/*  VERY Simple X interface

    J. Watlington, 9/13/95 - 10/25/95

    Significant parts from xline.c, Neil Gershenfeld  9/11/93
    Also included some of  xng.c, Neil Gershenfeld v 1.6 1993/09/01

	Restructured to contain the following interface :

	window_tag display_init_window( name, x_size, y_size, num_levels )
	display_update( window_tag )

	display_set_pixel( window_tag, x, y, raw_pixel_value )

	display_set_scale( window_tag, min, max )
	display_set_spixel( window_tag, x, y, scaled_value )

	display_set_fpixel( window_tag, x, y, scaled_value_float )
	
*/

#include <stdio.h>
#include <stdlib.h>
#include "display.h"

#define MAX_CLUT_VALUE  49152
#define MIN_CLUT_VALUE  16384

#define MIN_WINDOW_SIZE 64

window_desc  window_desc_table[DISPLAY_MAX_WINDOWS];
int          num_windows_open = 0;

/*   The following are declared globally, since they are needed for
     several of the functions.    */

static Display  *BigDisplay;
static int      BigScreen;

window_tag display_init_window( char *name, int xsize, int ysize,
	int num_levels )
{
   static int            first_time = 1;

   Visual                *V;
   Colormap              Cmap;
   XColor                Colors[DISPLAY_MAX_COLORS];

   XSetWindowAttributes  Attr;
   XVisualInfo           Info;

   window_desc           *wd;
   window_tag            wt;
   int                   i;

   if( num_levels > DISPLAY_MAX_COLORS )
   {
      printf("display_init_window: Max num levels is %d\n",
	  	DISPLAY_MAX_COLORS );
      return( -1 );
   }

   if( (xsize < MIN_WINDOW_SIZE) || (ysize < MIN_WINDOW_SIZE) )
   {
     printf("display_init_window: Size too small for X !\n" );
     return( -1 );
   }

   /*  assign a window_tag, and find the window descriptor   */

   wt = num_windows_open++;
   if( wt > DISPLAY_MAX_WINDOWS )
   {
     printf( "display_window_init: Too many windows open ! (%d max)\n",
	 	DISPLAY_MAX_WINDOWS );
	 return( -1 );
   }
   
   wd = window_desc_table + wt;

   /*  Some X stuff is only done for the first window that an
   	   application opens.   */

   if( first_time )
   {
	 BigDisplay = XOpenDisplay("");
     BigScreen = DefaultScreen( BigDisplay );
   	 first_time = 0;
   }

   /*  Now do the window specific X initialization.  */
   
   if( XMatchVisualInfo( BigDisplay, BigScreen, DISPLAY_DEPTH,
                         PseudoColor, &Info) == 0)
   {
     printf("Display can not handle %d bit pseudo color for the gray scale\n",
             DISPLAY_DEPTH);
     return( -1 );
   }
   
   V = Info.visual;

   /*  Now build the color table   */

   Colors[0].pixel = 0;
   Colors[0].red = 0;
   Colors[0].blue = 0;
   Colors[0].green = 0;
   Colors[0].flags = DoRed | DoGreen | DoBlue;

   for( i = 1; i < num_levels; ++i) {
      Colors[i].pixel = i;
      Colors[i].red = 0;
      Colors[i].green = (int)(((MAX_CLUT_VALUE*i)/num_levels) + MIN_CLUT_VALUE );
      Colors[i].blue = (int)(((MAX_CLUT_VALUE*i)/num_levels) + MIN_CLUT_VALUE );
      Colors[i].flags = DoRed | DoGreen | DoBlue;
   }
   
   Cmap = XCreateColormap( BigDisplay, RootWindow( BigDisplay, BigScreen),
   						   V, AllocAll );
   XStoreColors( BigDisplay, Cmap, Colors, num_levels );

   Attr.colormap = Cmap;
   Attr.background_pixel = WhitePixel( BigDisplay, BigScreen );
   Attr.border_pixel = BlackPixel( BigDisplay, BigScreen );

   wd->W = XCreateWindow( BigDisplay, DefaultRootWindow( BigDisplay ),
			 0, 0, xsize, ysize, 1,
			 DISPLAY_DEPTH, InputOutput, V,
			 CWColormap | CWBackPixel | CWBorderPixel, &Attr );
   XStoreName( BigDisplay, wd->W, name );
   XMapRaised( BigDisplay, wd->W );

   wd->Gc = XCreateGC( BigDisplay, wd->W, 0L, (XGCValues *)0 );
   
   /*  Allocate an image buffer and assign it to the window  */
   
   if( (wd->image = (unsigned char *)malloc( xsize * ysize )) == NULL )
   {
     printf("display_init_window: Unable to alloc %d bytes of mem for image\n",
	         xsize * ysize );
	 return( -1 );
   }

   wd->I = XCreateImage( BigDisplay, V, DISPLAY_DEPTH, ZPixmap, 0, wd->image,
   	                     xsize, ysize, DISPLAY_DEPTH, 0 );

   wd->x_size = xsize;
   wd->y_size = ysize;
   wd->num_levels = num_levels;
   wd->min = 0;
   wd->delta = 1;

   return( wt );
}

void display_update( window_tag id )
{
   window_desc   *wd = window_desc_table + id;
   
   XPutImage( BigDisplay, wd->W, wd->Gc, wd->I, 0, 0, 0, 0,
              wd->x_size, wd->x_size );
}