/**
 * ColorBar - one of the three bars in a ColorPanel
 *
 * This is strictly a helper class for ColorPanel.
 */

import java.awt.*;

/** ColorBar: A color bar */
final class ColorBar {
  /* what does one pixel in any direction mean to any color? */
  float maxdim = (float)1.0;
  float mindim = (float)0.0;
  ColorPanel  b;                     /* the panel in which this widget lives */

  float value;                                              /* current color */

  int   x1;                                          /* endpoints of the bar */
  int   y1;
  int   xmid;
  int   ymid;
  int   x2;
  int   y2;

  final int lenx;                                   /* length in x direction */
  final int leny;                                   /* length in y direction */
  final float sqrlen;                               /* lenx*lenx + leny*leny */
  final float abslen;                         /* sqrt(lenx*lenx + leny*leny) */
  final boolean xbigger;                            /* abs(lenx) > abs(leny) */
  final float xdelta;                                /* x pixels per y pixel */
  final float ydelta;                                /* y change per x pixel */
  final float xfrac;                                       /* 1.0/abs(x2-x1) */
  final float yfrac;                                       /* 1.0/abs(y2-y1) */
  final float xfrac255;                                   /* 255/abs(x2-x1) */
  final float yfrac255;                                   /* 255/abs(y2-y1) */
  final int mycolor;                                     /* RED, GREEN, BLUE */
  final static int RED   = 0x1000000;
  final static int GREEN = 0x0010000;
  final static int BLUE  = 0x0000100;
  final private int colormask;

  /* thickness of the bar -- other endpoint is 0,0 */
  final int thickx;
  final int thicky;
  /* bar is split into two parts by the handle, offset to not overlap handle */
  final int firstx;
  final int firsty;
  final int lastx;
  final int lasty;


  /** ColorBar: initialize a color bar */
  ColorBar(ColorPanel b,                           /* panel this is drawn on */
           int mycolor,                      /* ColorBar.RED, GREEN, or BLUE */
	   float value,                    /* color value, values 0.0 to 1.0 */
	   int lenx,                           /* length of bar, x direction */
	   int leny)                           /* length of bar, y direction */
  {
    this.sqrlen = (float)(lenx*lenx+leny*leny);
    this.abslen = (float)Math.sqrt(sqrlen);
    float  avoidhandle = (b.thickness*(float)1.5)/abslen;
    this.b = b;
    this.lenx = lenx;
    this.leny = leny;
    this.firstx = -(int)(lenx*avoidhandle);
    this.firsty = -(int)(leny*avoidhandle);
    this.lastx  = -this.firstx;
    this.lasty  = -this.firsty;
    this.xbigger = (Math.abs(lenx) > Math.abs(leny));
    this.thickx = 
      -(int)((leny*b.thickness)/abslen);
    this.thicky =
      (int)((lenx*b.thickness)/abslen);
    this.mycolor = mycolor;
    this.colormask = mycolor-(mycolor/256);
    move(value);
    this.xdelta = (y2==y1) ? (float)0.0 : Math.abs((float)lenx/(float)leny);
    this.ydelta = (x2==x1) ? (float)0.0 : Math.abs((float)leny/(float)lenx);
    this.xfrac = (x2==x1) ? (float)0.0 : mycolor/(float)Math.abs(lenx);
    this.yfrac = (y2==y1) ? (float)0.0 : mycolor/(float)Math.abs(leny);
    this.xfrac255 = ((float)255.0)*xfrac;
    this.yfrac255 = ((float)255.0)*yfrac;
  }

  /* move the color bar according to value and current pixel */
  void move(float value) {
    this.value = value;
    b.cc = ((b.cc&(0xffffff^colormask))^      /* change this component of cc */
	    ((int)(value*colormask)&colormask));
    x1 = b.currx+firstx-(int)(lenx*value)-(thickx/2);
    y1 = b.curry+firsty-(int)(leny*value)-(thicky/2);
    xmid = x1+(int)(lenx*value);
    ymid = y1+(int)(leny*value);
    x2 = x1+lenx+lastx-firstx;
    y2 = y1+leny+lasty-firsty;
  }

  /* clear a color bar */
  public void clear(Graphics g) {
    int i, x, y, xstop, ystop;
    float fx, fy;
    int xinc = (x1<x2) ? 1 : -1;
    int yinc = (y1<y2) ? 1 : -1;
    fx = (float)0.5;
    fy = (float)0.5;
    for (i=0, x=x1, y=y1, xstop=xmid, ystop=ymid;
	 i<2; ++i) {
      if (xbigger) {
	for (; x!=xstop; x+=xinc, fy+=ydelta) {
	  g.drawLine(x, y, x+thickx, y+thicky);
	  if (fy > 1.0) {
	    fy -= 1.0;
	    y += yinc;
	    g.drawLine(x, y, x+thickx, y+thicky);
	  }
	}
      }
      else  /* !xbigger */ {
	for (; y!=ystop; y+=yinc, fx+=xdelta) {
	  g.drawLine(x, y, x+thickx, y+thicky);
	  if (fx > 1.0) {
	    fx -= 1.0;
	    x += xinc;
	    g.drawLine(x, y, x+thickx, y+thicky);
	  }
	}
      }
      if (i==0) {
	x += lastx-firstx;
	y += lasty-firsty;
	xstop = x2;
	ystop = y2;
      }
    }
  }

  /* draw a color bar */
  public void draw(Graphics g) {
    int i, x, y, xstop, ystop;
    int basecolor = (b.cc & (0xffffff ^ colormask));
    float fx, fy, amount;
    int xinc = (x1<x2) ? 1 : -1;
    int yinc = (y1<y2) ? 1 : -1;
    fx = (float)0.5;
    fy = (float)0.5;
    for (i=0, x=x1, y=y1, xstop=xmid, ystop=ymid, amount=(float)0.0; 
	 i<2; ++i) {
      if (xbigger) {
	for (; x!=xstop; x+=xinc, fy+=ydelta, amount+=xfrac) {
	  int q = basecolor^(((int)amount)&colormask);
	  g.setColor(new Color(q));
	  g.drawLine(x, y, x+thickx, y+thicky);
	  if (fy > 1.0) {
	    fy -= 1.0;
	    y += yinc;
	    g.drawLine(x, y, x+thickx, y+thicky);
	  }
	}
      }
      else  /* !xbigger */ {
	for (; y!=ystop; y+=yinc, fx+=xdelta, amount+=yfrac) {
	  int q = basecolor^(((int)amount)&colormask);
	  g.setColor(new Color(q));
	  g.drawLine(x, y, x+thickx, y+thicky);
	  if (fx > 1.0) {
	    fx -= 1.0;
	    x += xinc;
	    g.drawLine(x, y, x+thickx, y+thicky);
	  }
	}
      }
      if (i==0) {
	x = x+lastx-firstx;
	y = y+lasty-firsty;
	xstop = x2;
	ystop = y2;
      }
    }
  }
}