List Widget Application header file <X11/Xaw/List.h> Class header file <X11/Xaw/ListP.h> Class listWidgetClass Class Name List Superclass Simple The List widget contains a list of strings formatted into rows and columns. When one of the strings is selected, it is highlighted, and the List widget's Notify action is invoked, calling all routines on its callback list. Only one string may be selected at a time. Resources When creating a List widget instance, the following resources are retrieved from the argument list or from the resource database: Name Class Type Notes Default Value accelerators Accelerators AcceleratorTable NULL ancestorSensitive AncestorSensitive Boolean D True background Background Pixel XtDefaultBackground backgroundPixmap Pixmap Pixmap XtUnspecifiedPixmap borderColor BorderColor Pixel XtDefaultForeground borderPixmap Pixmap Pixmap XtUnspecifiedPixmap borderWidth BorderWidth Dimension 1 callback Callback Callback NULL colormap Colormap Colormap Parent's Colormap columnSpacing Spacing Dimension 6 cursor Cursor Cursor XC_left_ptr cursorName Cursor String NULL defaultColumns Columns int 2 depth Depth int C Parent's Depth destroyCallback Callback XtCallbackList NULL font Font FontStruct XtDefaultFont fontSet FontSet XFontSet XtDefaultFontSet forceColumns Columns Boolean False foreground Foreground Pixel XtDefaultForeground height Height Dimension A Enough space to contain the list insensitiveBorder Insensitive Pixmap GreyPixmap internalHeight Height Dimension 2 internalWidth Width Dimension 4 international International Boolean C False list List Pointer name of widget longest Longest int A 0 mappedWhenManaged MappedWhenManaged Boolean True numberStrings NumberStrings int A computed for NULL terminated list pasteBuffer Boolean Boolean False pointerColor Foreground Pixel XtDefaultForeground pointerColorBackground Background Pixel XtDefaultBackground rowSpacing Spacing Dimension 2 screen Screen Screen R Parent's Screen sensitive Sensitive Boolean True translations Translations TranslationTable See below verticalList Boolean Boolean False width Width Dimension A Enough space to contain the list x Position Position 0 y Position Position 0 _ callback All functions on this list are called whenever the notify action is invoked. The call_data argument contains information about the element selected and is described in detail in the List Callbacks section. columnSpacing rowSpacing The amount of space, in pixels, between each of the rows and columns in the list. defaultColumns The default number of columns. This value is used when neither the width nor the height of the List widget is specified or when forceColumns is True. font The text font to use when displaying the list, when the international resource is false. fontSet The text font set to use when displaying the list, when the international resource is true. forceColumns Forces the default number of columns to be used regardless of the List widget's current size. foreground A pixel value which indexes the widget's colormap to derive the color used to paint the text of the list elements. \fPinternalHeight\fP \fPinternalWidth\fP The margin, in pixels, between the edges of the list and the corresponding edge of the List widget's window. list An array of text strings displayed in the List widget. If numberStrings is zero (the default) then the list must be NULL terminated. If a value is not specified for the list, then numberStrings is set to 1, and the name of the widget is used as the list, and longest is set to the length of the name of the widget. The list is used in place, and must be available to the List widget for the lifetime of this widget, or until it is changed with or . longest Specifies the width, in pixels, of the longest string in the current list. The List widget will compute this value if zero (the default) is specified. If this resource is set by hand, entries longer than this will be clipped to fit. numberStrings The number of strings in the current list. If a value of zero (the default) is specified, the List widget will compute it. When computing the number of strings the List widget assumes that the list is NULL terminated. pasteBuffer If this resource is set to True then the name of the currently selected list element will be put into CUT_BUFFER_0. verticalList If this resource is set to True then the list elements will be presented in column major order. List Actions The List widget supports the following actions: Highlighting and unhighlighting the list element under the pointer with Set and Unset Processing application callbacks with Notify The following is the default translation table used by the List Widget: <Btn1Down>,<Btn1Up>: Set(\|) Notify(\|) The full list of actions supported by List widget is: Set(\|) Sets the list element that is currently under the pointer. To inform the user that this element is currently set, it is drawn with foreground and background colors reversed. If this action is called when there is no list element under the cursor, the currently set element will be unset. Unset(\|) Cancels the set state of the element under the pointer, and redraws it with normal foreground and background colors. Notify(\|) Calls all callbacks on the List widget's callback list. Information about the currently selected list element is passed in the call_data argument (see List Callbacks below). List Callbacks All procedures on the List widget's callback list will have a XawListReturnStruct passed to them as call_data. The structure is defined in the List widget's application header file. typedef struct _XawListReturnStruct { String string; /* string shown in the list. */ int list_index; /* index of the item selected. */ } XawListReturnStruct; The list_index item used to be called simply index. Unfortunately, this name collided with a global name defined on some operating systems, and had to be changed. Changing the List To change the list that is displayed, use XawListChange . void XawListChange Widget w String* list intnitems, longest Boolean resize w Specifies the List widget. list Specifies the new list for the List widget to display. nitems Specifies the number of items in the list. If a value less than 1 is specified, list must be NULL terminated, and the number of items will be calculated by the List widget. longest Specifies the length of the longest item in the list in pixels. If a value less than 1 is specified, the List widget will calculate the value. resize Specifies a Boolean value that if True indicates that the List widget should try to resize itself after making the change. The constraints of the List widget's parent are always enforced, regardless of the value specified here. will unset all list elements that are currently set before the list is actually changed. The list is used in place, and must remain usable for the lifetime of the List widget, or until list has been changed again with this function or with . Highlighting an Item To highlight an item in the list, use XawListHighlight . void XawListHighlight Widget w int item w Specifies the List widget. item Specifies an index into the current list that indicates the item to be highlighted. Only one item can be highlighted at a time. If an item is already highlighted when is called, the highlighted item is unhighlighted before the new item is highlighted. Unhighlighting an Item To unhighlight the currently highlighted item in the list, use XawListUnhighlight . void XawListUnhighlight Widget w w Specifies the List widget. Retrieving the Currently Selected Item To retrieve the list element that is currently set, use XawListShowCurrent . XawListReturnStruct *XawListShowCurrent Widget w w Specifies the List widget. XawListShowCurrent returns a pointer to an XawListReturnStruct structure, containing the currently highlighted item. If the value of the index member is XAW_LIST_NONE, the string member is undefined, and no item is currently selected. Restrictions Many programmers create a ``scrolled list'' by putting a List widget with many entries as a child of a Viewport widget. The List continues to create a window as big as its contents, but that big window is only visible where it intersects the parent Viewport's window. (I.e., it is ``clipped.'') While this is a useful technique, there is a serious drawback. X does not support windows above 32,767 pixels in width or height, but this height limit will be exceeded by a List's window when the List has many entries (i.e., with a 12 point font, about 3000 entries would be too many.)