Object-oriented Software in Ada 95

314 A Text user interface
A dialog window is inherited from a Window and as well as all the API calls of a Window has the following
additional API call:
Note Function / procedure
1 procedure Framework ( The:in out Dialog;
Abs_X, Abs_Y:in Positive;
Max_X: in Positive;
Name:in String; Cb:in P_Cbf );
Note:
1 Sets the absolute position of the window on the screen. The size of the window is set with max_x. The
call-back function cb will be called after the user has constructed a message in the dialog box . This is
initiated by the user entering the Enter character (return key). When the Enter character is received
the Dialog window calls the call-back function with a string parameter containing the user’s entered
text. The signature of the call-back function is:
function Cb(Mes:in String) return String
where mes is the message typed by the user.
22.2.4 User interaction with the TUI
A user of an application program that is built using the TUI API has the following switch characters defined:
Switch character
TAB
ESC
^E
Description
Swaps the focus for user input to another window on
the VDU screen. The active window is indicated by a #
in the top left hand corner.
Activates the menu system.
The menu system is described in detail in Section 22.4.
Terminates the TUI session. All windows will be closed
and the user returned to the environment which initiated
the program.
A switch character is used to activate a specific window on the system or cause a global effect.
22.2.5 Classes used
The TUI API is contained in the following classes:
API for Contained in the package Notes
A window Class_Window -
A dialog box Class_Dialog Plus the API inherited from a
Window.
A Menu bar Class_Menu Plus the API inherited from a
Window.
A Menu Title Class_Menu_Title Plus the API inherited from a
Menu
The TUI set up Class_Input_Manager Controls the input sent to the
TUI.
22.3 An example program using the TUI
A short program to illustrate the use of many of the API calls is shown below. This example program converts a
distance in miles entered by the user into kilometres. The package Pack_Program contains the procedure Main
that implements this program.
© M A Smith - May not be reproduced without permission