Related Info: Dialog Manager

Looking Deeper into the Dialog Manager

Handling Modeless Dialogs

By Dave Mark, MacTech Magazine Regular Contributing Author

Over the last few columns, we’ve explored the mysteries of the Dialog Manager via a program called Dialogger. As promised, the next few columns will go deeper into the Dialog Manager, presenting a program called Modeless. Modeless implements a modeless dialog, a dialog that looks and acts like a regular window, but retains the benefits of being managed by the Dialog Manager. Because of Modeless’ size, we’ll create the Modeless resources and enter the Modeless source code this month, and put off a detailed discussion of the program till next month’s column.

Creating the Modeless Resources

Most of the resources we’ll need for this month’s column can be copied from last month’s resource file, Dialogger.Π.rsrc. Start by creating a new folder in your Development folder named Modeless ƒ. Next, duplicate the file Dialogger.Π.rsrc and drag the copy into the Modeless ƒ folder. Change the name of this file to Modeless.Π.rsrc.

Next, launch ResEdit by double-clicking on the file Modeless.Π.rsrc. The Modeless.Π.rsrc window should look similar to the one shown in Figure 1.

Figure 1. Modeless.Π.rsrc, before surgery.

Your first mission is to edit the ALRT, replacing any references to Dialogger with the appropriate reference to Modeless. Double-click on the ALRT icon. When the ALRT-picker window appears, double-click on the only ALRT listed, the one with a resource ID of 129. When the ALRT editor appears, double-click on the ALRT window so the DITL editor appears. Finally, double-click on the static text item and, when the static text editor appears, make your changes. Mine are shown in Figure 2.

Figure 2. A new version of the About... ALRT.

When you’re happy with your About... message, close all the windows until you are back at the main window. Next, you’ll change the About Dialogger... item in the • menu to read About Modeless....

Double-click on the MENU icon to bring up the MENU picker window. Next, double-click on the • MENU, bringing up the MENU editing window. Click on the About Dialogger... item and change it so it says About Modeless..., as shown in Figure 3.

Figure 3. A new version of the • MENU resource.

Close the • MENU editing window, then double-click on the File menu, bringing up the File MENU editing window. Click on the Settings... item and then click in the Cmd-key: field. Type the letter S in the Cmd-key: field. This ties the command-key equivalent S to the Settings... item in the File menu. My File MENU editing window is shown in Figure 4.

Figure 4. A new version of the File MENU resource.

Once you are done, close all the windows leaving just the main window open. Our final chore is to edit the DLOG and DITL resources that made up Dialogger’s modal dialog, changing them to reflect the look of a modeless dialog.

Double-click on the DLOG icon to bring up the DLOG-picker window. Next, double-click on the only DLOG listed, the one with the resource id of 128. The Settings... DLOG editing window should appear. First, click on the Initially visible check box, making sure it is unchecked.

Figure 5. The DLOG editing window, at the half-way point.

Next, click on the second window icon from the left, at the top of the editing window. The DLOG window should change to reflect your new selection. Modeless dialogs don’t have the traditional double-border of their modal cousins. Instead, they look like regular windows. In this case, we want to give our dialog window a close box, so make sure the Close box check box is checked.

We also want to give our dialog window a title. Select Set 'DLOG' Characteristics... from the DLOG menu. When the 'DLOG' Characteristics dialog appears, type the text Fred Settings in the Window title: field and click OK. Your new title should be reflected in the DLOG editing window. Figure 5 shows my DLOG editing window at this point in the process.

Next, we'll edit the DITL associated with this DLOG. Double click on the DLOG window (within the editing window) so the DITL editing window appears. You are now going to delete all the items in the DITL except the Pick one: static text item and the three radio buttons.

Click on the OK button and press the delete key. Click on the Cancel button and press the delete key. Click on the Show preview check box and press the delete key. Finally, click on the user item (the grey rectangle) and press delete.

Next, you'll change the positioning of the remaining four items. Double-click on the Pick one: static text item and change its coordinates to the ones shown in Figure 6. Close the window when you are done.

Figure 6. New coordinates for the Pick one: static text item.

Double-click on the Afghan radio button and change its coordinates to the ones shown in Figure 7. Close the window when you are done.

Figure 7. New coordinates for the Afghan radio button.

Double-click on the Elephant radio button and change its coordinates to the ones shown in Figure 8. Close the window when you are done.

Figure 8. New coordinates for the Elephant radio button.

Double-click on the Squirrel radio button and change its coordinates to the ones shown in Figure 9. Close the window when you are done.

Figure 9. New coordinates for the Squirrel radio button.

Now we're almost done. Close the DITL editing window, leaving you back in the DLOG editing window. The last thing left to do is to resize the DLOG to reflect its slimmed down and rearranged DITL. Change the Bottom: to 123 and the Right: to 234. The final version of our DLOG is shown in Figure 10.

Figure 10. The final version of our DLOG.

Quit ResEdit, being sure to save your changes. Now we're ready to enter our source code.

Creating the Modeless Project

Launch THINK C and create a new project named Modeless.Π in the Modeless ƒ folder. Add MacTraps to the project. Next, create a new source code window and type in the following:

/* 1 */

#define kBaseResID 128
#define kAboutALRTid 129
#define kDialogResID 128

#define kVisible true
#define kMoveToBackNULL
#define kMoveToFront (WindowPtr)-1L
#define kNoGoAwayfalse
#define kSleep   60L

#define kOn 1
#define kOff0

#define iAfghan  1
#define iElephant2
#define iSquirrel3

#define kLeftMargin5
#define kTopMargin 40

#define kFirstRadio1
#define kLastRadio 3

#define mApple   kBaseResID
#define iAbout   1

#define mFile    kBaseResID+1
#define iSettings1
#define iQuit    3


/*************/
/*  Globals  */
/*************/

Boolean gDone;
short   gCurrentPICT = kBaseResID;
DialogPtr gSettingsDLOG = NULL;
WindowPtr gFredWindow = NULL;


/***************/
/*  Functions  */
/***************/

void    ToolBoxInit( void );
PicHandle LoadPICT( short picID );
void    CreateWindow( void );
void    MenuBarInit( void );
void    EventLoop( void );
void    DoEvent( EventRecord *eventPtr );
void    DoDialogEvent( EventRecord *eventPtr );
void    HandleMouseDown( EventRecord *eventPtr );
void    HandleMenuChoice( long menuChoice );
void    HandleAppleChoice( short item );
void    HandleFileChoice( short item );
void    DoUpdate( EventRecord *eventPtr );
void    CreateDialog( void );
void    FlipControl( ControlHandle control );
void    SwitchPICT( void );
    

/******** main *********/

void  main( void )
{
 ToolBoxInit();
 MenuBarInit();
 
 CreateWindow();
 
 EventLoop();
}


/******* ToolBoxInit *******/

void  ToolBoxInit( void )
{
 InitGraf( &thePort );
 InitFonts();
 InitWindows();
 InitMenus();
 TEInit();
 InitDialogs( NULL );
 InitCursor();
}


/******** LoadPICT *********/

PicHandle LoadPICT( short picID )
{
 PicHandlepic;
 
 pic = GetPicture( picID );
 
 if ( pic == NULL )
 {
 SysBeep( 10 );  /*  Couldn't load the PICT resource!!!  */
 ExitToShell();
 }
 return( pic );
}


/******** CreateWindow *********/

void  CreateWindow( void )
{
 PicHandlepic;
 Rect   r;
 
 pic = LoadPICT( gCurrentPICT );
 
 r = (**pic).picFrame;
 
 OffsetRect( &r, kLeftMargin - r.left,
 kTopMargin - r.top );
 
 gFredWindow = NewWindow( NULL, &r, "\pMy Pet Fred",
 kVisible, noGrowDocProc, kMoveToBack, kNoGoAway, 0L );
 
 if ( gFredWindow == NULL )
 {
 SysBeep( 10 );  /*  Couldn't load the WIND resource!!!  */
 ExitToShell();
 }
 
 ShowWindow( gFredWindow );
 SetPort( gFredWindow );
}


/******* MenuBarInit ********/

void  MenuBarInit( void )
{
 Handle menuBar;
 MenuHandle menu;
 
 menuBar = GetNewMBar( kBaseResID );
 SetMenuBar( menuBar );

 menu = GetMHandle( mApple );
 AddResMenu( menu, 'DRVR' );
 
 DrawMenuBar();
}


/******** EventLoop *********/

void  EventLoop( void )
{
 EventRecordevent;
 
 gDone = false;
 while ( gDone == false )
 {
 if ( WaitNextEvent( everyEvent, &event, kSleep, NULL ) )
 DoEvent( &event );
 }
}


/********* DoEvent **********/

void  DoEvent( EventRecord *eventPtr )
{
 char   theChar;
 
 if ( IsDialogEvent( eventPtr ) )
 {
 DoDialogEvent( eventPtr );
 }
 else
 {
 switch ( eventPtr->what )
 {
 case mouseDown: 
 HandleMouseDown( eventPtr );
 break;
 case keyDown:
 case autoKey:
 theChar = eventPtr->message & charCodeMask;
 if ( (eventPtr->modifiers & cmdKey) != 0 ) 
 HandleMenuChoice( MenuKey( theChar ) );
 break;
 case updateEvt:
 DoUpdate( eventPtr );
 break;
 }
 }
}


/********** DoDialogEvent  **********/

void  DoDialogEvent( EventRecord *eventPtr )
{
 short  itemHit;
 short  itemType;
 Handle itemHandle;
 Rect   itemRect;
 short  curRadioButton, i;
 char   theChar;
 BooleanbecomingActive;
 MenuHandle menu;
 DialogPtrdialog;
 
 menu = GetMHandle( mFile );

 switch ( eventPtr->what )
 {
 case keyDown:
 case autoKey:
 theChar = eventPtr->message & charCodeMask;
 if ( (eventPtr->modifiers & cmdKey) != 0 ) 
 HandleMenuChoice( MenuKey( theChar ) );
 break;
 case activateEvt:
 becomingActive =
 ( (eventPtr->modifiers & activeFlag) == activeFlag );
 
 if ( becomingActive )
 {
 for ( i=kFirstRadio; i<=kLastRadio; i++ )
 {
 GetDItem( gSettingsDLOG, i, &itemType, 
 &itemHandle, &itemRect );
 HiliteControl( (ControlHandle)itemHandle, 0 );
 }
 DisableItem( menu, iSettings );
 }
 else
 {
 for ( i=kFirstRadio; i<=kLastRadio; i++ )
 {
 GetDItem( gSettingsDLOG, i, &itemType, 
 &itemHandle, &itemRect );
 HiliteControl( (ControlHandle)itemHandle, 255 );
 }
 EnableItem( menu, iSettings );
 }
 break;
 }
 
 if ( DialogSelect( eventPtr, &dialog, &itemHit ) )
 {
 switch ( itemHit )
 {
 case iAfghan:
 case iElephant:
 case iSquirrel:
 curRadioButton = gCurrentPICT - 
 kBaseResID + kFirstRadio;
 
 if ( curRadioButton != itemHit )
 {
 GetDItem( dialog, curRadioButton, &itemType,
 &itemHandle, &itemRect );
 FlipControl( (ControlHandle)itemHandle );
 
 GetDItem( dialog, itemHit, &itemType,
 &itemHandle, &itemRect );
 FlipControl( (ControlHandle)itemHandle );
 
 curRadioButton = itemHit;
 
 if ( gCurrentPICT != curRadioButton +
 kBaseResID - kFirstRadio )
 {
 gCurrentPICT = curRadioButton +
 kBaseResID - kFirstRadio;
 SwitchPICT();
 }
 }
 break;
 }
 }
}


/********* HandleMouseDown ********/

void  HandleMouseDown( EventRecord *eventPtr )
{
 WindowPtrwindow;
 short  thePart;
 long   menuChoice;
 GrafPtroldPort;
 long   windSize;
 Rect   growRect;
 MenuHandle menu;
 
 thePart = FindWindow( eventPtr->where, &window );
 
 switch ( thePart )
 {
 case inMenuBar:
 menuChoice = MenuSelect( eventPtr->where );
 HandleMenuChoice( menuChoice );
 break;
 case inSysWindow : 
 SystemClick( eventPtr, window );
 break;
 case inContent:
 SelectWindow( window );
 break;
 case inDrag : 
 DragWindow( window, eventPtr->where, 
 &screenBits.bounds );
 break;
 case inGoAway:
 if ( TrackGoAway( window, eventPtr->where ) )
 if ( window == gSettingsDLOG )
 {
 HideWindow( window );
 menu = GetMHandle( mFile );
 EnableItem( menu, iSettings );
 }
 break;
 }
}


/******** HandleMenuChoice **********/

void  HandleMenuChoice( long menuChoice )
{
 short  menu;
 short  item;
 
 if ( menuChoice != 0 )
 {
 menu = HiWord( menuChoice );
 item = LoWord( menuChoice );
 
 switch ( menu )
 {
 case mApple:
 HandleAppleChoice( item );
 break;
 case mFile:
 HandleFileChoice( item );
 break;
 }
 HiliteMenu( 0 );
 }
}


/******* HandleAppleChoice **********/

void  HandleAppleChoice( short item )
{
 MenuHandle appleMenu;
 Str255 accName;
 short  accNumber;
 
 switch ( item )
 {
 case iAbout:
 NoteAlert( kAboutALRTid, NULL );
 break;
 default:
 appleMenu = GetMHandle( mApple );
 GetItem( appleMenu, item, accName );
 accNumber = OpenDeskAcc( accName );
 break;
 }
}


/******** HandleFileChoice *********/

void  HandleFileChoice( short item )
{
 short  newPICTid;
 
 switch ( item )
 {
 case iSettings:
 if ( gSettingsDLOG == NULL )
 CreateDialog();
 else
 {
 ShowWindow( gSettingsDLOG );
 SelectWindow( gSettingsDLOG );
 }
 break;
 case iQuit:
 gDone = true;
 break;
 }
}


/********* DoUpdate ***********/

void  DoUpdate( EventRecord *eventPtr )
{
 PicHandlepic;
 WindowPtrwindow;
 Rect   r;
 
 window = (WindowPtr)eventPtr->message;
 
 pic = LoadPICT( gCurrentPICT );
 
 SetPort( window );
 
 BeginUpdate( window );
 
 r = window->portRect;
 DrawPicture( pic, &r );
 
 EndUpdate( window );
}


/******** CreateDialog  *********/

void  CreateDialog( void )
{
 short  itemType;
 Handle itemHandle;
 Rect   itemRect;
 short  curRadioButton;

 gSettingsDLOG = GetNewDialog( kDialogResID, 
 NULL, kMoveToFront );

 if ( gSettingsDLOG == NULL )
 {
 SysBeep( 10 );  /*  Couldn't load the DLOG resource!!!  */
 ExitToShell();
 }
 
 ShowWindow( gSettingsDLOG );
 SetPort( gSettingsDLOG );
 
 curRadioButton = gCurrentPICT - kBaseResID + kFirstRadio;
 GetDItem( gSettingsDLOG, curRadioButton, &itemType, 
 &itemHandle, &itemRect );
 SetCtlValue( (ControlHandle)itemHandle, kOn );
}


/******** FlipControl *********/

void  FlipControl( ControlHandle control )
{
 SetCtlValue( control, ! GetCtlValue( control ) );
}


/****** SwitchPICT  *********/

void  SwitchPICT( void )
{
 DisposeWindow( gFredWindow );
 
 CreateWindow();
}

Running Modeless

Save your source code as Modeless.c and add it to the project. Select Run from the Project menu to compile and run your program. When the program runs, the My Pet Fred window will appear, showing PICT 128. Pull down the • menu and verify that the first item reads About Modeless.... Select About Modeless... from the • menu and check out your About alert. Are your changes all there? Click the OK button to dismiss the About alert.

Hold down the mouse in the File menu and verify that the S command-key equivalent was added to the Settings... item. Select Settings.... The Settings... modal dialog box should appear (Figure 11).

Figure 11. The Settings... modal dialog box.

Click on the My Pet Fred window, bringing it to the front and sending the modeless dialog to the back. Notice that the radio buttons are dimmed when the dialog is no longer the front-most window (Figure 12).

Figure 12. The radio buttons are dimmed when the dialog box is not in front.

Now type the command-key equivalent S to bring the Settings... dialog to the front again. Once again, the radio buttons should be enabled. Click on the Elephant radio button. Notice that the My Pet Fred window changes appropriately, leaving the Settings...window in front. Click on a few more radio buttons. While you are at it, Click on the File menu. Notice that the Settings... item has been dimmed. Though this doesn't help us much in this program, it's important to be able to disable and enable certain menu items when a modeless dialog is in front.

When you are satisfied with your pet selection, drag the Settings... window to another part of your screen. Now click the close box. The Settings... window disappears. Select Settings... from the File menu. The Settings... window reappears at the position it was in when it disappeared and with the same radio button settings.

Finally, type the command-key equivalent Q to exit the program.

Till Next Month...

Modeless dialogs require a change in the usual modal programming strategy. Modal dialog handling code is usually pretty self-contained. Modeless code tends to be larger and more spread out. Next month, we'll look at the Modeless source code and talk about basic strategies for handling your own modeless dialogs.

Till then, I'm going to test drive the latest addition to my Mac: a Procom Mac-CD-MX CD-ROM drive. If you are in the market for a CD-ROM drive, do yourself a favor and check this one out. It's fast, well-designed, and is Photo-CD compatible. Now if only I could find a Photo-CD to test it with! Hmmm... I do have that roll of undeveloped film sitting on the kitchen counter. Anyone know where I can go to get it turned into a Photo-CD?

OOPS!

Correction to Getting Started, March, 1993.

Notice anything funny about the LoadPict() function in Dialogger and in Modeless? The idea of LoadPICT() was to load a PICT from the resource fork, then return a handle to the PICT. Trouble is, the routine doesn’t return a value. Ooops! Add the line:

return ( pic ) ;

to the end of the function. That should fix things. By the way, if your version of LoadPict() works without this line, you’ve discovered something interesting about the stack. Any guesses?