In this Chapter, the AMOS Professional programmer will learn how to create, control and use powerful on-screen menus. These techniques allow you to customise your own menu designs and operations, and offer true interactivity.
AMOS Professional menus can have as many as eight overlaid levels and any menu item can be repositioned anywhere on screen. There is no restriction to the inclusion of title styles and graphic images, and your own Bobs and icons can be used directly.
When reading your menus, branching to user-selected points in your programs can be automatic, whether triggered by the mouse or directly from the keyboard. And if you cannot wait to see all this in action, the Chapter is accompanied by a full range of ready-made demonstration programs available on the AMOSPro Tutorial disc.
SELECTING. All of these menus are activated by holding down the right mouse button. Once the relevant menu has appeared on screen, drag the mouse cursor over the option you wish to select and release the button. The selected option number is automatically returned to your program.
REPOSITIONING. A menu can be repositioned on screen by placing the mouse cursor over its lop left-hand corner and holding down the left mouse button. When a small box appears on the menu bar, drag it across the screen using the mouse. To freeze the current position of a menu, hold down the Shift key as well. This allows you to explore the menu without activating any of its options.
AMOS Professional menus can be created directly from within your programs, or you may prefer to use the menu defining program supplied on disc.
Simple menus
reserved variable: define a menu title or optionTo create a simple menu, its title line must first be defined. Each heading in a title line created with MENU$ must be assigned its own number. The title at the left-hand edge of the title line is represented by 1, the next title by 2, and so on, from left to right. The characters in your title string hold the name of the numbered title. This example sets up a menu title line offering two titles, and you should note the use of the spaces to separate titles when they appear in the title line:
Menu$(1)," Action"
Menu$(2)," Mouse"
The second type of usage of MENU$ defines a set of options that will be displayed in the vertical menu bar. The brackets after MENU$ contain two parameters, the first is the number of the menu heading that your option is to be displayed beneath, followed by the option number you want to install in the vertical menu bar. All options are numbered downwards from the top of the menu, starting from 1. The option string holds the name of your new option, and can consist of any text you choose. The following lines could be added to the last example above:
Rem Action menu has one option
Menu$(1,1)=" Quit " : Rem Ensure three spaces after Quit
Rem Mouse menu has three options
Menu$(2,1)="Arrow " : Rem Ensure five spaces after Arrow
Menu$(2,2)="Cross-hair"
Menu$(2,3)="Clock " : Rem Ensure five spaces after Clock
That specifies your list of alternatives for the "Action" and "Mouse" menus. Before this program can be run, it must first be activated.
instruction: activate a menu
Menu On
Use this command to initialise the menu previously defined by a MENU$, and the menu line will appear when the right mouse button is pressed. To activate the previous example, add the following lines:
Menu On
Wait Key
Trigger the menu and its options now, and use the left mouse button to re-locate the title bar. Now that this simple menu has been activated, the selected options must be read and reported back to the system.
function: read a menu
selection=Choice
title number=Choice(1)
option number=Choice(2)
CHOICE will return a value of -1 (true) if the menu has been highlighted by the user, otherwise a value of 0 (false) is returned. After the status of your menu is tested, the value held by CHOICE is automatically re-set to zero.
CHOICE(1) will return the value of the title number which has been chosen.
CHOICE(2) will return the value of the option number which has been selected.
Now remove the Wait Key from the last example, and replace it with the following lines. This should change the shape of the mouse cursor, depending on the option selected from your menu. Note that Choice=-1 can be simplified to Choice.
Do
If Choice and Choice(1)=1 Then Exit
If Choice(1)=2 and Choice(2)<>0 Then Change Mouse Choice(2)
Loop
The use of MENU$ and CHOICE is not limited to the creation of simple menus. In fact, their use can be extremely sophisticated.
MENU$ is used to define the appearance of each individual item in one of your menus, whether it is a title, an option, a sub-option, all the way down to the eighth layer of options in the menu hierarchy. In this Chapter, when "single item parameters" is used it simply means those numbers separated by commas and held inside a single pair of brackets, that refer to the position of a single item somewhere in the menu. Up to eight parameters can be used, separated by commas. To make sure that is clear, here are some examples of parameters defining the position of a single item in the menu hierarchy:
Menu$(1)="Title1"
Menu$(1 ,1)="Title1 Option1"
Menu$(2,3)="Title2, Option2"
Menu$(1,1,1,1)="Title1, Option1, Sub-option1, Sub-sub-option1"
Now look at these uses of MENU$, which are used to give a single item its own characteristics:
instruction: define appearance of a single item in a menu
Menu$(single item parameters)=normal$
Menu$(single item parameters)=normal$,selected$,inactive$,background$
Normal$ is simply the string of characters that make up the normal appearance of an item when it is displayed on screen. The following strings are all optional.
The selected$ changes the appearance of the item when it is selected by the mouse. As a default, selected items are highlighted by printing the string in inverse text.
The inactive$ comes into effect when an item has been deactivated using the MENU INACTIVE command, which is explained later. It can be used to display alternative text or appearance, but if it is omitted, inactive items are automatically displayed in italics.
The background$ creates a background effect for menu items when they are initially drawn, such as a box or a border created by the internal BAR or line drawing commands.
Similarly, the CHOICE function can return the option selected at a required level in the menu hierarchy. For example:
Menu$(1)="Title"
Menu$(1,1)="Option 1"
Menu$(1,2)="Option 2"
Menu$(1,2,1)="Option 2.1"
Menu On
Do
If Choice Then Print Choice(1),Choice(2),Choice(3)
Loop
For very large menus, the IF structure as used in the last example would become unwieldy, and cause delays while the menus were being read. AMOS Professional provides a method for handling the largest of menus.
instruction: automatic menu selection
On Menu Proc procedure1
On Menu Proc procedure1,procedure2
Each title in your menu can be assigned its own procedure which will be executed automatically when that option is selected by the user. Like the other ON MENU commands that are described next, ON MENU PROC uses interrupts, which means that it is performed 50 times a second. So your program can be engaged in other tasks while the menus are continually checked by the system.
When automatic selection takes place as the result of ON MENU PROC, the procedure is executed and the program will be returned to the instruction immediately after the ON MENU call. Procedures can make use of the CHOICE function to monitor which option has been triggered, and to perform the appropriate action.
instruction: automatic menu selection
On Menu Gosub label1
On Menu Gosub label1,label2
Depending on which option has been selected by the user, ON MENU GOSUB goes to the appropriate subroutine. Unlike Amiga Basic, each title on the menu title bar is handled by its own individual subroutine. After using this instruction, ON MENU should be used to activate the menu system before jumping back to the main program with a RETURN. Also note that the labels used with this command cannot be replaced by expressions, because the label will be evaluated once only when the program is run.
instruction: automatic menu selection
On Menu Goto label1
On Menu Goto label1, labe12...
Although this command is available for use, it has been superseded by the more powerful ON MENU PROC and ON MENU GOSUB instructions. It is retained to provide compatibility with programs written in STOS Basic.
To activate the automatic menu system created by the ON MENU PROC, GOSUB or GOTO commands, simply give the ON MENU ON command. After a subroutine has been accessed in this way, the system is automatically disabled. Therefore you must reactivate the system with ON MENU ON before returning to the main program.
To suspend the automatic menu system, ON MENU OFF is used. This can be vital if your program is executing a procedure which must be performed without interruptions, such as loading and saving information to disc. Menus are reactivated using ON MENU ON.
instruction: delete labels and procedures used by ON MENU
On Menu Del
Use ON MENU DEL to erase the internal list of labels or procedures created by the range of ON MENU commands. You are warned that this command can only be used after menus have been deactivated by ON MENU OFF.
instruction: activate a menu
Menu On
Menu On bank number
The simple form of this command has already been dealt with at the beginning of this Chapter. After MENU ON, a menu is displayed when the user next presses the right mouse button. If an optional bank number is included after the command, the appropriate menu will be taken from the numbered memory bank. Please see MAKE MENU BANK, below.
instruction: deactivate a menu
Menu Off
This command temporarily turns a menu off, making it inactive. The menu can be reactivated at any time with the MENU ON command.
instruction: delete one or more menu items
Menu Del
Menu Del(single item parameters)
On its own, MENU DEL erases the whole menu. But be warned, once the menu has been deleted it cannot be retrieved!
MENU DEL can also be qualified by up to eight parameters, separated by commas, and held in a single pair of brackets. These values represent the precise position of the item in the menu hierarchy to be deleted. For example:
Menu Del(1) : Rem Delete title number 1
Menu Del(1,2) : Rem Delete option 2 of title 1
Menu Del(2,3,4) : Rem Delete sub-option 4 of option 3 of title 2
instruction: save menu definitions into a memory bank
Menu To Bank number
Use this command to save your menu along with its entire structure of branch definitions to the numbered bank. Once the menu has been stored in the selected memory bank, it will automatically be saved along with your Basic program. By storing your menu definitions in a memory bank, the size of your program listings are reduced significantly, freeing valuable space in the editor memory. If the bank number you select already exists, the appropriate error message will be given.
instruction: restore a menu definition saved in a menu bank
Bank To Menu number
Follow BANK TO MENU with the number of the memory bank where your menu data is stored. The menu will be restored to its exact state when originally saved, so the restoration process may take a few seconds. To activate the restored menu, call MENU ON.
instruction: recalculate a menu
Menu Calc
Any item in an AMOS Professional menu can be changed during the course of a program. This is extremely useful for designing adventure games or creating self help programs, where individual menu options can be updated depending on the user's actions. After the menu has been defined, items may be added and options replaced as you please, and everything will be repositioned automatically as soon as the menu is called up with the right mouse button.
This is process may take a few seconds, particularly with very large menus, and the MENU CALC command is designed to perform this recalculation at the most suitable point in the program, in order to minimise any delays.
You are advised to freeze your menus with MENU OFF at the start of the recalculation procedure, to prevent the user calling the menu half way through an update. It may then be made active again using MENU ON after the updating process is over.
The AMOS Professional programmer is free to change the display format of any level of any menu, and design a customised layout. As a default, all titles are displayed in a horizontal bar with their related options arranged below in a vertical block. Here are the alternatives:
instruction: display menu options as a horizontal line
Menu Line level number
Menu Line (single item parameters)
Use this command to change the display of options that relate to a particular title from a vertical block into a horizontal line. The line of options will now start from the left-hand corner of the first menu title and stretch to the bottom right-hand corner of the last title. Follow MENU LINE with the number of the level you want to affect, and make sure that this command is only called during your menu definitions. The level number can range from 1 to 8, and it specifies the layer of the menu to be affected.
It is perfectly legal to set individual items by this method, and with the following MENU TLINE and MENU BAR commands. This can result in some highly eccentric displays.
Menu Line(1,1,1) : Rem Display sub-option 1,1,1 as a line
instruction: display a menu as a total line
Menu Tline level number
Menu Tline(single item parameters)
MENU TUNE is used to display a section of your menu as a total line, stretching from the extreme left to the extreme right of the screen. The complete line will be drawn even if the first item is centre screen. Use this instruction in the same way as MENU LINE during your menu definitions.
instruction: display menu items as a vertical bar
Menu Bar level number
Menu Bar(single item parameters)
This instruction displays.the selected menu items as a vertical bar whose width is automatically set to the length of the largest item in the menu. As a default, this option is used for levels 2 to 8 of your menu, and it must be used during the program's initialisation. There will be no effect if it is called after the menu has been activated.
When followed by a list of bracketed parameters, MENU BAR can also be used to change the style of your menus once they have been installed. Here is an example of a customised menu layout:
FLAG=0
SET_MEN
Do
If Choice and Choice(1)=2 and Choice(2)=1 Then CHANGE
Loop
Procedure SET_MEN
Menu$(1)="Try me first " : Menu$(2)="Select me " : Rem Four spaces
Menu$(1,1)="1 am useless " : Rem Five spaces
Menu$(2,1)="Please select me!"
Menu On
End Proc
Procedure CHANGE
Shared FLAG
Menu Del
If FLAG=0 Then Menu Bar 1: FLAG=1 Else Menu Tline 1: Flag=0
SET_MEN
End Proc
instruction: turn off a menu item
Menu Inactive level number
Menu Inactive(single item parameters)
Use this command to turn off options in your menu. By selecting the number of a level from 1 to 8, all items in that level will be deactivated. If you define an individual item in brackets by giving its parameters, only that item will become inactive.
If no inactive string has been defined when you originally set your menu up with MENU$, any menu options that have been made inactive will be shown in italics. Otherwise the special inactive string will appear.
instruction: activate a menu item
Menu Active level number
Menu Active(single item parameters)
MENU ACTIVE reverses the effect of a previous MENU INACTIVE command. An entire level or single item specified by its parameters can be re-activated and the original appearance of their title strings will be re-displayed.
As has been explained, AMOS Professional menus can be displayed anywhere on your screen. he display positions can be moved either by the user or by your program.
instruction: activate automatic menu movement
Menu Movable level number
Menu Movable(single item parameters)
The default condition is that the menu items at a particular level may be moved directly by the user. Any level can be repositioned by moving the mouse pointer over the first item in the menu and holding down the left mouse button. A rectangular box will appear around the selected menu item, and it can be dragged to its new screen position. When the left mouse button is released, the menu is re-drawn at this location, along with all of its associated items.
Use MENU MOVABLE to set the status of entire menu levels, or selected items in a menu hierarchy, but please note that this command does not allow you to change the status of any items below the selected level.
instruction: fix a menu in static position
Menu Static level number
Menu Static(single item parameters)
One characteristic of mobile menus is that the amount of memory they use changes during the course of the program. With large menus or programs that are on the boundary of available memory this can cause real problems. MENU STATIC can be used to avoid these difficulties by setting the level or item at which the entire menu becomes immovable by the user.
instruction: fix items in static positions
Menu Item Static level number
Menu Item Static(single item parameters)
This command locks one or more menu items into place, and is the default setting.
instruction: move individual menu options
Menu Item Movable level number
Menu Item Movable(single item parameters)
This is similar to MENU MOVABLE, but it allows the re-arrangement of various options in a particular level. Normally it is not possible to move items outside of the current menu bar, but this can be overcome by the MENU SEPARATE command, which is explained below.
To use MENU ITEM MOVABLE for changing the position of a menu item, the entire menu bar must itself be movable. So if MENU STATIC has been called, this command will have no effect. The first item in a menu bar can not be moved, because this would move the entire line. Furthermore, if the last item in a menu bar is moved, the size of that bar will be permanently reduced.
This problem can be overcome either by setting the last item into place with a MENU ITEM STATIC command, or by enclosing the whole menu bar with a rectangular box, like this:
Menu$(1 ,1)=,,,,"(Bar40,100)(Loc0,0)"
instruction: separate a list of menu items
Menu Separate level number
Menu Separate(single item parameters)
This command is used to separate all the items in the numbered level of the menu. Each item will then be treated independently. If no background string has been defined, every item is offset from the preceding item by two pixels, creating a stepped effect, which can be removed by editing from the Menu utility.
By specifying the parameters of a single item after the MENU SEPARATE command, a menu bar can be split at any chosen point. Once an item has been separated it can be affected by the MENU MOVABLE command instead of the ITEM instructions.
instruction: link a list of menu items
Menu Link level number
Menu Link(single item parameters)
This is the exact opposite of MENU SEPARATE, and is used to link one or more items together.
function: return the graphical x-coordinate of a menu item
x=X Menu(single item parameters)
The X MENU function allows you to get the position of a menu item, relative to the previous option on screen. This information can be used to set up very powerful menus.
function: return the graphical y-coordinate of a menu item
y=Y Menu(single item parameters)
Y MENU returns the y-coordinate of a menu option, measured relatively to the previous item on screen. Please refer to the demonstration program above.
instruction: move the starting position of a menu
Menu Base x,y
Use this command to move the starting point of the first level in your menu hierarchy to the absolute screen coordinates at x,y. All subordinate menu items will now be displayed relative to this starting point.
instruction: move a menu item
Set Menu(single item parameters) To x,y
SET MENU sets the screen position of the top left-hand corner of the menu item whose parameters are given in brackets. These coordinates are measured relative to the previous level, so the starting point for the entire menu can be set by the MENU BASE command. All levels of the menu below this single item will also be moved by your SET MENU command. The coordinates can be negative as well as positive, so you are free to position items anywhere on screen.
MENU MOUSE ON
MENU MOUSE OFF
instruction: display the menu at position of mouse cursor
Menu Mouse On
Menu Mouse Off
Use these commands to toggle the display of all menus starting from the current position of the mouse cursor. The mouse coordinates are added to the MENU BASE to calculate the menu position, so it is possible to lace a menu at a fixed distance from the mouse pointer.
Menus are an extremely useful system of selecting from a clear choice of options. They present the user with a simple method of performing some complex operations, and they are particularly suitable for the less experienced or younger user. But the AMOS Professional programmer can be more concerned with speed rather than simplicity, and menu operations can become a little tedious. This is why you may prefer to choose your options directly from the keyboard.
AMOS Professional allows you to assign a keyboard shortcut to any of your menu items, and these key presses are interpreted as their exact equivalents. They can be used with any menu command, including the ON MENU range.
instruction: assign a key to a menu item
Menu Key(single item parameters) To c$
Menu Key(single item parameter) To scancode, bitmap
Any key can be assigned to an item in a previously defined menu, provided that the item specified is at the bottom level of the menu. In other words, keyboard shortcuts cannot be used to select sub-menus because each command must correspond to a single option in the menu.
In its simplest form, define the single item parameters as usual, by giving their hierarchy numbers in brackets after MENU KEY. Then assign the item TO a string containing a single character. Any additional characters in this string will be ignored.
Because each key on the Amiga keyboard is assigned its own scancode, this code can be made use of for those keys that have no Ascii equivalents, the so-called control keys. Here is a simple routine to print out scancodes:
Do
Repeat
A$=inkey$
Until A$<>""
Z=Scancode
Print Z
Loop
The following scancodes can also be used with the MENU KEY command, instead of a character string:
| Scancode | Keys |
|---|---|
| 80 to 89 | Function keys F1 to F10 |
| 95 | Help |
| 69 | Esc |
An optional bitmap can also be added, to check for control key combinations such as Ctrl + A. Here are the alternatives:
| Bit | Key Tested | Notes |
|---|---|---|
| 0 | left Shift | only one Shift key can be tested at a time |
| 1 | right Shift | only one Shift key can be tested at a time |
| 2 | Caps Lock | either ON or OFF |
| 3 | Ctrl | |
| 4 | left Alt | |
| 5 | right Alt | this is the C= key on some keyboards |
| 6 | left Amiga | |
| 7 | right Amiga |
If more than a single bit is set in this pattern, several keys must be pressed at the same time in order to call up the associated menu item. Any of these keyboard shortcuts can be erased by using MENU KEY with no parameters. For example:
Menu Key(1,10) : Rem Erase shortcut assigned to item (1,10)
Here is an example that checks for key presses of the Amiga's ten function keys:
Menu$(1)="Function Keys"
For A=1 To 10
OPT$="F"+Str$(A)+" "
Menu$(1,A)=OPT$
Menu Key(1,A) To 79+A
Next A
Menu On
Do
If Choice Then Print "You have pressed Function Key ";Choice(2)
Loop
AMOS Professional menus offer complete freedom to make use of any text styles of graphics you want. The final part of this Chapter deals with the commands that make this possible.
Any menu string can include a powerful set of optional embedded commands that allow you to customise the appearance of your menus. These embedded commands must be enclosed between sets of brackets, and individual commands must be separated by colons, like this:
Menu$(1)"(LOcate 10,10: Ink 1,1)I am embedded"
Each embedded command consists of only two characters, which can be in either upper or lower case. Any other characters will be ignored. So the following characters will be treated as "LO" when entered as an embedded command:
LO
lo
locate
Lonniedonegan
Most embedded commands also require you to input one or more numbers. These numbers must never make use of expressions, because they will not be evaluated.
In the listings for all of the following embedded commands, the two important characters that make up the command are in upper case bold type.
embedded command: move the graphics cursor
LOcate x,y
The LOcate embedded command moves the graphics cursor to coordinates x,y measured relative to the top left-hand corner of the 'menu line. Please note that after this command, the graphics cursor will always be positioned at the bottom right of the object which has just be drawn. These coordinates will also be used to determine the location of any further items in your menu. For example:
Menu$(1)="Example " : Menu$(1,1)="Locate (LO 50,50) in action"
Menu$(1,2)="Please guess my coords"
Menu On : Wait Key
embedded command: draw a bob
BOb number
The BOb command draws the specified Bob image from the Object Bank at the current cursor position. The existence of any hot spot will be ignored. Colour zero will normally be treated as transparent, but this can be changed with NO MASK. All coordinates will be measured relative to the top left-hand corner.
embedded command: draw an icon
ICon number
embedded command: set pen, paper or outline colour
INk mode,value
The INk command assigns the colour index values to be used for the pen, paper and outline colours in your menu drawing. The numbers to be used for the various modes are as follows:
Number Mode 1 Set text PEN colour 2 Set PAPER colour 3 Set OUTLINE colour
embedded command: set font
SFont number
SFont sets the current menu font to the selected graphics font number. This font will now be used for all subsequent menu items. GET FONTS must be called before this instruction is executed.
embedded command: set font style
SStyle bit-pattern
SStyle sets the style of the "Current font to the selected bit-pattern. In the following table, a setting of 1 will have the listed effect, whereas a setting of zero will have no effect:
Bit Effect 0 underline 1 bold 2 italic
embedded command: draw a line
LIne x,y
LIne draws a line from the current cursor position to the graphics coordinates x,y.
embedded command: set line pattern
SLine pattern
SLine sets the line style to be used in all subsequent LIne commands to the selected bit-pattern. Because there is no evaluation of expressions, the bit-pattern must be converted into decimal notation before use.
embedded command: draw a bar
BAr x,y
BAr draws a rectangular bar from the current cursor coordinates to x,y.
embedded command: draw a pattern
PAttern number
embedded command: enclose a bar with an outline
OUtline value
OUtline draws a border in the current outline colour (set to ink colour 3) around all subsequent bars. A value of 1 activates the border and a value of 0 removes it.
ELlipse draws an ellipse centred on the current coordinates, with the chosen radii. To draw a circle centred at the current coordinates, simply make radius1 equal to radius2.
embedded command: call a procedure
PRoc NAME
PRoc allows you to call any AMOS Professional procedure directly within a menu line. The called procedure cannot include any parameters, otherwise a syntax error will be generated.
This is the command that allows you to customise your menu to your own needs and ignore the limitations of the available menu commands.
At the start of your procedure, the following values are held in the Amiga's 68000 processor registers:
DREG(0) holds the graphical x-coordinate of the top left-hand corner of the current menu item. Do not draw graphics to the left of this point on the screen unless you want to confuse the menu re-drawing process and generate bizarre effects.
DREG(1) holds the y-coordinate of your menu item. Avoid drawing below this point on the screen to minimalise possible errors.
DREG(2) holds the current status of your menu drawing operations. It contains a value of 0 (false) while the menu item is being drawn, in which case you must load DREG(0) and DREG(1) with the x,y-coordinates of the bottom right-hand corner of your menu zone, and return from the procedure immediately. If DREG(2) is -1 (true), you are free to perform the graphics operations used by the procedure. After completion, you should return the coordinates of the bottom right-hand corner of your item in DREG(0) and DREG(1) as above.
DREG(3) holds a value of -1 if the menu is selected and the first menu string is on display, otherwise it will contain a value of 0.
DREG(4) is set to TRUE when the menu branch is initially opened.
AREG(1) holds the address of the zone created with RESERVE. It is used to allow different procedures to communicate with one another.
Here is the general structure of a menu procedure:
Procedure ITEM
If DREG(2)
X=DREG(0) : Y=DREG(1)
drawing instructions go here
Endif
DREG(0)=BX : Rem x coord of bottom right corner of menu item
DREG(1)=BY : Rem y coord of bottom right corner of menu item
Endproc
The dimensions of the menu item as it is displayed on screen are set using the coordinates BX and BY. These must be loaded into registers DREG(0) and DREG(1) before leaving your procedure because they are needed to create the final menu bar.
While inside your procedure, most AMOS Professional instructions can be performed, including other procedures. However, the following rules must be observed to avoid your Amiga crashing!
embedded command: reserve a local data area for a procedure
REserve number of bytes
REserve allocates the chosen number of bytes of memory for a menu item. This area can then be accessed from within your menu procedure using the address held in AREG(1). The data area that is reserved in this way is for the storage of variables. This area is local to the menu item that calls the procedure.
The last two commands in this Chapter affect the automatic process which re-draws the selected menu 50 times every second.
instruction: re-draw a menu item continually
Menu Called(single item parameters)
MENU CALLED engages the automatic re-drawing process. This command is normally used with a menu procedure to generate animated menu items, often with spectacular moving graphic effects.
To use this facility, a menu procedure should first be defined, as explained above. Next, add a call to this procedure in the required title strings, using an embedded PRoc command. Finally, activate the updating process with MENU CALLED. When the user selects the chosen item, your procedure is repeatedly accessed by the menu system.
Because menu items are not double buffered, bobs may flicker a little, but the use of computed sprites will present no such problems.
instruction: turn off automatic re-drawing
Menu Once(single item parameters)
MENU ONCE turns off the automatic updating system instigated by MENU CALLED. After the command is given, each menu item will only be re-drawn once when the menu is called on the screen. It is used like this:
Menu Once(1,1)