XmProcessTraversal(library call) XmProcessTraversal(library call)
NAMEXmProcessTraversal — 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);
DESCRIPTIONXmProcessTraversal 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, XmPro‐
cessTraversal 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 sensi‐
tive 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 applica‐
tion unmaps a widget that has its XmNmappedWhenManaged resource
set to True, the result is undefined.
In a ScrolledWindow with an XmNscrollingPolicy of XmAUTO‐
MATIC, 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 XmNtraverseObscured‐
Callback routine can make the widget at least partially visi‐
ble 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; XmPro‐
cessTraversal 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 cur‐
rently 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 con‐
taining 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 con‐
taining 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 left‐
most widget in the upper row of the tab group this
action wraps to the non-tab-group widget at the right‐
most 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 con‐
taining 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.
· XmTRAVERSE_UP—If the XmNnavigationType of the contain‐
ing 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 left‐
most column of the tab group this action wraps to the
non-tab-group widget at the bottom widget of the right‐
most 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.
· 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 con‐
taining 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 cur‐
rent widget hierarchy and the containing tab group. The current
widget hierarchy is the widget hierarchy whose root is the near‐
est 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 con‐
tains 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 XmN‐
navigationType 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 con‐
tains 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 con‐
tains 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 XmN‐
losingFocusCallback 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.
RELATEDXmGetVisibility(3) and XmIsTraversable(3).
XmProcessTraversal(library call)
