// 先生.class
// Dr. dotimpact 98/8/27
// 98.8.31 考えるの面倒になったのでとりあえずRunnableで実装


import java.applet.Applet;
import java.awt.*;

public class sensei extends Applet implements Runnable{
    // スレッド
    Thread th;
    
    // ダブルバッファ
    Image buf;
    Graphics bufg;
    
    // 部品
    //Scrollbar slider;
    Wiper slider;
    
    // 変数
    Point last, there;
    int sliderpos;
    
public void init() {
    th = null;
    
    // ダブルバッファ確保
    buf = createImage(size().width, size().height - 30);
    bufg = buf.getGraphics();
    bufg.setColor(Color.lightGray);
    bufg.fillRect(0, 0, size().width, size().height - 30);
    bufg.setColor(Color.black);

    
    // 部品設定
    setLayout(null);
    slider = new Wiper(buf, size().width, size().height - 30);
    slider.reshape(5, size().height - 25, size().width - 10, 20);
    add(slider);
    // スライダをAdjustmentListenerに登録
    //slider.addAdjustmentListener(this);
    
    // 初期設定
    last = new Point(0, 0);
    there = new Point(0, 0);
    sliderpos = 0;
}

public void start() {
    if(th == null) {
	th = new Thread(this);
	th.start();
    }
}
public void stop() {
    if(th != null) {
	th.stop();
	th = null;
    }
}
public void run() {
    for(;;) {
	try {
	    Thread.sleep(100);
	} catch(Exception e){}
	repaint();
    }
}

    
public void update(Graphics g) {
    paint(g);
}
    
public void paint(Graphics g) {
    g.drawImage(buf, 0, 0, this);
}
    
public boolean mouseDown(Event ev, int x, int y) {
    last.x = x; last.y = y;
    return true;
}
public boolean mouseDrag(Event ev, int x, int y) {
    there.x = x; there.y = y;
    //draw();
    blushline(last.x, last.y, there.x, there.y);
    last.x = x; last.y = y;
    return true;
}
public boolean mouseUp(Event ev, int x, int y) {
    there.x = x; there.y = y;
    //draw();
    blushline(last.x, last.y, there.x, there.y);
    return true;
}

/*
public void adjustmentValueChanged(AdjustmentEvent e) {
    int cur = slider.getValue();
    bufg.setColor(Color.white);
    if(cur < sliderpos) {
	bufg.fillRect(cur, 0, sliderpos - cur, size().height - 25);
    } else {
	bufg.fillRect(sliderpos, 0, cur - sliderpos, size().height - 25);
    }
    sliderpos = cur;
    bufg.setColor(Color.black);
    repaint();
}
*/
    
    void blushline(int x1, int y1, int x2, int y2) {
	int x=0,y=0;
	int sign=0,dx,dy;
	
	if(x1==x2 && y1==y2) return;
	dx=Math.abs(x2-x1);
	dy=Math.abs(y2-y1);
	bufg.fillRect(x1, y1, 4, 4);
	if(dx > dy) {
	    int yy=dy/2;
	    if(x1 > x2) {
		int tmp;
		tmp=x1; x1=x2; x2=tmp;
		tmp=y1; y1=y2; y2=tmp;
	    }
	    sign=sgn(y2-y1);
	    while(x <= dx) {
		x=x+1;
		yy+=dy;
		if(yy >= dx) {
		    y+=sign;
		    yy-=dx;
		}
		bufg.fillRect(x1+x, y1+y, 4, 4);
	    }
	} else {
	    int xx=dx/2;
	    if(y1 > y2) {
		int tmp;
		tmp=x1; x1=x2; x2=tmp;
		tmp=y1; y1=y2; y2=tmp;
	    }
	    sign=sgn(x2-x1);
	    while(y <= dy) {
		y=y+1;
		xx+=dx;
		if(xx >= dy) {
		    x+=sign;
		    xx-=dy;
		}
		bufg.fillRect(x1+x, y1+y, 4, 4);
	    }
	}
	repaint();
    }

    int sgn(int val) {
	int ans;
	if(val==0) ans=0;
	else if(val<0) ans=-1;
	else ans=1;
	return(ans);
    }
}

class Wiper extends Scrollbar {
    Image img;
    Dimension dim;
    int last;
    
public Wiper(Image img, int width, int height) {
    super(Scrollbar.HORIZONTAL, 0, 1, 0, width);
    dim = new Dimension(width, height);
    this.img = img;
    last = 0;
}
public boolean handleEvent(Event ev) {
    Integer value = (Integer)ev.arg;
    switch (ev.id) {
    case Event.SCROLL_LINE_UP:
    case Event.SCROLL_LINE_DOWN:
    case Event.SCROLL_PAGE_UP :
    case Event.SCROLL_PAGE_DOWN :
	last = value.intValue();
	break;
    case Event.SCROLL_ABSOLUTE:
	//System.out.println("!");
	int cur = value.intValue();
	Graphics g = img.getGraphics();
	g.setColor(Color.lightGray);
	if(cur < last) {
	    g.fillRect(cur, 0, last - cur, dim.height);
	} else {
	    g.fillRect(last, 0, cur - last, dim.height);
	}
	last = cur;
	g.setColor(Color.black);
	//repaint();
	break;
    }
    return true;
}
}