prisonerjohn
commented
10 years ago 
I can't seem to find a way to attach a file, and I'm very inexperienced with git (and this project).
The entire fixed code file KeyboardFunctions.pde is:
/**
* Keyboard Functions.
* Modified from code by Martin.
* Original 'Color Typewriter' concept by John Maeda.
*
* Click on the window to give it focus and press the letter keys to type colors.
* The keyboard function keyPressed() is called whenever
* a key is pressed. keyReleased() is another keyboard
* function that is called when a key is released.
*/
int maxHeight = 40;
int minHeight = 20;
int letterHeight = maxHeight; // Height of the letters
int letterWidth = 20; // Width of the letter
int x = -letterWidth; // X position of the letters
int y = 0; // Y position of the letters
boolean newletter;
int numChars = 26; // There are 26 characters in the alphabet
color[] colors = new color[numChars];
void setup()
{
size(640, 360);
noStroke();
colorMode(HSB, numChars);
background(numChars/2);
// Set a gray value for each key
for(int i = 0; i < numChars; i++) {
colors[i] = color(i, numChars, numChars);
}
}
void draw()
{
if(newletter == true) {
// Draw the "letter"
int y_pos;
if (letterHeight == maxHeight) {
y_pos = y;
rect( x, y_pos, letterWidth, letterHeight );
} else {
y_pos = y + minHeight;
rect( x, y_pos, letterWidth, letterHeight );
fill(numChars/2);
rect( x, y_pos-minHeight, letterWidth, letterHeight );
}
newletter = false;
}
}
void keyPressed()
{
// If the key is between 'A'(65) and 'Z' (90) or 'a' (97) and 'z' (122)
if((key >= 'A' && key <= 'Z') || (key >= 'a' && key <= 'z')) {
int keyIndex;
if(key <= 'Z') {
keyIndex = key-'A';
letterHeight = maxHeight;
fill(colors[key-'A']);
} else {
keyIndex = key-'a';
letterHeight = minHeight;
fill(colors[key-'a']);
}
} else {
fill(0);
letterHeight = 10;
}
newletter = true;
// Update the "letter" position
x = ( x + letterWidth );
// Wrap horizontally
if (x > width - letterWidth) {
x = 0;
y+= maxHeight;
}
// Wrap vertically
if( y > height - letterHeight) {
y = 0; // reset y to 0
}
}
Error Description
The KeyboardFunctions example in Processing 2.0b8 on Mac OS X 10.8.3 accesses non-existent array indexes when keyboard characters between 'Z' and 'a' (exclusive) are pressed. This throws an exception in Java, but is treated as if the index was 0 in Processing.js.
The exception in Java when '[' is pressed is:
Error Diagnosis
This exceptions occurs because the code assumes that 'Z' is next to 'a', and fails to account for the 6 character gap, which contains
[ \ ] ^ _ `.There are two alternate fixes to the keyPressed function:
Fix Implementation
The fix to keyPressed() is:
These two lines are modified from the original:
This is the context of the code above (the function continues past this snippet):
Edit: explain difference between impact of bug in Java and JavaScript.