function selectPhoto(num) {
    var elem = document.getElementById("current_photo");
    if (elem && photosArr && num < photosArr.length) {
        elem.src = photosArr[num].src;
    }
    var elem = document.getElementById("current_photo_num");
    if (elem && elem.tagName.toLowerCase() == "input") {
        elem.value = num;
    }
}

function preloadPhotos() {
    if (photoFilesArr) {
        photosArr = new Array();
        for (i = 0; i < photoFilesArr.length; i++) {
            photosArr[i] = new Image();
            photosArr[i].src = photoFilesArr[i];
        }
    }
}