path: root/libXt/specs/CH05

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\&
.sp 1
.ce 3
\s+1\fBChapter 5\fP\s-1

\s+1\fBPop-Up Widgets\fP\s-1
.sp 2
.nr H1 5
.nr H2 0
.nr H3 0
.nr H4 0
.nr H5 0
.LP
.XS
Chapter 5 \(em Pop-Up Widgets
.XE
Pop-up widgets are used to create windows outside of the
window hierarchy defined by the widget tree.
Each pop-up child has a window that is a descendant of the root window,
so that the pop-up window is not clipped by the pop-up widget's parent window.
.\"One thing that all pop-ups in common is that they break 
.\"the widget/window hierarchy.
.\"Pop-ups windows are not geometry constrained by their parent widget.
.\"Instead, they are window children of the root.
Therefore, pop-ups are created and attached differently to their widget parent 
than normal widget children.
.LP
A parent of a pop-up widget does not actively manage its pop-up children;
in fact, it usually does not operate upon them in any way.
The \fIpopup_list\fP field in the
.PN CorePart
structure contains the list of its pop-up children.
This pop-up list exists mainly to provide the proper place in the widget
hierarchy for the pop-up to get resources and to provide a place for
.PN XtDestroyWidget
to look for all extant children.
.LP
A 
composite 
widget can have both normal and pop-up children.
A pop-up can be popped up from almost anywhere, not just by its parent.
The term \fIchild\fP always refers to a normal, geometry-managed widget
on the composite widget's list of children, and the term
\fIpop-up child\fP always refers to a
widget on the pop-up list.
.IN "pop-up" "" "@DEF@"
.IN "pop-up" "list"
.IN "pop-up" "child"

.NH 2
Pop-Up Widget Types
.LP
.XS
\fB\*(SN Pop-Up Widget Types\fP
.XE
There are three kinds of pop-up widgets:
.IP \(bu 5
Modeless pop-ups
.IP
A modeless pop-up (for example, a dialog box that does not prevent
continued interaction with the rest of the application)
can usually be manipulated by the window manager
and looks like any other application window from the
user's point of view.
The application main window itself is a special case of a modeless pop-up.
.IP \(bu 5
Modal pop-ups
.IP
A modal pop-up (for example, a dialog box that requires user input to
continue)
can sometimes be manipulated by the window manager,
and except for events that occur in the dialog box,
it disables user-event distribution to the rest of the application.
.IP \(bu 5
Spring-loaded pop-ups
.IP
A spring-loaded pop-up (for example, a menu)
can seldom be manipulated by the window manager,
and except for events that occur in the pop-up or its descendants,
it disables user-event distribution to all other applications.
.LP
Modal pop-ups and spring-loaded pop-ups are very similar and should be coded as
if they were the same.
In fact, the same widget (for example, a ButtonBox or Menu widget) can be used both
as a modal pop-up and as a spring-loaded pop-up within the same application.
The main difference is that spring-loaded pop-ups are brought up
with the pointer and, because of the grab that the pointer button causes,
require different processing by the \*(xI.
Furthermore, all user input remap events occurring outside the spring-loaded
pop-up (e.g., in a descendant) are also delivered to the spring-loaded
pop-up after they have been dispatched to the appropriate descendant, so
that, for example, button-up can take down a spring-loaded pop-up no
matter where the
button-up occurs.
.LP
Any kind of pop-up, in turn, can pop up other widgets.
Modal and spring-loaded pop-ups can constrain user events to
the most recent such pop-up or allow user events to be dispatched
to any of the modal or spring-loaded pop-ups
currently mapped.
.LP
Regardless of their type,
all pop-up widget classes are responsible for communicating with the
X window manager and therefore are subclasses of
one of the
Shell
widget classes.

.NH 2
Creating a Pop-Up Shell
.XS
\fB\*(SN Creating a Pop-Up Shell\fP
.XE
.LP
.IN "pop-up" "shell"
.IN "pop-up" "child"
For a widget to be popped up,
it must be the child of a pop-up shell widget.
None of the \*(xI-supplied shells will
simultaneously manage more than one child.
Both the shell and child taken together are referred to as the pop-up.
When you need to use a pop-up,
you always refer to the pop-up by the pop-up shell,
not the child.
.sp
.LP
To create a pop-up shell, use
.PN XtCreatePopupShell .
.LP
.IN "XtCreatePopupShell" "" "@DEF@"
.sM
.FD 0
Widget XtCreatePopupShell(\fIname\fP, \fIwidget_class\fP, \fIparent\fP, \
\fIargs\fP, \fInum_args\fP)
.br
      String \fIname\fP;
.br
      WidgetClass \fIwidget_class\fP;
.br
      Widget \fIparent\fP;
.br
      ArgList \fIargs\fP;
.br
      Cardinal \fInum_args\fP;
.FN
.IP \fIname\fP 1i
Specifies the instance name for the created shell widget.
.IP \fIwidget_class\fP 1i
Specifies the widget class pointer for the created shell widget.
.IP \fIparent\fP 1i
Specifies the parent widget.  \*(cI
.IP \fIargs\fP 1i
Specifies the argument list to override any other resource specifications.
.IP \fInum_args\fP 1i
Specifies the number of entries in the argument list.
.LP
.eM
The
.PN XtCreatePopupShell
function ensures that the specified class is a subclass of
Shell
and, rather than using insert_child to attach the widget to the parent's
.IN "insert_child procedure"
\fIchildren\fP list,
attaches the shell to the parent's \fIpopup_list\fP directly.
.LP
The screen resource for this widget is determined by first scanning
\fIargs\fP for the XtNscreen argument.  If no XtNscreen argument is
found, the resource database associated with the parent's screen
is queried for the resource \fIname\fP.screen, class
\fIClass\fP.Screen where \fIClass\fP is the \fIclass_name\fP
field from the
.PN CoreClassPart
of the specified \fIwidget_class\fP.
If this query fails, the parent's screen is used.
Once the screen is determined,
the resource database associated with that screen is used to retrieve
all remaining resources for the widget not specified in
\fIargs\fP.

.LP
A spring-loaded pop-up invoked from a translation table via
.PN XtMenuPopup
must already exist
at the time that the translation is invoked, 
so the translation manager can find the shell by name.
Pop-ups invoked in other ways can be created when
the pop-up actually is needed.
This delayed creation of the shell is particularly useful when you pop up
an unspecified number of pop-ups.
You can look to see if an appropriate unused shell (that is, not
currently popped up) exists and create a new shell if needed.
.sp
.LP
To create a pop-up shell using varargs lists, use
.PN XtVaCreatePopupShell .
.LP
.IN "XtVaCreatePopupShell" "" "@DEF@"
.sM
.FD 0
Widget XtVaCreatePopupShell(\fIname\fP, \fIwidget_class\fP, \fIparent\fP, ...)
.br
      String \fIname\fP;
.br
      WidgetClass \fIwidget_class\fP;
.br
      Widget \fIparent\fP;
.FN
.IP \fIname\fP 1i
Specifies the instance name for the created shell widget.
.IP \fIwidget_class\fP 1i
Specifies the widget class pointer for the created shell widget.
.IP \fIparent\fP 1i
Specifies the parent widget.  \*(cI
.IP ... 1i
Specifies the variable argument list to override any other
resource specifications.
.LP
.eM
.PN XtVaCreatePopupShell
is identical in function to
.PN XtCreatePopupShell
with \fIthe\fP args and \fInum_args\fP parameters replaced by a varargs list as
described in Section 2.5.1.

.NH 2
Creating Pop-Up Children
.XS
\fB\*(SN Creating Pop-Up Children\fP
.XE
.LP
Once a pop-up shell is created,
the single child of the pop-up shell can be created
either statically or dynamically.
.LP
At startup,
an application can create the child of the pop-up shell,
which is appropriate for pop-up children composed of a fixed set
of widgets. 
The application can change the state of the subparts of
the pop-up child as the application state changes.
For example, if an application creates a static menu,
it can call
.PN XtSetSensitive
(or, in general,
.PN XtSetValues )
on any of the buttons that make up the menu.
Creating the pop-up child early means that pop-up time is minimized,
especially if the application calls
.PN XtRealizeWidget
on the pop-up shell at startup.
When the menu is needed,
all the widgets that make up the menu already exist and need only be mapped.
The menu should pop up as quickly as the X server can respond.
.LP
Alternatively,
an application can postpone the creation of the child until it is needed,
which minimizes application startup time and allows the pop-up child to
reconfigure itself each time it is popped up.
In this case,
the pop-up child creation routine might poll the application
to find out if it should change the sensitivity of any of its subparts.
.LP
Pop-up child creation does not map the pop-up,
even if you create the child and call
.PN XtRealizeWidget
on the pop-up shell.
.LP
All shells have pop-up and pop-down callbacks,
which provide the opportunity either to make last-minute changes to a
pop-up child before it is popped up or to change it after it is popped down.
Note that excessive use of pop-up callbacks can make
popping up occur more slowly.

.NH 2
Mapping a Pop-Up Widget
.XS
\fB\*(SN Mapping a Pop-Up Widget\fP
.XE
.LP
Pop-ups can be popped up through several mechanisms:
.IP \(bu 5
A call to
.PN XtPopup
or
.PN XtPopupSpringLoaded .
.IP \(bu 5
One of the supplied callback procedures
.PN XtCallbackNone ,
.PN XtCallbackNonexclusive ,
or
.PN XtCallbackExclusive .
.IP \(bu 5
The standard translation action
.PN XtMenuPopup .
.LP
Some of these routines take an argument of type
.PN XtGrabKind ,
which is defined as
.sp
.sM
.Ds 0
typedef enum {XtGrabNone, XtGrabNonexclusive, XtGrabExclusive} XtGrabKind;
.De
.sp
.eM
.LP
The create_popup_child_proc procedure pointer
in the shell widget instance record is of type
.PN XtCreatePopupChildProc .
.LP
.IN "create_popup_child_proc"
.IN "Shell" "create_popup_child_proc"
.IN "XtCreatePopupChildProc" "" "@DEF@"
.sM
.FD 0
typedef void (*XtCreatePopupChildProc)(Widget);
.br
      Widget \fIw\fP;
.FN
.IP \fIw\fP 1i
Specifies the shell widget being popped up.
.LP
.eM
To map a pop-up from within an application, use
.PN XtPopup .
.LP
.IN "XtPopup" "" "@DEF@"
.sM
.FD 0
void XtPopup(\fIpopup_shell\fP, \fIgrab_kind\fP)
.br
      Widget \fIpopup_shell\fP;
.br
      XtGrabKind \fIgrab_kind\fP;
.FN
.IP \fIpopup_shell\fP 1i
Specifies the shell widget.
.IP \fIgrab_kind\fP 1i
Specifies the way in which user events should be constrained.
.LP
.eM
The
.PN XtPopup
function performs the following:
.IP \(bu 5
Calls
.PN XtCheckSubclass
to ensure \fIpopup_shell\fP's class is a subclass of
.PN shellWidgetClass .
.IP \(bu 5
Raises the window and returns if the shell's \fIpopped_up\fP field is already 
.PN True .
.IP \(bu 5
Calls the callback procedures on the shell's \fIpopup_callback\fP list,
specifying a pointer to the value of \fIgrab_kind\fP as the \fIcall_data\fP
argument.
.IP \(bu 5
Sets the shell \fIpopped_up\fP field to 
.PN True ,
the shell \fIspring_loaded\fP field to 
.PN False ,
and the shell \fIgrab_kind\fP field from \fIgrab_kind\fP.
.IP \(bu 5
If the shell's \fIcreate_popup_child_proc\fP field is non-NULL,
.PN XtPopup
calls it with \fIpopup_shell\fP as the parameter.
.IP \(bu 5
If \fIgrab_kind\fP is either
.PN XtGrabNonexclusive
or
.PN XtGrabExclusive ,
it calls
.LP
.Ds
XtAddGrab(\fIpopup_shell\fP, (\fIgrab_kind\fP == XtGrabExclusive), False)
.De
.IP \(bu 5
Calls
.PN XtRealizeWidget 
with \fIpopup_shell\fP specified.
.IP \(bu 5
Calls
.PN XMapRaised
with the window of \fIpopup_shell\fP.
.sp
.LP
To map a spring-loaded pop-up from within an application, use
.PN XtPopupSpringLoaded .
.LP
.IN "XtPopupSpringLoaded" "" @DEF@"
.sM
.FD 0
void XtPopupSpringLoaded(\fIpopup_shell\fP)
.br
      Widget \fIpopup_shell\fP;
.FN
.IP \fIpopup_shell\fP 1i
Specifies the shell widget to be popped up.
.LP
.eM
The
.PN XtPopupSpringLoaded
function performs exactly as
.PN XtPopup
except that it sets the shell \fIspring_loaded\fP field to
.PN True
and always calls
.PN XtAddGrab
with \fIexclusive\fP
.PN True
and \fIspring-loaded\fP
.PN True .
.sp
.LP
To map a pop-up from a given widget's callback list,
you also can register one of the
.PN XtCallbackNone ,
.PN XtCallbackNonexclusive ,
or
.PN XtCallbackExclusive
convenience routines as callbacks, using the pop-up shell widget as the
client data.
.LP
.IN "XtCallbackNone" "" "@DEF@"
.sM
.FD 0
void XtCallbackNone(\fIw\fP, \fIclient_data\fP, \fIcall_data\fP)
.br
      Widget \fIw\fP;
.br
      XtPointer \fIclient_data\fP;
.br
      XtPointer \fIcall_data\fP;
.FN
.IP \fIw\fP 1i
Specifies the widget.
.IP \fIclient_data\fP 1i
Specifies the pop-up shell.
.IP \fIcall_data\fP 1i
Specifies the callback data argument,
which is not used by this procedure.
.sp
.LP
.IN "XtCallbackNonexclusive" "" "@DEF@"
.FD 0
void XtCallbackNonexclusive(\fIw\fP, \fIclient_data\fP, \fIcall_data\fP)
.br
      Widget \fIw\fP;
.br
      XtPointer \fIclient_data\fP;
.br
      XtPointer \fIcall_data\fP;
.FN
.IP \fIw\fP 1i
Specifies the widget.
.IP \fIclient_data\fP 1i
Specifies the pop-up shell.
.IP \fIcall_data\fP 1i
Specifies the callback data argument,
which is not used by this procedure.
.sp
.LP
.IN "XtCallbackExclusive" "" "@DEF@"
.FD 0
void XtCallbackExclusive(\fIw\fP, \fIclient_data\fP, \fIcall_data\fP)
.br
      Widget \fIw\fP;
.br
      XtPointer \fIclient_data\fP;
.br
      XtPointer \fIcall_data\fP;
.FN
.IP \fIw\fP 1i
Specifies the widget.
.IP \fIclient_data\fP 1i
Specifies the pop-up shell.
.IP \fIcall_data\fP 1i
Specifies the callback data argument,
which is not used by this procedure.
.LP
.eM
The
.PN XtCallbackNone ,
.PN XtCallbackNonexclusive ,
and
.PN XtCallbackExclusive
functions call
.PN XtPopup
with the shell specified by the \fIclient_data\fP argument
and \fIgrab_kind\fP set as the name specifies.
.PN XtCallbackNone ,
.PN XtCallbackNonexclusive ,
and
.PN XtCallbackExclusive
specify
.PN XtGrabNone ,
.PN XtGrabNonexclusive ,
and
.PN XtGrabExclusive ,
respectively.
Each function then sets the widget that executed the callback list 
to be insensitive by calling
.PN XtSetSensitive .
Using these functions in callbacks is not required.
In particular,
an application must provide customized code for
callbacks that create pop-up shells dynamically or that must do more than
desensitizing the button.
.sp
.LP
Within a translation table,
to pop up a menu when a key or pointer button is pressed or when the pointer
is moved into a widget, use
.PN XtMenuPopup ,
or its synonym,
.PN MenuPopup .
From a translation writer's point of view,
the definition for this translation action is
.LP
.IN "MenuPopup" "" "@DEF@"
.IN "XtMenuPopup" "" "@DEF@"
.sM
.FD 0
void XtMenuPopup(\fIshell_name\fP)
.br
      String \fIshell_name\fP;
.FN
.IP \fIshell_name\fP 1i
Specifies the name of the shell widget to pop up.
.LP
.eM
.PN XtMenuPopup
is known to the translation manager,
which registers the corresponding built-in action procedure
.PN XtMenuPopupAction
using
.PN XtRegisterGrabAction
specifying \fIowner_events\fP
.PN True ,
\fIevent_mask\fP
.PN ButtonPressMask
\fB|\fP
.PN ButtonReleaseMask ,
and \fIpointer_mode\fP and \fIkeyboard_mode\fP
.PN GrabModeAsync .
.LP
If
.PN XtMenuPopup
is invoked on
.PN ButtonPress ,
it calls
.PN XtPopupSpringLoaded
on the specified shell widget.
If
.PN XtMenuPopup
is invoked on
.PN KeyPress
or
.PN EnterWindow ,
it calls
.PN XtPopup
on the specified shell widget with \fIgrab_kind\fP set to
.PN XtGrabNonexclusive .
Otherwise, the translation manager generates a
warning message and ignores the action.
.LP
.PN XtMenuPopup
tries to find the shell by searching the widget tree starting at
the widget in which it is invoked.
If it finds a shell with the specified name in the pop-up children of
that widget, it pops up the shell with the appropriate parameters.
Otherwise, it moves up the parent chain to find a pop-up child with the
specified name.
If
.PN XtMenuPopup
gets to the application top-level shell widget and has not
found a matching shell, it generates a warning and returns immediately.

.NH 2
Unmapping a Pop-Up Widget
.XS
\fB\*(SN Unmapping a Pop-Up Widget\fP
.XE
.LP
Pop-ups can be popped down through several mechanisms:
.IP \(bu 5
A call to
.PN XtPopdown 
.IP \(bu 5
The supplied callback procedure
.PN XtCallbackPopdown 
.IP \(bu 5
The standard translation action
.PN XtMenuPopdown 
.sp
.LP
To unmap a pop-up from within an application, use
.PN XtPopdown .
.LP
.IN "XtPopdown" "" "@DEF@"
.sM
.FD 0
void XtPopdown(\fIpopup_shell\fP)
.br
      Widget \fIpopup_shell\fP;
.FN
.IP \fIpopup_shell\fP 1i
Specifies the shell widget to pop down.
.LP
.eM
The
.PN XtPopdown
function performs the following:
.IP \(bu 5
Calls
.PN XtCheckSubclass
.\".PN XtCheckSubclass(popup_shell, popupShellWidgetClass)
to ensure \fIpopup_shell\fP's class is a subclass of
.PN shellWidgetClass .
.IP \(bu 5
Checks that the \fIpopped_up\fP field of \fIpopup_shell\fP is
.PN True ;
otherwise, it returns immediately.
.IP \(bu 5
Unmaps \fIpopup_shell\fP's window and, if \fIoverride_redirect\fP is
.PN False ,
sends a synthetic
.PN UnmapNotify
event as specified by the \fI\*(xC\fP.
.IP \(bu 5
If \fIpopup_shell\fP's \fIgrab_kind\fP is either
.PN XtGrabNonexclusive
or
.PN XtGrabExclusive ,
it calls
.PN XtRemoveGrab .
.\".PN XtRemoveGrab(popup_shell)
.IP \(bu 5
Sets \fIpopup_shell\fP's \fIpopped_up\fP field to 
.PN False .
.IP \(bu 5
Calls the callback procedures on the shell's \fIpopdown_callback\fP list,
specifying a pointer to the value of the shell's \fIgrab_kind\fP field
as the \fIcall_data\fP argument.
.sp
.LP
To pop down a pop-up from a callback list, you may use the callback 
.PN XtCallbackPopdown .
.LP
.IN "XtCallbackPopdown" "" "@DEF@"
.sM
.FD 0
void XtCallbackPopdown(\fIw\fP, \fIclient_data\fP, \fIcall_data\fP)
.br
      Widget \fIw\fP;
.br
      XtPointer \fIclient_data\fP;
.br
      XtPointer \fIcall_data\fP;
.FN
.IP \fIw\fP 1i
Specifies the widget.
.IP \fIclient_data\fP 1i
Specifies a pointer to the
.PN XtPopdownID
structure.
.IP \fIcall_data\fP 1i
Specifies the callback data argument,
which is not used by this procedure.
.LP
.eM
The
.PN XtCallbackPopdown
function casts the \fIclient_data\fP parameter to a pointer of type
.PN XtPopdownID .
.LP
.sM
.Ds 0
.TA .5i 3i
.ta .5i 3i
typedef struct {
	Widget shell_widget;
	Widget enable_widget;
} XtPopdownIDRec, *XtPopdownID;
.De
.LP
.eM
The \fIshell_widget\fP is the pop-up shell to pop down,
and the \fIenable_widget\fP is usually the widget that was used to pop it up
in one of the pop-up callback convenience procedures.
.LP
.PN XtCallbackPopdown
calls
.PN XtPopdown
with the specified \fIshell_widget\fP 
and then calls
.PN XtSetSensitive
to resensitize \fIenable_widget\fP.
.sp
.LP
Within a translation table,
to pop down a spring-loaded menu when a key or pointer button is
released or when the
pointer is moved into a widget, use
.PN XtMenuPopdown
or its synonym,
.PN MenuPopdown .
From a translation writer's point of view,
the definition for this translation action is
.LP
.IN "XtMenuPopdown" "" "@DEF@"
.IN "MenuPopdown" "" "@DEF@"
.sM
.FD 0
void XtMenuPopdown(\fIshell_name\fP)
.br
      String \fIshell_name\fP;
.FN
.IP \fIshell_name\fP 1i
Specifies the name of the shell widget to pop down.
.LP
.eM
If a shell name is not given,
.PN XtMenuPopdown
calls
.PN XtPopdown
with the widget for which the translation is specified.
If \fIshell_name\fP is specified in the translation table,
.PN XtMenuPopdown
tries to find the shell by looking up the widget tree starting at the
widget in which it is invoked.
If it finds a shell with the specified name in the pop-up children 
of that widget, it pops down the shell;
otherwise, it moves up the parent chain to find a pop-up child with the
specified name.
If 
.PN XtMenuPopdown 
gets to the application top-level shell widget 
and cannot find a matching shell, 
it generates a warning and returns immediately.
.bp