var how_many_previews = 0;
var memo_which_img = 1;
var memo_which_expoimg = 1;
var find_preview_srcs_done = 0;
all_preview_srcs = new Array();

function find_preview_srcs() {
	how_many_previews = (document.images.length - 1) / 2; // "-1" = logo, "/2" = anzahl previews (pro preview kommt 1 grosses bild dazu)
	for (var i = 1; i <= how_many_previews; i++) {
		var complete_img_src = document.images[i].src	
		var startof_img_src = complete_img_src.indexOf("previews/") + 9 ; //  9 = Anzahl Zeichen von String "previews/" in der Bildquelle
		var img_src = complete_img_src.substr(startof_img_src);
		all_preview_srcs[i] = img_src;
	}
	find_preview_srcs_done = 1;
	set_gallery(memo_which_img);
}

function set_gallery(nr) { 
	var which_img = nr;	
	if (find_preview_srcs_done == 1) {
		var restore_preview_src = all_preview_srcs[memo_which_img] + '" alt="preview image" />';	
		document.getElementById("preview_" + memo_which_img).innerHTML ='<img src="material/images/previews/' + restore_preview_src;
		var actual_preview_src = all_preview_srcs[which_img];
		var new_preview_src = actual_preview_src.replace(/k-/, "kb-") + '" alt="preview image" />';
		document.getElementById("preview_" + which_img).innerHTML ='<img src="material/images/previews/' + new_preview_src;		
	}
	document.getElementById("gallery_content_" + memo_which_img).style.display = "none";			
	document.getElementById("gallery_content_" + which_img).style.display = "block";
	memo_which_img = which_img;
}

function set_expoimg(nr) { 
	var which_img = nr;		
	document.getElementById("expo_img_" + memo_which_expoimg + "a").style.display = "none";		
	document.getElementById("expo_img_" + memo_which_expoimg + "b").style.display = "none";	
	document.getElementById("expo_img_" + which_img + "a").style.display = "block";		
	document.getElementById("expo_img_" + which_img + "b").style.display = "block";
	document.getElementById("expo_txt_" + memo_which_expoimg).className = "wrap-singleexpo-passive";
	document.getElementById("expo_txt_" + which_img).className = "wrap-singleexpo-active";									
	memo_which_expoimg = which_img;
}