The concept of a class hierarchy is often an extremely difficult one for new C++ programmers to master. While simple to define (A class hierarchy is a set of classes that build on top of each other using inheritance and virtual functions) and simple to justify (the main reason to create class hierarchies is reusability), it is rather difficult to move from concept to proficiency because hierarchies tend to be large self-referencing masses of code. It can take quite a bit of time to master a large hierarchy, especially if it is your first.
None the less, one of the best ways to learn about C++ is to examine and use existing hierarchies. In this way you can begin to understand the advantages of inheritance and polymorphism, and you can also gain access to a number of valuable design techniques. The problem with existing hierarchies is that in most cases they are quite complex. For example, the MFC class hierarchy contains hundreds of classes, thousands of member functions and tens of thousands of lines of code. People may spend years completely understanding all aspects of the hierarchy.
The purpose of this article is to introduce SST - the Super Simple Toolkit - as an example class hierarchy. SST is a GUI class hierarchy that allows you to create super simple GUI applications very easily. As such, you can compare it to MFC, Borland's OWL classes, Turbo Vision, the Java class hierarchy, etc. SST is, as the name implies, super simple. However, in its simplicity it carries three important advantages:
- Because it is so simple, you can master SST in just a day or two. That is, you can completely understand the use of the hierarchy, create simple applications with it, add several new controls to it, and understand the source code that creates it, in just a couple of days.
- SST, although small, carries all the core ideas found in larger class hierarchies. By exposing you to these fundamental concepts, SST can make it much easier to understand larger hierarchies
- SST is extremely portable, and has been compiled under Visual C++, Borland C++, AT&T's C-Front compiler, etc. It is therefore very easy to adapt to a variety of learning environments.
SST is therefore a valuable learning tool for the beginning C++ programmer.
Introduction to the SST Hierarchy
All GUI hierarchies let you create standard GUI objects such as buttons, labels, scroll bars, etc. SST is no different: It is just a bit simpler. The SST toolkit lets you create buttons, labels, and edit areas. It is simple enough to be used, understood and extended in just a few days. In addition, you can examine the source code (all source code for SST appears at the end of this article) and learn from the inheritance techniques that it contains. SST follows standard usage patterns seen in most GUI toolkits.
SST is a portable, character-based toolkit. This feature allows it to run on almost any platform, although it does inhibit beauty just a bit. A typical program created using SST looks like this:
{width=”349” height=”224”}
SST Application Example
In this window, there are static labels ("Celsius Temperature", "Fahrenheit Temperature", and "212"), an Input area into which the value 100 has been typed, and two buttons ("Convert" and "Quit"). The Input area has focus, as represented by the '=' (equal sign) around it. The application shown implements a simple Celsius-to-Fahrenheit converter.
An SST program can contain the following GUI objects:
- main window (one)
- labels
- buttons
- input areas
SST understands the following keyboard semantics:
- change control focus with the tab key (or Shift-tab)
- activate buttons with the return key
Edit controls accept keystrokes and the backspace character.
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The SST hierarchy contains 10 classes. Six of the classes are arranged in a hierarchy as shown below:
{width=”200” height=”125”}
The remaining four are Auxiliary classes:
- Event - event class used in Object::HandleEvent
- ObjectList - object list class used in Window
- Screen - screen drawing class used in Object
- Strclass - a simple string class used in Input
In the following sections you will learn how to create simple applications using these classes, and you will also learn how the source code for the classes works.
Creating the Simplest SST Application
All SST applications share several fundamental elements. No matter how simple or complex, you will always take the following steps in every SST application:
- Derive your application from the Window class. Declare its controls as members
- Create a constructor for the derived class that creates and initializes the controls inside the window
- Override the HandleEvent member of the window class to handle events from buttons
Using these steps, the simplest possible application that you can create is a window that contains a quit button. To create such an application, you would start by inheriting from the Window class:
#include <IOSTREAM.H>
#include <STRSTREA.H>
#include "button.h"
#include "rect.h"
#include "window.h"
class App: public Window
{
public:
App( char *s, Rect &r );
virtual void HandleEvent( Event &event );
};
App app( "Test", Rect(1, 1, 80, 24) );
...
void main()
{
app.Execute();
}
Note that this code declares a class named App derived from Window, and this derived class overrides the constructor and the HandleEvent function. Next the program creates an instance of this class as a global variable and passes it the string "Test" (which will act as the window's name) and the size and position of the Window on the screen (you can assume the screen to be a 2-D character grid with a size of 80 characters wide by 24 characters high, so the size specification here fills the screen). Then the code calls the class's Execute member in the main function to get the ball rolling.
You would then create a new constructor for the App class. This constructor's job is to Insert controls into the window:
const int QUIT = 100;
App::App( char *s, Rect &r ):
Window( s, r ), count( 0 )
{
Insert( new Button(" Quit", Rect(50, 18, 57, 20), QUIT) );
}
The Insert function creates a new instance of the Button class, passing the button its title ("Quit"), location and size, and an ID of 100 in the constant named QUIT. The ID will be used to handle events generated by the button.
You would then override the HandleEvent member function in the Window class to handle events produced by the Quit button:
void App::HandleEvent( Event &event)
{
Window::HandleEvent( event );
if( event.type == COMMAND )
{
switch( event.message )
{
case QUIT:
Close();
screen.Clear();
break;
}
}
event.type = CLEAR;
}
This code first calls the Window class's default HandleEvent function so it can handle any events it understands automatically. Any unhandled events are then tested to see if they are COMMAND events. If so, then they are tested to see if they come from the QUIT button. If so, the application terminates by closing the window and clearing the screen.
If you assemble these pieces and run the application, you will find that the window appears, that it contains a quit button, and when you press the return key (to activate the button) the application terminates. The easiest way to compile the program is to take all of the SST classes (shown at the end of the article) and place them in a directory. Add the code shown here to an additional CPP file. Include all of the CPP files in a project or MAKEFILE and compile and link them (If you are using the Visual C++ or Borland compilers, you will want to create a normal text-based console application). Then execute the application. SST assumes that the output window handles ANSI character sequences, so if you are using DOS or Win 95 be sure to set a device to ANSI.SYS in the config.sys file (in other words, add "DEVICE=ANSI.SYS" to the config.sys file) and reboot. If you are using NT or UNIX, special versions of appropriate files are supplied.
Below is a slightly more advanced program that makes use of two of the controls available in SST (labels and buttons). This program implements a simple increment facility. When you activate the "Increment" button, the counter increments by one. When you activate the "Quit" button the program terminates. You move focus between the two buttons by pressing the Tab key, and activate the currently focused button by hitting the return key.
// Counter program
#include <IOSTREAM.H>
#include <STRSTREA.H>
#include "button.h"
#include "input.h"
#include "label.h"
#include "rect.h"
#include "window.h"
class App: public Window
{
Label *number;
int count;
public:
App( char *s, Rect &r );
virtual void HandleEvent( Event &event );
};
App app( "Test", Rect(1, 1, 80, 24) );
const int QUIT = 100;
const int COUNT = 101;
App::App( char *s, Rect &r ):
Window( s, r ), count( 0 )
{
Insert( new Label("Count: ",
Rect(20, 5, 30, 7)) );
number = new Label("0",
Rect(31, 5, 40, 7));
Insert( number );
Insert( new Button(" Increment",
Rect(28, 18, 40, 20), COUNT) );
Insert( new Button(" Quit",
Rect(50, 18, 57, 20), QUIT) );
}
void main()
{
app.Execute();
}
void App::HandleEvent( Event &event)
{
char t[100];
ostrstream ostr ( t, 100 );
Window::HandleEvent( event );
if( event.type == COMMAND )
{
switch( event.message )
{
case COUNT:
count++;
ostr.width(4);
ostr << count << ends;
number->SetTitle( t );
break;
case QUIT:
Close();
screen.Clear();
break;
}
}
event.type = CLEAR;
}
The only difference between this program and the first program is the fact that more controls are inserted into the window in the window constructor, and the HandleEvent function handles two events instead of one: one coming from the COUNT button and the other coming from the QUIT button.
Exercise: A good exercise at this point would be to add a new button to this program named "Decrement" and have it decrement the counter. To do this, insert a new button (perhaps rearranging the other controls in the process) and add a new event handler. You might also add a "Clear" button to reset the counter to zero.
As a final example, the following code implements the temperature conversion program seen earlier. This code demonstrates the use of an Input control.
#include <iostream.h>
#include <strstrea.h>
#include "button.h"
#include "input.h"
#include "label.h"
#include "rect.h"
#include "window.h"
class App: public Window
{
InputLine *fahr;
Label *cel;
public:
App( char *s, Rect &r );
virtual void HandleEvent( Event &event );
};
const int QUIT = 100;
const int CONVERT = 101;
App app( "Test", Rect(1, 1, 80, 24) );
App::App( char *s, Rect &r ): Window( s, r )
{
fahr = new InputLine ("fahr", Rect(40, 5, 50, 7) );
Insert( fahr );
Insert( new Label("Fahrenheit Temperature: ", Rect(14, 5, 38, 7)) );
Insert( new Label("Celsius Temperature:", Rect(14, 9, 38, 11)) );
cel = new Label("0", Rect(40, 9, 45, 11));
Insert( cel );
Insert( new Button(" Convert", Rect(28, 18, 40, 20), CONVERT) );
Insert( new Button(" Quit", Rect(50, 18, 57, 20), QUIT) );
}
void App::HandleEvent( Event &event)
{
char s[100];
char t[100];
float f;
istrstream istr( s, 100 );
ostrstream ostr( t, 100 );
Window::HandleEvent( event );
if( event.type == COMMAND )
{
switch( event.message )
{
case CONVERT:
fahr->GetText( s, 100 );
istr >> f;
ostr.width(6);
ostr.precision(2);
ostr << (f-32) * 5/9.0 << ends;
cel->SetTitle( t );
break;
case QUIT:
Close();
screen.Clear();
break;
}
}
event.type = CLEAR;
}
void main()
{
app.Execute();
}
When running this program, use the tab key to move focus between the input control and the two buttons. Press return to activate a button. When the Input control has focus, you may type characters or the backspace key.
Understanding the SST class hierarchy
To understand the three programs shown above, it is helpful to look at several of the classes in the SST hierarchy and understand how they relate to one another. Let's start with the hierarchy's base class: Rect:\
class Rect
{
public:
int top, bottom, left, right;
Rect();
Rect( int x1, int y1, int x2, int y2 );
int Height();
void SetSize( Rect &r );
int Width();
};
The Rect class is very simple (if you look at the CPP file at the end of this article you can see just how simple it really is - each function contains just a line or two of code). The class contains the four data members needed to hold the top, left, right and bottom coordinates of the rectangle. The default constructor sets these coordinates to zero. There is also a second constructor that initializes them to specified values. The Height and Width members calculate the height and width of the rectangle through simple subtraction. The SetSize member allows you to change the coordinates of the rectangle at any time.
The Object class inherits from the Rect class (you could argue that the object class should be the base class and it should have a "uses a" relationship with the Rect class as opposed to the "is a" relationship found in this hierarchy - that is good reasoning, so change the hierarchy if you like). The object class knows how to handle events and accept focus:
class Object: public Rect
{
protected:
char *title;
int takesFocus;
int focused;
Screen screen;
public:
Object();
Object( char *s, Rect &r );
virtual ~Object();
int AcceptsFocus();
virtual void Draw();
virtual void HandleEvent( Event &event );
virtual void ReleaseFocus();
virtual void SetFocus();
virtual void SetTitle( char *s );
};
The class has two constructors, the second one being the one generally used. This constructor accepts a string that acts as the title for the object and a rectangle that controls the size and placement of the object. An object can accept focus of not (a label is a control that does not accept focus, while a button does). You can query the AcceptsFocus function to determine whether or not the object accepts focus. All objects know how to draw themselves, and you cause them to draw themselves by calling the Draw member. This function draws a rectangle around the object. All objects also can handle events, and do so in their HandleEvent member. You can give an object focus by calling its SetFocus member and take it away with ReleaseFocus. Finally, you can change the title string with SetTitle. Look at OBJECT.CPP and you will find that all of the member functions are extremely simple.
The Object class makes use of the Screen helper class. The Screen class knows draw onto the screen, and contains three members: GotoXY moves the cursor on the screen, CharXY draws a character at a specific location, and Clear clears the whole screen. Look at SCREEN.H to see how simple the class is. The class uses standard ANSI escape sequences to move the cursor around and clear the screen.
The Window class inherits from the Object class. The Window class is an Object, and it also holds a list of other objects. In the list goes all of the controls contained by the window. Because it knows of all of its controls, the window class can do several things.
- It can refresh itself by traversing the list and calling the Draw member function of all controls in the list.
- It can change the control with focus by calling ReleaseFocus on the object that has focus and SetFocus on the object to get focus.
- It can pass events that it cannot handle to the control that has focus.
The Window class contains the following functions:\
class Window: public Object
{
protected:
ObjectList list;
int running;
public:
Window();
Window( char *s, Rect &r );
~Window();
int Close();
virtual void Draw();
void Execute();
virtual void HandleEvent( Event &event );
void Insert( Object *obj );
void MoveFocus( char direction );
void Remove( Object *obj );
int WindowRunning();
};
You have seen in the example programs that the main function must call the window's Execute function. This function, if you look at the code, simply loops and retrieves keystrokes, passing them to the HandleEvent function. The HandleEvent function moves focus if the Tab key is pressed, terminates if the ESC key is pressed, or passes the event on to the focused object otherwise.
It is in the Draw and HandleEvent functions where virtual functions come into play. For example, look at the Draw function in the Window class. It loops through all of the objects in the object list and calls the Draw function. Each object, depending on its type (Button, Input, Label) has its own implementation for the Draw function so each one draws itself appropriately. The HandleEvent function in the Window class is another good example. The Execute function calls HandleEvent. Since we have inherited from the Window class, out version of HandleEvent gets called first. In our code, we call back down to the default function Window::HandleEvent so it can do any automatic handling on the TAB or ESC keys, and also gives the focused object a crack at handling events it understands. If either can handle the event they do, and they also clear the event to mark it as handled. When Window::HandleEvent returns, our code can process any events left over.
If you look in EVENT.H, you will see that the event helper class knows of only three event types:
const char KEYBOARD = 100;
const char COMMAND = 101;
const char CLEAR = 102;
The window can create KEYSTROKE events. A button control can massage a KEYSTROKE into a COMMAND event. To mark an event as "handled" it is set to CLEAR.
The Insert function, also seen in the examples, simply inserts a control into the list of controls. Remove is able to remove a control from the list.
The three controls are very simple and are easily understood by looking at their H and CPP files at the end of this article. The Label control displays text. You can change its text at any time. It does not accept focus, so it never handles events. The Input control accepts keystrokes and displays them. It holds the keystrokes in a string. You can initialize it with SetText or retrieve the string with GetText. The Button class inherits from the label class. Its main goal is to look for return keys and massage the event into a command event.
As you can see, there is not a lot of code involved. What is interesting is the way the code intertwines to create a self-referential whole. Any larger GUI hierarchy works exactly the same way, but obviously handles more capabilities. What is interesting, however, is the fact that larger hierarchies rest on exactly the same principles. For example, user input is limited, generally, to the keyboard and the mouse. That is it. So while the variety and diversity of a class hierarchy can implement far more frills, the basic foundation is the same as that seen here in SST.
Adding a New Control
You can learn a bit more about SST by creating a new control. Here we will create a new scale control and use it to modify the temperature conversion program. A scale control will look like this:
+---------------+
| 20 |
| o--x--------o |
| 0 100 |
+---------------+
By pressing the 'j' and 'k' keys the scale will decrement and increment by 1. By pressing the 'h' and 'l' keys it will decrement or increment by one "notch". It can be extremely educational to attempt to create this control yourself before looking at the code. Ask yourself the following questions in order to get started:
- How do you go about designing this control?
- What data members does it need?
- What member functions does it need?
- How do you fit it into the existing hierarchy?
Try to create a version of the control yourself using the existing controls as examples.
Here is one solution to the problem:
SCALE.H
class Scale: public Object
{
int minValue, maxValue, currentValue, numNotches;
float notchValue;
public:
Scale();
Scale( char *s, Rect &r, int min = 0, int max = 100 );
void Dec( int number = 1 );
void DecNotch( int number = 1 );
virtual void Draw();
int GetPosition();
virtual void HandleEvent( Event &event );
void Inc( int number = 1 );
void IncNotch( int number = 1 );
void SetPosition( int value );
};
SCALE.CPP
#include "scale.h"
Scale::Scale() : Object(), minValue(0), maxValue(0),
currentValue(0), numNotches(0), notchValue(0)
{}
Scale::Scale( char *s, Rect &r, int min, int max )
: Object( s, r ), minValue(min), maxValue(max),
currentValue(min), numNotches(0), notchValue(0)
{
numNotches = right - left - 6;
notchValue = (maxValue - minValue) / (float)numNotches;
}
void Scale::Dec( int number )
{
if( currentValue - number >= minValue )
{
currentValue -= number;
Draw();
}
}
void Scale::DecNotch( int number )
{
if( (currentValue - notchValue * number) >= minValue )
currentValue -= notchValue * number;
else
currentValue = minValue;
Draw();
}
void Scale::Draw()
{
int i, pos;
Object::Draw();
// draw the ends of the scale
screen.CharXY( left+2, top+2, 'O' );
screen.CharXY( right-2, top+2, 'O' );
// draw the middle of the scale
for( i = 0; i <= numNotches; i++ )
{
screen.CharXY( left+3+i, top+2, '-' );
}
// draw the min and max values of the scale
screen.GotoXY( left+2, top+3 );
cout << minValue;
screen.GotoXY( right-2-2, top+3 );
cout << setiosflags(ios::right) << setw(3) << maxValue;
// draw the current position
pos = (left + 3) + ((currentValue - minValue) / notchValue);
screen.CharXY( pos, top+2, 'x' );
// clear old value and draw new value
for( i = left+1; i < right; i++ )
screen.CharXY( i, top+1, ' ' );
screen.GotoXY( pos-2, top+1 );
cout << setiosflags(ios::right) << setw(3) << currentValue;
}
int Scale::GetPosition()
{
return currentValue;
}
void Scale::HandleEvent( Event &event )
{
if( event.type == KEYBOARD )
{
switch( event.message )
{
case 'j':
Dec();
break;
case 'k':
Inc();
break;
case 'h':
DecNotch();
break;
case 'l':
IncNotch();
break;
}
}
}
void Scale::Inc( int number )
{
if( currentValue + number <= maxValue )
{
currentValue += number;
Draw();
}
}
void Scale::IncNotch( int number )
{
if( (notchValue * number + currentValue) <= maxValue )
currentValue += notchValue * number;
else
currentValue = maxValue;
Draw();
}
void Scale::SetPosition( int value )
{
if( (value >= minValue) && (value <= maxValue) )
currentValue = value;
Draw();
}
F2C2.CPP: A Sample program
The following program recreates the temperature conversion program seen previously using the scale control
#include <iostream.h>
#include <strstrea.h>
#include "button.h"
#include "input.h"
#include "label.h"
#include "rect.h"
#include "scale.h"
#include "window.h"
class App: public Window
{
Label *cel;
Scale *scale;
public:
App( char *s, Rect &r );
virtual void HandleEvent( Event &event );
};
const int QUIT = 100;
const int CONVERT = 101;
App app( "Test", Rect(1, 1, 80, 24) );
App::App( char *s, Rect &r ): Window( s, r )
{
scale = new Scale("scale", Rect(40,4,66,8), 0, 100 );
Insert( scale );
Insert( new Label("Fahrenheit Temperature: ", Rect(14, 5, 38, 7)) );
Insert( new Label("Celsius Temperature:", Rect(14, 9, 38, 11)) );
cel = new Label("0", Rect(40, 9, 45, 11));
Insert( cel );
Insert( new Button(" Convert", Rect(28, 18, 40, 20), CONVERT) );
Insert( new Button(" Quit", Rect(50, 18, 57, 20), QUIT) );
}
void App::HandleEvent( Event &event)
{
char s[100];
Window::HandleEvent( event );
if( event.type == COMMAND )
{
switch( event.message )
{
case CONVERT:
int f = scale->GetPosition();
ostrstream ostr ( s, 100 );
ostr << (f-32) * 5/9.0 << ends;
cel->SetTitle( s );
break;
case QUIT:
Close();
screen.Clear();
break;
}
}
event.type = CLEAR;
}
void main()
{
app.Execute();
}
Conclusion
In this article you have seen how to use a simple GUI class hierarchy called SST. You have also had the chance to extend the hierarchy and understand its inner workings. We hope that this exprience helps you to more easily understand larger class hierarchies in the future.
Code Listings
The following listings contain all of the code for the SST classes.
/* ----------------------------------------------------------------------- *
* b u t t o n . h
*
* buttons are windows that display a label and respond to the enter
* key when they have focus.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __BUTTON_H
#define __BUTTON_H
#include "keys.h"
#include "rect.h"
#include "label.h"
class Button: public Label
{
int data;
public:
Button();
Button( char *s, Rect &r, int d );
virtual void Draw();
virtual void HandleEvent( Event &event );
void SetData( int d );
};
#endif
/* ----------------------------------------------------------------------- *
* b u t t o n . c p p
*
* buttons are windows that display a label and respond to the enter
* key when they have focus.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#include "button.h"
Button::Button(): Label()
{
takesFocus = 1;
focused = 0;
}
Button::Button( char *s, Rect &r, int d )
: data(d), Label( s, r )
{
takesFocus = 1;
focused = 0;
}
void Button::Draw()
{
Label::Draw();
Object::Draw();
}
void Button::HandleEvent( Event &event )
{
if( (event.type == KEYBOARD) && (event.message == RETURN) )
{
event.type = COMMAND;
event.message = data;
}
}
void Button::SetData( int d )
{
data = d;
}
/* ----------------------------------------------------------------------- *
* e v e n t . h
*
* class for events
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __EVENT_H
#define __EVENT_H
const char KEYBOARD = 100;
const char COMMAND = 101;
const char CLEAR = 102;
class Event
{
public:
char type;
char message;
Event(): type(COMMAND), message(0) {}
Event( char t, char k ): type(t), message(k) {}
};
#endif
/* ----------------------------------------------------------------------- *
* i n p u t . h
*
* a simple class to get input from the user.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __INPUT_H
#define __INPUT_H
#include "keys.h"
#include "object.h"
#include "strclass.h"
class InputLine: public Object
{
String input;
public:
InputLine();
InputLine( char *s, Rect &r );
void GetText( char *s, int n );
virtual void Draw();
virtual void HandleEvent( Event &event );
void SetText( char *s );
};
#endif
/* ----------------------------------------------------------------------- *
* i n p u t . c p p
*
* a simple class to get input from the user.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#include "input.h"
InputLine::InputLine()
{
takesFocus = 1;
focused = 0;
}
InputLine::InputLine( char *s, Rect &r )
: Object( s, r )
{
takesFocus = 1;
focused = 0;
}
void InputLine::GetText( char *s, int n )
{
strncpy( s, input.GetString(), n );
}
void InputLine::Draw()
{
int i;
Object::Draw();
if( (Height() > 2) && (Width() > 2) )
{
screen.GotoXY( left + 1, top + 1 );
cout << input.GetString();
for( i = left + input.GetLength(); i < right - 1; i++ )
cout << " ";
}
}
void InputLine::HandleEvent( Event &event )
{
if( event.type == KEYBOARD )
{
switch( event.message )
{
case BACKSPACE:
if( input.GetLength() > 0 )
{
screen.GotoXY( left + input.GetLength(), top + 1 );
cout << " ";
screen.GotoXY( left + input.GetLength(), top + 1 );
input.Remove();
}
break;
case RETURN:
break;
default:
if( event.message == 0 )
break;
if( input.GetLength() + left < right - 1 )
{
input.Insert(event.message);
screen.GotoXY( left + input.GetLength(), top + 1 );
cout << char(event.message);
}
break;
}
}
}
void InputLine::SetText( char *s )
{
input.Clear();
input.Insert( s );
Draw();
}
/* ----------------------------------------------------------------------- *
* k e y s . h
*
* defines useful keyboard key codes.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __KEYS_H
#define __KEYS_H
const char BACKSPACE = 8;
const char TAB = 9;
const char RETURN = 13;
const char SHIFT_TAB = 15;
const char ESC = 27;
#endif
/* ----------------------------------------------------------------------- *
* l a b e l . h
*
* a static label class. labels do not process events.
* ----------------------------------------------------------------------- */
#ifndef __LABEL_H
#define __LABEL_H
#include <iostream.h>
#include <iomanip.h>
#include "object.h"
class Label: public Object
{
public:
Label();
Label( char *s, Rect &r );
virtual void Draw();
void SetTitle( char *s );
};
#endif
/* ----------------------------------------------------------------------- *
* l a b e l . c p p
*
* a static label class. labels do not process events.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#include "label.h"
Label::Label(): Object()
{
takesFocus = 0;
focused = 0;
}
Label::Label( char *s, Rect &r )
: Object( s, r )
{
takesFocus = 0;
focused = 0;
}
void Label::Draw()
{
if( (Height() > 2) && (Width() > 2) )
{
screen.GotoXY( left + 1, top + 1 );
cout << title;
}
}
void Label::SetTitle( char *s )
{
Object::SetTitle( s );
Draw();
}
/* ----------------------------------------------------------------------- *
* o b j e c t. h
*
* the base class for all screen objects.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __OBJECT_H
#define __OBJECT_H
#include <string.h>
#include "event.h"
#include "rect.h"
#include "screen.h"
class Object: public Rect
{
protected:
char *title;
char takesFocus;
char focused;
Screen screen;
public:
Object();
Object( char *s, Rect &r );
~Object();
char AcceptsFocus();
virtual void Draw();
virtual void HandleEvent( Event &event );
virtual void ReleaseFocus();
virtual void SetFocus();
virtual void SetTitle( char *s );
};
#endif
/* ----------------------------------------------------------------------- *
* o b j e c t . c p p
*
* the base class for all screen objects.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#include <iostream.h>
#include "object.h"
Object::Object(): Rect(), title(0), takesFocus(1)
{
}
Object::Object( char *s, Rect &r )
: Rect( r )
{
title = new char[ strlen(s) + 1 ];
strcpy( title, s );
takesFocus = 1;
}
Object::~Object()
{
delete [] title;
}
char Object::AcceptsFocus()
{
return takesFocus;
}
void Object::Draw( )
{
char style;
int i;
if( focused )
style = '=';
else
style = '-';
for( i = left + 1; i < right; i++ )
{
screen.CharXY( i, top, style );
screen.CharXY( i, bottom, style );
}
for( i = top + 1; i < bottom; i++ )
{
screen.CharXY( left, i, '|' );
screen.CharXY( right, i, '|' );
}
screen.CharXY( left, top, '+' );
screen.CharXY( right, top, '+' );
screen.CharXY( left, bottom, '+' );
screen.CharXY( right, bottom, '+' );
}
void Object::HandleEvent( Event &event )
{
}
void Object::ReleaseFocus()
{
focused = 0;
}
void Object::SetFocus()
{
focused = 1;
}
void Object::SetTitle( char *s )
{
delete [] title;
title = new char[ strlen(s) + 1 ];
strcpy( title, s );
}
/* ----------------------------------------------------------------------- *
* o b j l i s t . h
*
* a class to manage a list of objects in a window.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __OBJLIST_H
#define __OBJLIST_H
class Object;
typedef struct ObjectNode
{
Object *object;
ObjectNode *next;
ObjectNode *prev;
} ObjectNode;
class ObjectList
{
ObjectNode *top;
ObjectNode *bottom;
ObjectNode *current;
public:
ObjectList();
~ObjectList();
void Insert( Object *obj );
Object *GetCurrent();
Object *GetFirst();
Object *GetLast();
Object *GetNext();
Object *GetPrev();
void Remove( Object *obj );
void SetCurrent( Object *obj );
};
#endif
/* ----------------------------------------------------------------------- *
* o b j l i s t . c p p
*
* implementation of a class to manage a list of objects for a window.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#include "objlist.h"
ObjectList::ObjectList(): top(0), bottom(0), current(0)
{
}
ObjectList::~ObjectList()
{
current = top;
while( current != 0 )
{
top = current->next;
delete current;
current = top;
}
}
void ObjectList::Insert( Object *obj )
{
if( obj == 0 )
return;
if( top == 0 )
{
top = new ObjectNode;
top->object = obj;
top->next = 0;
top->prev = 0;
bottom = current = top;
}
else
{
bottom->next = new ObjectNode;
bottom->next->prev = bottom;
bottom = bottom->next;
bottom->object = obj;
bottom->next = 0;
}
}
Object *ObjectList::GetCurrent()
{
if( current == 0 )
return 0;
else
return current->object;
}
Object *ObjectList::GetFirst()
{
if( top == 0 )
return 0;
current = top;
return top->object;
}
Object *ObjectList::GetLast()
{
if( bottom == 0 )
return 0;
current = bottom;
return bottom->object;
}
Object *ObjectList::GetNext()
{
if( current == 0 )
return 0;
current = current->next;
if( current == 0 )
return 0;
else
return current->object;
}
Object *ObjectList::GetPrev()
{
if( current == 0 )
return 0;
current = current->prev;
if( current == 0 )
return 0;
else
return current->object;
}
void ObjectList::Remove( Object *obj )
{
ObjectNode *temp;
if( obj == 0 )
return;
temp = top;
while( (temp != 0) && (temp->object != obj) )
temp = temp->next;
if( temp->object == obj )
{
if( temp == top )
{
top = temp->next;
if( top == 0 )
bottom = 0;
else
top->prev = 0;
if( current == temp )
current = top;
}
else if( temp == bottom )
{
bottom = temp->prev;
if( bottom == 0 )
top = 0;
else
bottom->next = 0;
if( current == temp )
current = bottom;
}
else
{
temp->next->prev = temp->prev;
temp->prev->next = temp->next;
if( current == temp )
current = temp->next;
}
delete temp;
}
}
void ObjectList::SetCurrent( Object *obj )
{
current = top;
while( (current != 0) && (current->object != obj) )
current = current->next;
if( current == 0 )
current = top;
}
/* ----------------------------------------------------------------------- *
* r e c t . h
*
* a simple rectangle class.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __RECT_H
#define __RECT_H
class Rect
{
public:
char top, bottom, left, right;
Rect();
Rect( int x1, int y1, int x2, int y2 );
char Height();
void SetSize( Rect &r );
char Width();
};
#endif
/* ----------------------------------------------------------------------- *
* r e c t . c p p
*
* a simple rectangle class.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#include "rect.h"
Rect::Rect(): top(0), bottom(0),
right(0), left(0)
{
}
Rect::Rect( int x1, int y1, int x2, int y2 )
: left(x1), top(y1), right(x2), bottom(y2)
{
}
char Rect::Height()
{
return bottom - top;
}
void Rect::SetSize( Rect &r )
{
top = r.top;
bottom = r.bottom;
right = r.right;
left = r.left;
}
char Rect::Width()
{
return right - left;
}
/* ----------------------------------------------------------------------- *
* s c r e e n . h
*
* a class to manage an ansi text screen. allows moving to
* an x, y location and clearing the screen.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __SCREEN_H
#define __SCREEN_H
#include <iostream.h>
class Screen
{
public:
Screen( )
{
}
void GotoXY( int x, int y )
{
cout << "\033[" << y
<< ";" << x << "H";
}
void CharXY( int x, int y, char c)
{
GotoXY( x, y );
cout << c;
}
void Clear()
{
cout << "\033[2J";
}
};
#endif
/* ----------------------------------------------------------------------- *
* s t r c l a s s . h
*
* a simple string class.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __STRCLASS_H
#define __STRCLASS_H
#include <string.h>
class String
{
protected:
char string[80];
int pos;
public:
String();
String( char *s );
void Clear();
int GetLength();
const char *GetString();
void Insert( char c );
void Insert( char *s );
void Remove();
};
#endif
/* ----------------------------------------------------------------------- *
* s t r c l a s s . c p p
*
* a simple string class.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#include "strclass.h"
String::String(): pos(0)
{
string[0] = 0;
}
String::String( char *s )
{
strcpy( string, s );
pos = strlen( string );
}
void String::Clear()
{
string[0] = 0;
pos = 0;
}
int String::GetLength()
{
return pos;
}
const char *String::GetString()
{
return string;
}
void String::Insert( char c )
{
string[pos] = c;
pos++;
string[pos] = 0;
}
void String::Insert( char *s )
{
strcat( string, s );
pos = strlen( string );
}
void String::Remove()
{
if( pos > 0 )
{
pos--;
string[pos] = 0;
}
}
/* ----------------------------------------------------------------------- *
* w i n d o w . h
*
* the basic window class. all screen objects are derived from
* this class.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __WINDOW_H
#define __WINDOW_H
#include <conio.h> // !!!
#include <string.h>
#include <iostream.h>
#include <iomanip.h>
#include "event.h"
#include "keys.h"
#include "object.h"
#include "objlist.h"
#include "rect.h"
const char WIN_NEXT = 1;
const char WIN_PREV = 2;
class Window: public Object
{
protected:
ObjectList list;
char running;
public:
Window();
Window( char *s, Rect &r );
~Window();
int Close();
virtual void Draw();
void Execute();
virtual void HandleEvent( Event &event );
void Insert( Object *obj );
void MoveFocus( char direction );
void Remove( Object *obj );
char WindowRunning();
};
#endif
/* ----------------------------------------------------------------------- *
* w i n d o w . c p p
*
* the basic window class. all screen objects are derived from
* this class.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#include "window.h"
Window::Window(): running(1)
{
takesFocus = 1;
}
Window::Window( char *title, Rect &r )
: Object( title, r )
{
running = 1;
takesFocus = 1;
}
Window::~Window()
{
}
int Window::Close( )
{
running = 0;
return 1;
}
void Window::Draw( )
{
Object *temp, *current = list.GetCurrent();
SetFocus();
Object::Draw();
// draw all the child objects
temp = list.GetFirst();
while( temp != 0 )
{
temp->Draw();
temp = list.GetNext();
}
list.SetCurrent( current );
}
void Window::Execute( )
{
Event event;
list.GetLast();
MoveFocus( WIN_NEXT );
screen.Clear();
Draw();
do
{
event.type = KEYBOARD;
event.message = getch();
HandleEvent( event );
} while( WindowRunning() );
}
void Window::HandleEvent( Event &event )
{
if( event.type == KEYBOARD )
{
switch( event.message )
{
case TAB:
case SHIFT_TAB:
if( list.GetCurrent() == 0 )
break;
if( event.message == TAB )
MoveFocus( WIN_NEXT );
else
MoveFocus( WIN_PREV );
event.type = CLEAR;
break;
case ESC:
Close();
break;
default:
if( list.GetCurrent() == 0 )
break;
list.GetCurrent()->HandleEvent( event );
break;
}
}
}
void Window::Insert( Object *obj )
{
list.Insert( obj );
obj->Draw();
}
void Window::MoveFocus( char direction )
{
int listScanned = 0;
Object *current = list.GetCurrent();
if( current == 0 )
return;
current->ReleaseFocus();
current->Draw();
do
{
if( direction == WIN_NEXT )
current = list.GetNext();
else
current = list.GetPrev();
if( current == 0 )
{
listScanned++;
if( direction == WIN_NEXT )
current = list.GetFirst();
else
current = list.GetLast();
}
} while( (listScanned < 2) && !current->AcceptsFocus() );
if( current->AcceptsFocus() )
{
current->SetFocus();
current->Draw();
}
listScanned = 0;
}
void Window::Remove( Object *obj )
{
Object *current;
current = list.GetCurrent();
if( current )
current->ReleaseFocus();
list.Remove( obj );
current = list.GetCurrent();
if( current )
current->SetFocus();
screen.Clear();
Draw();
}
char Window::WindowRunning()
{
return running;
}
### If you are working in NT, the following modified files will be useful (we were unable to get the NT command prompt to understand ANSI sequences)
/* ----------------------------------------------------------------------- *
* s c r e e n . h
*
* a class to manage a Windows NT console. allows moving to
* an x, y location and clearing the screen.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __SCREEN_H
#define __SCREEN_H
#include <iostream.h>
class Screen
{
public:
Screen();
~Screen();
void GotoXY( int x, int y );
void CharXY( int x, int y, char c);
void Clear();
};
#endif
/* ----------------------------------------------------------------------- *
* s c r e e n . c p p
*
* a class to manage an Windows NT console. allows moving to
* an x, y location and clearing the screen.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
// for NT Screen Console functions
#include <windows.h>
#include "screen.h"
static HANDLE hConsole = 0;
static int instanceCount = 0;
Screen::Screen()
{
if( instanceCount == 0 )
{
hConsole = GetStdHandle( STD_OUTPUT_HANDLE );
}
instanceCount++;
Clear();
}
Screen::~Screen()
{
instanceCount--;
if( instanceCount == 0 )
{
// CloseHandle( hConsole );
}
}
void Screen::GotoXY( int x, int y )
{
COORD coord;
coord.X = x - 1;
coord.Y = y - 1;
SetConsoleCursorPosition( hConsole, coord );
}
void Screen::CharXY( int x, int y, char c)
{
COORD coord;
DWORD numWritten;
coord.X = x - 1;
coord.Y = y - 1;
SetConsoleCursorPosition( hConsole, coord );
WriteConsoleOutputCharacter( hConsole, &c, 1, coord, &numWritten );
}
void Screen::Clear()
{
COORD coordScreen = { 0, 0 }; /* here's where we'll home the cursor */
BOOL bSuccess;
DWORD cCharsWritten;
CONSOLE_SCREEN_BUFFER_INFO csbi; /* to get buffer info */
DWORD dwConSize; /* number of character cells in the current buffer */
/* get the number of character cells in the current buffer */
bSuccess = GetConsoleScreenBufferInfo(hConsole, &csbi);
dwConSize = csbi.dwSize.X * csbi.dwSize.Y;
/* fill the entire screen with blanks */
bSuccess = FillConsoleOutputCharacter(hConsole, (TCHAR) ' ',
dwConSize, coordScreen, &cCharsWritten);
/* get the current text attribute */
bSuccess = GetConsoleScreenBufferInfo(hConsole, &csbi);
/* now set the buffer's attributes accordingly */
bSuccess = FillConsoleOutputAttribute(hConsole, csbi.wAttributes,
dwConSize, coordScreen, &cCharsWritten);
/* put the cursor at (0, 0) */
bSuccess = SetConsoleCursorPosition(hConsole, coordScreen);
return;
}
### If you are working in UNIX, the following modified files will be useful
/* ----------------------------------------------------------------------- *
* v e r s i o n . h
*
* defines whether we are building an msdos or unix version
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
//#define SST_UNIX // uncomment this line to build a UNIX version
/* ----------------------------------------------------------------------- *
* k e y s . h
*
* defines useful keyboard key codes.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __KEYS_H
#define __KEYS_H
#include "version.h"
const char BACKSPACE = 8;
const char TAB = 9;
#ifdef SST_UNIX
const char RETURN = 10;
#else
const char RETURN = 13;
#endif
const char SHIFT_TAB = 15;
const char ESC = 27;
#endif
/* ----------------------------------------------------------------------- *
* w i n d o w . h
*
* the basic window class. all screen objects are derived from
* this class.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#ifndef __WINDOW_H
#define __WINDOW_H
#include "version.h"
#ifdef SST_UNIX
#include <stdio.h>
#include <ctype.h>
#include <termio.h>
#else
#include <conio.h> // dos specific
#endif
#include <string.h>
#include <iostream.h>
#include <iomanip.h>
#include "event.h"
#include "keys.h"
#include "object.h"
#include "objlist.h"
#include "rect.h"
const char WIN_NEXT = 1;
const char WIN_PREV = 2;
class Window: public Object
{
protected:
ObjectList list;
int running;
public:
Window();
Window( char *s, Rect &r );
~Window();
int Close();
virtual void Draw();
void Execute();
virtual void HandleEvent( Event &event );
void Insert( Object *obj );
void MoveFocus( char direction );
void Remove( Object *obj );
int WindowRunning();
};
#endif
/* ----------------------------------------------------------------------- *
* w i n d o w . c p p
*
* the basic window class. all screen objects are derived from
* this class.
*
* Copyright 1996 by Interface Technologies, Inc. All Rights Reserved.
* ----------------------------------------------------------------------- */
#include "window.h"
#ifdef SST_UNIX
static struct termio ostate;
#endif
Window::Window(): running( 0 )
{
#ifdef SST_UNIX
struct termio nstate;
ioctl(0, TCGETA, &ostate);
nstate = ostate;
nstate.c_lflag &= ~(ICANON|ECHO|ECHOE|ECHOK|ECHONL);
nstate.c_cc[VMIN] = 1;
nstate.c_cc[VTIME] = 0;
ioctl(0, TCSETAW, &nstate);
#endif
takesFocus = 1;
}
Window::Window( char *title, Rect &r )
: running( 0 ), Object( title, r )
{
#ifdef SST_UNIX
struct termio nstate;
ioctl(0, TCGETA, &ostate);
nstate = ostate;
nstate.c_lflag &= ~(ICANON|ECHO|ECHOE|ECHOK|ECHONL);
nstate.c_cc[VMIN] = 1;
nstate.c_cc[VTIME] = 0;
ioctl(0, TCSETAW, &nstate);
#endif
takesFocus = 1;
}
Window::~Window()
{
#ifdef SST_UNIX
ioctl( 0, TCSETAW, &ostate );
#endif
}
int Window::Close( )
{
running = 0;
return 1;
}
void Window::Draw( )
{
Object *temp, *current = list.GetCurrent();
SetFocus();
Object::Draw();
// draw all the child objects
temp = list.GetFirst();
while( temp != 0 )
{
temp->Draw();
temp = list.GetNext();
}
list.SetCurrent( current );
}
void Window::Execute( )
{
Event event;
// make cin and cout work with buffers of length 1
cin.setf( ios::unitbuf );
cout.setf( ios::unitbuf );
// we are now up and running
running = 1;
list.GetLast();
MoveFocus( WIN_NEXT );
screen.Clear();
Draw();
do
{
event.type = KEYBOARD;
#ifdef SST_UNIX
event.message = getchar();
#else
event.message = getch();
#endif
HandleEvent( event );
} while( WindowRunning() );
}
void Window::HandleEvent( Event &event )
{
if( event.type == KEYBOARD )
{
switch( event.message )
{
case TAB:
case SHIFT_TAB:
if( list.GetCurrent() == 0 )
break;
if( event.message == TAB )
MoveFocus( WIN_NEXT );
else
MoveFocus( WIN_PREV );
event.type = CLEAR;
break;
case ESC:
Close();
break;
default:
if( list.GetCurrent() == 0 )
break;
list.GetCurrent()->HandleEvent( event );
break;
}
}
}
void Window::Insert( Object *obj )
{
list.Insert( obj );
if( WindowRunning() )
obj->Draw();
}
void Window::MoveFocus( char direction )
{
int listScanned = 0;
Object *current = list.GetCurrent();
if( current == 0 )
return;
current->ReleaseFocus();
current->Draw();
do
{
if( direction == WIN_NEXT )
current = list.GetNext();
else
current = list.GetPrev();
if( current == 0 )
{
listScanned++;
if( direction == WIN_NEXT )
current = list.GetFirst();
else
current = list.GetLast();
}
} while( (listScanned < 2) && !current->AcceptsFocus() );
if( current->AcceptsFocus() )
{
current->SetFocus();
current->Draw();
}
listScanned = 0;
}
void Window::Remove( Object *obj )
{
Object *current;
current = list.GetCurrent();
if( current )
current->ReleaseFocus();
list.Remove( obj );
current = list.GetCurrent();
if( current )
current->SetFocus();
screen.Clear();
Draw();
}
int Window::WindowRunning()
{
return running;
}