XmProcessTraversal(library call) XmProcessTraversal(library call)

NAME

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

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:

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

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

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

+o 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.

+o 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.

+o 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:

+o 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

+o 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:

+o 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:

+o 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.

+o 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.

+o 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.


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.

+o 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.


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.

+o 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.

+o 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.

+o 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.

+o 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.:

+o 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.

+o 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.

+o 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:

+o 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.

RELATED

XmGetVisibility(3) and XmIsTraversable(3).

XmProcessTraversal(library call)