Ubuntu Manpage: XmProcessTraversal — A function that determines which component receives keyboard events

NAME

       XmProcessTraversal  —  A function that determines which component receives keyboard events
       when a widget has the focus "XmProcessTraversal"

SYNOPSIS

       #include <Xm/Xm.h>
       Boolean XmProcessTraversal(
       Widget widget,
       XmTraversalDirection direction);

DESCRIPTION

XmProcessTraversal determines which component of a hierarchy receives keyboard events when
the hierarchy that contains the given widget has keyboard focus.

XmProcessTraversal changes focus only when the keyboard focus policy of the widget
hierarchy is explicit. If the XmNkeyboardFocusPolicy of the nearest shell ancestor of the
given widget is not XmEXPLICIT, XmProcessTraversal returns False without making any focus
changes.

widget Specifies the widget ID of the widget whose hierarchy is to be traversed

direction Specifies the direction of traversal

DEFINITIONS
In order to be eligible to receive keyboard focus when the shell's XmNkeyboardFocusPolicy
is XmEXPLICIT, a widget or gadget must meet the following conditions:

• The widget and its ancestors are not in the process of being destroyed.

• The widget and its ancestors are sensitive. A widget is sensitive when its
XmNsensitive and XmNancestorSensitive resources are both True.

• The XmNtraversalOn resource for the widget and its ancestors is True.

• The widget is viewable. This means that the widget and its ancestors are managed,
realized, and (except for gadgets) mapped. Furthermore, in general, some part of
the widget's rectangular area must be unobscured by the widget's ancestors. If an
application unmaps a widget that has its XmNmappedWhenManaged resource set to True,
the result is undefined.

In a ScrolledWindow with an XmNscrollingPolicy of XmAUTOMATIC, a widget that is
obscured because it is not within the clip window may be able to receive focus
if some part of the widget is within the work area and if an
XmNtraverseObscuredCallback routine can make the widget at least partially
visible by scrolling the window.

In general only primitives, gadgets, and Drawing Area are eligible to receive focus. Most
managers cannot receive focus even if they meet all these conditions.

The direction argument identifies the kind of traversal action to take. The descriptions
of these actions below refer to traversable non-tab-group widgets and traversable tab
groups.

• A traversable non-tab-group widget is a widget that is not a tab group and that
meets all the conditions for receiving focus described above.

• A traversable tab group widget is a tab group widget that meets the same conditions,
except that a manager that is a tab group and meets the other conditions is also
eligible for traversal as long as it contains a descendant that can receive focus.

A tab group is a widget whose XmNnavigationType is:

• XmTAB_GROUP or XmSTICKY_TAB_GROUP, if the hierarchy (up to the nearest shell
ancestor) that contains the widget has no widget whose XmNnavigationType is
XmEXCLUSIVE_TAB_GROUP

• XmEXCLUSIVE_TAB_GROUP or XmSTICKY_TAB_GROUP, if the hierarchy (up to the nearest
shell ancestor) that contains the widget has any widget whose XmNnavigationType is
XmEXCLUSIVE_TAB_GROUP

TRAVERSAL ACTIONS
The hierarchy to be traversed is that containing the widget argument. This hierarchy is
traversed only up to the nearest shell; XmProcessTraversal does not move focus from one
shell to another. If the shell containing widget does not currently have the focus, any
change that XmProcessTraversal makes to the element with focus within that shell does not
take effect until the next time the shell receives focus.

XmProcessTraversal begins the traversal action from the widget in the hierarchy that
currently has keyboard focus or that last had focus when the user traversed away from the
shell hierarchy.

The value of the direction argument determines which of three kinds of traversal action to
take:

• Traversal to a non-tab-group widget. This kind of traversal is possible only when
the widget that currently has focus is not a tab group; otherwise,
XmProcessTraversal returns False for these actions.

These actions do not move focus from one tab group to another. The actions
first determine the containing tab group. This is the tab group containing the
widget that currently has focus. The actions traverse only to a non-tab-group
widget within the containing tab group.

A non-tab-group widget is eligible for this kind of traversal if the widget is
traversable and has no tab group ancestors up to the containing tab group. If
the tab group contains no traversable non-tab-group widgets, XmProcessTraversal
returns False.

Following are the possible values of the direction argument. Note that when
actions wrap, wrapping occurs in the traversal direction. The following
describes what happens in a left to right environment:

• XmTRAVERSE_RIGHT—If the XmNnavigationType of the containing tab group is
not XmEXCLUSIVE_TAB_GROUP, focus moves to the next traversable non-tab-
group widget to the right of the widget that currently has focus. In a
left to right environment, at the right side of the tab group this action
wraps to the non-tab-group widget at the left side and next toward the
bottom. At the rightmost widget in the bottom row of the tab group this
action wraps to the non-tab-group widget at the leftmost widget in the
upper row.

In a right to left environment, at the right side of the tab group,
this action wraps to the non-tab-group widget at the left side and
next toward the top. At the rightmost widget in the upper row of the
tab group this action wraps to the non-tab-group widget at the
leftmost widget in the bottom row.

If the XmNnavigationType of the containing tab group is
XmEXCLUSIVE_TAB_GROUP, focus moves to the next traversable non-tab-
group widget in the tab group, proceeding in the order in which the
widgets appear in their parents' XmNchildren lists. After the last
widget in the tab group, this action wraps to the first non-tab-group
widget.

• XmTRAVERSE_LEFT—If the XmNnavigationType of the containing tab group is
not XmEXCLUSIVE_TAB_GROUP, focus moves to the next traversable non-tab-
group widget to the left of the widget that currently has focus. In a
left to right environment, at the left side of the tab group this action
wraps to the non-tab-group widget at the right side and next toward the
top. At the leftmost widget in the upper row of the tab group this action
wraps to the non-tab-group widget at the rightmost widget in the bottom
row.

In a right to left environment, at the left side of the tab group this
action wraps to the non-tab-group widget at the right side and next
toward the bottom. At the leftmost widget in the bottom row of the tab
group this action wraps to the non-tab-group widget at the rightmost
widget in the upper row.

If the XmNnavigationType of the containing tab group is
XmEXCLUSIVE_TAB_GROUP, focus moves to the previous traversable non-
tab-group widget in the tab group, proceeding in the reverse order in
which the widgets appear in their parents' XmNchildren lists. After
the first widget in the tab group, this action wraps to the last non-
tab-group widget.

• XmTRAVERSE_DOWN—If the XmNnavigationType of the containing tab group is
not XmEXCLUSIVE_TAB_GROUP, focus moves to the next traversable non-tab-
group widget below the widget that currently has focus. In a left to
right environment, at the bottom of the tab group this action wraps to the
non-tab-group widget at the top and next toward the right. At the bottom
widget in the rightmost column of the tab group this action wraps to the
non-tab-group widget at the top widget in the leftmost column.

In a right to left environment, at the bottom of the tab group this
action wraps to the non-tab-group widget at the top and next toward
the left. At the bottom widget of the leftmost widget of the tab group
this action wraps to the non-tab-group widget at the top widget of the
rightmost column.

• XmTRAVERSE_UP—If the XmNnavigationType of the containing tab group is not
XmEXCLUSIVE_TAB_GROUP, focus moves to the next traversable non-tab-group
widget above the widget that currently has focus. In a left to right
environment, at the top of the tab group this action wraps to the non-tab-
group widget at the bottom and next toward the left. At the top widget of
the leftmost column of the tab group this action wraps to the non-tab-
group widget at the bottom widget of the rightmost column.

In a right to left environment, at the top of the tab group this
action wraps to the non-tab-group widget at the bottom and next toward
the right. At the top widget of the right most column of the tab group
this action wraps to the non-tab-group widget at the bottom widget of
the leftmost column.

• XmTRAVERSE_NEXT—Focus moves to the next traversable non-tab-group widget
in the tab group, proceeding in the order in which the widgets appear in
their parents' XmNchildren lists. After the last widget in the tab group,
this action wraps to the first non-tab-group widget.

• XmTRAVERSE_PREV—Focus moves to the previous traversable non-tab-group
widget in the tab group, proceeding in the reverse order in which the
widgets appear in their parents' XmNchildren lists. After the first
widget in the tab group, this action wraps to the last non-tab-group
widget.

• XmTRAVERSE_HOME—If the XmNnavigationType of the containing tab group is
not XmEXCLUSIVE_TAB_GROUP, focus moves to the first traversable non-tab-
group widget at the initial focus of the tab group.

If the XmNnavigationType of the containing tab group is
XmEXCLUSIVE_TAB_GROUP, focus moves to the first traversable non-tab-
group widget in the tab group, according to the order in which the
widgets appear in their parents' XmNchildren lists.

• Traversal to a tab group. These actions first determine the current widget
hierarchy and the containing tab group. The current widget hierarchy is the widget
hierarchy whose root is the nearest shell ancestor of the widget that currently has
focus. The containing tab group is is the tab group containing the widget that
currently has focus. If the current widget hierarchy contains no traversable tab
groups, XmProcessTraversal returns False.

Following are the possible values of the direction argument. If any tab group in
the current widget hierarchy has an XmNnavigationType of XmEXCLUSIVE_TAB_GROUP,
traversal of tab groups in the hierarchy proceeds to widgets in the order in
which their XmNnavigationType resources were specified as XmEXCLUSIVE_TAB_GROUP
or XmSTICKY_TAB_GROUP.:

• XmTRAVERSE_NEXT_TAB_GROUP—Finds the hierarchy that contains widget, finds
the active tab group (if any), and makes the next tab group the active tab
group in the hierarchy.

• XmTRAVERSE_PREV_TAB_GROUP—Finds the hierarchy that contains widget, finds
the active tab group (if any), and makes the previous tab group the active
tab group in the hierarchy.

• Traversal to any widget. In this case the widget argument is the widget to which
XmProcessTraversal tries to give focus. If the widget is not traversable,
XmProcessTraversal returns False.

Following are the possible values of the direction argument:

• XmTRAVERSE_CURRENT—Finds the hierarchy and the tab group that contain
widget. If this tab group is not the active tab group, this action makes
it the active tab group. If widget is an item in the active tab group,
this action makes it the active item. If widget is the active tab group,
this action makes the first traversable item in the tab group the active
item.

CAUTIONS
Using XmProcessTraversal to traverse to MenuBars, Pulldown menu panes, or Popup menu panes
is not supported.

XmProcessTraversal cannot be called recursively. In particular, an application cannot
call this routine from an XmNfocusCallback or XmNlosingFocusCallback procedure.

RETURN

       Returns    True   if   the   traversal   action   succeeded.    Returns   False   if   the
       XmNkeyboardFocusPolicy of the nearest shell ancestor of widget is not XmEXPLICIT,  if  the
       traversal  action  finds  no  traversable  widget  to receive focus, or if the call to the
       routine has invalid arguments.

       XmGetVisibility(3) and XmIsTraversable(3).

                                                                            XmProcessTraversal(3)

NAME

SYNOPSIS

DESCRIPTION

RETURN

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