-4: The answers to these are all "yes", because all of these features you are asking about are part of the POSIX standard. Cygwin is basically a POSIX layer for Windows so, naturally, Cygwin includes all of these features.
5: No, Cygwin binaries will not execute under the Linux kernel, because ultimately the code generated by Cygwin is Windows native code. It will link with the usual Windows DLLs (like kernel32.dll), whereas Linux does not even have a notion of DLLs (it has shared objects which are similar, but different). More importantly, executables built under Cygwin will be in the PE format, but Linux generally uses the ELF format for executables. You could, of course, do cross-compiling under Cygwin, and thereby generate native Linux executables, but it doesn't sound like this is what you are looking for. Also, compiling a new version of GCC to use as a cross-compiler under Cygwin is probably no trivial task.
6: GCC under Cygwin doesn't require use of -lpthread because all of the pthread code under Cygwin is in cygwin1.dll which is always linked in by default.
7: This is a bug in GCC (on all platforms). It has been around for a long time and will probably never be fixed.
8: ConcernedOfTunbridgeWells did a great job of explaining this, so there's not much left for me to say. However, it's worth noting that Cygwin has the X.org X Window System in its package list. With Cygwin 1.7.x, setting it up and using it is a breeze and it seems pretty rock-solid. If you want to use Qt with X, I'd recommend using Cygwin's X server.
In response to #7, the version of the C++ compiler that you have is probably out of date. If you don't need linux/posix portability, I'd switch to the non-cygwin MinGW GCC compiler - you can get 4.4.1 at http://tdragon.net/recentgcc/
Regarding 6, you don't need -lpthread because Pthreads support is part of the Cygwin DLL.