BButton¶
A BButton
object draws a labeled button on-screen and
responds when the button is clicked or when it’s operated from the
keyboard. If the BButton
is the default button for its window
and the window is the active window, the user can operate it by pressing
the Enter key.
BButton
s have a single state. Unlike check boxes and radio
buttons, the user can’t toggle a button on and off. However, the button’s
value changes while it’s being operated. During a click (while the user
holds the mouse button down and the cursor points to the button on-screen),
the BButton
’s value is set to 1
(B_CONTROL_ON
). Otherwise, the value is 0
(B_CONTROL_OFF
).
This class depends on the control framework defined in the
BControl
class. In particular, it calls these
BControl
functions:
- SetValue(). To make each change in theBControl’s value.
This is a hook function that you can override to take collateral action when the value changes.
Invoke(). To post a message each time the button is clicked or operated from the keyboard.
: You can designate the object that should handle the message by calling
BControl
’s SetTarget()
function inherited from BInvoker
. A model for the message is
set by the BButton
constructor (or by BControl
’s
SetMessage()
function inherited from
BInvoker
).
IsEnabled(). To determine how the button should be drawn and whether it’s enabled to post a message.
: You can call BControl
’s SetEnabled()
to enable and disable the button.
A BButton
is an appropriate control device for initiating an
action. Use a BCheckBox
, a BPictureButton
, or
BRadioButton
s to set a state.