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The CW_BGROUP function creates a widget base of buttons. It handles the details of creating the proper base (standard, exclusive, or non-exclusive) and filling in the desired buttons. Events for the individual buttons are handled transparently, and a CW_BGROUP event returned. This event can return any one of the following:
Only buttons with textual names are handled by this widget. Bitmaps are not understood.
The returned value of this function is the widget ID of the newly-created button group widget.
This routine is written in the IDL language. Its source code can be found in the file
cw_bgroup.pro
in the
lib
subdirectory of the IDL distribution.
An array of user values to be associated with each button and returned in the event structure. If this keyword is set, the user values are always returned, even if the any of the RETURN_ID, RETURN_INDEX, or RETURN_NAME keywords are set.
A string containing the name of a function to be called by the WIDGET_EVENT function when an event arrives from a widget in the widget hierarchy rooted at the newly-created widget. This function is called with the return value structure whenever a button is pressed, and follows the conventions for user-written event functions.
Set this keyword to cause buttons to be placed in an exclusive base, in which only one button can be selected at a time.
The name of the font to be used for the button titles. The font specified is a "device font" (an X Windows font on Motif systems; a TrueType or PostScript font on Windows or Macintosh systems). See for details on specifying names for device fonts. If this keyword is omitted, the default font is used.
Set this keyword to cause buttons to be placed in an non-exclusive base, in which any number of buttons can be selected at once.
Set this keyword to return the widget ID of the button in the VALUE field of returned events. This keyword is ignored if the BUTTON_UVALUE keyword is set.
Set this keyword to return the zero-based index of the button within the base in the VALUE field of returned events. This keyword is ignored if the BUTTON_UVALUE keyword is set. THIS IS THE DEFAULT.
Set this keyword to return the name of the button within the base in the VALUE field of returned events. This keyword is ignored if the BUTTON_UVALUE keyword is set.
If set, the base will include scroll bars to allow viewing a large base through a smaller viewport.
The space, in pixels, to be left around the edges of a row or column major base. This keyword is ignored if EXCLUSIVE or NONEXCLUSIVE are specified.
The horizontal space, in pixels, between children of a row or column major base. This keyword is ignored if EXCLUSIVE or NONEXCLUSIVE are specified.
The widget ID returned by most compound widgets is actually the ID of the compound widget's base widget. This means that many keywords to the WIDGET_CONTROL and WIDGET_INFO routines that affect or return information on base widgets can be used with compound widgets.
In addition, you can use the GET_VALUE and SET_VALUE keywords to WIDGET_CONTROL to obtain or set the value of the button group. The values for different types of CW_BGROUP widgets is shown in the table below:
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Vector indicating the position of each button (1-set, 0-unset) |
See Compound Widgets for a more complete discussion of controlling compound widgets using WIDGET_CONTROL and WIDGET_INFO .
Button Group widgets generates event structures with the following definition:
event = {ID:0L, TOP:0L, HANDLER:0L, SELECT:0, VALUE:0 }
The SELECT field is passed through from the button event. VALUE is either the INDEX, ID, NAME, or BUTTON_UVALUE of the button, depending on how the widget was created.