List widget

Application Header file <X11/Xraw/List.h>
Class Header file <X11/Xraw/ListP.h>
Class listWidgetClass
Class Name List
Superclass Simple --> Core

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.

New Resources

Name Class Type Notes Default Value
callback Callback Callback NULL
columnSpacing Spacing Dimension 6
defaultColumns Columns int 2
forceColumns Columns Boolean False
foreground Foreground Pixel XtDefaultForeground
internalHeight Height Dimension 2
internalWidth Width Dimension 4
list List Pointer name of widget
longest Longest int A 0
numberStrings NumberStrings int A computed for NULL terminated list
pasteBuffer Boolean Boolean False
rowSpacing Spacing Dimension 2
verticalList Boolean Boolean False
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.
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.
internalHeight  
internalWidth 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 XtSetValues or XawListChange.
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 not correctly specified, selection of list items may not work properly.
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 is 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;

Note

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(w, list, nitems, longest, resize)
	Widget w;
	String * list;
	int nitems, 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.

XawListChange 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 XtSetValues.

Highlighting an Item

To highlight an item in the list, use XawListHighlight. 

void XawListHighlight(w, item)
	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 XawListHighlight 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(w)
	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(w)
	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.

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Vladimir T. Romanovski
romsky@hp1.oea.ihep.su