import java.awt.*;
import java.awt.event.*;

/*	This is sample program to demonstrate the use of mouse listeners, certain GUI
	controls, and double-buffered graphics.
	By Dan Schroeder, December 2011
*/

class SimplePaint extends Canvas implements MouseListener, MouseMotionListener {

	int canvasSize = 400;					// width and height of canvas in pixels
	Image offScreenImage;					// the off-screen image, for storing what's painted
	Graphics offScreenGraphics;				// graphics object of the off-screen image
	boolean mouseInCanvas = false;			// true when mouse is within canvas
	int mX, mY;								// current mouse coordinates
	Choice colorChoice = new Choice();		// popup menu for choosing colors
	Color purple = new Color(150,0,255);	// since Java doesn't predefine "Color.purple"
	Checkbox largeBrushCheck = new Checkbox("Large brush",false);	// checked to enlarge brush

	// Constructor method initializes everything:
	SimplePaint() {

		// Create a Frame to hold everything:
		Frame theFrame = new Frame("Simple Paint!");
		theFrame.addWindowListener(new WindowAdapter() { 
			public void windowClosing(WindowEvent e) { 
				System.exit(0); 		// exit when user clicks close button
			} 
		});
		theFrame.setResizable(false);
		Panel canvasPanel = new Panel();
		theFrame.add(canvasPanel);
		canvasPanel.add(this);
		
		// Set the Canvas properties, including MouseListener and MouseMotionListener:
		setSize(canvasSize,canvasSize);
		setBackground(Color.white);
		addMouseListener(this);
		addMouseMotionListener(this);
		
		// Add some controls:
		Panel controlPanel = new Panel();	// Panel to hold controls
		theFrame.add(controlPanel,BorderLayout.SOUTH);
		controlPanel.add(colorChoice);		// Popup menu for colors
		colorChoice.add("Purple");			// Order must be same as in currentColor()
		colorChoice.add("Red");
		colorChoice.add("Green");
		colorChoice.add("Blue");
		colorChoice.add("Cyan");
		colorChoice.add("Yellow");
		colorChoice.add("Magenta");
		colorChoice.add("Black");
		colorChoice.add("White");
		controlPanel.add(largeBrushCheck);
		Button clearButton = new Button("Clear");
		controlPanel.add(clearButton);
		clearButton.addActionListener(new ActionListener() {
			public void actionPerformed(ActionEvent e) {
				clear();
			}
		});

		// That's all, so pack the frame, set up the off-screen image, and go live:
		theFrame.pack();
		offScreenImage = createImage(canvasSize,canvasSize);
		offScreenGraphics = offScreenImage.getGraphics();		// must come after pack
		theFrame.setVisible(true);
		
	}	// end of constructor method

	// MouseListener methods keep track of mouse location and handle initial press:
	public void mouseEntered(MouseEvent e) {
		mouseInCanvas = true;
		mX = e.getX(); mY = e.getY();
		repaint();
	}
	public void mouseExited(MouseEvent e) {
		mouseInCanvas = false;
		repaint();
	}
	public void mousePressed(MouseEvent e) {
		mX = e.getX(); mY = e.getY();
		draw(mX,mY);
		repaint();
	}
	public void mouseReleased(MouseEvent e) {}	// not needed but required for interface
	public void mouseClicked(MouseEvent e) {}
	
	// MouseMotionListener methods keep track of mouse location and handle dragging:
	public void mouseMoved(MouseEvent e) {
		mX = e.getX(); mY = e.getY();
		repaint();
	}
	public void mouseDragged(MouseEvent e) {
		mX = e.getX(); mY = e.getY();
		draw(mX,mY);
		repaint();
	}

	// Returns the current drawing Color:
	Color currentColor() {
		int c = colorChoice.getSelectedIndex();
		if (c == 0) return purple;		// order of colors must match that in constructor
			else if (c == 1) return Color.red;
			else if (c == 2) return Color.green;
			else if (c == 3) return Color.blue;
			else if (c == 4) return Color.cyan;
			else if (c == 5) return Color.yellow;
			else if (c == 6) return Color.magenta;
			else if (c == 7) return Color.black;
			else return Color.white;
	}

	// Returns the current brush size (only two possibilities):
	int currentBrushSize() {
		if (largeBrushCheck.getState()) return 30;
			else return 10;
	}

	// Draw on the off-screen image with the current pen settings at the given location:
	void draw(int x, int y) {
		int width = currentBrushSize();
		offScreenGraphics.setColor(currentColor());
		offScreenGraphics.fillOval(mX-width/2,mY-width/2,width,width);
		repaint();
	}

	// Clear the off-screen image:
	void clear() {
		offScreenGraphics.setColor(Color.white);
		offScreenGraphics.fillRect(0,0,canvasSize,canvasSize);
		repaint();
	}

	// Paint method copies off-screen image to Canvas and adds temporary "brush" at cursor:
	public void paint(Graphics g) {
		g.drawImage(offScreenImage,0,0,null);
		if (mouseInCanvas) {
			int width = currentBrushSize();
			g.setColor(currentColor());
			g.fillOval(mX-width/2,mY-width/2,width,width);		// draw the "brush"
		}
	}

	// Main method just gets us started:
	public static void main(String[] arg) {
		new SimplePaint();
	}
}