/* Simple interface for defining viewport and window. If "just"=1,  */
/* X and Y scales will be the same, otherwise they are scaled       */
/* independently. The "axis" parameter is interpreted as follows:   */
/* axis=-2 : draw no box, axis or labels                            */
/* axis=-1 : draw box only                                          */
/* axis= 0 : Draw box and label with coordinates                    */
/* axis= 1 : Also draw the coordinate axes                          */
/* axis= 2 : Draw a grid at major tick positions                    */
/* axis=10 : Logarithmic X axis, L!=r Y axis, No X=0 axis         */
/* axis=11 : Logarithmic X axis, L!=r Y axis, X=0 axis            */
/* axis=20 : L!=r X axis, Logarithmic Y axis, No Y=0 axis         */
/* axis=21 : L!=r X axis, Logarithmic Y axis, Y=0 axis            */
/* axis=30 : Logarithmic X and Y axes                               */

#include "plplot.h"
#include <math.h>

void plenv(xmin,xmax,ymin,ymax,just,axis)
int just,axis;
float xmin, xmax, ymin, ymax;
{
    int level;
    float chrdef, chrht;
    float lb, rb, tb, bb, dx, dy;
    float xsize, ysize, xscale, yscale;
    float spxmin, spxmax, spymin, spymax;
    float vpxmin, vpxmax, vpymin, vpymax;
    float scale;

    glev(&level);
    if (level < 1) fatal("Please call PLSTAR before PLENV.");
    
    if (xmin == xmax) fatal("Invalid xmin and xmax arguments in PLENV");
    if (ymin == ymax) fatal("Invalid ymin and ymax arguments in PLENV");
    if ((just != 0) && (just != 1)) fatal("Invalid just option in PLENV");


    pladv(0);
    if (just == 0)
      plvsta();
    else {
      gchr(&chrdef,&chrht);
      lb = 7.0 * chrht;
      rb = 4.0 * chrht;
      tb = 4.0 * chrht;
      bb = 4.0 * chrht;
      dx = fabs(xmax-xmin);
      dy = fabs(ymax-ymin);
      plgspa(&spxmin,&spxmax,&spymin,&spymax);
      xsize = spxmax - spxmin;
      ysize = spymax - spymin;
      xscale = dx/(xsize - lb - rb);
      yscale = dy/(ysize - tb - bb);
      scale = max(xscale,yscale);
      vpxmin = max(lb,0.5*(xsize - dx/scale));
      vpxmax = vpxmin + (dx/scale);
      vpymin = max(bb,0.5*(ysize - dy/scale));
      vpymax = vpymin + (dy/scale);
      plsvpa(vpxmin,vpxmax,vpymin,vpymax);
    }
    plwind(xmin,xmax,ymin,ymax);
    if (axis == -2)
       ;
    else if (axis == -1)
       plbox("bc",0.0,0,"bc",0.0,0);
    else if (axis == 0) 
       plbox("bcnst",0.0,0,"bcnstv",0.0,0);
    else if (axis == 1) 
       plbox("abcnst",0.0,0,"abcnstv",0.0,0);
    else if (axis == 2) 
       plbox("abcgnst",0.0,0,"abcgnstv",0.0,0);
    else if (axis == 10) 
       plbox("bclnst",0.0,0,"bcnstv",0.0,0);
    else if (axis == 11) 
       plbox("bclnst",0.0,0,"abcnstv",0.0,0);
    else if (axis == 20) 
       plbox("bcnst",0.0,0,"bclnstv",0.0,0);
    else if (axis == 21) 
       plbox("bcnst",0.0,0,"abclnstv",0.0,0);
    else if (axis == 30) 
       plbox("bclnst",0.0,0,"bclnstv",0.0,0);
    else
       fatal("Invalid axis argument in plenv");
}