/*  Copyright 1992 John Bovey, University of Kent at Canterbury.
 *
 *  You can do what you like with this source code as long as
 *  you don't try to make money out of it and you include an
 *  unaltered copy of this message (including the copyright).
 */

char xvt_sbar_c_sccsid[] = "@(#)sbar.c	1.1 14/7/92 (UKC)";

#include <stdio.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xresource.h>
#include "rvt.h"
#include "xsetup.h"
#include "command.h"
#include "sbar.h"

/*  External global variables that are initialised at startup.
 */
extern Display *display;
extern Window sb_win;		/* scroll bar window */
extern GC sbgc;

static unsigned int width;	/* scrollbar width */
static unsigned int height;	/* scrollbar height */
static int mtop;		/* top of marked area */
static int mbot;		/* bottom of marked area */

/*  Most recent arguments to sbar_show
 */
static int last_length = 100;	/* initial values to give a full bar */
static int last_low = 0;
static int last_high = 100;

static char stipple_bits[] = {
	0x55, 0x55,
	0xaa, 0xaa,
	0x55, 0x55,
	0xaa, 0xaa,
	0x55, 0x55,
	0xaa, 0xaa,
	0x55, 0x55,
	0xaa, 0xaa,
	0x55, 0x55,
	0xaa, 0xaa,
	0x55, 0x55,
	0xaa, 0xaa,
	0x55, 0x55,
	0xaa, 0xaa,
	0x55, 0x55,
	0xaa, 0xaa,
};
/*  Initialise scrollbar data structures - called just once.
 */
void
sbar_init()
{
	Pixmap stipple;
	XGCValues gcv;

	stipple = XCreateBitmapFromData(display, sb_win, stipple_bits, 16, 16);
	if (stipple == NULL) {
		error("Cannot create scrollbar bitmap");
		quit(1);
	}
	gcv.fill_style = FillOpaqueStippled;
	gcv.stipple = stipple;
	XChangeGC(display, sbgc, GCFillStyle | GCStipple, &gcv);
	sbar_reset();
}
/*  Redraw the scrollbar after a size change
 */
void
sbar_reset()
{
	Window root;
	int x, y;
	unsigned int border_width, depth;

	XGetGeometry(display, sb_win, &root, &x, &y, &width, &height, &border_width, &depth);
	mbot = -1;		/* force a redraw */
	sbar_show(last_length, last_low, last_high);
}
/*  Redraw the scrollbar to show the area from low to high proportional to length.
 */
void
sbar_show(length, low, high)
	int length, low, high;
{
	int top, bot;

	if (length == 0)
		return;

	last_length = length;
	last_low = low;
	last_high = high;

	top = height - 1 - height * high / length;
	bot = height - 1 - height * low / length;

	if (top == mtop && bot == mbot)
		return;
	if (top > 0)
		XClearArea(display, sb_win, 0, 0, width, top - 1, False);
	if (bot >= top)
		XFillRectangle(display, sb_win, sbgc, 0, top, width, bot - top + 1);
	if (bot < height - 1)
		XClearArea(display, sb_win, 0, bot + 1, width, height - bot - 1, False);
}