//-------------------------------------------------------------------
//	gpmslide.cpp
//
//	This program shows the essential steps in utilizing Linux's 
//	'General Purpose Mouse' programming-interface ('libgpm') in 
//	a simple graphics application: the user can move a 'slider'
//	object back and forth, toward the left or toward the right.  	
//
//	  compile: $ g++ gpmslide.cpp int86.cpp -lgpm -o gpmslide
//
//	programmer: ALLAN CRUSE
//	written on: 21 AUG 2003
//	revised on: 21 SEP 2005 -- replaces svgalib with 'int86()'
//-------------------------------------------------------------------

#include <fcntl.h>	// for open() 
#include <unistd.h>	// for lseek() 
#include <termios.h>	// for tcgetattr(), tcsetattr() 
#include <sys/mman.h>	// for mmap() 
#include <gpm.h>	// for Gpm_Open()
#include "int86.h"	// for init8086(), int86()

int vesa_mode = 0x4101, hres = 640, vres = 480; 
unsigned char *vram = (unsigned char*)0xA0000000; 
struct vm86plus_struct	vm;

// global variables (for control of the 'slider' object)
int	minx = 100, maxx = 340, locy = 236;
int	wide = 200, high = 8, bgcolor = 0;
int	curr = 220, prev = 220, fgcolor = 10;

void fill_rectangle( int x, int y, int h, int v, int color )
{
	int	minx = x, maxx = x+h, miny = y, maxy = y+v;
	for (y = miny; y < maxy; y++) 
		for (x = minx; x < maxx; x++)
			vram[ y*hres + x ] = color;
}	

int my_mouse_handler( Gpm_Event *evt, void *data )
{
	// for now we just ignore all mouse-events except 'moves'
	if ( evt->type != GPM_MOVE ) return 0;
	
	prev = curr;		// save slider's current position
	curr += 2*evt->dx;	// compute slider's next location
	// but make sure the slider won't be moving 'out-of-sight'
	if ( curr < minx ) curr = minx;	// if too far leftward
	if ( curr > maxx ) curr = maxx;	// if too far rightward
	if ( curr != prev ) // does the slider position change?
		{	    // yes, erase it and then redraw it 
		fill_rectangle( prev, locy, wide, high, bgcolor );
		fill_rectangle( curr, locy, wide, high, fgcolor );
		}
	return	0;
}	

void draw_rectangle( int x, int y, int h, int v, int color ) 
{
	int	minx = 0, miny = 0, maxx = hres-1, maxy = vres-1; 

	do { vram[ y*hres + x ] = color; ++x; } while ( x < maxx ); 
	do { vram[ y*hres + x ] = color; ++y; } while ( y < maxy ); 
	do { vram[ y*hres + x ] = color; --x; } while ( x > minx ); 
	do { vram[ y*hres + x ] = color; --y; } while ( y > miny ); 
}


int main( void )
{
	// memory-map the frame-buffer into user address-apace
	int	fd = open( "/dev/vram", O_RDWR ); 
	if ( fd < 0 ) { perror( "/dev/vram" ); return -1; } 
	int	size = lseek( fd, 0, SEEK_END );
	int	prot = PROT_READ | PROT_WRITE; 
	int	flag = MAP_FIXED | MAP_SHARED; 
	if ( mmap( (void*)vram, size, prot, flag, fd, 0 ) == MAP_FAILED ) 
		{ perror( "mmap" ); return -1; } 

	// enable non-canonical keyboard input
	struct termios	otty; 
	tcgetattr( 0, &otty ); 
	struct termios	tty = otty; 
	tty.c_lflag &= ~( ICANON | ECHO | ISIG ); 
	tty.c_cc[ VMIN ] = 1; 
	tty.c_cc[ VTIME ] = 0; 
	tcsetattr( 0, TCSAFLUSH, &tty ); 

	// enter graphics mode
	init8086();
	vm.regs.eax = 0x4F02;
	vm.regs.ebx = vesa_mode;
	int86( 0x10, vm );

	// draw a screen border and initial image of the 'slider'  
	int	bordercolor = 15; 
	draw_rectangle( 0, 0, hres, vres, bordercolor ); 
	fill_rectangle( curr, locy, wide, high, fgcolor );

	// establish our connection with the GPM daemon-process
	Gpm_Connect	conn;
	conn.eventMask = ~0;	
	conn.defaultMask = 0;
	conn.minMod = 0;
	conn.maxMod = ~0;
	if ( Gpm_Open( &conn, 0 ) != -1 ) 
		{
		gpm_handler = my_mouse_handler;
		while ( Gpm_Getc( stdin ) != '\e' );
		Gpm_Close();
		}

	// leave graphics mode
	vm.regs.eax = 0x0003;
	int86( 0x10, vm );

	// restore canonical keyboard-input 	
	tcsetattr( 0, TCSAFLUSH, &otty ); 
}