Reading/manipulating images in C++ - c++

I am a frustrated newbie of C++ who would like to do the simple task of extracting a pixel matrix from an image file, do some transformation, and then output the modified matrix to an image format of my choosing.
I've given libpng a try and it's API is a mess and hardly readable. Interestingly, some people said it's the best available for C++. I gave my software developer cousin a call and he told me to use OpenGL. So, I did some Googling and I still haven't found a straight answer.
It appears getting a simple "int* readPNG(char* path)" is too much to ask for when the likes of Java, Matlab, and python have these things included in their standard libraries. This is just ridiculous! How do you pros come by and what libraries do you use?
Also a few trivial C++ questions:
- Is there any way to organize classes in a hierarchy like how packages are used in Java? I tried filters in Visual C++ but they don't seem to be the same thing.
- Is there any way to get easily comprehensible stack traces for runtime failures?

Try OpenCV. It is an image processing library with very simple features for editing and saving the images. It will serve your purpose. It also comes with very elegant documentation.

I've found ImageMagick's Magick++ library to be the most useful tool for handling image formatted data programmatically.
C++ has namespaces like Java but they are much more difficult to use and may only make things less readable. As for stack traces, I recommend combing the existing stackoverflow answers for that. In short, it's not simple.

I suggest you improve your Google-fu. There are lots of image processing libraries for C++, including the Boost Generic Image Library, which is as close to standard as you'll get. If you don't have Boost installed and minimal fuss installing libraries, you can always try The CImg Library.
As for your other questions (e.g. stack traces), you'll need to ask separate questions.

I'd suggest Magick++, the C++ API to ImageMagick.
As for packages: you can use namespaces, but that's not nearly comparable to Java's packages (no package-level access etc). They're mostly what they're called: a means to organize names.
Stack traces are not trivial in C++. And there's no platform-independent way of implementing them that I'm aware of.
If you need these features, I just wonder why you don't stick with Java or Python or the likes ? ...

1) Try freeImage - very easy to use and the documentation is readable.
freeimage site
2) for stack traces: which environment are you working with? In Visual Studio there is Stack window (Debug/Windows/Call Stack - Alt 7),
You can also use DebugView and OutputDebugString - not really traces the stack, but can be very usable in debugging. .

I recommend DevIL (formerly known as OpenIL). It has read and write support for 17 formats, and supports many more for just reading.

This is my answer to my very own question here:
Some of the suggested libraries up there have issues with installation with Visual Studio 2010, offer practically no instructions for installation with Visual Studio (i.e. FreeImage), or simply have ridiculously messy API's (i.e. libpng).
If you are new to C/C++, please be careful about what library to choose. Even if there are technical forums roaming with gurus who knows all the answers, you are most likely on your own spending days experimenting and piecing up clues that experienced volunteers could've easily answered in 2 sentences (if they bothered).
Now, what works for me is the OpenCV image library (http://opencv.willowgarage.com/), which is introduced by Mister daerty0153 up there. When you go on the website, don't download the superpack from sourceforge. Instead, read the installation instructions (http://opencv.willowgarage.com/wiki/InstallGuide) and choose what platform you are using.
In my case, I use Visual Studio 2010 as my IDE and so this is the actual subpage that is relevant: http://opencv.willowgarage.com/wiki/VisualC%2B%2B
One problem I encountered is letting VS2010 recognize the .dll files and is not remedied by following those instructions. My solution was to copy all of them to my project folder and that solves all the problem. Some suggested it is a VS 2010 bug.
Hope it helps others suffering from the same situation.

Related

Beginner questions: how to use these obscure commands like 'RenderWindow' in C++

This is kind of a beginner question, so please let me know if this is appropriate for this website and if not, where else I should be asking this.
I've just gotten into the basics of C++ (pretty much what's being taught in this video from FreeCodeCamp: https://www.youtube.com/watch?v=vLnPwxZdW4Y). Obviously, not everything there is to know is discussed in this tutorial and I've been running into a couple of things in other demonstration vids that I don't quite get yet.
For example, this quick demonstration of how Tetris can be coded: https://www.youtube.com/watch?v=zH_omFPqMO4&t=0m25s) you can see him use the command 'RenderWindow', which apparently creates a new window the size of his choice (320*480 pixels in this case). This doesn't seem to be a standard function in C++, so I assume he somehow imported it. How can I do this myself? Does it have to with the file inclusions written at the top of the file (#include <SFML/Graphics.hpp>)? If so, how can I learn more about such files, where can I find them (is it anything like the Python Package Index, or interfaces in Java) and can I create them myself? Any general explanatory words on this?
Thanks in advance.
This doesn't seem to be a standard function in C++
That is correct. There are no functions for graphics nor window handling in C++.
so I assume he somehow imported it. How can I do this myself?
Usually, you would pick a library of your choice (there are many), or do it yourself by using whatever API your operating system provides.
Does it have to with the file inclusions written at the top of the file (#include <SFML/Graphics.hpp>)?
Yes, SFML is one of those libraries.
If so, how can I learn more about such files
You would go to the library's homepage and read the documentation.
where can I find them
Try searching the web for lists of libraries, articles, projects, etc.
is it anything like the Python Package Index
No, there is no standard one for C++. There are several package managers, build systems, etc. Popular libraries are in most of them and support one or more build systems.

Import a library to Visual C++

I have some experience with C#/Java, PHP, ASP and all the other web based fuss languages but recently I've been trying to learn the real deal, which to me is C++. I must admit syntax is a bit weird to me, coming from managed environments but I started managing it. I bought some books but most of their examples, which I do understand, but they doesn't really help with the IDE, of course not, since they're not specialized about that.
So either way, I decided I've had enough with theory and simple book jobs so I came up with a "project" to test myself. I thought to myself that It should have some sort of INI parser, but I didn't want to write one myself, the "task" was to implement a 3rd party library/solution. Now from visual studio for C# I know how to add shared DLLs, which is not the problem. After some digging I've found this
http://code.jellycan.com/simpleini/
Cool thing about it is that it is claimed to be cross-platform which should be a win/win. It's open source as well, which is great.
But the question is, how I add it to visual studio so that when I include SimpleINI.h my IDE would compile it as well on each build. One way is to have it compiled as a shared DLL, I think, but I don't really want that :< . I really like the idea of open source and I imagine myself throwing code out there in the wild, in the future and I would like to include all the sources including the libraries, with proper credit.
How do you guys do it? I'd appreciate if you suggest a book or are "step-by-step" guide.

Creating/Organising a portable C++ library

I'm not sure the way I'm organising my library is the most elegant way to organise it. I'm mainly concerned about making all the code that I type compile/run for all systems that I'm targeting (keeping it portable), and also keeping it up-to-date for every system.
For example:
I'm not sure using __declspec(dllexport/dllimport) would be used for Mac or Linux. I assume that it's not, but I don't know what the equivalent is for Mac/Linux is. Or another example might be calling specific Operating System functions, which I try to avoid. However, things such as: measuring how long something takes to happen*, in a precise manner, does require me to call OS specific functions.
*as in getting the user's time precisely (down to micro/milli-seconds).
The systems that I am currently (perhaps more in the future) aiming for is Mac, Windows and Linux. But testing that the code compiles (and runs correctly) for every system just seems like a waste of time. As currently, the way I'm proposing to do it, requires me to make a separate project for every system. i.e. I create a Visual Studio Project for Windows, an Xcode project for Mac, and use the command line for Linux or use some other IDE.
Okay, so my main problems with the way I organise things are:
1. Time Consumption, as in creating the projects for all systems and keeping each indiviual project, for each system up-to-date.
2. Knowledge on all IDE's/Compilers that I require to use
Please note, I've never really used* Linux before, I'm thinking about switching. The only problem that I'm concerned about is finding the right tools for me to use with it, and finding the right Distro that would suit me, for what I need. I would really appreciate if someone that is experienced with Linux could guide me, or give me some advice whether to switch or not.
I really like Visual Studio, and it's been my main IDE for quite a while now. I'm just not sure if I want to ditch Visual Studio or not, for Linux; as I don't know if the tools that are available for Linux can do what Visual Studio can or not. What I mean is, it being as user friendly as Visual Studio is. I'm afraid to learn how to use Linux's tools, I'm just not sure if it's worth doing so. Time isn't a major factor on this library, I have plenty of time, I'm fairly young and determined to program as my career in the future.
*I have used it before, but I've never replaced it for Windows.
I am currently hosting all my source code for my project on BitBucket, but at the moment, I only have the RAW code on my repo. There is no project files or any other tool to compile it with, just the code and a readme file. I was thinking of using Makefiles, since they seem popular. But I've never made a Makefile before, don't get me wrong, I am willing to learn. I'm just not really sure where to start. I've heard that people use CMake to create portable libraries, such as SFML and Ogre3D. I've built a couple of libraries with CMake, but I have no clue on how to actually make my own library with it to make my project/make files. Should I learn and incorporate CMake with my library, or is there a better option available?
EDIT:
I'm not aiming to write a library for actual Software that uses a GUI. I'm mainly aimed to write games.
1 - Boost. Boost will help your portability more than you can imagine. Its only real sticking point is, believe it or not, OS X.
2 - Use CMake. It integrates with Visual Studio project files as the build tool, and you can put most of your different-platform compilation voodoo in there.
3 - If you're seriously writing a portable library, consider writing it in C/writing a C wrapper, or making it header-only, or providing the source-code. Making it a shared or statically linkable library does not mean that it will play nice. Name mangling leads to inconsistencies that will blow your mind.
4 - Always be explicit about the number of bits in each variable.
5 - use git. It'll allow you to setup a crappy local server for a repository very easy and get very fast transfers of the kind of huge changes MSVC will make annoyingly
There are a lot more best-practices that can be discussed about cross-platform development. All of that advice isn't applicable in every case; I have a very code-heavy Linux/Windows library that I code almost exclusively in MSVC2k10 and mostly build/test for in Linux, and it is nowhere close to header-only.
EDIT in response to comments:
git was suggested because I find it very easy to use and manage locally. I've use svn before and liked it, I won't really endorse any others, but there are probably plenty of fine ones.
To expound on point 3,
A C wrapper would make it so that anyone anywhere could use your library - FORTRAN developers, Ruby, even Java.
Otherwise you generally have to have similar compiler versions to link properly and it will only link to other C++ code, outside the case of DLLs, and there are still versioning issues. It's one of the stupidest problems in C++ left over, check "name mangling" on Wikipedia. There is a reason widely-used libraries are written in C or have C wrappers, such as libz, openssl etc.
There are other advantages to it. Exception propagation across dynamic libraries is non-existent; with static libraries it can be inconsistent or non-existent.
You'll find that the most widely-used C++ libraries are mostly header-only, like Boost. A header-only library solves many problems by putting all the code directly into a project in a relatively intuitive way, and modern compilers can still optimize away much (but certainly not all) of the extra compile time associated with it.
With all this said, it is certainly possible to do without a C wrapper or header-only, it is just annoying and very troublesome. DLL hell and its Linux equivalents still exist.
You also asked about Boost. That depends. If you're distributing the sourcecode then you certainly must distribute Boost with your code/have people install it. Having people install libraries in order to compile other libraries or use programs is common practice. Think of how specific versions of DirectX come with games for an example.
However if you are distributing binary versions of your library, statically linking against Boost will eliminate any need to include it as long as you are careful to keep Boost headers out of the outward-facing parts of your library. This is where you start seeing things like void * pointers inside C++ headers; an unfortunate side-effect of some of the shortcomings of C++ compilation and library distribution unfortunately.
CMake is a good choice. You can learn to use it. Read a tutorial:
http://www.cmake.org/cmake/help/cmake_tutorial.html
But, if your targets are Linux and Windows only. It is probably OK, in your case (small/average first multi-platform project), to maintain 2 separate build systems.
On Linux, Use Make. It is standard and has a very good reference manual:
http://www.gnu.org/software/make/manual/make.html
On Windows. Use your IDE project file, be it Visual, DevC++ or other. That is the simplest way to go.
Most important, make it easy to test your library/software on different platforms. Install a virtual machine on your desktop. Or at least compile your library into Cygwin.
Once you are here come back on stackoverflow and we will help !
Personally I'd leverage a framework like Qt, because it is quite portable, it does abstract a lot of OS functionality (files, timing, threads, networking), and you get a decent, free IDE (Qt Creator) that is also portable and runs on Windows, OS X and any Unix flavor that runs Qt. It'd give you the lowest barrier to entry. Qt Creator can leverage the Visual Studio compiler and the CDB debugger if they are available.
You do not need to use OpenGL to use Qt, in fact you're not bound to any particular graphics subsystem. Qt only "uses" OpenGL in Qt 5 for the Qt Quick 2 graphics backend. It's not needed for Qt 4, nor for Qt Quick 1 (even in Qt 5!).
You can use any 2D or 3D framework you fancy to push images and other content to the screen. What Qt is good at is creating the kind of 2D imagery that is often needed in games - menus, configuration screens, HUDs, etc. There's a lot of controls and drawing primitives that Qt makes easy to leverage for your purposes.
Qt also lets you use a reasonably powerful model-view and networking frameworks, thus you'd be able to reasonably easily generate server or client lists that update in real time.
There'd need to be a small amount of shim code between Qt and DirectX, of course. On the output side, you typically end up with a QImage in Qt, and then use DirectX, SDL, OpenGL, etc. to push it to the screen. On the input side, you need to call qApp->processEvents() within your main game loop, and you will need to post user input events from DirectX etc. to Qt's event queue using qApp->postEvent(...). This would be only needed if, say, DirectX main loop consumes all Windows messages and won't let standard winapi/win32 code (Qt's windows event dispatcher) see them. I haven't deal with DirectX much, so others feel free to chime in with details, of course.

What Linux Full Text Indexing Tool Has A Good C++ API?

I'm looking to add full text indexing to a Linux desktop application written in C++. I am thinking that the easiest way to do this would be to call an existing library or utility. This article reviews various open source utilities available for the Gnome and KDE desktops; metatracker, recoll and stigi are all written in C++ so they each seem reasonable. But I cannot find any notable documentation on how to use them as libraries or through an API. I could, instead, use something like Clucene or Xapian, which are generic full text indexing libraries. They seem more straightforward but if I used them, I'd have to implement my own indexing daemon, an unappealing prospect.
Also, Xesam seems to be the latest thing, does anyone have any evidence that it works?
So, does anyone have experience using any of the applications or libraries? How did you use it and what documentation was useful?
I used CLucene, which you mentioned (and also Lucene.NET), and found it to be pretty good.
There's also Strigi which AFAIK works with Xesam and is the default used in KDE.
After further looking around, I found and worked with Recol. It believe that it has the best C++ interface to a full text search engine, in this case Xapian.
It is important to realize that clucene and Xapian are both highly complex libraries designed primarily for multi-user server applications. Cutting them down to a level appropriate for a client-system is not easy. If I remember correctly, Strigi has a complex, pure C interface which isn't adapted.
Clucene also doesn't seem to be that actively maintained currently and Xapian seems to be maintained. But the thing is the existence of recol, which allows you to index particular files without the massive, massive setup that raw Xapian or clucene requires - creating your own "stemming" set is not normally desirable, etc.

Cross-platform C++ IDEs? [closed]

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I'm looking for a good IDE for C++ that has most or all of the following properties (well, the first 4 or 5 ones are mandatory):
cross-platform (at least Mac, Linux)
of course, syntax highlighting and other basic coding editor functionality
reasonably responsive GUI, not too sluggish on mid-size (say, 100 files) projects (both my Linux and Mac computers are 5 years old)
code completion
integration with gdb
SVN integration would be nice too
refactoring (rename a variable semi-automatically throughout the codebase, etc.)
can display class hierarchy
can add hypertext-style links to the code (so you can click on a function/class name and it brings you to the declaration),
can show code parts that (potentially) call my function (I know that's hard to do for C++ so I added the potentially)
So far, I've been using Emacs for everything, but I think advanced features that give me more overview and search capabilities like the last three would be nice. I'm tired of just using grep and find on my codebase.
Basically, I want most of the things for C++ development that Java IDEs usually do.
I see Netbeans can be used for C++, as well as Eclipse. I think they would fit my requirements. Has anyone actually used them for daily coding? What are the differences? What are your experiences? Code::Blocks is more lightweight and doesn't do many of the things listed above, right?
Note: I don't need a GUI builder.
Update: With the bullet point 10 I mean that I can give it a function name (e.g. Foo::setValue), and it shows me all occurrences where this particular function (and not other functions of the same name, like Bar::setValue) is called in my codebase.
Code::Blocks does the first 5 and it's also got class method browsing (though not a heirarchy display). It's a much more lightweight solition thaen Eclipse or NetBeans, but if you like the minimalist approach it's pretty good.
To summarise CB versus your requirements:
Yes
Yes
Yes
Yes
Yes
No - but you can add it easily
No
No, but similar functionality
No
Can go from definition to decl and vice versa, but no callers list
As all the solutions you mention are free, you could always try them all and then make a decision on which one to stick with. That's what I did.
In addition to the ones mentioned, there's QTCreator, which has "Rapid code navigation tools" though I've not used it.
I think though that the non-essential requirements aren't so good, you can easily see where a method is being called using search! (of course, if you have a huge class hierarchy where every class has the same named method, you've only yourself to blame :) if you havn't laid your classes out in an easily understandable way)
I'd recomend Netbeans, in 6.5, its pretty fast IDE and offers all 10 of your requirements.
I recently asked this same question. I ended up choosing Eclipse with the CDT plugin and the Cygwin libraries. I've been pretty happy with it, except I haven't quite got the hang of the debugger. The window for walking through source on the debug perspective is pretty small, for some reason I haven't figured out how to see into arrays, and I think I knocked out one of the windows for displaying variables and don't know how to get it back. I've ended up abandoning the debugger perspective and just walk through debugs in the normal perspective.
Also, I use Eclipse for Java, so the helped minimize the learning curve. It can do refactoring and you can integrate svn.
Java based IDEs (Netbeans and Eclipse) are sometimes somewhat slow. Also their main focus is Java. One problem with Eclipse is that it is difficult to use for small screens, such as in laptops. I prefer to work usually in vim + ctags (to perform the functions of grep and find), and when I have some advanced operations like comparing two directory hierarchies, I use Eclipse. I've not used Code::Blocks much, but I hear good things about it.
Coming from Emacs, I think you'd prefer something lightweight and not heavy-weight. I would consider Code::Blocks then as a good candidate for exploration.
codeblocks is open source !!
http://www.codeblocks.org/
Go for Eclipse. If you have a decent computer, it is fast enough and has best possibilities with its plug-ins.
codeblocks have a lot of features just check them up !
and it is free !
If you already know Emacs, it may be easier to just start using a few more packages, than learn a whole new IDE.
For example, you can easily do #9 with Emacs: just run tags once and then M-. RET anywhere.
You also have to weigh the IDE's features against what you lose. For example, most IDEs don't tend to have Emacs' easy macro capabilities or numeric prefixes, which are often like a more general form of refactoring.
It is not only the IDE that matters - you would probably need to be able to build you application outside of the IDE (i.e. continuous integration).
Consider using CMake to create a cross-platform description of your build scripts. Once you have the CMake Script (which is straightforward) you can generate from it project files for the IDE of your choice - eclipse, kdevelop, Visual Studio, codeblocks, etc.
I would suggest using eclipse as an IDE. There are few options of how to use CMake with eclipse. Play around, and find the best for you.
Once more - CMake is not only cross-platform it is also cross-IDE. And CMake scripts are very readable, a simple make file would look like this:
project(hello)
add_executable(hello hello.cpp)
Now compare that with makefiles, or setting up a project in your favorite IDE!
My two cents (in no particular order ... and not all these options are c++):
Qt ... my first productive GUI building framework
Lazarus ... what a cool name, and very productive tool (not c++ though)
MonoDevelop ... I'm falling in love with c# development (very much like c++)
Java ... ubiquitous ( a bit like c++)
CHEERS!
Sublime Text Editor is the best cross platform editor so far I have seen. Try using it http://www.sublimetext.com/. It comes with unlimited demo period without suppressing any of its functionality. But if you are satisfied with that, please buy and use it to credit the author.