I wanted to know if there is any library in C available for calculating the Font Metrics (Basically i wanted to know the width of a string of Particular Font).
QT has QFontMetrics. Is there any way I can get similar data in C.
I wouldn't say just use FreeType, unless you are on a system that uses X as the graphics display. If you are on Windows, use the Windows API to get font metrics information and on Mac use whatever Cocoa provides.
It might also help if you told us what you are trying to do.
EDIT: Since the output of your library is intended to be consumed by a particular GUI app, you will probably want to use the same GUI library to get the font metrics information as the app is using. Even better would be to have the app provide metrics information to the library, or a callback method that can provide that information. Then the library doesn't even have to know how the font metrics were derived, reducing an unnecessary dependency. This also means that you can use Qt (C++) in your GUI app, but still write your library in C and not have to figure out a way to call C++ from C, which is very difficult, especially if you are trying to make it cross-platform.
C is (just) a programming language. By design C has no embedded functions at all, not even for File I/O.
So you will have to indicate what Graphics/GUI platform you are using.
You can use freetype2 : http://www.freetype.org/freetype2/docs/reference/ft2-base_interface.html#FT_Glyph_Metrics
Check out FreeType: http://freetype.sourceforge.net/freetype2/docs/tutorial/step2.html
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I would like to code an app that captures a video from a webcam connected to the PC. I have found tutorials in other webs but they were in C++ or C# and I'm interested in doing it using C.
Do you know some web or have some knowledge that could help me with it?
I imagine that I would have to start my code "asking permission" to the SO to allow me to connect to the webcam but.... I have no idea how to do it neither how to continue.
I've noted your tag that you are on Windows, so this c library video4linux would not work for you.
However, in many cases OpenCV(in C/C++) will do it just fine. A lot parts of OpenCV are pure C, in which "Video Analysis" part might suits part of your need. Find this: http://opencv.willowgarage.com/documentation/c/
If you have to call the C++ part of OpenCV, you can write a c wrapper for the C++ part, while your remaining code could stay pure C. Reference this: Developing C wrapper API for Object-Oriented C++ code
Capturing video input is very system dependent, as different systems handles it in different ways. You can use a library that is doing the hard work for you (either system independently or not) or you could write your own library to do what you want.
If you want a system independent solution you can take a look at OpenCV
I am looking into making a C program which is divided into a Core and Extensions. These extensions should allow the program to be extended by adding new functions. so far I have found c-pluff a plugin framework which claims to do the same. if anybody has any other ideas or reference I can check out please let me know.
You're not mentioning a platform, and this is outside the support of the language itself.
For POSIX/Unix/Linux, look into dlopen() and friends.
In Windows, use LoadLibrary().
Basically, these will allow you to load code from a platform-specific file (.so and .dll, respectively), look up addresses to named symbols/functions in the loaded file, and access/run them.
I tried to limit myself to the low-level stuff, but if you want to have a wrapper for both of the above, look at glib's module API.
The traditional way on windows is with DLLs. But this kind of obselete. If you want users to actually extend your program (as opposed to your developer team releasing official plugins) you will want to embed a scripting language like Python or Lua, because they are easier to code in.
You can extend your core C/C++ program using some script language, for example - Lua
There are several C/C++ - Lua integration tools (toLua, toLua++, etc.)
Do you need to be able to add these extensions to the running program, or at least after the executable file is created? If you can re-link (or even re-compile) the program after having added an extension, perhaps simple callbacks would be enough?
If you're using Windows you could try using COM. It requires a lot of attention to detail, and is kind of painful to use from C, but it would allow you to build extension points with well-defined interfaces and an object-oriented structure.
In this usage case, extensions label themselves with a 'Component Category' defined by your app, hwich allows the Core to find and load them withough havng to know where their DLLs are. The extensions also implement interfaces that are specified using IDL and are consumed by the core.
This is old tech now, but it does work.
In our Bioinformatics lab we've recently been asked to create a GUI for a program written (and optimized) in C. Any GUI we designed would need to be able to feed input to and receive output from the C program, while also being easily portable to both Windows and Mac. What are ways to go about doing this?
If your looking for a GUI toolkit that works on windows/mac in C, have you considered GTK?
Download QT or wxWidgets.
Why do the hard work when someone already has and will let you use it for free? I prefer QT myself, btw.
Edit: It does mean using C++ but it will work perfectly with C code.
Use a separate program.
It doesn't break the existing code - especially important if the code has bio knowledge that a programmer might not know/understand/test.
Gui's change often, in a couple of years you are going to be rewriting the gui for NewSuperOsToolkit(tm) but the underlying worker code won't change. We have atmospheric modelling code that I'm sure was originally written in latin.
You keep the ability to run the engine code as a batch, in parallel on MPI in the cloud, and a bunch of other ways you haven't thought of.
You could write the front end GUIs in Java, and have them feed input and receive output from your C programs. I've known a couple of groups here at work that do something similar with C# and C code (but they don't have the multi-platform restraint).
This way you don't necessarily have to create your GUIs using a C toolkit.
Depending on the nature of the program, you could create an entirely separate GUI application (in any language you prefer), and fork/execute the existing program from it, redirecting it's stdin and stdout to your GUI program. Depending on how the existing program works, this could work well, or be very cumbersome.
You could also extend the existing program with GUI code in something like GTK (which has a C API), or you could use Qt (which is C++, but there's usually no problems calling C functions from C++ if you define them as 'extern "C"').
There are a number of scripting with languages that can make this easy. I'd go for tcl/tk it works on mac pretty much out of the box, and is cross platform across pretty much any machine you can think of.
Also GTK is great and a number of scripting languages have bindings for it.
You probably don't want to write your gui in c if you don't have to. use a rapid develoment scripting language.
If you want a native GUI, then go with wxWidgets or QT. (I use wxWidgets ...)
The alternative is to have an HTML based interface using Javascript and CSS. You avoid GUI libraries altogether, you get cross-platform support and the outcome is better on some dimensions, worse on others.
If you really want a standalone user interface, you can integrate it into a binary with something like WebKit.
I'm working on a project that's supposed to work on both Windows and Linux (with an unofficial Mac port as well) that emulates a true colour system console.
My problem is that recently there appeared a request for textfield support (yes, console-based) and it would be cool to add the possibility of copying text to clipboard and pasting from it. Is there a way of achieving this that will:
be done in C (not C++),
work in both Windows and in Linux (preprocessor macros are an option if there's no platform-independent code),
require no extra libraries to link to?
Thanks in advance for your help.
If you're not using a cross platform UI library (like wx or something), then it sounds like you're just going to have to write native clipboard code for each platform you want to support.
Remember, on Macintoshes, you copy with Command-C, not Ctrl+C :)
The clipboard is inherently an operating system defined concept. The C language itself has no knowledge of what a clipboard is or how to operate on it. You must either interface directly with the OS, or use a portability library that does this on your behalf. There is no way around this.
Personally I would define my your own function
getClipboardText();
That is defined in two different header files (linux_clipboard.h, windows_clipboard.h, etc) and then do pre-proccessor stuff to load the appropriate one accordingly. I don't really code in C/C++ so I'm sorry if that didn't make any sense or is bad practice but that's how I'd go about doing this.
#if WIN32
#include windows_clipboard.h
#endif
That sort of thing
Remember:
For linux you have to deal with different window managers (Gnome, KDE) all with different ways of managing the clipboard. Keep this in mind when designing your app.
You may be able to communicate to the clipboard by using xclip. You can use this python script here to do this job via communicating with 'dcop' and 'klipper' here. That is for KDE, I do not know how it would be done under GNOME... You may also be able to do this independantly of either GNOME/KDE by using DBUS, although I cannot say 100% confidently on that either...
Just be aware, that for a truly cross-platform job, you have to take into account of the different GUI's such as under Linux, X is the main window manager interface and either GNOME/KDE sits on top of it..I am not singling out other GUI's such as FluxBox, WindowMaker to name but a few, and that there will be a lot of platform dependant code, and also in conjunction, you will be dealing with Windows clipboard as well..all in all, a big integrated code...
Have you not considered looking at the raw X programming API for clipboard support? Maybe that might be better as I would imagine, GNOME/KDE etc are using the X's API to do the clipboard work...if that is confirmed, then the work would be cut out and be independant of the major GUI interfaces...(I hope that would be the case as it would make life easier for your project!)
Perhaps using compile-time switches, for each platform...WIN, KDE, GNOME, MAC or use the one that is already pre-defined..
Hope this helps,
Best regards,
Tom.
I'm lookin for a portable wiimote library. I want to use the wiimote for the hardware it has (but I don't need to access any data stored on it).
Required features:
access to all the buttons (as an exception, no use of the power button is OK)
make the wiimote play sound
talk to nunchuks and classic controllers
preferably: make the wiimote rumble.
interface with C. Preferably native C. Bonus points for bindings with Haskell or python.
The library should port to Linux, Windows and OS X (in order of importance) and should be agnostic with respect to CPU architecture.
Anyone got a good suggestion?
Haven't use it (I've only read about the managed Wiimote library really), but you may want to check out wiiuse. It seems like the most complete of the native libararies.
Others include:
GlovePIE
WiiYourself
You can use my WiiMouse program to do this (which is based on the wiimotelib open source project), it allows you to connect via named pipes and play PCM sounds and use all the attachments including the MotionPlus, it even calculates the MotionPLus vectors for you, you can get it here:
http://home.exetel.com.au/amurgshere/wiimouse.phtml
See the download for an example on how to connect to a wiimote via named pipes and play sounds and stuff.