// Rubber2.java    basic rubber band for shape 
//                 Draw rectangle. left mouse down=first point      
//                 Drag to second point. left mouse up=final point 
//                 right mouse changes color of first figure area
//                 show grid and snap to grid

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

public class Rubber2 extends Frame
{
  int winWidth = 500;
  int winHeight = 500;
  boolean tracking = false; // left button down, sense motion 
  int startX = 0;
  int startY = 0;
  int currentX = 0;
  int currentY = 0;
  int num_fig = 0;        // number of figures to draw
  int select = 0;         // the currently selected figure index
  boolean grid = true;    // display grid points
  boolean snap = true;    // snap mouse press/release/motion to grid
  int gridSize = 25;
  Fig figure[] = new Fig[100]; // num_fig is number of figures to display
  
  Rubber2()
  {
    setTitle("Rubber2");
    setSize(winWidth,winHeight);
    setBackground(Color.white);
    setForeground(Color.black);
    addWindowListener(new WindowAdapter()
    {
      public void windowClosing(WindowEvent e)
      {
        System.exit(0);
      }
    });
    setVisible(true);
    this.addMouseListener (new mousePressHandler());
    this.addMouseListener (new mouseReleaseHandler());
    this.addMouseMotionListener (new mouseMotionHandler());
  }
  
  class Fig // just partial structure, may add more
  {
    int kind;           // kind of fig
    int x0, y0, x1, y1; // rectangle boundary
    double r, g, b;     // color values
    double width;
    
    Fig(){ kind=0; x0=0; y0=0; x1=0; y1=0;
                  r=0.0; g=0.0; b=0.0; width=0.0;}
  }  

  void snapxy(int x[], int y[]) // like swap, use single element array
  {
    int xg, yg;

    xg = (x[0]+gridSize/2)/gridSize;
    yg = (y[0]+gridSize/2)/gridSize;
    x[0] = xg*gridSize;
    y[0] = yg*gridSize;
  }
  
  void mouseMotion(int x, int y)
  {
    if(tracking)
    {
      currentX = x;
      currentY = y;
      requestFocus();
      repaint();
    } 
  }

  void startMotion(int x, int y)
  {
    tracking = true;
    startX = x;
    startY = y;
    currentX = x;
    currentY = y; // zero size, may choose to ignore later 
    requestFocus();
    repaint();
  }

  void stopMotion(int x, int y)
  {
    tracking = false; // no more rubber_rect 
    // save final figure data for 'display' to draw 
    currentX = x;
    currentY = y; 
    figure[num_fig] = new Fig();
    figure[num_fig].kind = 1; /* just rectangles here */
    figure[num_fig].x0 = startX;
    figure[num_fig].y0 = startY;
    figure[num_fig].x1 = currentX;
    figure[num_fig].y1 = currentY;
    figure[num_fig].r = 1.0;
    figure[num_fig].g = 0.0;
    figure[num_fig].b = 0.0;
    figure[num_fig].width = 2.0;
    num_fig++;
    requestFocus();
    repaint();
  }

  class mousePressHandler extends MouseAdapter
  {
    public void mousePressed (MouseEvent e)
    {
      int b;
      int xx[] = new int[1];
      int yy[] = new int[1];

      b = e.getButton();
      xx[0] = e.getX();
      yy[0] = e.getY();
      // System.out.println("press x="+xx[0]+"   y="+yy[0]+
      //                    "   b="+b); // debug print
      if(snap) snapxy(xx, yy);
      if(b==1) startMotion(xx[0], yy[0]);  // right mouse
      if(b==3) pick(xx[0], yy[0]);         // left mouse
    }
  }

  class mouseReleaseHandler extends MouseAdapter
  {
    public void mouseReleased (MouseEvent e)
    {
      int b;
      int xx[] = new int[1];
      int yy[] = new int[1];

      b = e.getButton();
      xx[0] = e.getX();
      yy[0] = e.getY();
      if(snap) snapxy(xx, yy);
      if(b==1) stopMotion(xx[0], yy[0]);
    }
  }

  class mouseMotionHandler extends MouseMotionAdapter
  {
    public void mouseDragged (MouseEvent e)
    {
      int b;
      int xx[] = new int[1];
      int yy[] = new int[1];

      b = e.getButton();
      xx[0] = e.getX();
      yy[0] = e.getY();
      if(snap) snapxy(xx, yy);
      mouseMotion(xx[0], yy[0]);
    }
  }

  void rubberRect(Graphics g, int x0, int y0, int x1 , int y1)
  { 
    // can apply to all figures 
    // draw a rubber rectangle, mouse down, tracks mouse
    int x,y,x2,y2,x3,y3; // local coordinates
    x2=x0;
    x3=x1;
    if(x1<x0) {x2=x1; x3=x0;};
    y2=y0;
    y3=y1;
    if(y1<y0) {y2=y1; y3=y0;};
    g.setColor(Color.black);
    for(x=x2; x<x3-3; x=x+8) // Java does not seem to have a
    {                        // dashed or stippled rectangle or line
      g.drawLine(x, y0, x+4, y0);
      g.drawLine(x, y1, x+4, y1);
    }
    for(y=y2; y<y3-3; y=y+8)
    {
      g.drawLine(x0, y, x0, y+4);
      g.drawLine(x1, y, x1, y+4);
    }
  }

  void drawRect(Graphics g, Fig rect)
  {
    int x, y;
    
    g.setColor(new Color((float)rect.r, (float)rect.g, (float)rect.b));
    // g.setLineWidth(rect.width); ???
    x=rect.x0;
    if(rect.x1<rect.x0) x=rect.x1;;
    y=rect.y0;
    if(rect.y1<rect.y0) y=rect.y1;
    g.drawRect(x, y, Math.abs(rect.x1-rect.x0),
                     Math.abs(rect.y1-rect.y0));
    if(rect.width>1.0)
    g.drawRect(x-1, y-1, Math.abs(rect.x1-rect.x0)+2,
                         Math.abs(rect.y1-rect.y0)+2);
  }
  
  void pick(int x, int y)
  {
    int i;
    float t;
  
    // search figures in list, select
    for(i=0; i<num_fig; i++)
    {
      if(figure[i].x0 < figure[i].x1)
        if(x<figure[i].x0 || x>figure[i].x1) continue;
      if(figure[i].x1 < figure[i].x0)
        if(x<figure[i].x1 || x>figure[i].x0) continue;
      if(figure[i].y0 < figure[i].y1)
        if(y<figure[i].y0 || y>figure[i].y1) continue;
      if(figure[i].y1 < figure[i].y0)
        if(y<figure[i].y1 || y>figure[i].y0) continue;
      // select here by just changing color
      figure[select].r = 1.0;
      figure[select].g = 0.0;
      select = i;
      figure[select].r = 0.0;
      figure[select].g = 1.0;
      break;
    }
    requestFocus();
    repaint();
  }
  
  public void paint(Graphics g)
  {
    if(tracking) rubberRect(g, startX, startY, currentX, currentY);
    // draw figures per list
    for(int i=0; i<num_fig; i++)
    {
      /* should do switch on figure[i].kind */
      drawRect(g, figure[i]);
    }  
    if(grid)
    {
      g.setColor(new Color(0.5F,0.5F,0.5F));
      for(int i=gridSize; i<winWidth; i=i+gridSize)
        for(int j=gridSize; j<winHeight; j=j+gridSize)
          g.fillOval(i, j, 1, 1);
    }
  }

  public static void main(String args[])
  {
    new Rubber2();
  }
}