| |
Read
the keyboard
There are two ways to read the calculator's keyboard.
Each way has its own advantages.
GetKey( )
The
first is the GetKey function. It is a function
that waits for the user to press a key and returns
the key's value.
Example :
Procedure MAIN:
'The startpoint of your program
Local key as Integer
Do
key = GetKey()
Clear
Locate 10,30,key,4
Loop While key<> 264 |
This small example allows the user to see the value
of each key. We only get outside the Do-While
loop when we press [ESC], which has a corresponding
value of 264.
GetKey function has some important properties :
- The function waits the to user press a key.
This can be an advantage, with a simple menu.
But with GetKey, it is not possible to continue
executing things before the key is pressed.
- The [2nd], [SHIFT], [alpha] and [diamond]
keys do not return a value. They are like a
secondary keyboard. For example, on the TI-89,
pressing [alpha] and then [8] gives the letter
"h". The returned by Getkey represents
"h" and not "8". To sum
up, GetKey returns a value of a character, and
not of a key.
- If you press more than one key, GetKey returns
only one value that means nothing. To test several
keys, or a key if the user presses several ones,
you must use the second way descibed below.
Some properties of GetKey are good, but its use
is sometimes not the best (like in games).
Boolean functions (KEY89_LEFT , KEY92_DIAMOND
, etc...)
To read the keyboard, you can also use boolean
functions (that returns TRUE or FALSE). These
functions have the advantage of being very fast
and very close to the hardware. When you write
:
If KEY89_LEFT Then
Instructions...
EndIf |
The calculator will check the physic contact of
the conductors under the left arrow key.
This is very fast and has the other advantage to
test only one key, even if the user presses more
than one.
To test several keys at the same time, it's very
simple :
If KEY89_LEFT And KEY89_DIAMOND Then
Instructions...
EndIf |
Instructions will be executed if the user presses
[LEFT] and [diamond] together.
The matrix of each calculator is different, so you
must tell which calculator you want to use. The
same program for a TI-92+ or a Voyage 200 will be
written :
If KEY92_LEFT And KEY92_DIAMOND Then
Instructions...
EndIf |
Using these functions do not set a waiting time.
You must set up a loop.
Do
Clear
'make anything you want here...
If KEY89_UP Then
Locate 60,1,"UP",4
EndIf
If KEY89_LEFT Then
Locate 1,40,"LEFT",4
EndIf
If KEY89_RIGHT Then
Locate 100,40,"RIGHT",4
EndIf
If KEY89_2ND Then
Locate 40,20,"2ND",4
EndIf
If KEY89_ENTER Then
Locate 40,60,"ENTER",4
EndIf
Loop While Not (KEY89_ESC) |
Here is the list of existing boolean functions :
| For TI-89 : |
For TI92+ and Voyage 200: |
KEY89_UP
KEY89_DOWN
KEY89_LEFT
KEY89_RIGHT
KEY89_DIAMOND
KEY89_ALPHA
KEY89_2ND
KEY89_SHIFT
KEY89_ENTER
KEY89_CLEAR
KEY89_ESC |
KEY92_UP
KEY92_DOWN
KEY92_LEFT
KEY92_RIGHT
KEY92_DIAMOND
KEY92_ENTER2
KEY92_2ND
KEY92_SHIFT
KEY92_ESC
KEY92_HAND
|
|
.gif){kind=small}