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.TH XRCHECKBOX 3X "Xrlib Version 10"
.fi
.ad 1
.SH NAME
XrCheckBox - an editor for check boxes
.SH SYNOPSIS
#include <X/Xlib.h>
.br
#include <Xr/Xrlib.h>
.br
.sp 1
XrEditor*
.br
.B XrCheckBox (instance, message, data)
.in 7
.br
xrEditor * instance;
.br
INT32      message;
.br
INT8     * data;
.br
.in
.sp 1
.SH DESCRIPTION
.sp
.P
The checkbox editor is used to create and process a
group of related checkboxes within a given window.  
The number of checkboxes, and how they are displayed,
is completely controlled by the application.
Each checkbox may also include an optional text
label, which will be displayed to the right
of the checkbox.
.P
The size of the checkboxes are proportional to the
size of the font being used to display the text labels.
By allowing an application to specify this font,
the size of the checkboxes can be adjusted for individual displays.
.P
This field editor supports two distinct sets of state flags:
those associated with the whole instance (which are modified
using
.B MSG_GETSTATE
and
.B MSG_SETSTATE),
and those which are assigned to the individual checkboxes (which
are modified using
.B MSG_GETITEMSTATES
and 
.B MSG_SETITEMSTATES).
The state flags which are associated with the instance as a whole have
precedence over the individual state flags.
For example, if the
.B XrVISIBLE
flag is cleared for the instance, then none of the checkboxes
will be displayed, regardless of their individual state flag settings.
But, if the 
.B XrVISIBLE
flag is set for the instance, then the field editor will look
at the state of the
.B XrVISIBLE
flag associated with each checkbox, to determine if the
entity should be displayed.
.P
Using the cursor and the mouse, a user can interactively
select a checkbox, by moving the cursor over one
of the boxes, and 'clicking' the mouse button.
This will cause the state of the chosen box to toggle.
If the box had previously been active (filled), then it
will now become inactive (not filled).
Likewise, if the box was previously inactive (not filled),
then it will now become active (filled).
An application will then be notified of the change, and
may handle it accordingly.
.P
The checkbox editor will not restrict the number of boxes
which may be active at any given moment, within a given
instance.
Instead, each checkbox in an instance is treated like
an independent entity; its value does not rely on
nor affect the value of any other checkbox in the instance.
.P
A checkbox editor instance is composed of 3 components:
.sp
.nf
.in 8
- The editor instance's background area.
- The individual checkboxes.
- The checkbox labels.
.fi
.in
.P
Of these 'selectable' regions, only select events which occur in one of
the individual checkboxes will affect the instance.  
When one of these is selected,
the editor will toggle the state of the checkbox, and then
the application program will be notified that the value of
one of the checkboxes has changed, along with the index
of the checkbox which was modified.
If a select event occurs in any
of the other components, the application will be notified
that a select occurred, but the editor instance was not
modified.
.P
When an editor instance is created, the initial value and
the label strings for each checkbox will be specified by 
the application program.
For the values, a pointer to an array of 8 bit integer
values must be passed in.
For the label strings, a pointer to an array of 
character strings may be passed in.
The checkbox editor will not save copies of these pieces 
of data.
Instead, it will save a copy of the pointers only.
This will allow an application program to have immediate access
to the checkbox values, since the array resides in the
application's domain.
.P
The editor allows an application to modify the data values
associated with the checkboxes, however, the checkbox labels
must not be modified, once the instance has been created.
This editor will rely on the fact that when an application
modifies any of the  checkbox data values, the
application will tell the editor to redraw;
this allows the editor to remain in sync with the current
checkbox data.
Modifying the data, without doing a redraw, will cause
the editor to behave in an unfriendly fashion.
.P
This editor allows an application program to obtain information
about an instance in two ways:
.sp
.in 8
.nf
By means of an input event returned when a checkbox
is modified.
.sp
By means of the shared data values mentioned above.
This refers to the array of data describing the
value of each checkbox.
.in
.fi
.P
When the editor draws the specified checkbox instance,
it will attempt to space out the checkboxes, to take
full advantage of the specified 
.I editorRect.
If the rectangle is larger than needed, then the extra
space will be divided equally as blank space between the
rows and columns.
If the rectangle is too small, then the request will fail.

.SH EDITOR MESSAGES
.IP MSG_NEW
This message will be the means by which an application program
can create a checkbox editor instance in a port.  It will
expect the 
.I instance
parameter to be set to
.B NULL,
and the
.I data 
parameter to point to a filled out instance of the following structure:
.sp
.nf
     typedef struct {
          Window       editorWindowId;
          RECTANGLE    editorRect;
          INT8         editorState;
          INT32        editorFGColor;
          INT32        editorBGColor;
          FontInfo   * editorFont;
          INT16        numFields;
          INT16        numCols;
          INT8      ** labels;
          INT8       * values;
          INT8       * stateFlags;  
      } xrCheckBoxInfo;
.fi
.sp
.in 7
.ul 1
editorWindowId
.br
.in
.in 9
This field indicates the window to which the editor instance
is to be attached.
Anytime the instance is redrawn, it will be redrawn in this window.
.in
.sp
.in 7
.ul 1
editorRect
.br
.in
.in 9
.VL 16
This describes the location and size of the region 
into which the checkbox instance is to be located.
If the rectangle is larger than is needed to hold the specified
instance, then the extra space will be used as padding
between the checkboxes.
If the rectangle is too small, then the request will fail.
.in
.sp
.in 7
.ul 1
editorState
.br
.in
.in 9
This field contains the initial value of the state flags
for this editor instance.
It can be composed of any combination of the
.B XrSENSITIVE
and
.B XrVISIBLE
flags.
.in
.sp
.in 7
.ul 1
editorFGColor
.br
.in
.in 9
This field specifies the foreground color
to be used when drawing the editor instance.
It will be used to display the checkbox labels,
and the checkbox borders.
If this is set to -1, the default foreground color (see
.B XrInit(3X)
) will be used.
.in
.sp
.in 7
.ul 1
editorBGColor
.br
.in
.in 9
This field specifies the background color
to be used when drawing the editor instance.
It will be used to fill the interior of an inactive
checkbox.
If this is set to -1, the default background color (see
.B XrInit(3X)
) will be used.
.in
.sp
.in 7
editorFont
.br
.in
.in 9
This is a pointer to a structure which describes the font
to be used when creating this editor instance.
If the pointer has been set to 
.B NULL, 
then the editor will use the default system base font.
The font is important not only because it describes how
the labels will look, but it will also be used to determine
how large the checkboxes should be.
.LE
.sp
.in 7
.ul 1
numFields
.br
.in
.in 9
This value indicates the total number of checkboxes which are
included in this instance.
Once specified, this value cannot be changed.
.in
.sp
.in 7
.ul 1
numCols
.br
.in
.in 9
This value indicates the number of columns into which the
checkboxes are to be displayed.
Using this value, and 
.I numFields, 
the editor will
automatically calculate the number of rows.
If this value is greater than 
.I numFields,
then the create request will fail.
.in
.sp
.in 7
.ul 1
labels
.br
.in
.in 9
This is a pointer to an array of 
.B NULL 
terminated 
character strings, representing the labels associated with each checkbox.
If this pointer is 
.B NULL, 
then none of the checkboxes will
have labels.
The first entry in the array will correspond to checkbox 0,
the second to checkbox 1, etc.
If an entry in this array is set to 
.B NULL, 
then the corresponding checkbox will have no label.
The editor will not keep a copy of each of these strings;
instead, it will only keep a copy of the pointer to
the string array.
It will rely on the application to NOT modify these strings,
once the instance has been created.
.in
.sp
.in 7
.ul 1
values
.br
.in
.in 9
This is a pointer to an array of 8 bit integer values,
representing the initial state of each of the checkboxes.
If this pointer is 
.B NULL, 
then the create request will fail.
The first entry in this array corresponds to the value of
checkbox 0, etc.
A value of 
.B TRUE 
signifies that the checkbox should be drawn
as 'active' (filled), while a value of 
.B FALSE 
signifies that a checkbox should be drawn as 'inactive' (not filled).
The editor will not keep a copy of this array.
Instead, it will only keep a copy of the pointer to this array.
Anytime the value of a checkbox is modified, the editor
will update the appropriate location in this array, and then
notify the application.
The application will then have immediate access to the checkbox
values, since the array resides in its data area.
.in
.sp
.in 7
.ul 1
stateFlags
.br
.in
.in 9
This is a pointer to an array of values, each containing
the initial state flag settings to be associated with
each checkbox in the instance.
If this pointer has been set to
.B NULL,
then the state flags for each entity will be set to
.B XrSENSITIVE
and
.B XrVISIBLE.
The first entry in this array corresponds to checkbox 0, etc.
.in
.sp
.IP
The editor will then draw the checkbox editor instance in the 
specified window.
.IP
Upon successful completion, a pointer to the newly created
editor structure will be returned to the application
This value must be used thereafter, whenever the application
wishes to refer to this particular editor instance.

.IP MSG_FREE
This message is the mechanism by which an editor instance can be destroyed.
The only parameter of importance is the 
.I instance
parameter, which is a pointer to the
editor structure, which was returned by the 
.B MSG_NEW 
message; this
parameter specifies which instance is to be destroyed.
.IP
When a checkbox instance is destroyed, it will be internally
disconnected from the window to which it was attached, it will
no longer handle mouse selects, and it will be removed from the
window, if the instance is visible.
.IP
After an editor instance has been destroyed, no further
messages should be issued in regard to that instance.

.IP MSG_GETSTATE
This message returns the current state of the 
.B XrVISIBLE 
and 
.B XrSENSITIVE
flags for the specified checkbox editor instance.  The
.I instance
parameter specifies which instance to use. 
The 
.I data 
parameter should be a pointer to an 8 bit integer value,
into which the current state flags will be placed.

.IP MSG_SETSTATE
This message allows an application program to modify the setting of
the 
.B XrSENSITIVE 
and 
.B XrVISIBLE 
flags, for a given checkbox editor instance.
The 
.I data 
parameter is interpreted as an 8 bit integer value, containing
the new state flag values.
After saving the new state flags, the editor instance will be redrawn,
to reflect the new state.
If an instance is not visible, then the
rectangle which it occupies will be drawn using the background tile
for the window, thus making it invisible. 
If an instance is visible, but not sensitive, then 
each checkbox will be drawn and filled with a 50% pattern.

.IP MSG_GETITEMSTATES
This message allows an application to obtain a copy of the individual
state flags associated with each of the checkboxes contained within
the specified editor instance.
These state flags differ from the state flags obtained using
.B MSG_GETSTATE.
The
.I instance
parameter must specify the editor instance to be queried, while the
.I data
parameter should point to an array of 8 bit integer values.
The state flags will be returned by means of this array.
The flags associated with checkbox 0 will be returned in the
first slot in the array, etc.

.IP MSG_SETITEMSTATES
This message allows an application to modify the individual state
flags associated with each of the checkboxes contained within the
specified editor instance.
Presently, only the 
.B XrVISIBLE
and the
.B XrSENSITIVE
flags are supported.
The
.I instance
parameter must specify the editor instance which is to be modified,
while the
.I data
parameter should point to an array of 8 bit integer values.
The new state flags which are to be assigned to each entity within the
instance will be obtained from this array.
The value in the first slot of the array will be assigned to checkbox 0,
etc.
After the new state flags have been saved, only those checkboxes whose
state flags changed will be redrawn.

.IP MSG_GETITEMCOUNT
This message allows an application to obtain a count, which
indicates the number of individual checkboxes in the specified instance.
The editor will assume that the 
.I instance
parameter specifies the editor instance to be queried, and the
.I data 
parameter points
to a 32 bit integer value; the item count value will be
returned by means of this integer.
.IP
This message is useful when used in conjunction with the
.B MSG_GETITEMRECTS 
message.
It allows an application to obtain the number of items in the
instance, so that the application can then allocate enough
memory to hold the rectangle information returned by
.B MSG_GETITEMRECTS.

.IP MSG_GETITEMRECTS
This message returns the coordinates for the rectangle which
describes each of the individual checkboxes; these rectangles describe only the
individual checkboxes - it does not include the labels.
The message will expect the 
.I instance
parameter to indicate the editor instance to be queried, and the
.I data 
parameter to point to a structure of the following format:
.sp
.nf
	RECTANGLE   itemRects[x];
.fi
.sp
This array will then be filled with the rectangle information, and
returned to the application.
.IP
Before an application can make this call, it needs to know
the number of items in the specified instance, so that it can
allocate a structure large enough to hold all of the rectangle
information.
The application should use the 
.B MSG_GETITEMCOUNT 
message to
obtain this information; the application can then allocate
an array large enough to hold all of the rectangle entries.
.IP
The order of the rectangle items returned in the array directly
correlates to the order the items were originally created in.
The first element in the array will describe checkbox 0, the
second checkbox 1, etc.
.IP
This message is useful to those applications which have a need
of knowing where the individual items in a checkbox instance are located.
The most common use would be by a forms controller, which would
use the information to place an 'active field' indicator by a
given item.

.IP MSG_REDRAW
This editor provides an application with the means for
requesting that an instance of checkboxes be redrawn.
The current values, labels and font information will be used.
.IP
When this message is issued, the 
.I instance
parameter must be a pointer to the editor structure associated 
with the instance to be redrawn.
The 
.I data
parameter must be a 32 bit integer which 
specifies the type of redraw to perform.
.IP
The checkbox editor supports the following redraw mode:
.sp
.in 8
.nf
.B - XrREDRAW_ALL
.fi
.in
.IP
If any other redraw mode is specified, then the request will fail.

.IP MSG_SIZE
This message allows an application to obtain the rectangle needed to
contain a checkbox editor instance.
The checkbox editor expects the 
.I instance
parameter to be set to
.B NULL, 
and the
.I data 
parameter to point to an instance of the following structure:
.sp
     typedef struct {
          Window       editorWindowId;
          RECTANGLE    editorRect;
          INT8         editorState;
          INT32        editorFGColor;
          INT32        editorBGColor;
          FontInfo   * editorFont;
          INT16        numFields;
          INT16        numCols;
          INT8      ** labels;
          INT8       * values;
          INT8       * stateFlags;
      } xrCheckBoxInfo;
.sp
.IP
The only fields which must be filled out by the application program BEFORE
issuing this call, are the 
.I numFields, 
.I numCols, 
.I labels,
and 
.I editorFont 
fields; all other fields are ignored.
.IP
Using the supplied information, the editor will determine
the size of the rectangle needed to contain this instance.
In return, the
.I editorRect
field will be filled in with the coordinates for the
0 based rectangle needed to contain this instance;
an application program can then offset this rectangle, to
position it where ever it likes, within its window.
.IP
If 
.I numCols > numFields, 
then the request will fail.

.IP MSG_MOVE
This message provides an application with a means for quickly relocating 
a particular editor instance within a window.
The size of the 
.I editorRect 
associated with the instance is not changed.
To relocate an editor instance, a new origin point for the instance's
.I editorRect 
must be specified; the top left corner of the editor rectangle 
will then be translated such that it now coincides with the new origin.
The origin point is interpreted as an absolute position within the window.
.IP
When this message is issued, the
.I instance
parameter must point to the editor structure associated with the
instance which is to be moved, while the
.I data
parameter must point to a 
.I POINT 
structure, containing the new
.I editorRect 
origin.
.IP
When an editor instance is relocated, the field editor will automatically
remove the visual image of the instance from the window, and will then redraw
the instance at its new location; this occurs only if the instance is
visible.

.IP MSG_RESIZE
This message provides an application with a means for both changing the
size of the 
.I editorRect
associated with a particular editor instance, and also the location of
the new
.I editorRect.
All restrictions regarding the
.I editorRect
size which applied when the instance was first created using
.B MSG_NEW,
still apply.
If an invalid 
.I editorRect
is specified, then the resize request will fail.
.IP
When this message is issued, the
.I instance
parameter must point to the editor structure associated with the instance
which is to be resized, while the
.I data
parameter must point to a 
.I RECTANGLE 
structure containing the
new size and origin for the 
.I editorRect.
.IP
When an editor instance is resized, the field editor will automatically
remove the visual image of the instance from the window, and will then
redraw the instance using the new size and location information; this
occurs only if the instance is visible.

.IP MSG_EDIT
Normally, an application will not issue this message;
it is usually issued by the Xrlib input routines, when
an input event occurs within a checkbox instance.
.IP
When such an event occurs, a 
.B MSG_EDIT 
message will be issued to the editor, with
the first parameter,
.I instance,
indicating which checkbox instance to process, and
the third parameter,
.I data,
pointing to an 
.I XEvent
structure.
.IP
The checkbox editor only handles an event if 
it maps to an
.B XrSELECT
event, as described by
.B XrMapButton(3X)
and
.B XrInit(3X);
all others are ignored.  When a select event
occurs within a checkbox instance, the first thing done is to determine
if one of the checkboxes was selected.
.IP
If one of the checkboxes was selected, then the value of the
selected checkbox will be toggled, and the particular box redrawn.
Afterwards, an input event will be added to the front of the
application's input queue, informing it that one of the
checkboxes was selected.
The returned 
.I xrEvent
structure is set to the following value:
.sp
.nf
   type       = XrXRAY
   source     = the window id
   inputType  = XrEDITOR
   inputCode  = XrCHECKBOX
   value1     = XrSELECT
   value2     = index of the modified checkbox
   valuePtr   = pointer to instance's editor structure
.fi
.IP
The editor will update the value of the selected checkbox
in the array shared with the application program.
This value is then directly available to the application program.
.IP
If a select occurs within a checkbox instance, but not within
the boundary of a checkbox, then the editor will do
nothing but push an input event onto the front of the application's
input queue.
The event will notify the application that the editor was selected,
but no action took place.
In addition, the cursor position at the time the select event
occurred will be returned.
The returned 
.I xrEvent
structure is set to the following value:
.sp
.nf
   type      = XrXRAY
   source    = the window id
   inputType = XrEDITOR
   inputCode = XrCHECKBOX
   value1    = NULL
   valuePt   = cursor position
   valuePtr  = pointer to instance's editor structure
.fi
.sp
.SH RETURN VALUE
Upon successful completion of any of the messages, a non-NULL
value will be returned.
In the case of 
.B MSG_NEW,
this non-NULL value will be the pointer to the
newly created editor instance structure.
.sp
.SH ERROR CONDITIONS
Messages to the checkbox editor will fail, set the
.I xrErrno
global and return a NULL
value, under the following conditions:
.sp
.IP MSG_NEW
.I data
is set to NULL [XrINVALIDPTR].
.IP
.I editorWindowId
is an invalid Id [XrINVALIDID].
.IP
.I numCols > numFields [XrINVALIDPARM].
.IP
.I values
is set to NULL [XrINVALIDPTR].
.IP
An invalid editor rectangle is specified [XrINVALIDRECT].
.IP
A call to 'X' fails { XMakePixmap() } [XrXCALLFAILED].
.IP
Memory cannot be allocated [XrOUTOFMEM].
.sp
.IP MSG_REDRAW
A redraw mode other than
.B XrREDRAW_ALL
was specified [XrINVALIDOPTION].
.sp
.IP MSG_SIZE
.I data
is set to NULL [XrINVALIDPTR].
.IP
.I numCols > numFields [XrINVALIDPARM].
.sp
.IP MSG_RESIZE
An invalid editor rectangle is specified [XrINVALIDRECT].
.sp
.IP "MSG_GETSTATE, MSG_MOVE, MSG_RESIZE, MSG_GETITEMRECTS,"
.IP "MSG_GETITEMSTATES, MSG_SETITEMSTATES and MSG_GETITEMCOUNT"
.I data
is set to NULL [XrINVALIDPTR].
.sp
.IP "All messages, except MSG_NEW and MSG_SIZE"
The
.I instance
parameter is set to NULL [INVALIDID].

.SH "SEE ALSO"
XrInput(3X), XrInit(3X)
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