// File:    BezierCanvas.java

import java.awt.*;

/** Draws the curves and processes the mouse input. **/

public class BezierCanvas extends Canvas {

  protected State state;
  protected CurveManager curveManager;
  protected PointManager pointManager;

  protected Point[] temporaryCurve = new Point[4];
  protected int temporaryLength = 0;

  public BezierCanvas(State state,
            CurveManager curveManager,
            PointManager pointManager) {
    this.state = state;
    this.curveManager = curveManager;
    this.pointManager = pointManager;
  }

  public boolean mouseDown(Event e, int x, int y) {
    Point p = new Point(x,y);
    if (state.getState()==State.PASSIVE) {
      if (pointManager.isControlPoint(p)) {
   ControlPoint cp = pointManager.getControlPoint(p);
   pointManager.activatePoint(cp);
   state.setState(State.EDITING);
      }
    }
    else if (state.getState()==State.CREATING) {
      temporaryCurve[temporaryLength] = p;
      temporaryLength++;
      repaint();
    }
    return true;
  }

  public boolean mouseUp(Event e, int x, int y) {
    if (state.getState()==State.CREATING) {
      if (temporaryLength==4) {
   Point[] p = temporaryCurve;
   curveManager.addCurve(p[0],p[1],p[2],p[3]);
   temporaryLength = 0;
   state.setState(State.PASSIVE);
   repaint();
      }
    }
    else if (state.getState()==State.EDITING) {
      state.setState(State.PASSIVE);
    }
    return true;
  }

  public boolean mouseDrag(Event e, int x, int y) {
    int s = state.getState();
    if (s==State.EDITING) {
      pointManager.setActivePoint(new Point(x,y));
      repaint();
    }
    else if (s==State.CREATING) {
      temporaryCurve[temporaryLength-1]=new Point(x,y);
      repaint();
    }
    return true;
  }

  public void update(Graphics g) {
    paint(g);
  }

  /** Possible improvement: Separate static and dynamic layer; only
      update curves bein edited and store the rest as an Image. **/
  public void paint(Graphics g) {
    Image offscreen = createImage(size().width, size().height);
    Graphics og = offscreen.getGraphics();

    // Draw all the curves
    curveManager.paint(og,state.getSamples());

    // If a curve is under creation, draw a simple approximation of it:
    if (temporaryLength != 0) {
      Point[] p = temporaryCurve;
      og.setColor(Color.red);
      for (int i=1; i<temporaryLength; i++) {
   og.drawLine(p[i-1].x-1, p[i-1].y-1,
          p[i].x-1, p[i].y-1);
      }
      for (int i=0; i<temporaryLength; i++) {
   og.fillRect(p[i].x-3,p[i].y-3,5,5);
      }
      og.setColor(Color.black);
    }

    // If we are not in preview mode, draw all the points

    if (!state.isPreview()) pointManager.paint(og);

    g.drawImage(offscreen,0,0,this);

  }

}