import java.awt.*;

/** Canvas that handles painting and interaction with a Polygontri
*/

public class PolygonCanvas extends Canvas {
  
  PolygonTri p;
  int startVertex = -1;
  Graphics xorg;
  int n;

  public PolygonCanvas() {
  }

  public void setPolygon(PolygonTri p) {
    if (xorg == null) {
      xorg = getGraphics().create();
      xorg.setXORMode(Color.red);
    }
    this.p = p;
    repaint();
  }

  public void paint(Graphics g) {
    p.setSize(size());
    p.paint(getGraphics());
  }

  int lastx;
  int lasty;

  public boolean mouseDown(Event e, int x, int y) {
    requestFocus();
    startVertex = p.pick(x,y);
    if (startVertex != -1) {
      Point pt = p.getPoint(startVertex);
      xorg.drawLine(pt.x, pt.y, x, y);
      lastx = x;
      lasty = y;
    }
    return true;
  }

  public boolean mouseDrag(Event e, int x, int y) {
    if (startVertex != -1) {
      Point pt = p.getPoint(startVertex);
      xorg.drawLine(pt.x, pt.y, lastx, lasty);
      lastx = x;
      lasty = y;
      xorg.drawLine(pt.x, pt.y, x, y);
    }
    return true;
  }

  public boolean mouseUp(Event e, int x, int y) {
    if (startVertex != -1) {
      Point pt = p.getPoint(startVertex);
      xorg.drawLine(pt.x, pt.y, lastx, lasty);
      int endVertex = p.pick(x,y);
      if (endVertex != -1) {
	p.addEdgeDeleteCross(startVertex, endVertex);
	repaint();
      }
    }
    return true;
  }

  public boolean MouseEnter(Event e, int x, int y) {
    requestFocus();
    return false;
  }

  public boolean keyDown(Event e, int key) {
    char c = (char) key;
    if ("cio".indexOf(c) >= 0) {
      if ((char)key == 'i') {
	p.zoomIn(e.x,e.y);
      } else if ((char)key == 'o') {
	p.zoomOut(e.x,e.y);
      } else if ((char)key == 'c') {
	p.centreView(e.x,e.y);
      }
      repaint();
    }
    return true;
  }
}