var gal_img=0;

function OpenGallery(num) {
    px = document.getElementById("main").offsetWidth;
    py = document.getElementById("main").offsetHeight;
    document.getElementById("overlay").style.width = px + "px";
    document.getElementById("overlay").style.height = py + "px";
    document.getElementById("overlay").style.visibility = "visible";
	gal_img=num;
	ShowImage();
}
function ShowImage() {
    px = document.getElementById("main").offsetWidth;
    document.getElementById("Foto").setAttribute("src", "");
    wdt = 640;
    hgt = 480;
    fy = 50
    fx = (px / 2) - (wdt / 2);
    document.getElementById("fondo_foto").style.top = fy + "px";
    document.getElementById("fondo_foto").style.left = fx + "px";
    document.getElementById("fondo_foto").style.width = (wdt + 20) + "px";
    document.getElementById("fondo_foto").style.height = (hgt + 40) + "px";
    document.getElementById("fondo_foto").style.visibility = "visible";

    document.getElementById("Foto").style.marginTop = "5px";
    document.getElementById("Foto").style.width = wdt + "px";
    document.getElementById("Foto").style.height = hgt + "px";
    document.getElementById("Foto").setAttribute("src", "tfile_gall_1_" + gal_img+".jpg");
}
function CloseImage() {
    document.getElementById("fondo_foto").style.visibility = "hidden";
    document.getElementById("Foto").setAttribute("src", "");
    document.getElementById("fondo_foto").style.top = "0px";
    document.getElementById("fondo_foto").style.left = "0px";
    document.getElementById("fondo_foto").style.width = "0px";
    document.getElementById("fondo_foto").style.height = "0px";
    document.getElementById("overlay").style.visibility = "hidden";
    document.getElementById("overlay").style.width = "0px";
    document.getElementById("overlay").style.height = "0px";
}
function NextImage() {
    if (gal_img < 30) {
        gal_img++;
    }
    else {
        gal_img = 1;
    }
    ShowImage();
}
function PrevImage() {
    if (gal_img >1) {
        gal_img--;
    }
    else {
        gal_img = g;
    }
    ShowImage();
}