//This is a drawing program

void DrawIt()
{
  ClearWindowText;
}

I4 dx,dy,dd,scale=10;

void DoodlePlot(GrBitMap *base,I4 x,I4 y,I4 z)
{
z;
  GrLine3(base,x/scale+dy,y/scale-dx,0,
	       x/scale-dy,y/scale+dx,0);
}

public void DoodleLine(GrBitMap *base,I4 x1,I4 y1,I4 x2,I4 y2)
{
  Line(base,x1,y1,0,x2,y2,0,&DoodlePlot);
}

//This is good for drawing palm trees
public void Doodle2()
{
  I8 cmd,x1,y1,x2,y2,p1,p2,color=GR_BLACK;
  U4 old_update_window=Fs->update_window;
  U4 old_ip_double=Bts(&Fs->crt_flags,CRTf_NO_DOUBLE_CLICK);
  U4 old_inhibit=ip_inhibit_win_operations;
  GrBitMap *base=GrNew(grbase);
  base->color=ROP_EQU+(color ^ GR_WHITE);
  ip_inhibit_win_operations=TRUE;
  MaximizeWindow;
  Fs->update_window=&DrawIt;
  GrClear;
  PutS("$$CL$$");
  while (TRUE) {
    cmd=GetMsg(&p1,&p2,
      (1<<MSG_KEY_DOWN)+(1<<MSG_IP_L_DOWN)+
      (1<<MSG_IP_R_UP));
    if (cmd==MSG_KEY_DOWN) {
      Fs->update_window=old_update_window;
      GrClear;
      AssignBit(&Fs->crt_flags,CRTf_NO_DOUBLE_CLICK,old_ip_double);
      ip_inhibit_win_operations=old_inhibit;
      GrDel(base);
      return;
    } else if (cmd==MSG_IP_R_UP) {
      ip_inhibit_win_operations=FALSE;
      color=PopUpColor;
      base->color=ROP_EQU+(color ^ GR_WHITE);
      ip_inhibit_win_operations=TRUE;
    } else {
      x1=p1; y1=p2;
      x2=p1; y2=p2;
      while (cmd!=MSG_IP_L_UP) {
	dx=x2-x1; dy=y2-y1;
	dd=Sqrt(dx*dx+dy*dy);
	if (dd) {
	  dx=dx*ip_speed/dd/0x5000000;
	  dy=dy*ip_speed/dd/0x5000000;
	  DoodleLine(base,x1*scale,y1*scale,x2*scale,y2*scale);
	}
	cmd=GetMsg(&p1,&p2,
  	  (1<<MSG_IP_L_UP)+(1<<MSG_IP_MOVE));
	x1=x2; y1=y2;
	x2=p1; y2=p2;
      }
      GrLine3(base,x1,y1,0,x2,y2,0);
    }
  }
}

Doodle2;  //Execute when #included
 