/*----------------------------------------------------------------------*
 * g0 DIS								*
 * Basics of Graphics							*
 * L&L 1.6, 2.9-2.10							*
 *----------------------------------------------------------------------*/

/*----------------------------------------------------------------------*
 * Graphics and Pixels							*
 *----------------------------------------------------------------------*
 * You may draw pictures on the computer screen. These pictures are	*
 * images called GRAPHICS. Unlike the recent examples of drawing stars	*
 * and other ASCII (text) characters, you can fill in points on the	*
 * screen called PIXELS. Pixels are the smallest unit of resolution on	*
 * the screen. Filling areas of pixels creates images, like lines,	*
 * polygons, and other nifty things you might enjoy seeing.		*
 *----------------------------------------------------------------------*/

/*----------------------------------------------------------------------*
 * Coordinate Systems							*
 *----------------------------------------------------------------------*
 * Since the computer monitor is "flat," you may draw only in two	*
 * dimensions. Represent the horizontal direction as X and the		*
 * vertical direction as Y. Java considers the screen as positive	*
 * coordinates:								*
 *									*
 * (0,0)								*
 *   +---------------> X						*
 *   |									*
 *   |    + (X,Y)  Java represents each point as an (X,Y) coordinate.	*
 *   |									*
 *   V									*
 *   Y									*
 *									*
 *----------------------------------------------------------------------*/

/*----------------------------------------------------------------------*
 * Color								*
 *----------------------------------------------------------------------*
 * You can represent a color image with light using RED, GREEN, and	*
 * BLUE (RGB). A number from 0 to 255 represents the level of R, G, or	*
 * B. A mixture to represent another color requires a R, G, and/or B	*
 * value.								*
 *----------------------------------------------------------------------*/

/*----------------------------------------------------------------------*
 * Use Graphics routines from the Java API				*
 * You must include this statement for your Graphics to work.		*
 *----------------------------------------------------------------------*/
import java.awt.*;

/*----------------------------------------------------------------------*
 * The Main Class acts as a "driver" by instantiating objects that	*
 * contain code that uses the Graphics class.				*
 *----------------------------------------------------------------------*/
public class g0 {
    public static void main (String[ ] args) {

	//--------------------------------------------------------------
	// Instantiate an object that uses Grapics
	// The class Drawing contains methods that handle the drawing.
	// The values of 500 are inputs to the $window$ method used to
	// set a window size and cause the window to appear.
	//--------------------------------------------------------------
	Drawing d = new Drawing();
	d.window(500,500);
	
    } // method main
} // class g0

/*----------------------------------------------------------------------*
 * To create a graphical window with a title and border, use the	*
 * $extends Frame$ code after your class name. See pp. 680-681 in L&L.	*
 * Java will create a window that will store Graphics objects used in	*
 * the class you're develop below.					*
 *----------------------------------------------------------------------*/

class Drawing extends Frame {

    //------------------------------------------------------------------
    // The following method sets up the window where Graphics will
    // appear. Paramters $w$ and $h$ refer to window width and height.
    // This drawing area is the GRAPHICS CONTEXT (L&L, pg 94) for this
    // example. You could improve the code by using constructors as
    // demonstrated in g0_brief2.java.
    //------------------------------------------------------------------
    void window(int w, int h) {
	setSize(w,h);		    // set window size to 500x500 pixels
	setBackground(Color.white); // set background color of window
	setTitle("G0 Example!");    // Place title in border of window
	show();			    // must include to show window!
    }

    //------------------------------------------------------------------
    // Java uses the following method to draw Graphics to the window
    // you have set up in the Drawing constructor. You may then draw
    // all kinds of wonderful things with statements that use the $g$
    // reference.
    //------------------------------------------------------------------
    public void paint(Graphics g) {

	// Accomodate for the titlebar and left border of the window:
	g.translate(getInsets().left,getInsets().top);
	
	// Set foreground color -- the color of the image you're about
	// to draw:
	g.setColor(Color.blue);

	// Draw a rectangle with upper left corner at (0,0) and size
	// 100x100 pixels:
	g.drawRect(0,0,100,100);

	// Change the color of the next image
	g.setColor(Color.green);

	// Draw a filled-in oval at (200,300) and size (100,50)
	// (these dimensions refer to a bounding rectangle that
	// contains the oval):
	g.fillOval(200,300,100,50);

    } // method paint
    
} // class Drawing