September 95 - Multipane Dialogs
Multipane Dialogs
Norman Franke
As
applications grow in power and complexity, so does the tendency to present
users with numerous cluttered dialog boxes. To simplify the user interface,
developers are moving increasingly to dialogs with multiple panes. This article
describes how to implement multipane dialogs that users navigate by clicking in
a scrolling list of icons.
Dialog boxes with multiple panes ("pages" of controls) are an increasingly
popular element of the Macintosh user interface. Like simple dialogs, multipane
dialogs can be presented when users need to indicate preferences, set
attributes of text or graphic objects, or give specifications for complex
operations such as searches or formatting, among other things. By grouping
related options and providing a single point of interaction for manipulating
them, multipane dialogs simplify life for the user and the developer.
Five different kinds of controls for navigating multipane dialogs are in
general use: the scrolling list of icons, the pop-up menu, index tabs
(simulating the look of tabs on the tops of file folders in a file cabinet),
Next/Previous buttons, and icon button sets. Although there aren't any
hard-and-fast rules about when you should use one over another, these
considerations (suggested by Elizabeth Moller of Apple's Human Interface Design
Center) generally apply:
- Novice users have trouble with pop-up menus, so choose a different kind of
control if your target audience includes large numbers of these users.
- Index tabs work well for small numbers of panes, but they may not work
well when the tabs start overlapping or the number of panes is variable.
- Next/Previous buttons are a good choice when there's more than one
mandatory pane. They make it easy for users to step through mandatory and
optional panes in sequence.
The sample application MPDialogs on this
issue's CD demonstrates the use of a multipane preferences dialog navigated by
clicking in a scrolling list of icons, similar to the Control Panel in System 6
and print dialogs in QuickDraw GX. After describing the user interface
presented by this sample program, I'll go into the details of how to implement
a similar multipane dialog in your own application. Source code for the
routines I'll discuss is also included on the CD. This code requires System 7
and is compatible with both black-and-white and color displays.
To experience how multipane dialogs work, run the sample program MPDialogs.
When you choose Preferences from the File menu, you'll be presented with the
interface shown in Figure 1. This is a good illustration of the elements of a
multipane dialog.
The long vertical rectangle on the left side of the dialog box contains the
pane selection icon list. Each icon in this scrolling list has a one-word label
under it for identification and represents one pane of the dialog, which is
displayed when the user clicks the icon. If you click the Defense icon, for
instance, you'll see the pane shown in Figure 2. The arrow and tab keys on the
keyboard can also be used to change the pane selection; however, if the current
pane contains multiple editable text fields, the tab key will work as in a
normal dialog and move the cursor to the next text field.
The bottom portion of the dialog below the line contains two buttons that act
on the dialog as a whole: Cancel and OK. The OK button accepts the settings and
Cancel aborts all changes and closes the dialog. The two buttons above the line
act only on the current pane and are optional: Revert restores the control
values in the current pane to what they were when that pane was last opened,
and Use Defaults resets the control values in that pane to factory defaults.
The large region above the buttons is where the pane's controls are placed. The
sample code supplied on the CD handles actions for checkboxes, radio button
groups, and pop-up menus. Command-key equivalents can be used to toggle
checkboxes and radio buttons, in addition to the standard keyboard equivalents
for OK (Return/Enter) and Cancel (Escape/Command-period). After experimenting
with making changes to the control values in the sample program, you can choose
Display from the File menu to see the results of your changes.
A couple of custom capabilities can be added to a pane through optional
procedures:
- taking special action such as dimming or undimming other controls when
items are clicked
- performing data validation such that if validation fails, the user
isn't permitted to change panes or exit the dialog with the OK button
These
two capabilities are demonstrated in the sample multipane dialog. When you
click the Enable Self-Destruct checkbox in the Defense pane, the Self-Destruct
checkbox is undimmed. When you enter nondigits in the editable text field in
the Communications pane, data validation fails and you're unable to change
panes or click OK.
Note that multipane dialogs, like simple dialogs, can take one of three forms:
- standard modal dialog -- a dialog that has a border around it and no title
bar, that can't be moved around on the screen, and that stays frontmost as long
as it's open
- movable modal dialog -- a dialog that has a border around it and a
title bar, that can be moved around on the screen, and that stays frontmost as
long as it's open and the application is frontmost
- modeless dialog -- a dialog that looks and behaves like a normal
document window with a title bar and a close box, and that isn't always
frontmost
The sample program displays a movable modal dialog, but the code
provided supports all three forms.
That's all there is to the interface. For some words of wisdom about things to
take into account as you design your own multipane dialogs, see "Tips for
Designing Multipane Dialogs." Now we'll move along to the details of how to
incorporate the multipane dialog routines on the CD into your own application:
the resources you need to define, the calls to make to the main routines to
open the dialog and handle events, and the customizing you can do with optional
procedures.
BY ELIZABETH MOLLER OF APPLE'S HUMAN INTERFACE DESIGN CENTER
A multipane dialog is appropriate only when the panes you're presenting are
obviously related to one another in some way. With that caveat in mind, here
are some suggestions for making your multipane dialogs easy to understand and
use:
- Provide a sentence or title to help clarify your intent. For example, you
might precede a scrolling list of icons in a preferences dialog with a sentence
like "Select items from this list to set your SurfWriter preferences."
- If you use an icon list, label the icons in your list to help users
recognize them.
- Visually separate buttons that apply only to the current pane from
those that work on all panes (like OK and Cancel in a modal dialog).
- Don't change the size of the dialog or window as the user navigates
from pane to pane. Pick a size that accommodates the pane with the most
controls.
- Design the dialog so that changing the settings in one pane doesn't
change the settings in another. For example, clicking a checkbox in one pane
shouldn't disable a checkbox in another pane, because the user won't see the
latter action occur and thus won't understand the cause and effect.
- Be consistent in your use of controls. If you use a particular type of
control to mean "choose a setting," for instance, don't use the same type of
control to mean "navigate between panes" in the same dialog. Users should be
able to easily distinguish controls that navigate through multiple panes from
controls that make choices in the dialog.
- Order the panes from mandatory to optional, by frequency of use, from
general to specific, or, when no other order is apparent, alphabetically. If
there are mandatory fields and controls, be sure to put them in the first pane
or step the user through mandatory panes before optional ones.
- When the dialog is closed, remember the pane that was last used, unless
there are mandatory controls in a pane. If there is a mandatory pane, it should
always be displayed when the dialog reopens.
The first step in incorporating the multipane dialog routines is to define the
custom resources the code needs. You'll find ResEdit TMPL templates for all the
needed resources on the CD. You can put these in the ResEdit Preferences file
to make them available at all times or leave them in the application you're
editing.
The first resource that needs to be created is the main DLOG and its associated
DITL, which will form the basis for the dialog. A sample is provided in the
file MPDialogs Resources that you can simply copy into a new project's resource
file. The DITL should include six items, numbered as follows:
- OK button
- Cancel button
- Revert button
- Use Defaults button
- a user item that defines the icon list rectangle
- a hidden static text field for default Command-key equivalents
The
Revert and Use Defaults buttons can be moved offscreen to make either of them
unavailable. (Alternatively, the buttons can be removed and the control
#defines in the main header file, MPDialogs.h, can be changed to reflect the
new numbering.) The icon list is always displayed vertically, and the rectangle
doesn't include the scroll bar. The sample application provides the standard
Command-key equivalents for OK and Cancel. The standard equivalents for OK are
handled in the code; those for Cancel are handled by means of the hidden static
text field, which defines default Command-key equivalents for the rest of the
controls in the dialog as well.
A DITL needs to be created for each pane. The first item is a hidden static
text field that defines Command-key equivalents for the items in the pane; this
is in addition to the default list in the main DITL. See "Code for Dialog
Command-Key Equivalents" for details of the syntax.
The Command-key equivalent code I provide in the sample uses a modified version
of KeyEquivFilter, a routine in Utilities.c, which is part of DTS Lib on the
CD. It takes these two additional parameters:
- The ID of the static text item that contains the mappings. My dialog code
calls this routine twice, once for the bottom buttons and a second time for the
items in the pane.
- An offset to add to the item numbers when a hit occurs. This allows the
code to use relative item numbering for easier specification of Command-key
equivalents in panes.
The static text item is an item-match string that
follows the general format =cxxyyzz or ccxxyyzz. The =c matches the character
c, and cc matches the character by its ASCII value. The next number, xx (a flag
byte with the bits set to specify the modifier keys you're checking for), is
logically ANDed with the modifier flags from the key-down event and compared to
yy (a flag byte with the bits set to specify the values of the modifier keys --
for example, you can force the Control key to be up). If this comparison is
true and if the character c matches the character the user typed, the item zz
is returned as being hit.
Each item-match string is eight characters long and is separated from other
such strings that follow by a comma. The numbers in the strings are hexadecimal
and case is significant for character matches.
For example, the hidden static text field that's checked for each pane in the
sample application is
=.190102,1B190102,1B190002
The
first item-match string checks for a period and for the Control, Option, and
Command keys. If only the Command key has been pressed, item 2 is returned as
being hit. Similarly, the next item-match string handles Command-Escape (Escape
is 1B) and the last item-match string handles Escape by itself.
The items are numbered local to each DITL, so that, for example, the first
control would be item 2. All user items in the DITL are set to the DrawGray
procedure, which outlines the item's rectangle with either the gray color or a
stippled gray pattern, depending on the user's monitor.
Next, a DTL# resource should be created with the same resource ID as the main
DLOG resource. It contains a list of the resource IDs of the DITLs that
comprise a specific multipane dialog and the text displayed under each icon in
the list. Then the icon groups are created; they have the same resource ID as
the DITL to which they correspond. Small versions of the icons aren't needed,
but color versions should be created for display on color-capable Macintosh
computers.
Optional DGRP resources can be created for specifying radio button groups. The
resource ID is the same as that of the corresponding pane's DITL. Each DGRP can
contain multiple groups per pane, if desired; however, a particular radio
button should only be used in a single group. Like the per-pane Command-key
equivalent strings, items are numbered local to the DITL.
You should also copy the following:
- the pseudo-CDEF with resource ID 251, which provides support for using the
icon list as a control (in the file MPDialogs Resources)
- the LDEF with resource ID 130, which implements the icon list
definition for the List Manager (in the file Icon LDEF in the LDEF folder)
- optionally, the 'hdlg' resource and corresponding STR# resource for
Balloon Help support (in the file MPDialogs Resources)
You can add Balloon
Help to a multipane dialog by adding two help items to the individual DITL
resources that make up each pane. One is for the controls in the main DITL and
uses an 'hdlg' resource and an STR# resource with the same ID. The second help
item is an 'hdlg' resource for each pane's DITL; it should start at item 8 for
the first control in the pane. See the file MPDialogs.u.rsrc on the CD for a
sample 'hdlg' resource for the first pane.
Now we'll review the calls your application needs to make to the main routines
in order to open and close the multipane dialog, handle events, and access the
values of the controls in the dialog. But first, let's look at the data your
application needs to maintain.
Your application must maintain a DialogPtr for each dialog used. You also need
to declare a handle for storing the returned settings. Passing a pointer to
NULL causes the code to allocate a new handle and return it to the caller;
otherwise, a handle to an existing record must be provided. For a preferences
dialog, this data should be maintained in the application's preferences file in
the Preferences folder.
Implementing preferences files is discussed in the article "The Right Way to
Implement Preferences Files" in develop Issue 18.*
The sample code internally allocates an MPDHdl for each open multipane dialog
for storing state information. The handle is stored in the refCon of the dialog.
Your application should call OpenMPDialog for each desired multipane dialog,
taking any actions necessary when a dialog is opened, such as disabling menus.
This call is passed the resource ID of the DLOG for the dialog, a reference to
the handle that stores the returned settings, and four optional parameters,
which are described later.
Here's an example:
DialogPtr prefDlog = NULL;
Handle thePrefs = NULL;
prefDlog = OpenMPDialog (kPrefDLOG, NULL, NULL, NULL, NULL,
&thePrefs);
if (prefDlog) SetMenusBusy();
// If NULL, the dialog couldn't be opened.
The
main event loop should call DoMPDialogEvent after each event is returned from
WaitNextEvent. If DoMPDialogEvent returns true, the multipane dialog routines
have handled the event; your application should inspect the DialogPtr to
determine whether the dialog has been closed, so that the application can
recover from the dialog state. A return value of false indicates that your
application should process the event as it would normally. For example:
if (DoMPDialogEvent(&prefDlog, &mainEventRec)) {
// A NULL DialogPtr means the dialog has been closed.
if (!prefDlog)
SetMenusIdle();
} else {
// Process the event as usual.
...
}
To
dispose of the dialog without user interaction, your application can call
CloseMPDialog:
CloseMPDialog(prefDlog);
After
the dialog has been closed, it's the application's responsibility to dispose of
or save the data handle created with the call to OpenMPDialog. The code I've
provided assumes this handle is maintained by the application after creation.
The following two routines are provided for accessing the control values stored
in the data handle:
- GetMPDItem retrieves the value of the control corresponding to the pane
and item specified and stores it in a buffer.
- SetMPDItem stores in the handle a value retrieved from a buffer.
Both of these routines assume that the caller knows the length and type of
the control's data representation. Items are numbered differently from in the
DITL resource -- only items that have a value are included, and the values for
radio button groups come after those for all other controls in the data. The
values of checkboxes, enabled buttons in radio button groups, and pop-up menus
are stored as 16-bit integers. Return codes are defined in the header file.
Errors are returned for invalid pane and item numbers and buffer lengths.
The routines are declared as follows:
short GetMPDItem (Handle theData, short pane, short item, Ptr ptr,
short len)
short SetMPDItem (Handle theData, short pane, short item, Ptr ptr,
short len)
The
sample application, in the code for DialogDisplay, provides a basic example of
the use of these routines to display the current settings of the controls in
the previously closed dialog.
Normally, these routines should be sufficient to access the data in the handle.
However, those applications for which it would be more efficient to manipulate
the handle directly can use the following format:
Last Open Pane
Offset to Pane 1, Offset to Pane 2, ..., Offset to Pane n, NULL
(Pane 1) Length of Item 1, Data for Item 1, ..., Length of Item m,
Data for Item m, NULL
...
(Pane n) Length of Item 1, Data for Item 1, ..., Length of Item m,
Data for Item m, NULL
The
Last Open Pane and the Offset to Pane fields are all long integers and the
Length of Item fields are all short integers. The Length of Item value doesn't
include the length of itself; to get to the next field you would add
Length of Item + sizeof(short)
to
the pointer. The Last Open Pane field allows the multipane dialog code to
display the dialog with the last pane the user had open as the current pane.
That's all you need to know to make basic use of my multipane dialog code. But
you can also go a step further: you can customize certain aspects of a
multipane dialog by using the four optional parameters to OpenMPDialog
mentioned above.
The second through fifth parameters to OpenMPDialog can indicate action
procedures that customize dialog behavior by responding to certain events. A
value of NULL for any of these parameters tells the application to use the
default behavior. To provide custom behavior, you would pass a universal
procedure pointer instead of NULL. The procedures can also be changed
dynamically, with the InstallAction routine.
The action procedures and the default actions are as follows:
- The Set Defaults action procedure (parameter 2) provides factory defaults
for controls. The default action is to set them to 0.
- The Click action procedure (parameter 3) enables you to customize the
actions resulting from clicking a control, such as dimming or undimming other
controls or performing data validation. The default action is to toggle
checkboxes and handle radio buttons via the Radio Group action procedure.
- The Edit action procedure (parameter 4) enables special handling of
editable text fields, such as converting the string to an integer. The default
action is to store the entire string as a Str255.
- The Radio Group action procedure (parameter 5) enables you to customize
the behavior of radio button groups, such as how the values are stored. The
default action is to store the value as the index number of the radio button
that's enabled in the group; the default value is 1 (the first radio button in
the group).
All the action procedure pointers are declared as
UniversalProcPtrs for compatibility in case of PowerPC compilation, so they
must be allocated before use. The sample program does this by declaring a
UniversalProcPtr for each desired action procedure. For example, the one for
the Click action procedure is declared as follows:
ClickActionUPP myClickAction = NULL;
It's
initialized in the main routine of the application like this:
myClickAction = NewClickActionProc(MyClickAction);
Depending
on what you want to do in the action procedures, you may need to make use of
the MPDHdl stored in the dialog's refCon, mentioned earlier. This is a handle
to an MPDRec (shown in Listing 1), which is the main data structure used by the
multipane dialog code for state information. None of the elements of this
structure should be modified by user code. The four UPP fields can be
manipulated via calls to InstallAction and RemoveAction.
Listing 1. The MPDRec structure
typedef struct MPDRec {
short numPanes; // Number of panes in the dialog
short currentPane; // Current pane being displayed
short baseItems; // Item number of first item in panes
short *paneIDs; // List of IDs for the pane's DITLs
short paneDirty; // Whether Revert should be enabled
RadioGroupPt radio; // Linked list of radio button groups
Handle theData; // Actual storage for dialog values
Handle tmpData; // Temporary storage for dialog values
Handle *IconHandles;// List of icon suites
ListHandle theList; // List Manager list for the icon list
ClickActionUPP ClickAction; // Action procedures
EditActionUPP EditAction;
GroupActionUPP GroupAction;
DefActionUPP DefAction;
} MPDRec, *MPDPtr, **MPDHdl;
The
baseItems field will be the most useful in the action procedures. It holds the
item number of the first item in the pane, which is the hidden static text item
used for Command-key equivalents. Thus, if dataH is of type MPDHdl, the index
of the first real control (the second DITL entry) in the pane will be
(*dataH)->baseItems + 1.
Now let's take a closer look at each of the action procedures.
The Set Defaults action procedure provides factory defaults for checkboxes and
other controls, except for radio button groups (handled in the Radio Group
action procedure). It's called with a pointer to -- and the length of -- a
buffer holding the internal representation of the value of a single control
corresponding to a specific pane and item number. You can call DefaultAction to
take the default action for items your code doesn't handle.
The procedure is declared like this:
void MySetDefAction (Ptr theData, short len, short iType, short pane,
short item)
The
Set Defaults action procedure's defaults for radio buttons apply only to those
that aren't part of a radio button group. But using single radio buttons is
definitely not advised; all radio buttons should be in groups to be consistent
with the Macintosh Human Interface Guidelines.
The Click action procedure enables you to customize the actions resulting from
clicking a control. For instance, this procedure can handle dimming or
undimming other items when certain controls are clicked. It can also provide
validation for control settings when the user tries to change the pane or click
OK, to ensure that the entered settings make sense.
The procedure receives a DialogPtr and the pane and item numbers. It's declared
as follows:
short MyClickAction(short mType, DialogPtr dlog, short pane,
short item)
The
mType parameter specifies the message to process when the action procedure is
called. The procedure is called with a kInitAction message right after the
control is set when the pane is first displayed; this gives you an opportunity
to set up the initial state of the dialog. The procedure is called with a
kClickAction message after the user has released the mouse button in a control.
A kValidateAction message is received for data validation; it's the
responsibility of the Click action procedure to put up an alert to notify the
user if a setting is unacceptable.
Listing 2 is a Click action procedure from the sample application that undims
the third checkbox in the Defense pane (Self-Destruct) if the second checkbox
(Enable Self-Destruct) is checked. It also ensures that the editable text field
in the Communications pane contains only digits; if this field contains
nondigits, the validation fails and the user can't change panes or click OK.
Listing 2. A sample Click action procedure
short MyClickAction(short mType, DialogPtr dlog, short pane,
short item)
{
MPDHdl dataH;
short iType, val = 0;
Rect iRect;
Handle iHandle;
// Obtain multipane dialog state record.
dataH = (MPDHdl) GetWRefCon(dlog);
// Handle the second item validation.
if (mType == kValidateAction) {
// Validation fails if nondigits are in the field.
if (pane == kCommPane &&
item == kFrequency + (*dataH)->baseItems) {
GetDialogItem(dlog, item, &iType, &iHandle, &
iRect);
GetDialogItemText(iHandle, theStr);
val = VerifyDigits(theStr);
if (val)
StopAlert(ALERT_Invalid, NULL);
}
// All other items validate OK.
return val;
}
// If this isn't the second checkbox, handle things the default
// way.
if (pane != kMiscellaneousPane ||
item != kEnableSelfDestruct + (*dataH)->baseItems)
return (DefaultClickAction(mType, dlog, pane, item));
// Initialize and Click messages are handled almost the same.
// Dim the third checkbox based on the value of the second.
GetDialogItem(dlog, item, &iType, &iHandle, &iRect);
val = GetControlValue((ControlHandle) iHandle);
switch (mType) {
// Toggle the item in response to the user click.
case kClickAction:
val = !val;
SetControlValue((ControlHandle) iHandle, val);
// Fall through!
// In either case, enable/disable next checkbox.
case kInitAction:
AbleDItem(dlog, kSelfDestruct + (*dataH)->baseItems, val);
break;
}
// Initialize and Click messages should never fail.
return 0;
}
The
default Click action procedure, DefaultClickAction, calls the Radio Group
action procedure to handle buttons in a radio button group; thus, actions in
response to a click in a radio button group should be handled there. Call
DefaultClickAction to inherit default functionality for controls not handled in
your customization procedure.
The Edit action procedure enables special handling of editable text fields. A
common implementation is to store the field's string as a long integer,
converting the string value to and from this form as needed.
This procedure receives a pointer to a buffer for storage of the control's
internal value, a handle to the control, and the pane and item numbers; it
returns the length of the space required for the text field. The first
parameter is a message that informs the procedure whether to calculate the
storage size for this field, initialize the value, or copy the value to or from
the field.
The procedure is declared as follows:
short MyEditAction(short mType, Ptr hPtr, Handle iHandle, short pane,
short item)
The
kCalcAction message requests the amount of storage required for the
representation of the field value in memory. The kInitAction message requests
that the value of the field be initialized. The kP2TAction message requests
that the code retrieve the value of the field and store it in memory (in other
words, that the permanent storage value be transferred to the temporary storage
area -- P2T is shorthand for "permanent to temporary"). Conversely, the
kT2PAction message ("temporary to permanent") requests that the code set the
field to the value indicated by the representation in memory. Default behavior
can be maintained by calling DefaultEditAction, if desired.
Listing 3 is an Edit action procedure from our sample application. Normally,
the procedure should check the item and pane numbers to distinguish between
different text fields, but the sample application has only one such field.
Listing 3. A sample Edit action procedure
short MyEditAction(short mType, Ptr hPtr, Handle iHandle, short pane,
short item)
{
short ret = 0;
long val;
Str255 textStr;
Assert(hPtr != NULL);
switch (mType) {
case kP2TAction: // Save value of control.
GetItemDialogText(iHandle, textStr);
StringToNum(textStr, &val);
*(long *) hPtr = val;
ret = sizeof(long);
break;
case kT2PAction: // Set value of control.
val = *(long *) hPtr;
NumToString(val, textStr);
SetIText(iHandle, textStr);
ret = sizeof(long);
break;
case kInitAction: // Initialize value.
*(long *) hPtr = 0;
ret = sizeof(long);
break;
case kCalcAction: // How much storage do we need for this?
ret = sizeof(long);
break;
}
return ret;
}
To simplify using radio button groups, a single value is stored for the entire
group. This value is the relative item number of the enabled button in the
group. For example, the value of a group of three radio buttons with the second
one enabled would be 2.
In the sample program, radio button groups are stored in a linked list starting
from the radio field of the MPDRec structure. The RadioGroup structure is
defined as shown in Listing 4.
Listing 4. The RadioGroup structure
typedef struct RadioGroup {
struct RadioGroup *next;
short pane;
short num;
short items[1];
} RadioGroup, *RadioGroupPtr;
The
next field points to the next radio button group, to enable traversing the
linked list of groups. The pane field is the pane number this group belongs to.
The num field holds the number of items that make up this radio button group.
The relative item numbers of these radio buttons are stored in the items
array.
The Radio Group action procedure enables you to customize the behavior of radio
button groups. For instance, an application could choose to store radio button
group values differently from the default or handle dimming or undimming of
items in response to the user's actions. The Radio Group action procedure
receives the same messages as the Edit action procedure. It returns the length
of the space required for the radio button group's internal storage; the
default is four bytes per group, two for the number of radio buttons and two
for the value as a short integer.
Like the Edit action procedure, the Radio Group action procedure is called with
the kInitAction and kCalcAction messages. However, these messages occur before
the dialog is opened, so the DialogPtr will be NULL at that time. The procedure
is declared like this:
short MyGroupAction(short mType, RadioGroupPtr group, Handle dataH,
DialogPtr dlog, Ptr hPtr, short pane, short item)
Note
that in response to the kInitAction message, the action procedure is expected
to store the number of radio buttons in the group in the first two bytes of the
internal storage. Here's an example from the default Radio Group action
procedure (dataH is of type MPDHdl):
for (i = 0; i < group->num; i++) {
if (GetCheckOrRadio(dlog, group->
items[i] + (*dataH)->baseItems - 1))*(short *) hPtr = i + 1;
}
To
obtain the actual item number for the control in the dialog, you just add
(*dataH)->baseItems - 1
to
the relative number stored in the items array, as shown in the above code. As
mentioned earlier, the baseItems field of dataH is the number of the first
pane-specific item in the dialog.
The code that accompanies this article on this issue's CD provides an
easy-to-implement method for adding icon-selected multipane dialogs to any
application. (The routines for managing radio button groups could be extracted
without much difficulty and used elsewhere.) The sample program also provides
an example of using the AppendDITL and ShortenDITL routines. So experiment with
the sample application and then try out multipane dialogs as a way of
simplifying the user interface in your own application.
NORMAN FRANKE misses the large electrical storms and green things of his native
Pennsylvania, but not the humidity. He's using the B.S. in computer science he
earned from Carnegie Mellon as he writes Macintosh software for a large
national laboratory in northern California. Now working on an M.S. in computer
science at Stanford, he enjoys writing sound manipulation software for his
Macintosh and watching classic and action/adventure movies in his spare
time.*
Thanks to our technical reviewers Tim Craycroft, Nitin Ganatra, C. K. Haun, and
Elizabeth Moller. Thanks also to Eric Soldan for ListControl and KeyEquivFilter
from DTS Lib.*
