Volume 6A: Motif Programming Manual

XmDIALOG_COMMAND

XmDIALOG_FILE_SELECTION

These values should be self−explanatory, with the exception of XmDIALOG_WORK_AREA. This value is set when a

SelectionBox is not the child of a DialogShell and it is not one of the other types of dialogs. In other words, if you

create a SelectionDialog using XmCreateSelectionDialog(), the value is XmDIALOG_SELECTION, but if

you use XmCreateSelectionBox(), the value is XmDIALOG_WORK_AREA. When a SelectionBox is created as

the child of a DialogShell, the Apply button is automatically managed, except if XmNdialogType is set to

XmDIALOG_PROMPT. Otherwise, the button is created but not managed.

The different types of SelectionDialogs are meant to be used for unique purposes. Each dialog provides different

components that the user can interact with to perform a task. In the following sections, we examine each of the

SelectionDialogs in turn.

7.2 SelectionDialogs

The SelectionDialog provides a ScrolledList that allows the user to select from a list of choices, as well as a TextField

where the user can type in choices. When the user makes a selection from the list, the selected item is displayed in the

text entry area. The user can also type new or existing choices into the text entry area directly. The dialog does not

take any action until the user activates one of the buttons in the action area or presses the RETURN key. If the user

double−clicks on an item in the List, the item is displayed in the text area and the OK button is automatically

activated. the source code demonstrates the use of a SelectionDialog. XtSetLanguageProc() is only available in

X11R5; there is no corresponding function in X11R4. XmStringCreateLocalized() is only available in Motif

1.2; XmStringCreateSimple() is the corresponding function in Motif 1.1. XmFONTLIST_DEFAULT_TAG

replaces XmSTRING_DEFAULT_CHARSET in Motif 1.2.

/* select_dlg.c −− display two pushbuttons: days and months.

* When the user selections one of them, post a selection

* dialog that displays the actual days or months accordingly.

* When the user selects or types a selection, post a dialog

* the identifies which item was selected and whether or not

* the item is in the list.

*

* This program demonstrates how to use selection boxes,

* methods for creating generic callbacks for action area

* selections, abstraction of data structures, and a generic

* MessageDialog posting routine.

*/

#include <Xm/SelectioB.h>

#include <Xm/RowColumn.h>

#include <Xm/MessageB.h>

#include <Xm/PushB.h>

Widget PostDialog();

char *days[] = {

"Sunday", "Monday", "Tuesday", "Wednesday",

"Thursday", "Friday", "Saturday"

};

char *months[] = {

"January", "February", "March", "April", "May", "June",

"July", "August", "September", "October", "November", "December"

};

typedef struct {

char *label;

char **strings;

7 Selection Dialogs 7.2 SelectionDialogs

144

int size;

} ListItem;

ListItem month_items = { "Months", months, XtNumber (months) };

ListItem days_items = { "Days", days, XtNumber (days) };

/* main() −−create two pushbuttons whose callbacks pop up a dialog */

main(argc, argv)

char *argv[];

{

Widget toplevel, button, rc;

XtAppContext app;

void pushed();

XtSetLanguageProc (NULL, NULL, NULL);

toplevel = XtVaAppInitialize (&app, "Demos", NULL, 0,

&argc, argv, NULL, NULL);

rc = XtVaCreateWidget ("rowcolumn",

xmRowColumnWidgetClass, toplevel, NULL);

button = XtVaCreateManagedWidget (month_items.label,

xmPushButtonWidgetClass, rc, NULL);

XtAddCallback (button, XmNactivateCallback, pushed, &month_items);

button = XtVaCreateManagedWidget (days_items.label,

xmPushButtonWidgetClass, rc, NULL);

XtAddCallback (button, XmNactivateCallback, pushed, &days_items);

XtManageChild (rc);

XtRealizeWidget (toplevel);

XtAppMainLoop (app);

}

/* pushed() −−the callback routine for the main app's pushbutton.

* Create a dialog containing the list in the items parameter.

*/

void

pushed(widget, client_data, call_data)

Widget widget;

XtPointer client_data;

XtPointer call_data;

{

Widget dialog;

XmString t, *str;

int i;

extern void dialog_callback();

ListItem *items = (ListItem *) client_data;

str = (XmString *) XtMalloc (items−>size * sizeof (XmString));

t = XmStringCreateLocalized (items−>label);

for (i = 0; i < items−>size; i++)

str[i] = XmStringCreateLocalized (items−>strings[i]);

dialog = XmCreateSelectionDialog (widget, "selection", NULL, 0);

XtVaSetValues (dialog,

XmNlistLabelString, t,

XmNlistItems, str,

XmNlistItemCount, items−>size,

XmNmustMatch, True,

NULL);

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145

XtSetSensitive (

XmSelectionBoxGetChild (dialog, XmDIALOG_HELP_BUTTON), False);

XtAddCallback (dialog, XmNokCallback, dialog_callback, NULL);

XtAddCallback (dialog, XmNnoMatchCallback, dialog_callback, NULL);

XmStringFree (t);

while (−−i >= 0)

XmStringFree (str[i]); /* free elements of array */

XtFree (str); /* now free array pointer */

XtManageChild (dialog);

XtPopup (XtParent (dialog), XtGrabNone);

}

/* dialog_callback() −−The OK button was selected or the user

* input a name by himself. Determine whether the result is

* a valid name by looking at the "reason" field.

*/

void

dialog_callback(widget, client_data, call_data)

Widget widget;

XtPointer client_data;

XtPointer call_data;

{

char msg[256], *prompt, *value;

int dialog_type;

XmSelectionBoxCallbackStruct *cbs =

(XmSelectionBoxCallbackStruct *) call_data;

switch (cbs−>reason) {

case XmCR_OK:

prompt = "Selection: ";

dialog_type = XmDIALOG_MESSAGE;

break;

case XmCR_NO_MATCH:

prompt = "Not a valid selection: ";

dialog_type = XmDIALOG_ERROR;

break;

default:

prompt = "Unknown selection: ";

dialog_type = XmDIALOG_ERROR;

}

XmStringGetLtoR (cbs−>value, XmFONTLIST_DEFAULT_TAG, &value);

sprintf (msg, "%s%s", prompt, value);

XtFree (value);

(void) PostDialog (XtParent (XtParent (widget)), dialog_type, msg);

if (cbs−>reason != XmCR_NO_MATCH) {

XtPopdown (XtParent (widget));

XtDestroyWidget (widget);

}

}

/*

* PostDialog() −− a generalized routine that allows the programmer

* to specify a dialog type (message, information, error, help,

* etc..), and the message to show.

*/

Widget

PostDialog(parent, dialog_type, msg)

Widget parent;

int dialog_type;

char *msg;

7 Selection Dialogs 7.2 SelectionDialogs

146

{

Widget dialog;

XmString text;

dialog = XmCreateMessageDialog (parent, "dialog", NULL, 0);

text = XmStringCreateLocalized (msg);

XtVaSetValues (dialog,

XmNdialogType, dialog_type,

XmNmessageString, text,

NULL);

XmStringFree (text);

XtUnmanageChild (

XmMessageBoxGetChild (dialog, XmDIALOG_CANCEL_BUTTON));

XtSetSensitive (

XmMessageBoxGetChild (dialog, XmDIALOG_HELP_BUTTON), False);

XtAddCallback (dialog, XmNokCallback, XtDestroyWidget, NULL);

XtManageChild (dialog);

return dialog;

}

The output of the program is shown in the figure.

Output of select_dlg.c

The program displays two PushButtons, one for months and one for the days of the week. When either button is

activated, a SelectionDialog that displays the list of items corresponding to the button is popped up. In keeping with

the philosophy of modular programming techniques, we have broken the application into three routines −− two

callbacks and one general−purpose message posting function. The lists of day and month names are stored as arrays of

strings. We have declared a data structure, ListItem, to store the label and the items for a list. Two instances of this

data structure are initialized to the correct values for the lists of months and days. We pass these data structures as the

client_data to the callback function pushed(). This callback routine is associated with both of the

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147