C++ developing a GUI - classes?

Question

I do have to say I'm fairly inexperienced when it comes to C++, don't be too harsh on me.

Recently stumbled unto the wonders of the win32 API and have chosen to practice using it (I'd rather not use MFC/wxWidgets/etc at this point, just for educational purposes).

Well, my real question is: How do you properly code your win32 GUI stuff into classes. I mean, sure, you can make a class that saves individual window handles, allows for easier modification of window properties, has a more simplified version of CreateWindow(). But as I understand it you will need a messagepump and several callback functions for your created windows. How does that work when combining them with classes?

Could anyone point me in the right direction here? I don't mind reading (a lot of) example code as long as it is commented.

PS: I'm also having trouble finding good (read: easy) documentation on using 'resource files' for my window decorations. Bonuspoints for that! :)

Answer 1

I personally would use MFC instead of reinventing the wheel here. However, if you insist you need to have an application object that is instantiated when the program is run and contains the message loop and a mechanism for forwarding messages to the correct window objects.

That's the way MFC does it, at least. I'm not sure if the MFC source code is available for download, but if you have access to Visual C++ install disks (any version) you should be able to install the source code on your computer to review.

Answer 2

I program in C++ for a living. I like C++.

That said, your life will be so much easier if you do your windows GUI in something .Net, e.g., C#. Win32 is very low-level and you will be building tons of stuff that you will get for free with the .Net libraries. Win32 is not a wonder, anymore. :-)

If you want to learn C++, pick something other than a GUI to do with it.

Answer 3

Look at MFC or ATL/WFC. If you want to re-invent the wheel, the best reference source for how to do so is the wheel itself, especially since the source code is readily available.

Answer 4

The only reason I would recommend not reinventing the wheel is you are neither an expert at C++ nor the Win32 API. Trying to learn two unrelated subjects at once will not be productive. If you want to become better at C++, write a library for a subject you know a lot about. If you want to learn the Win32 API, program it raw to understand how it works before creating (or using) a wrapper for it.

Answer 5

The biggest problem I faced back when I used the Win32 API (have since moved on to Linux and cross-platform solutions) were the callbacks. Especially the winproc one, AKA the message pump. I found this, which should be a good hint. I did what that page suggests when I rolled my own wrapper.

Answer 6

There is a pretty good C++ Windows API tutorial on the Reliable Software site.

Answer 7

The best way to learn this is to go and readCharles Petzold's original book. He does a good job of showing how to set up the base message loop and how to build statements for routing the various events to handlers. The real problem here is that by reinventing everything you are going to be spending hours and hours writing and debugging windows event hanlding code instead of writing your own application.

Unless you have a compelling reason for doing this yourself, you woudl be far better served using someone else's construct like MFC.

The only reason I see for coding all this yourself is if you want a basic understanding of how it works before you switch over to MFC or something similar. At least this way you would see how it works under the covers before you can forget it forever.

Answer 8

I would suggest reading Windows++ by Paul Dilascia. It takes you through the whole process of building a class library in C++ on top of the Windows API. It's written for 16-bit Windows, but all of the concepts presented in the book still apply. Plus, you can get it really cheap since it's "out of date".

And make sure you learn about message crackers (#include <windowsx.h>), they will keep you from pulling out too much hair. ;-)

Answer 9

Many years ago, I developed a set of classes to encapsulate the API (various reasons why we couldn't use MFC). I learned a lot from the MFC source code.

The big key is that every window has a UserInfo data member - you can use it for whatever you want. What you'll want to use it for is the class's this pointer.

Now, the other tricky thing is that the message handler callback function cannot be a normal class member function, as Windows uses C calls and not C++. So your callbacks must be statics. However, since you've saved the class's this pointer, its just a matter of getting the class's userinfo, casting it to your class's this pointer and then calling whatever (non-static) class functions you need.

If you plan it correctly, inheritance will work well, including all of the inheritance that the windows themselves exhibit (ie, an Edit is a Control is a Window).