Weird Text( Behavior?

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Nexuist
Member (Posts: 126)

Weird Text( Behavior?
26 Oct 2012 04:48:49 pm

Before I get started, this is a TI-83+ OS 1.19 ROM running on jsTIfied.

Quote:

ClrDraw
// Declare vars
44→A
20→B
0→K
// Draw box
Line(7,5,7,86
Line(57,5,57,86
Line(7,5,57,5
Line(7,86,57,86
// Game loop
While K≠45
getKey→K
// Left
If K=24 and A>6
Then
A-1→A
End
// Up
If K=25 and B<85
Then
B-1→B
End
If K=26 and A<56
Then
A+1→A
End
Text(B,A,"+"
End

When I move up and left, the cursor seems to leave no trail. But when I go right....

http://imgur.com/Kk1p8

...That happens.

Is this some random bug with the OS or am I doing something wrong?

NOTE: This program was tested on an actual calc as well, so it can't be jsTIfied causing the glitch.

christop
Power User (Posts: 385)

26 Oct 2012 05:01:08 pm

You're not erasing the previous "+" character before you print another one. The small font "+" character has one column of blank pixels on the right side, so every time you move it left by one pixel that one column automatically erases the previous character.

Try adding/subtracting larger values (try something like 10) from A and B and you'll see what happens.

Nexuist
Member (Posts: 126)

26 Oct 2012 05:24:02 pm

Ah! See, that was the problem that I originally thought was the cause of it, but I became confused because it only happened when I went right. Your explanation, ahem, explains it. Thanks.

tifreak8x
Guru (Posts: 11009)

26 Oct 2012 06:09:58 pm

You can do a couple of things with your code there:

1 - Right after the getKey->K, add If K:Text(B,A," " (three spaces). This will clear out the cursor no matter what button is pressed.

2 - If you are using an If statement, and that conditional only executes one command, like A-1->A, you don't need a Then or End.

Nexuist
Member (Posts: 126)

26 Oct 2012 06:14:07 pm

Thanks for the tip. I'll modify my code accordingly.

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