Noob here! Need help drawing shapes on screen!

Well I'm at very best a beginner in programming and electronics in general. I'm completely lost when it comes to drawing shapes and what not, heck I was excited when I got to draw a line! The library was made from the sample code, since it was a bit overwhelming for my noobness, was lucky enough to find somebody who converted it into a library! (Thanks again Thomas!)

I'm not really sure what all I should include here, so I'll shoot for what I think! Basically I'm trying to make it easy to make a circle by typing a few bytes rather than 8 lines of code.

Well here's the header file, I guess I'm just looking for the mathematical equation for a circle, and maybe a little help incorporating it in with my code.

``````/*
NokiaLCD.h - Library for a Nokia LCD with the epson driver.
Created by Thomas Jespersen, July 2009 (Originally Arduino Sketch by Gravitech.us)
Released into the public domain.
*/
#ifndef NokiaLCD_h
#define NokiaLCD_h

#include "WProgram.h"

class NokiaLCD
{
public:
void LCD_put_pixel(byte color, byte x, byte y);
void lcd_set_box(byte x1, byte y1, byte x2, byte y2);
void lcd_clear(byte color, byte x1, byte y1, byte x2, byte y2);
void lcd_init();
void draw_color_bar();
void draw_text_line(byte fcolor, byte bcolor,byte x, byte y,char c);
void lcd_draw_text(byte fcolor, byte bcolor, byte x, byte y,char *text);

private:
void shiftBits(byte b);
void sendData(byte data);
void sendCMD(byte data);
};

#endif
``````

Or use y2 + y2 = r2 (don't you love Pythagorus?).
Don't forget eight-way symmetry.
Don't use sin/cos.
For extra points, avoid the use of "sqrt".

Well I kind of understand it, lol just not really sure how to implement it in code.. let alone, everytime I try to make a new function in the library, shows up that there's no such function with that name, even copy and pasting code already in the .cpp and changing the name by 1 letter, and changing it in the header, still same issue, me so confused.
But other than that,
including the nokiaLcd.lcd_put_pixel(byte color, byte x, byte y) into math equations in code, haha gosh I feel so .. noobish Gotta love learning strictly from the internet!
Thanks again for the algorithm, now just to figure out how to use it and I'll be good to go!

Here's a look at my code, right now just uses 2 Potentiometers and a button to draw, kinda ghetto etch a sketch! Kind of looking for the kind of code to use to make a menu per say, I've tried using void menu and setting em up previous to setup but yeah, no real clue how to include selecting a menu, highlighting your selection and whatnot.. but one thing at a time!
Thanks again!

``````/*
Nokia LCD Demo - A demo using the NokiaLCD library for a Nokia LCD with the epson driver.
Created by Thomas Jespersen, July 2009 (Originally Arduino Sketch by Gravitech.us)
Released into the public domain.
*/

#include <LED13.h>
#include <NokiaLCD.h>

// Nokia LCD Setup settings
#define RED                  0xE0
#define GREEN                  0x1C
#define BLUE                  0x03
#define YELLOW                  0xFC
#define MAGENTA                  0xE3
#define CYAN                  0x1F
#define BLACK                  0x00
#define WHITE                  0xFF
NokiaLCD nokiaLcd;
LED13 led;

const int buttonPin = 10;
const int potPin = 2; // X
const int potPin2 = 3;// Y
int lcdDraw = 0;      // POT #1 Pixel
int lcdDraw2 = 0;     // POT #2 Pixel
int buttonState = 0;  // Variable for reading pushbutton status
char analogString[4]; // potPin
char analogString2[4];// potPin2

void setup()
{
DDRD |= B01111100;   // Set SPI pins as output
PORTD |= B01111100;  // Set SPI pins HIGH

pinMode(buttonPin, INPUT);
nokiaLcd.lcd_init();
delay(500);
nokiaLcd.lcd_clear(BLUE,0,0,131,131);   // Sets background as blue
nokiaLcd.lcd_clear(WHITE, 5,5,15,20);   // Small box, upper left
}

void loop()
{
char text [50];

itoa(lcdDraw, analogString, 10);
itoa(lcdDraw2, analogString2, 10);

strcpy(text, "X:");
nokiaLcd.lcd_draw_text(BLUE, BLACK, 90, 115, text);
strcpy(text, analogString);     // First pot # input, printed in BLUE  X
nokiaLcd.lcd_draw_text(BLUE, BLACK, 100, 115, text);

strcpy(text, "Y:");
nokiaLcd.lcd_draw_text(RED, BLACK, 90, 105, text);
strcpy(text, analogString2);    // Second pot # input, printed in RED  Y
nokiaLcd.lcd_draw_text(RED, BLACK, 100, 105, text);