Popup Menu BASIC
|Column Tag:||BASIC School
Related Info: Menu Manager
Pop Up Menus in True BASIC
By Dave Kelly, MacTutor Editorial Board
Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.
New users of the Macintosh are sometimes fascinated with the use of pull-down menus. Even experienced users head straight for the menu bar when they get a new program to see just what it does. Usually the menus get checked out before the manual does. Hierarchical menus added additional capabilities for the user. A little over a year ago, we began seeing the appearance of pop-up menus as another interface for the user. The various versions of BASIC cover the regular pull-down menus pretty easily. Hierarchical menus and pop-up menus are now being used in most of the software which is now being released. This column will attempt to explain how to set up pop-up menus using True Basic. Similar methods for implementing may be used in ZBasic or any other language for that matter. The method is about the same in whatever language is used and since many of the commands come from the Macintosh Toolbox. It should be pointed out that you must be using System 4.1 or greater for Hierarchical or pop-up menus to work. You should upgrade to the latest version (6.02).
It is advisable to know when it is appropriate to use pop-up menus. Apple recommends that pop-up menus be used for setting values or choosing from lists of related items. A pop-up menu could pop up anywhere (its location is global), but usually used in a dialog. The indication that there is a pop-up menu is that there is a box with a one-pixel thick drop shadow which is drawn around the current value. When the user presses the mouse button which pointing within the box, the pop-up menu appears with the current value checked and highlighted. Other than that, the pop-up menu acts just like any other menu.
The Macintosh ROM takes care of the pop-up menu action, but you must take care of drawing the shadowed box which indicates that there is a pop-up menu. You must take care of inverting the title when the menu is showing. The current value should appear in the pop-up menu when it is selected. Apple also recommends that you NOT use Hierarchical pop-up menus. You should consider very carefully if you really need to use a pop-up menu. Some features could better be implemented with icons or with the normal menus in the menu bar. Dont use commands in your pop-up menus unless you have to. If you do use commands, you should duplicate the item in the menu bar menus. All commands that are in general use throughout the application should appear in the menu bar. This assures that the most important commands are always visible and available to the user. (refer to Commands in pop-up Menu from HI Update #13).
How it works....
Inside Macintosh Volume. V menu manager routines added one new ROM function for doing pop-up menus. The function PopUpMenuSelect allows pop-up menus to be handled and created anywhere on the screen. Since the pop-up menu resources are handled the same as for other menus, they may contain color and submenus. The True Basic demo program has a basic event loop structure which can be used as a basic skeleton for other applications if you want. The libraries which are used come from the True Basic Macintosh Programmers Kit which is essential for any serious Macintosh program development.
To implement pop-up menus, the program uses an array to set up the menu items. These items are declared in the PopItem$ array which is dimensioned near the beginning of the program. SysEnvirons is called to see if the system has the pop-up menu routines. If it doesnt, the program quits. It would be better to display a dialog to warn the user why the program quit. In addition to setting up the menu bar, the menu used in the pop-up is created and stored in a resource where MyMenus$(4) is the handle to the menu resource. After the menu resource is created, the only thing left to do is draw the pop-up title and shadowed box then wait for an event.
The top and left corner of the pop-up are assigned at the beginning of the Drawpopup routine so that you may place the pop-up wherever you like. Be sure to leave room for the title. The routine figures out the width of the Title and longest menu item and draws them at the appropriate locations. When the pop-up menu comes up, the shadowed box should always line up with the pop-up menu. This is simple, but you can get confused unless you realize that the shadowed box and title are drawn with local window coordinates, but the pop-up menu location is determined by global screen coordinates. It is necessary to convert this location from local to global to tell the pop-up select routine where the menu should go. If the window gets moved (by someone dragging it), remember that the global coordinate is now different, but the local coordinate stayed the same.
You determine that a pop-up menu needs to be handled by checking to see if the mouse was clicked within the shadowed box. The GetNextEvent function returns the point where the click occurred. This point is compared with the PtInRect routine to determine if the point is within the shadowed rectangle where the pop-up will appear. If so then the program handles the pop-up event by calling the PopUpMenuSelect routine. PopUpMenuSelect takes the menu handle, the left and top coordinates where the menu will appear, and the currently selected menu item and handles the menu by displaying the menu then returns the item number of the menu item that was selected. That item is then redrawn into the shadowed box and becomes the newly selected item. The program should then handle whatever action or flag the menu item should do.
This process is simple enough after seeing a few examples. The main problem with pop-up menus as with other controls that you may want to use is that you must be careful not to clutter up the window too much. The graphic design of the interface is just as important as the code that is written. Thats why there will always be a demand for good programs even though HyperCard and other tools make developing programs easier.
By the way, some of the programming in True Basic can be simplified by using the TrueWindows Library. The problem comes when you want to create an application using the Runtime package. The Binder utility asks for the compiled libraries and then the compiled program and outputs them to an application that contains the True Basic interpreter. If you use libraries that have calls or functions with the same name, they may work fine until you bind them together into an application with Binder. Binder gives an error when putting the libraries together which says that you have more than one call with the same name. This could happen if you are using TrueWindows and the other Macintosh Programmers Kit routines (like the ones used in this program). You may be able to get around this by going to the source code files and removing the duplicate name and recompiling the library. Be sure to keep it separate from the original so that they dont get mixed up or someday you may need a routine that you deleted and wonder why things dont work.
I set up my copy of the True Basic runtime application with my own icon and when I create an application, the information is already set up provided that I want to use the same one each time I make a new application. Usually you will want them to be different. I use the Prof. Mac icon for any applications that I make for MacTutor.
! PopUp Menu Demo
! True Basic version 2.01
! Requires True Basic Macintosh Developers ToolKit Libraries
! by Dave Kelly
! ©1989 MacTutor
REM Open up libraries
LIBRARY MenuLib* ! Menu Manager
LIBRARY WindowLib* ! Window Manager
LIBRARY DeskLib* ! Desk Manager
LIBRARY EventLib* ! Event Manager
LIBRARY QuickLib* ! Quickdraw
LIBRARY DataLib* ! Desk Acc and system calls
LIBRARY MacLib* ! True Basic event control
LIBRARY System* ! System Calls
REM following variables are used globally throughout program
DECLARE DEF NIL$, POINTER$,screenBits$,bounds$,top,left,bottom,right,TopLeft$,H,V
DECLARE DEF OpenDeskAcc,NewWindow$,SystemEdit
DECLARE DEF MenuSelect,PtInRect,TrackGoAway
CALL SysEnvirons(sysEnvRec$,status) ! Get current system revision
CALL UnpackEnvirons(sysEnvRec$,envversion, machine,sysversion,processor,
IF sysversion=0 then ! Do we have the right ROM?
CALL TakeMac ! turn off True Basic and let the program do its own thing
LET everyevent=-1 ! event mask for all events
LET doneFlag=0 ! this flag is set when program ending
has been selected.
LET z$=bounds$(screenBits$) ! Get the size of the screen.
! Create a window
CALL SetPort(myWindow$) ! Access the new window
CALL SetUpMenus ! Turn on menus
CALL Drawwindow ! Set up window info
! Main Event Loop
CALL SystemTask ! Handle System tasks/DAs
! check for events
IF eResult<>0 then ! if no event error occurred then...
SELECT CASE what
! what represents the kind of event that occurred.
CASE 1 ! mouse down event occurred
SELECT CASE wResult
CASE 1 ! Event was in the menu bar
CASE 2 ! Event was in a system window
! Pass the event to the system
CASE 3 ! Event was in content region of a window
! convert coordinates for the window
IF PtInRect(where$,PopRect$)=1 THEN
! see if popup was selected
CALL PopUpEvent ! if so, handle the popup event
CASE 4 ! Event in the windows drag region
CASE 6 ! Event in go-away region of active window
CASE 6 ! update event occurred
CASE else ! anything else?
LOOP until doneFlag<>0
CALL DisposeWindow(myWindow$) ! Throw away window handle
CALL ClearMenuBar ! Clear Menus
FOR i=Lbound(MyMenus$) to Ubound(MyMenus$)
CALL GiveMac ! Return control back to True Basic
STOP ! End the program
SUB DrawWindow ! Draw message in window
CALL textfont(2) ! Set font to New York font
CALL textsize(12) ! Set size to 12 point
CALL textface(1) ! Set text to bold
CALL textmode(0) ! Set to copy mode
CALL DrawString(True BASIC Version 2.0 PopUp Menu demo)
CALL textface(0) ! Set text to plain
SUB DoMenu(code) ! handle Menu events
LET Menuitem = Unpackb(s$,17,-16)
SELECT CASE MenuNumber
CASE 1 ! Apple Menu
CASE 2 ! File Menu
CASE 3 ! Edit Menu
DECLARE DEF NewMenu$,StringWidth ! Declare variables used
DECLARE DEF GetFontInfo$ ! in toolbox functions
LET MyMenus$(1)=NewMenu$(1,chr$(20)) ! The first menu is
CALL AddResMenu(MyMenus$(1),DRVR) ! Apple menu.
LET MyMenus$(2)=NewMenu$(2,File) ! File menu is second
LET MyMenus$(3)=NewMenu$(3,Edit) ! Next the Edit menu
LET PopTitle$=PopUp Menu Title: ! Save pop up title
LET MyMenus$(4)=NewMenu$(4,PopTitle$) ! Create pop up menu
LET Popitem$(1)=Item 1"
LET Popitem$(2)=Item 2"
LET Popitem$(3)=Item 3"
FOR i=1 to 3
CALL AppendMenu(MyMenus$(4),Popitem$(i)) ! Add popup items
FOR i=lbound(MyMenus$) to Ubound(MyMenus$)-1 ! put the menus into
CALL insertMenu(MyMenus$(i),0) ! the menu bar
CALL InsertMenu(MyMenus$(4),-1) ! Add pop up menu
CALL CheckItem(MyMenus$(4),PopItem,1) ! check default item
REM Get maximum length of PopUp items
CALL TextFont(0) ! Set to system font
CALL TextSize(12) ! Set to 12 point size
LET ascent = Unpackb(fontinfo$,1,-16)
LET descent = Unpackb(fontinfo$,17,-16)
LET widMax = Unpackb(fontinfo$,33,-16)
LET leading = Unpackb(fontinfo$,49,-16)
FOR i=1 to NoOfPopItems
IF StrWidth>MaxItemLength then LET MaxItemLength=StrWidth
CALL TextFont(0) ! Set Font to Chicago (System)
CALL TextSize(12) ! Set Size to 12 point
LET Popuptop=100 ! Top of Popup menu
LET Popupleft=200 ! Left of Popup menu
CALL SetRect(PopRect$, Popupleft,Popuptop, Popupleft+5+MaxItemLength+13,
Popuptop+ascent+ descent+ leading+1)
CALL FrameRect(PopRect$) ! Draw currently selected item
CALL Drawstring(PopTitle$) ! Draw the Popup menu title
! Draw the currently selected item
DECLARE DEF PopUpMenuSelect ! Declare function
CALL InvertRect(InvertTitleRect$) ! invert popup title
CALL LocalToGlobal(TempPoint$) ! Change to global coords
! Do the Popup
CALL Packb(s$,1,32,Result) ! Get the menu result
! Ignore Menunumber, we know which menu this is
LET Menuitem = Unpackb(s$,17,-16) ! Get the menu item
IF MenuItem=PopItem THEN
! Invert the title to normal if old item selected
CALL CheckItem(MyMenus$(4),PopItem,0) ! uncheck last item
CALL CheckItem(MyMenus$(4),MenuItem,1) ! check new item
CALL EraseRect(PopRect$) ! Draw the current menu item
SELECT CASE MenuItem ! Handle menu event
REM Do Item 1
REM Do Item 2
REM Do Item 3
CALL TextFont(0) ! Set font to Chicago (System)
CALL Drawstring(PopItem$(PopItem)) ! draw selected popup item