Windows Programming in C++

Transcription

1 Windows Programming in C++ You must use special libraries (aka APIs application programming interfaces) to make something other than a text-based program. The C++ choices are: The original Windows SDK (Software Development Kit), a C library MFC (Microsoft Foundation Classes), a sophisticated wrapper around the Windows SDK ATL (Active Template Library), a lightduty wrapper around the Windows SDK.NET, Microsoft's new technology

2 Why Use the Windows SDK? Games generally take over the whole screen Windows SDK is the simplest route to getting to the point where the screen has been taken over.net not univerally installed yet We cover MFC/ATL/.NET in other courses

3 Basic Windows SDK Concepts Write a WinMain(), not a classical main() #include <windows.h> and probably <windowsx.h> Often #define WIN32_LEAN_AND_MEAN before those #includes to cut down on further #includes of rarely used header files Use many #define- and typedef-created data types from those header files (e.g. BOOL, HWND) Use MS-specific declaration modifiers (e.g. WINAPI, CALLBACK) for functions

4 Basic Windows SDK Concepts Some Data Types are: BOOL - a boolean value (TRUE or FALSE) HWND - handle to a window UINT - unsigned integer (32 bit) WPARAM - word parameter (32 bit, originally 16, for passing an integer value, for example) LPARAM - long parameter (32 bit, for passing an address, for example) LRESULT - 32 bit return code from a function HINSTANCE - handle to a running instance of a program

5 Messages MS Windows uses Messages to communicate with the windows in a program Every window in a windows program (which includes Controls, which are preprogrammed sub-windows like buttons and list boxes) has a Window Procedure, which is the code to handle any message that may be sent to the window A window is customized by writing a custom window procedure for it, and supplying that procedure's address to Windows, which will call the procedure when needed.

6 Messages A window procedure is passed four things: An HWND, identifying the window for whom the message is intended A UINT, identifying which message it is A WPARAM, containing a piece of data An LPARAM, containing another piece of data (typically a pointer to more data, but not necessarily) The WPARAM and LPARAM meaning and usage varies between different messages

7 Messages Messages can come from: Windows, based on user interaction or some other operating system activity Another window (in the same program or another) The program code itself, using either SendMessage() (waits until message is handled) or PostMessage() (puts the message on a queue but doesn't wait for it to be handled)

8 Messages Controls (like buttons) have a window procedure that you don't see Controls will send a WM_COMMAND message to the parent window when the user interacts with them, its WPARAM identifies the control and the operation Macros LOWORD() and HIWORD() can extract the low- and high-order 16 bits of a WPARAM or LPARAM (or you can do the bit manipulation operations yourself)

9 Dialogs A Dialog is a pop-up window that typically contains a bunch of controls A dialog can be laid out using a resource file (extension.rc) to describe the controls, rather than creating the controls from within the C++ code A header file is typically used to interlink the C++ code with the resource code by using symbolic names for IDs, since both languages understand the #define and #include syntax

10 Dialogs A dialog is supplied the address of a Dialog Procedure, which is a window procedure specifically designed to handle a dialog (return value is BOOL rather than LRESULT) Can get the HWND of a control on a dialog using GetDlgItem() Can send a message to a control on a dialog using SendDlgItemMessage() or PostDlgItemMessage() [alternative to calling GetDlgItem() then Send/PostMessage()]

11 Dialogs WM_INITDIALOG is the ID of the message sent to a dialog just after it is first created, giving you a chance to initialize its controls and do other one-time setup WM_COMMAND is the ID of the message sent to a window when (among other things) one of its controls (ID in low order 16 bits of WPARAM) has something to pass along IDCANCEL is a predefined control ID that corresponds to a user request to close the window

12 Dialogs Each kind of control has different messages that can be sent to it E.g. CB_GETCURSEL is the ID of the message you send to a ComboBox to get the index of the item in the combobox that is currently selected E.g. LB_ADDSTRING is the ID of the message you send to a ListBox to add another string (passed in the LPARAM) to the listbox

13 Dialogs Dialogs can be modal (application waits until dialog has been completed) or not (dialog and other application windows can be used at the same time) Modal dialogs can be created by calling DialogBox() Modal dialogs should be terminated by calling EndDialog()