Windows API Tutorials

The tutorials start with the most basic Windows program, the windows equivalent of "hello world!", Winnie. Then we move on to a more Genericprogram, which serves as a skeleton for a simple Windows application. Then we discuss various Controls. Using these controls one can build a complete dialog-basedapplication, whose main window is a dialog. We are then ready to discuss a Generic Dialog, a framework with which one can quickly build specific dialogs.

To do some simple graphicsone needs a Canvasobject. You use Pens and Brushesto paint on the canvas.

More advancedtopics include programming with Threadswith a practical example of a Folder Watcher— a program that watches directories for changes.

Modernwindows programming requires some knowledge of the Shell API, which leads us to the discussion of OLE and COM. We show how one can encapsulate OLE in C++ to create Smart OLE. OLE is also used in Automation, which lets your application talk to other applications.

Controls are nothing but specialized windows. You can easily create your own controls, as evidenced by the Splitter Bartutorial.

For graphicsprogrammer, we give a short introduction on using Bitmapsfor animation and a more advanced tutorial on using Direct Draw.

You can subscribeto our tutorials directly, or you can view our tutorials off-line by using the subscription option in your browser. Both Microsoft Internet Explorer 4.0 and Netscape Navigator 4.0 or later have this option.

Some of you asked why we don't provide a zipped version of the tutorials. Unfortunately we don't have the resources to keep both versions in synch. Sorry!

Here is how you subscribe to tutorials in IE 4.0:

• Add current pageto your Favoritesand

• Choose the option to subscribe by clicking on " Yes, notify me of updates and download the page for offline viewing."

• Click on " Customize,"

• Choose " Download this page and pages linked to it."

• Choose link depth 1to get all the windows tutorials (or 2, if you want the source code for the examples).

The tutorial is less than 0.5 MB and the book is about a megabyte, and you can do the downloading during off-peak hours. To update the pages on your computer,

• Select Manage Subscriptionsfrom the Favoritesmenu.

• Select the subscription(s) you want to refresh and

• Click on the Updatebutton.

When you are ready to browse, Select Work Off-linefrom your browser's Filemenu and go to your Favoritesmenu.

Follow instructions above to subscribe to each chapter separately using depth 3. Subscribing to the top page will result in following the links to Amazon, Barnes & Noble, and Microsoft.

Before you can even begin thinking about programming in windows, you have to be able to understand how this simple program works. Remember to compile this and other windows programs with the STRICTcompilation flag defined!

Note: This is a Win32 program — it will run under Windows 95 and Windows NT (if they want you to program for the 16-bit platform, they should pay you twice as much!). Windows API calls are highlighted in blueand windows specific data types are shown in green. I will also usually put a double colon in front of API calls. In C++, that simply means that i'm calling a global function, in case there is some ambiguity.

Remember to compile sources as a Windows application. For instance, in Visual C++ select File.New.Projects.Win32 Application. Otherwise you'll get the error: unresolved external _main . (I provided a project file for those of you who use MS VC++ 6.0)

First, you have to define a class of windows that will be displayed by your application. In our case we will display only one window, but still, we need to give Windows some minimal information about its class. The most important part of the WinClassis the address of the callback procedure, or the window procedure. Windows is supposed to call us —it sends messages to our program by calling this procedure.

Notice the declaration of WindowProcedure. windows will call us with a handle to the window in question, the message, and two data items associated with the message, the paramters, wparam and lparam.

In WinClass we also have to specify things like the program instance handle HINSTANCE, the mouse cursor (we just load the standard arrow cursor), the brush to paint the window's background (we chose the default window color brush), and the name of our class.

Once all the fields of WNDCLASS are filled, we register the class with the Windows system.

#include

LRESULT CALLBACK WindowProcedure(HWND hwnd, unsigned int message, WPARAM wParam, LPARAM lParam);

class WinClass{

public:

WinClass (WNDPROC winProc, char const * className, HINSTANCE hInst);

void Register () {

::RegisterClass(&_class);

}

private:

WNDCLASS _class;

};

WinClass::WinClass(WNDPROC winProc, char const * className, HINSTANCE hInst) {

_class.style = 0;

_class.lpfnWndProc = winProc;// window procedure: mandatory

_class.cbClsExtra = 0;

_class.cbWndExtra = 0;

_class.hInstance = hInst; // owner of the class: mandatory

_class.hIcon = 0;

_class.hCursor = :: LoadCursor(0, idc_arrow); // optional

_class.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1); // optional

_class.lpszMenuName = 0;

_class.lpszClassName = className;

// mandatory

}

Once the Window Class is registered, we can proceed with the creation of a window. This is done by calling the CreateWindowAPI. It takes a lot of arguments, the name of the window class that we have just registered, the caption that will appear in the title bar, style, position and size, and the application instance. the rest of the arguments, for the time being, will be left equal to zero.

The window will not appear on the screen until you tell Windows to show it.

class WinMaker{

public:

WinMaker (): _hwnd (0) {}

WinMaker (char const * caption, char const * className, HINSTANCE hInstance);

void Show (int cmdShow) {

::ShowWindow(_hwnd, cmdshow);

::UpdateWindow(_hwnd);

}

protected:

HWND _hwnd;

};

WinMaker::WinMaker(char const * caption, char const * className, HINSTANCE hInstance) {

_hwnd = :: CreateWindow(

className, // name of a registered window class

caption, // window caption

WS_OVERLAPPEDWINDOW, // window style

CW_USEDEFAULT, // x position