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15.1 Z-ORDER 2
15.2 WINDOWS REVIEW 2
15.2.1 CREATEWINDOW
2
15.2.2 CHILD
WINDOWS
2
15.2.3 WINDOW
PROCEDURE
3
15.2.4 NOTIFICATION CODE
3
15.2.5 WM_COMMAND NOTIFICATION
CODE 3
15.3 EXAMPLE APPLICATION 3
15.3.1 DESCRIPTION
3
15.3.2 OBJECTIVES
4
15.3.3 WINDOWS
MANAGEMENT
FUNCTIONS
4
15.3.4 WINDOW CLASSES
5
15.3.4.1 Main Window class 5
15.3.4.2 Popup Window class 5
15.3.4.3 System Window classes 5
15.3.5 CREATING
MAIN
WINDOWS
5
15.3.6 CREATING
CHILD
WINDOWS
6
15.3.7 USER DEFINED
MESSAGES
7
15.3.8 APPLICATION’S
MAIN
WINDOW
PROCEDURE
7
15.3.8.1 Drawing in Popup Window- I 7
15.3.8.2 Drawing in Popup Window- II 8
15.3.8.3 Drawing in Popup Window- III 8
15.3.9 INFORMING BACK TO
MAIN
WINDOW
9
15.3.10 QUIT
APPLICATION
VIA CONTROL IN POPUP
WINDOW 9
SUMMARY 10
EXERCISES 10
Windows Management 2
15.1 Z-Order
• The Z order of a window indicates the
window's position in a stack of overlapping
windows. This window stack is oriented along an imaginary axis, the z-axis,
extending outward from the screen.
• The window at the top of the Z order overlaps
all other windows.
• The window at the bottom of the Z order is
overlapped by all other windows.
15.2 Windows Review
15.2.1 CreateWindow
CreateWindow function have been discussing in our previous lectures. Much of
its details
including styles, class name, parent handles, instance handle and
coordinates, etc have
been discussed in chapter 11.
CreateWindow Function is used to create window. CreateWindow function can
create
parent, child, popup and overlapped windows with dimensions x, y, width and
height.
HWND CreateWindow
(
LPCTSTR lpClassName, // registered class name
LPCTSTR lpWindowName, // window name
DWORD dwStyle, // window style
int x, // horizontal position of window
int y, // vertical position of window
int nWidth, // window width
int nHeight, // window height
HWND hWndParent, // handle to parent or owner window
HMENU hMenu, // menu handle or child identifier
HINSTANCE hInstance, // handle to application instance
LPVOID lpParam // window-creation data
);
15.2.2 Child Windows
Following are the characteristics of child windows.
• A child window always appears within the
client area of its parent window.
• Child windows are most often as controls.
• A child window sends WM_COMMAND notification
messages to its parent
window.
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• When a child window is created a unique
identifier for that window is specified in
hMenu parameter of CreateWindow()
15.2.3 Window Procedure
LRESULT CALLBACK WindowProc
(
HWND hwnd, // handle to window
UINT uMsg, // WM_COMMAND
WPARAM wParam, // notification code and identifier
LPARAM lParam // handle to control (HWND)
);
15.2.4 Notification code
Common controls are normally taken as child windows that send notification
messages to
the parent window when events, such as input from the user, occur in the
control. The
application relies on these notification messages to determine what action
the user wants
it to take. Except for trackbars, which use the WM_HSCROLL and WM_VSCROLL
messages to notify their parent of changes, common controls send
notification messages
as WM_NOTIFY messages.
15.2.5 WM_COMMAND Notification code
• The wParam parameter of Window Procedure
contains the notification code and
control identifier.
• low word: ID of the control n high word:
notification code
• BUTTON
BN_CLICKED
• EDIT
EN_CHANGE etc
15.3 Example Application
For demonstration purpose we are going to create an example application.
15.3.1 Description
Our application will be parent-child window application. This application
will consist of
three push buttons of names:
• RECTANGLE
• CIRCLE
• MESSAGE”
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And Edit child window or edit control in its client area.
Floating popup window with caption bar and one push button bearing a
name”QUIT
APPLICATION”.
15.3.2 Objectives
• Parent-child communication
• Message Routing
• Use of GDI function calls
15.3.3 Windows Management Functions
Building our application, we will use following windows management functions
in our
application.
Windows management function - I
HWND GetParent
(
HWND hWnd // handle to child window
);
GetParent function returns the parent handle of the specified child. This
function will be
useful when the parent of the child window to use.
Windows management function - II
HWND GetDlgItem
(
HWND hDlg, // handle to dialog box
int nIDDlgItem // control identifier
);
GetDlgItem function returns the handle of a dialog item. Using this function
we can
easily get the handle of the edit control, displayed on dialog box.
HWND FindWindow
(
LPCTSTR lpClassName, // class name
LPCTSTR lpWindowName // window name
);
FindWindow function finds the window with the given class name or window
name.
Windows Management 5
15.3.4 Window classes
The Window classes used in this application are:
• mainWindowClass
• popupWindowClass
• System Window Classes
15.3.4.1 Main Window class
wc.lpfnWndProc = mainWindowProc;
wc.hInstance = hAppInstance = hInstance;
wc.hCursor = LoadCursor(NULL, IDC_UPARROW);
wc.hbrBackground= (HBRUSH)GetStockObject (GRAY_BRUSH);
wc.lpszClassName= "MainWindowClass";
if(!RegisterClass(&wc))
{
return 0;
}
15.3.4.2 Popup Window class
wc .lpfnWndProc = popupWindowProc;
wc.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wc.hCursor = LoadCursor(NULL, IDC_HELP);
wc.lpszClassName = "PopupWindowClass";
if(!RegisterClass(&wc))
{
return 0;
}
15.3.4.3 System Window classes
System window classes are pre-registered. They do not need to register in
our
application. In this application, we will only used to create them not to
register them.
15.3.5 Creating Main Windows
Create a Main Window of the Application.
hWndMain = CreateWindow("MainWindowClass",
"Virtual University",
Windows Management 6
WS_OVERLAPPEDWINDOW | WS_VISIBLE,
100, 100, 400, 300,
NULL, NULL, hInstance, NULL
);
// check the returned handle, don’t need to proceed if the returned handle
is NULL
if(!hWnd)
{
MessageBox(NULL,”Cannot Create Main Window”,”Error”,
MB_ICONHAND|MB_OK);
return 0;
}
Now create a popup window with caption and visible style bit on.
hWndPopup = CreateWindow("PopupWindowClass", //window name (optional)
"Popup Window", //class name
WS_POPUP | WS_CAPTION | WS_VISIBLE,
250, 250, 300, 250,
hWndMain, NULL, hInstance, NULL
);
15.3.6 Creating Child Windows
Create a button window bearing a text “Rectangle”.
hWndButton=CreateWindow("BUTTON",
"Rectangle",
WS_CHILD | WS_VISIBLE,
10, 10, 100, 50,
hWndMain, 5,
hInstance, NULL
);
Create an Edit Window bearing a text “Message”
CreateWindow("EDIT",
"Message",
WS_CHILD | WS_VISIBLE n | ES_LOWERCASE,
10, 190, 200, 25,
hWndMain, 8,
hInstance, NULL
);
Windows Management 7
15.3.7 User defined Messages
System defined messages are already defined in WINUSER.H
#define WM_LBUTTONDOWN 0x0201 (513)
#define WM_DESTROY 0x0002 (2)
#define WM_QUIT 0x0012 (18)
#define WM_USER 0x0400 (1024)
These message are already defined, user don’t need to define them again.
Here, we will define our own messages.
#define WM_DRAW_FIGURE WM_USER+786
//user defined message are in valid range, in our case it is WM_USER + 786
15.3.8 Application’s Main Window Procedure
Message send to main window will be received and processed in mainWndProc
function.
In windows procedure we will process WM_COMMAND message. In
WM_COMMAND message we check the LOWORD and HIWORD parameters of the
messages. In LOWORD we have the control ID, always and in HIWORD we have
notification code. Using control id we identify a window.
case WM_COMMAND:
wControlID = LOWORD(wParam);
wNotificationCode = HIWORD(wParam);
if(wNotificationCode == BN_CLICKED)
{
switch(wControlID)
{
case 5:
SendMessage(hWndPopup, WM_DRAW_FIGURE, RECTANGLE, 0);
break;
case 6:
SendMessage(hWndPopup, WM_DRAW_FIGURE, CIRCLE, 0); break;
case 7: SendMessage(hWndPopup, WM_DRAW_FIGURE,
TEXT_MESSAGE, 0); break;
}
15.3.8.1 Drawing in Popup Window- I
Windows Management 8
here we check the button if button rectangle is pressed then draw a
rectangle with Light
Gray stock brush.
case WM_DRAW_FIGURE:
hDC = GetDC(hWndPopup);
switch(wParam)
{
case RECTANGLE:
SelectObject(hDC,GetStockObject(
LTGRAY_BRUSH));
Rectangle(hDC, 50, 10, 230, 150);
break;
}
15.3.8.2 Drawing in Popup Window- II
In case of Circle, we create hatch brush, we created a hatch brush which has
a style of
diagonal cross lines. After creating a hatch brush we select it on device
context to draw a
figure. After drawing, brush must be deleted.
case CIRCLE:
hBrush = CreateHatchBrush(HS_DIAGCROSS, RGB(170, 150, 180));
SelectObject(hDC, hBrush);
Ellipse(hDC, 70, 10, 210, 150);
DeleteObject(hBrush);
break;
15.3.8.3 Drawing in Popup Window- III
By pressing the button a text must be display with the stock object Ansi
variable fonts
and background brush. Text are displayed using TextOut GDI function.
case TEXT_MESSAGE:
{
TextOut(hDC, 50, 100, "Virtual University", 18);
SelectObject(hDC, GetStockObject(
ANSI_VAR_FONT));
SetBkColor(hDC, RGB(10, 255, 20));
TextOut(hDC, 50, 115, "knowledge Beyond Boundaries", 27);
break;
}
ReleaseDC(hWndPopup, hDC);
Windows Management 9
15.3.9 Informing back to Main Window
case WM_DRAW_FIGURE:
hDC = GetDC(hWndPopup);
hwndEdit = GetDlgItem(GetParent(hWnd), 8);
switch(wParam)
{
case RECTANGLE:
SelectObject(hDC,GetStockObject(LTGRAY_BRUSH));
Rectangle(hDC, 50, 10, 230, 150);
SendMessage(hwndEdit, WM_SETTEXT, 0, "Rectangle DrAwN!");
break;
}
15.3.10 Quit Application via control in Popup window
Main window is destroyed through button’s notification message BN_CLICKED.
Main
Window can be destroyed using DestroyWindow Function.
WM_CREATE:
CreateWindow("BUTTON",
"Quit Application",
WS_CHILD | WS_VISIBLE, n 75, 155, 150, 40, hWnd, 1234,
hAppInstance, NULL);
break;
case WM_COMMAND:
wControlID = LOWORD(wParam);
wNotificationCode = HIWORD(wParam);
if(wNotificationCode == BN_CLICKED)
{
switch(wControlID)
{
case 1234:
DestroyWindow(GetParent(hWnd));
break;
}
}
Windows Management 10
Summary
This chapter uses Windows management functions whose details have been
discussed in our previous lectures. These functions are very helpful to
interact with
windows and hierarchy of windows and also with windows handling, windows
manipulation and windows management. Our main objective in this application
was to
create a full fledge application. Before continue, we overviewed all the
functions that we
had to use. Function includes GetParent, GetDlgItem, CreateWindow and
notification
codes that are sent to window by controls or other child windows. Controls
are normally
considered are child windows, because these can be placed in any windows and
become
the part of the window but controls can be main window. Notification
messages are
considered to transfer informations to parent window by child windows. Child
windows
can send notification message to parent windows which aim only to inform
about some
events to parent window. The notification events could be e.g. in case of
edit control is
selection change i.e. EN_SELCHANGE or EN_CLICKED in case of button. Finally
we
wrote a code for our application. This code displays a window and three
child windows
including button that contains text like rectangle, messages etc. we also
make a popup
window, popup window is not a child window. Popup windows are very useful
when to
show message on screen or working in full screen modes in Microsoft Windows
Operating systems.
Exercises
1. Create a full screen popup window and then create another popup window
with a
caption box, system menu and with no close style.
2. Create your own status bar and show it in a window at its proper
location. This
status bar should display current time. |