This is really cool if you want it for your paint. 

LinkedList<MousePathPoint> mousePath = new LinkedList<MousePathPoint>();

    public class MousePathPoint extends Point {

        private long finishTime;
        private double lastingTime;

        public MousePathPoint(int x, int y, int lastingTime) {
            super(x, y);
            this.lastingTime = lastingTime;
            finishTime = System.currentTimeMillis() + lastingTime;
        }

        public boolean isUp() {
            return System.currentTimeMillis() > finishTime;
        }
    }

  public void nextRGB() {
        if ( r == 255 && g < 255 && b == 0 )
        {
            g++;
        }
        if ( g == 255 && r > 0 && b == 0 )
        {
            r--;
        }
        if ( g == 255 && b < 255 && r == 0 )
        {
            b++;
        }
        if ( b == 255 && g > 0 && r == 0 )
        {
            g--;
        }
        if ( b == 255 && r < 255 && g == 0 )
        {
            r++;
        }
        if ( r == 255 && b > 0 && g == 0 )
        {
            b--;
        }
    }
    public Color nextColor() {
        nextRGB();
        return makeColor();
    }
    public Color makeColor()
    {
        return new Color(r, g, b);
    }

Example:

   @Override
    public void onPaint(Graphics2D g) {

    while (!mousePath.isEmpty() && mousePath.peek().isUp())
                    mousePath.remove();
                Point clientCursor = mouse.getPosition();
                MousePathPoint mpp = new MousePathPoint(clientCursor.x, clientCursor.y, 500);
                if (mousePath.isEmpty() || !mousePath.getLast().equals(mpp))
                    mousePath.add(mpp);
                MousePathPoint lastPoint = null;
                for (MousePathPoint a : mousePath) {
                    if (lastPoint != null) {
                        g.setColor(nextColor());
                        g.drawLine(a.x, a.y, lastPoint.x, lastPoint.y);
                    }
                    lastPoint = a;
                }
}

Edited August 30, 201510 yr by Dark Magician

You are performing the same check multiple times. For example:

if ( r == 255 && g < 255 && b == 0 ) {
    g++;
}

if ( r == 255 && b > 0 && g == 0 ) {
    b--;
}

You check if r == 255 twice. Consider using if-else statements:

 

if(r == 255) {
    if(g < 255 && b == 0) {
        g++;
    } else if(g == 0 && b > 0) {
        b--;
    }
} else if(r == 0) {
    if(b < 255 && g == 255) {
        b++;
    } else if(b == 255 && g > 0) {
        g--;
    }
} else if(r > 0 && r < 255) {
    if(g == 255 && b == 0) {
        r--;
    } else if(g == 0 && b == 255) {
        r++;
    }
}

Although this helps with the checks, it can still be improved greatly.

 

First, there is a specific time for a specific color to increase and for it to decrease. It's a little easier to understand if you label your conditions:

 

boolean maxRed = r == 255;
boolean noRed = r == 0;
boolean someRed = r > 0 && r < 255;


boolean maxGreen = g == 255;
boolean noGreen = g == 0;
boolean someGreen = g > 0;
boolean notAllGreen = g < 255;


boolean maxBlue = b == 255;
boolean noBlue = b == 0;
boolean someBlue = b > 0;
boolean notAllBlue = b < 255;


if(maxRed) {
    if(notAllGreen && noBlue) {
        g++;
    } else if(noGreen && someBlue) {
        b--;
    }
} else if(noRed) {
    if(notAllBlue && maxGreen) {
        b++;
    } else if(maxBlue && someGreen) {
        g--;
    }
} else if(someRed) {
    if(maxGreen && noBlue) {
        r--;
    } else if(noGreen && maxBlue) {
        r++;
    }
}

So green only increases when there is max red, no blue and notAllGreen (0 to 254 green). It goes down if theres no red, max blue and some green (1 to 255).

 

With that knowledge, and the help of the variables (which could be inlined if wanted), you can use a nested ternary. Although people find nesting ternaries to be abuse (hard to read sometimes), it's a lot easier to understand than what you got going on now:

boolean needsGreen = maxRed && noBlue && notAllGreen;
boolean reduceGreen = noRed && maxBlue && someGreen;

g += needsGreen ? 1 : reduceGreen ? -1 : 0;
b += ...; //do same for blue
r += ...; //do same for red

This code is a victim of the same problem I mentioned before (double checks), but not only is it cleaner, ternaries help avoid branch predictor failures (see this for more info). 

 

I'm gonna be honest, I haven't tested the code I presented, but the philosophy still applies

 

Edited August 30, 201510 yr by fixthissite

 

You are performing the same check multiple times. For example:

if ( r == 255 && g < 255 && b == 0 ) {
    g++;
}

if ( r == 255 && b > 0 && g == 0 ) {
    b--;
}

You check if r == 255 twice. Consider using if-else statements:

 

if(r == 255) {
    if(g < 255 && b == 0) {
        g++;
    } else if(g == 0 && b > 0) {
        b--;
    }
} else if(r == 0) {
    if(b < 255 && g == 255) {
        b++;
    } else if(b == 255 && g > 0) {
        g--;
    }
} else if(r > 0 && r < 255) {
    if(g == 255 && b == 0) {
        r--;
    } else if(g == 0 && b == 255) {
        r++;
    }
}

Although this helps with the checks, it can still be improved greatly.

 

First, there is a specific time for a specific color to increase and for it to decrease. It's a little easier to understand if you label your conditions:

 

boolean maxRed = r == 255;
boolean noRed = r == 0;
boolean someRed = r > 0 && r < 255;


boolean maxGreen = g == 255;
boolean noGreen = g == 0;
boolean someGreen = g > 0;
boolean notAllGreen = g < 255;


boolean maxBlue = b == 255;
boolean noBlue = b == 0;
boolean someBlue = b > 0;
boolean notAllBlue = b < 255;


if(maxRed) {
    if(notAllGreen && noBlue) {
        g++;
    } else if(noGreen && someBlue) {
        b--;
    }
} else if(noRed) {
    if(notAllBlue && maxGreen) {
        b++;
    } else if(maxBlue && someGreen) {
        g--;
    }
} else if(someRed) {
    if(maxGreen && noBlue) {
        r--;
    } else if(noGreen && maxBlue) {
        r++;
    }
}

So green only increases when there is max red, no blue and notAllGreen (0 to 254 green). It goes down if theres no red, max blue and some green (1 to 255).

 

With that knowledge, and the help of the variables (which could be inlined if wanted), you can use a nested ternary. Although people find nesting ternaries to be abuse (hard to read sometimes), it's a lot easier to understand than what you got going on now:

boolean needsGreen = maxRed && noBlue && notAllGreen;
boolean reduceGreen = noRed && maxBlue && someGreen;

g += needsGreen ? 1 : reduceGreen ? -1 : 0;
b += ...; //do same for blue
r += ...; //do same for red

This code is a victim of the same problem I mentioned before (double checks), but not only is it cleaner, ternaries help avoid branch predictor failures (see this for more info). 

 

I'm gonna be honest, I haven't tested the code I presented, but the philosophy still applies

 

 

Thanks for the feedback! The code above works just as presented. 

true

 

I'm using this Mouse Trail in all my scripts.

I'm using this Mouse Trail in all my scripts.

 

Uhm lol I'm a newb but https://gyazo.com/1e9031eaf1699a57f81f914e62c73f71 r, g, and b give off errors, you never gave the variables out. and im lezy

Edited September 2, 201510 yr by run3warfar3

Uhm lol I'm a newb but https://gyazo.com/1e9031eaf1699a57f81f914e62c73f71 r, g, and b give off errors, you never gave the variables out. and im lezy

 

 

private int r = 255;
private int g = 0;
private int b = 0;

Thank you! Nice work 

doesn't seem to work (only shows red) lol

This is a godsend, couldn't figure out how to make a mouse trail.