Tribblix: manual page: XmDrawingArea.3

XmDrawingArea(library call) XmDrawingArea(library call)

NAME

XmDrawingArea -- The DrawingArea widget class

SYNOPSIS

#include <Xm/DrawingA.h>

DESCRIPTION

DrawingArea is an empty widget that is easily adaptable to a variety
of purposes. It does no drawing and defines no behavior except for
invoking callbacks. Callbacks notify the application when graphics
need to be drawn (exposure events or widget resize) and when the
widget receives input from the keyboard or mouse.

Applications are responsible for defining appearance and behavior as
needed in response to DrawingArea callbacks.

DrawingArea is also a composite widget and subclass of XmManager that
supports minimal geometry management for multiple widget or gadget
children.

DrawingArea uses the XmNinitialFocus resource of XmManager to define
whether or not DrawingArea will receive focus when it is traversed
to, even if it has traversable children. If XmNinitialFocus is NULL,
DrawingArea receives focus only if it does not have any traversable
children. If XmNinitialFocus is not NULL, then DrawingArea receives
focus when traversed to. In the latter case, the application first
needs to be able to realize that the DrawingArea will receive focus,
then, as appropriate, needs to either call the XmProcessTraversal
function for the desired child, or to navigate across the private
DrawingArea graphics objects.

The following resources are not currently used by the DrawingArea
widget: XmNshadowThickness, XmNtopShadowPixmap,
XmNbottomShadowPixmap, XmNtopShadowColor, and XmNbottomShadowColor

Data Transfer Behavior

DrawingArea has no widget class conversion or destination procedure.
Subclasses and the XmNconvertCallback procedures are responsible for
any conversion of selections. Subclasses and the
XmNdestinationCallback procedures are responsible for any data
transfers to the widget.

Classes

DrawingArea inherits behavior and resources from the Core, Composite,
Constraint, and XmManager classes.

The class pointer is xmDrawingAreaWidgetClass.

The class name is XmDrawingArea.

New Resources

The following table defines a set of widget resources used by the
programmer to specify data. The programmer can also set the resource
values for the inherited classes to set attributes for this widget.
To reference a resource by name or by class in a .Xdefaults file,
remove the XmN or XmC prefix and use the remaining letters. To
specify one of the defined values for a resource in a .Xdefaults
file, remove the Xm prefix and use the remaining letters (in either
lowercase or uppercase, but include any underscores between words).
The codes in the access column indicate if the given resource can be
set at creation time (C), set by using XtSetValues (S), retrieved by
using XtGetValues (G), or is not applicable (N/A).

+----------------------------------------------------------------------------------+
| XmDrawingArea Resource Set |
|Name | Class | Type | Default | Access |
+-----------------------+-----------------+----------------+--------------+--------+
|XmNconvertCallback | XmCCallback | XtCallbackList | NULL | C |
+-----------------------+-----------------+----------------+--------------+--------+
|XmNdestinationCallback | XmCCallback | XtCallbackList | NULL | C |
+-----------------------+-----------------+----------------+--------------+--------+
|XmNexposeCallback | XmCCallback | XtCallbackList | NULL | C |
+-----------------------+-----------------+----------------+--------------+--------+
|XmNinputCallback | XmCCallback | XtCallbackList | NULL | C |
+-----------------------+-----------------+----------------+--------------+--------+
|XmNmarginHeight | XmCMarginHeight | Dimension | 10 | CSG |
+-----------------------+-----------------+----------------+--------------+--------+
|XmNmarginWidth | XmCMarginWidth | Dimension | 10 | CSG |
+-----------------------+-----------------+----------------+--------------+--------+
|XmNresizeCallback | XmCCallback | XtCallbackList | NULL | C |
+-----------------------+-----------------+----------------+--------------+--------+
|XmNresizePolicy | XmCResizePolicy | unsigned char | XmRESIZE_ANY | CSG |
+-----------------------+-----------------+----------------+--------------+--------+
+-----------------------+-----------------+----------------+--------------+--------+
XmNconvertCallback
Specifies a list of callbacks called when the DrawingArea
is asked to convert a selection. The type of the structure
whose address is passed to these callbacks is
XmConvertCallbackStruct. The reason is XmCR_OK.

XmNdestinationCallback
Specifies a list of callbacks called when the DrawingArea
is the destination of a transfer operation. The type of
the structure whose address is passed to these callbacks is
XmDestinationCallbackStruct. The reason is XmCR_OK.

XmNexposeCallback
Specifies the list of callbacks that is called when
DrawingArea receives an exposure event. The callback
reason is XmCR_EXPOSE. The callback structure also
includes the exposure event.

The default bit gravity for Manager windows is
NorthWestGravity. This may cause the XmNexposeCallback
procedures not to be invoked when the DrawingArea window is
made smaller.

XmNinputCallback
Specifies the list of callbacks that is called when the
DrawingArea receives a keyboard or mouse event (key or
button, up or down). The callback reason is XmCR_INPUT.
The callback structure also includes the input event.

XmNmarginHeight
Specifies the minimum spacing in pixels between the top or
bottom edge of DrawingArea and any child widget.

XmNmarginWidth
Specifies the minimum spacing in pixels between the left or
right edge of DrawingArea and any child widget.

XmNresizeCallback
Specifies the list of callbacks that is called when the
DrawingArea is resized. The callback reason is
XmCR_RESIZE.

XmNresizePolicy
Controls the policy for resizing DrawingArea widgets.
Possible values include XmRESIZE_NONE (fixed size),
XmRESIZE_ANY (shrink or grow as needed), and XmRESIZE_GROW
(grow only).

Inherited Resources

Callback Information

A pointer to the following structure is passed to the
XmNexposeCallback, XmNinputCallback, and XmNresizeCallback
procedures:

typedef struct
{
int reason;
XEvent * event;
Window window;
} XmDrawingAreaCallbackStruct;

reason Indicates why the callback was invoked.

event Points to the XEvent that triggered the callback. This is
NULL for the XmNresizeCallback.

window Is set to the widget window.

A pointer to the following structure is passed to the
XmNconvertCallback procedures:

typedef struct
{
int reason;
XEvent *event;
Atom selection;
Atom target;
XtPointer source_data;
XtPointer location_data;
int flags;
XtPointer parm;
int parm_format;
unsigned long parm_length;
int status;
XtPointer value;
Atom type;
int format;
unsigned long length;
} XmConvertCallbackStruct;

reason Indicates why the callback was invoked.

event Points to the XEvent that triggered the callback. It can
be NULL.

selection Indicates the selection for which conversion is being
requested. Possible values are CLIPBOARD, PRIMARY,
SECONDARY, and _MOTIF_DROP.

target Indicates the conversion target.

source_data
Contains information about the selection source. When the
selection is _MOTIF_DROP, source_data is the DragContext.
Otherwise, it is NULL.

location_data
Contains information about the location of data to be
converted. If the value is NULL, the data to be
transferred consists of the widget's current selection.

flags Indicates the status of the conversion. Following are the
possible values:

XmCONVERTING_NONE
This flag is currently unused.

XmCONVERTING_PARTIAL
The target widget was able to be converted, but
some data was lost.

XmCONVERTING_SAME
The conversion target is the source of the data
to be transferred.

XmCONVERTING_TRANSACT
This flag is currently unused.

parm Contains parameter data for this target. If no parameter
data exists, the value is NULL.

When selection is CLIPBOARD and target is
_MOTIF_CLIPBOARD_TARGETS or
_MOTIF_DEFERRED_CLIPBOARD_TARGETS, the value is the
requested operation (XmCOPY, XmMOVE, or XmLINK).

parm_format
Specifies whether the data in parm should be viewed as a
list of char, short, or long quantities. Possible values
are 0 (when parm is NULL), 8 (when the data in parm should
be viewed as a list of chars), 16 (when the data in parm
should be viewed as a list of shorts), or 32 (when the data
in parm should be viewed as a list of longs). Note that
parm_format symbolizes a data type, not the number of bits
in each list element. For example, on some machines, a
parm_format of 32 means that the data in parm should be
viewed as a list of 64-bit quantities, not 32-bit
quantities.

parm_length
Specifies the number of elements of data in parm, where
each element has the size specified by parm_format. When
parm is NULL, the value is 0.

status An IN/OUT member that specifies the status of the
conversion. The initial value is XmCONVERT_DEFAULT. The
callback procedure can set this member to one of the
following values:

XmCONVERT_DEFAULT
This value means that the widget class conversion
procedure, if any, is called after the callback
procedures return. If the widget class
conversion procedure produces any data, it
overwrites the data provided by the callback
procedures in the value member.

XmCONVERT_MERGE
This value means that the widget class conversion
procedure, if any, is called after the callback
procedures return. If the widget class
conversion procedure produces any data, it
appends its data to the data provided by the
callback procedures in the value member. This
value is intended for use with targets that
result in lists of data, such as TARGETS.

XmCONVERT_DONE
This value means that the callback procedure has
successfully finished the conversion. The widget
class conversion procedure, if any, is not called
after the callback procedures return.

XmCONVERT_REFUSE
This value means that the callback procedure has
terminated the conversion process without
completing the requested conversion. The widget
class conversion procedure, if any, is not called
after the callback procedures return.

value An IN/OUT parameter that contains any data that the
callback procedure produces as a result of the conversion.
The initial value is NULL. If the callback procedure sets
this member, it must ensure that the type, format, and
length members correspond to the data in value. The
callback procedure is responsible for allocating, but not
for freeing, memory when it sets this member.

type An IN/OUT parameter that indicates the type of the data in
the value member. The initial value is INTEGER.

format An IN/OUT parameter that specifies whether the data in
value should be viewed as a list of char, short, or long
quantities. The initial value is 8. The callback
procedure can set this member to 8 (for a list of char), 16
(for a list of short), or 32 (for a list of long).

length An IN/OUT member that specifies the number of elements of
data in value, where each element has the size symbolized
by format. The initial value is 0.

A pointer to the following callback structure is passed to the
XmNdestinationCallback procedures:

typedef struct
{
int reason;
XEvent *event;
Atom selection;
XtEnum operation;
int flags;
XtPointer transfer_id;
XtPointer destination_data;
XtPointer location_data;
Time time;
} XmDestinationCallbackStruct;

reason Indicates why the callback was invoked.

event Points to the XEvent that triggered the callback. It can
be NULL.

selection Indicates the selection for which data transfer is being
requested. Possible values are CLIPBOARD, PRIMARY,
SECONDARY, and _MOTIF_DROP.

operation Indicates the type of transfer operation requested.

+o When the selection is PRIMARY, possible values are
XmMOVE, XmCOPY, and XmLINK.

+o When the selection is SECONDARY or CLIPBOARD,
possible values are XmCOPY and XmLINK.

+o When the selection is _MOTIF_DROP, possible values
are XmMOVE, XmCOPY, XmLINK, and XmOTHER. A value of
XmOTHER means that the callback procedure must get
further information from the XmDropProcCallbackStruct
in the destination_data member.

flags Indicates whether or not the destination widget is also the
source of the data to be transferred. Following are the
possible values:

XmCONVERTING_NONE
The destination widget is not the source of the
data to be transferred.

XmCONVERTING_SAME
The destination widget is the source of the data
to be transferred.

transfer_id
Serves as a unique ID to identify the transfer transaction.

destination_data
Contains information about the destination. When the
selection is _MOTIF_DROP, the callback procedures are
called by the drop site's XmNdropProc, and destination_data
is a pointer to the XmDropProcCallbackStruct passed to the
XmNdropProc procedure. When the selection is SECONDARY,
destination_data is an Atom representing a target
recommmended by the selection owner for use in converting
the selection. Otherwise, destination_data is NULL.

location_data
Contains information about the location where data is to be
transferred. The value is always NULL when the selection
is SECONDARY or CLIPBOARD. If the value is NULL, the data
is to be inserted at the widget's cursor position.
location_data is only valid for the duration of a transfer.
Once XmTransferDone procedures start to be called,
location_data will no longer be stable.

time Indicates the time when the transfer operation began.

Translations

XmDrawingArea inherits translations from XmManager. Before calling
the XmManager actions, all events in the inherited translations
except <BtnMotion>, <EnterWindow>, <LeaveWindow>, <FocusIn>, and
<FocusOut> also call the DrawingAreaInput() action.

XmDrawingArea has the following additional translations. The
following key names are listed in the X standard key event
translation table syntax. This format is the one used by Motif to
specify the widget actions corresponding to a given key. A brief
overview of the format is provided under VirtualBindings(3). For a
complete description of the format, please refer to the X Toolkit
Instrinsics Documentation.

<BtnDown>:
DrawingAreaInput()

<BtnUp>: DrawingAreaInput()

<KeyDown>:
DrawingAreaInput() ManagerGadgetKeyInput()

<KeyUp>: DrawingAreaInput()

Action Routines

The XmDrawingArea action routines are

DrawingAreaInput():
Unless the event takes place in a gadget, calls the
callbacks for XmNinputCallback

ManagerGadgetKeyInput():
Causes the current gadget to process a keyboard event

Additional Behavior

The XmDrawingArea widget has the following additional behavior:

<Expose>: Calls the callbacks for XmNexposeCallback

<Widget Resize>:
Calls the callbacks for XmNresizeCallback

Virtual Bindings

The bindings for virtual keys are vendor specific. For information
about bindings for virtual buttons and keys, see VirtualBindings(3).

Composite(3), Constraint(3), Core(3), XmCreateDrawingArea(3),
XmManager(3), XmVaCreateDrawingArea(3), and
XmVaCreateManagedDrawingArea(3).

XmDrawingArea(library call)