Button(3I)

NAME
ButtonState, Button, TextButton, PushButton, RadioButton, CheckBox - interactive buttons

SYNOPSIS
#include <InterViews/button.h>

DESCRIPTION
Button is a class of interactors that can set the value of a piece of state. ButtonState is a class of objects that contain a value and a list of buttons that can set its value. A value is either an integer or an arbitrary pointer.

TextButton is a subclass of Button that has an associated text label to be displayed inside or to the right of the button. PushButton, RadioButton, and CheckBox are subclasses of TextButton that provide particular displays for buttons. Each kind of button will display itself differently for each of the five possible cases: ``enabled'', when the button is listening to input, ``disabled'', when the button is not listening, ``chosen'', when the button's value is equal to its button state's value, ``hit'', when a button that is not chosen first receives a DownEvent, and ``same-hit'', when a button that is chosen receives a DownEvent.

When a button receives a DownEvent, it calls the virtual Refresh() to update its display. It then reads input waiting for an UpEvent. If the UpEvent coordinates are also within the button, then it calls the virtual Press(). The default Press operation sets the associated state's value to the button's value.

A button can have a list of attached buttons. When a button is not chosen its attached buttons are ``disabled'', meaning they ignore all input events.

BUTTONSTATE OPERATIONS

ButtonState()

ButtonState(int)

ButtonState(void*)
    Define a button state optionally with an initial value.

void Attach(Button*)
    Add a button to the list associated with a button state. The button will be notified when the button state's value is modified.

void Detach(Button*)
    Remove a button from the list associated with a button state.

void GetValue(int&)

void GetValue(void*&)
    Get the value of a button.

void SetValue(int)

void SetValue(void*)
    Set the value of a button state and notify all the buttons associated with the state.

void operator=(ButtonState&)
    Copy the value of one button state to another. The button list associated with the source button state is not copied.

BUTTON OPERATIONS

void PushButton(const char* text, ButtonState* s, int v)

void PushButton(const char* text, ButtonState* s, void* v)
    Construct a button with text in the center and a polygon on the outside. The polygon is like a rectangle, but with rounded corners. When chosen, the entire button is drawn with foreground and background colors reversed.

void RadioButton(const char* text, ButtonState* s, int v)

void RadioButton(const char* text, ButtonState* s, void* v)
    Construct a button with a circle on the left and text on the right. When hit, a second circle is drawn inside the first. When chosen, a filled circle is drawn inside the outer circle.

void CheckBox(const char* text, ButtonState* s, int on, int off)

void CheckBox(const char* text, ButtonState* s, void* on, void* off)
    Construct a button with a rectangle on the left and text on the right. When hit, a second rectangle is drawn inside the first. When chosen, two diagonal lines are drawn connecting the opposite corners of the rectangle. When a checkbox is pressed the first time, it sets s to off if the value is on and sets s to on otherwise. Subsequent presses swap the values of the checkbox and s.

void Attach(Button*)
    Add to this button's list of associated buttons. These buttons are enabled when the button is chosen and disabled when it is not chosen.

void Detach(Button*)
    Remove a button from this button's list of associated buttons.

void Disable()
    Stop listening to input events. Disabled buttons are typically ``grayed out'' by drawing a half-filled rectangle in the background.

void Enable()
    Start listening to input events.

void Choose()
    Make the button as chosen, enabling any associated buttons.

void Handle(Event&)
    If the event type is DownEvent and the button is enabled, call Refresh and read events until an UpEvent occurs. If the button is the target of the UpEvent, then call Press.

virtual void Press()
    Take the appropriate action for the button being pressed. The default is to set the associated state to the button's value, which will trigger all related buttons to update their display.

virtual void Refresh()
    Update the button display.

void SetDimensions(int width, int height)
    Specify the natural size of the button. The default size is a function of the size of the text. This routine is obsolete; use Interactor::Reshape instead.

void UnChoose()
    Mark the button as not chosen, disabling any associated buttons.

SEE ALSO
Event(3I), Interactor(3I)