/* gray.c 1.1 */
/*
    Copyright 1992, 1993 O'Reilly and Associates, Inc.  Permission to
    use, copy, and modify this program is hereby granted, as long as
    this copyright notice appears in each copy of the program source
    code.
*/

#include "book_utils.h"

#define WIN_GEOM	"500x500+50+50"
#define NUM_GRAYS	64

static Display		*dpy;
static Window		window;
static PEXStructure	struct_id;
static PEXRenderer	renderer;

static void
redraw()
{
    /* Redraw the window, after first erasing (clearing) it. */
    XClearWindow( dpy, window );
    PEXRenderNetwork( dpy, window, renderer, struct_id );
    XFlush( dpy );
}

#define X0	0.1
#define XN	0.9
#define Y0	0.6
#define YN	0.9
#define YP0	0.1
#define YPN	0.4
	
static void
create_structure( num_grays )
    int		num_grays;
{
    int		i, j, k, nr = 4, ng = 4, nb = 4, num_colors;
    double	x, dx, dc;
    PEXColor	color;
    PEXCoord2D	pts[4];
    
    dx = (XN - X0) / num_grays;
    dc = 1.0 / (num_grays - 1); /* color increment */
    
    /* Create the structure. */
    struct_id = PEXCreateStructure( dpy );
    
    /* Set the interior style to solid. */
    PEXSetInteriorStyle( dpy, struct_id, PEXOCStore,
			PEXInteriorStyleSolid );
    
    /* Show the gray scale. */
    for ( i = 0, x = X0; i < num_grays; i++, x += dx ) {
	color.rgb.red = color.rgb.green = color.rgb.blue = i * dc;
	PEXSetSurfaceColor( dpy, struct_id, PEXOCStore,
			   PEXColorTypeRGB, &color );
	pts[0].y = pts[1].y = Y0;
	pts[2].y = pts[3].y = YN;
	pts[0].x = pts[3].x = x;
	pts[1].x = pts[2].x = x + dx;
	PEXFillArea2D( dpy, struct_id, PEXOCStore,
		      PEXShapeConvex, False, 4, pts );
    }
    
    
    /* Create the "colored" scales. */
    num_colors = nr * ng * nb;
    dx = (XN - X0) / num_colors;
    x = X0;
    for ( i = 0; i < nr; i++ ) {
	for ( j = 0; j < ng; j++ ) {
	    for ( k = 0; k < nb; k++ ) {
		color.rgb.red = i * 1.0 / (nr - 1);
		color.rgb.green = j * 1.0 / (ng - 1);
		color.rgb.blue = k * 1.0 / (nb - 1);
		PEXSetSurfaceColor( dpy, struct_id, PEXOCStore,
				   PEXColorTypeRGB, &color );
		pts[0].y = pts[1].y = YP0;
		pts[2].y = pts[3].y = YPN;
		pts[0].x = pts[3].x = x;
		pts[1].x = pts[2].x = x + dx;
		PEXFillArea2D( dpy, struct_id, PEXOCStore,
			      PEXShapeConvex, False, 4, pts );
		x += dx;
	    }
	}
    }
}

main( argc, argv )
    int		argc;
    char	*argv[];
{
    XEvent		event;
    XVisualInfo		*vis_info, vis_templ;
    XColor			bkgd_color;
    XStandardColormap	cmap_info;
    PEXColorApproxEntry	capx_info;
    PEXExtensionInfo	*pexinfo;
    PEXRendererAttributes	rattrs;
    int			done = 0, num_vis;
    
    /* Open a display and initialize PEX. */
    dpy = ora_init_pex( argv, &pexinfo );
    if ( !dpy ) exit(1);
    
    /* Get a GrayScale visual. */
    vis_templ.screen = DefaultScreen( dpy );
    vis_templ.class = GrayScale;
    vis_info = XGetVisualInfo( dpy,
	VisualScreenMask | VisualClassMask ,
	&vis_templ, &num_vis );
    if ( num_vis == 0 ) {
	fprintf ( stderr, "No gray-scale visual.\n" );
	exit(1);
    }
    
    /* Create a colormap for the visual. */
    if ( !ora_create_gray_map( dpy, vis_info, NUM_GRAYS, &cmap_info,
			       &capx_info ) ) {
	fprintf ( stderr, "Cannot create a colormap\n" );
	exit(1);
    }

    /* Create the window, giving it a gray background. */
    bkgd_color.red = bkgd_color.green = bkgd_color.blue = 0x5555;
    bkgd_color.flags = DoRed | DoGreen | DoBlue;
    window = ora_create_window( dpy, vis_info, &cmap_info, WIN_GEOM,
			        &bkgd_color );
    
    /* Create the renderer and the structure. */
    if ( STRUCTURE_SPT( pexinfo ) ) {
	renderer = ora_setup_renderer( dpy, window, &capx_info,
				       &rattrs );
	create_structure( NUM_GRAYS );
    } else {
	fprintf( stderr, "Structures not supported.\n" );
	exit(1);
    }
    
    /* Read and respond to X events. */
    XSelectInput( dpy, window, ExposureMask | ButtonPressMask );
    while ( !done ) {
	XNextEvent( dpy, &event );
	switch ( event.type ) {
	case Expose:
	    /* Flush remaining Expose events, then redraw. */
	    while ( XCheckTypedWindowEvent( dpy, window,
					    Expose, &event ) )
		; /* empty statement */
	    redraw();
	    break;
	case ButtonPress:
	    done = 1;
	    break;
	}
    }

    XCloseDisplay( dpy );
    return 0;
}