//JavaScript for explanatory windows on client side maps
//Set up browser-dependent parameters for the new windows. The challenge is
//to position appropriately sized explanatory windows on screen for a range
//of screen sizes, resolutions, browser types and version numbers.
var bn, sw, sh; //browser type, screen width and height
var ex, ey; //mouseover event location
var sx=0, sy=0; //scroll position [Netscape only]
var newwindow; //pop-up window for explanatory text
var tempwindow; //pop-up window for diagrams etc
var testwindow; //pop-up window for self-assessment tests
var offset; //horizontal offset for pop-up windows
var bv=parseInt(navigator.appVersion);
//bn=1 for old browser, 2 for Netscape, 3 for Microsoft, bv = version no.
if (bv < 4) {window.alert("Please update your browser to fully exploit this website. We recommend Netscape version 4.5 or better."); bn=1; sw=640; sh=400} else {sw=screen.width; sh=screen.height};
if (navigator.appName == "Netscape") {bn=2}
if (navigator.appName == "Microsoft Internet Explorer") {bn=3}
var ww=Math.ceil(sw/2.2); //pop-up window width in pixcels
var wh=105; //pop-up window default height
var hsos=Math.ceil(sw/2); //half screen offset in pixcels
var lh=Math.ceil(sh/30); //message line height in pixcels
var specs="toolbar=no,directories=no,resizable,width=";
var keyflag=true;
//
//The following function displays explanatory text within
//a new adjustable window in response to mouseover events.
function Display(ex, ey, key, msg) {
var chars=msg.length;
var lines=Math.ceil(chars/50);
if (key != 0) {lines ++}
wh=Math.ceil(lh*lines);
var moreH=",height=" + wh;
var moreX;
if (ex<=hsos) {offset=sw-ww-10;} else {offset=0};
if (bn==2) {sx=window.pageXOffset; ex -= sx; moreX=",screenX="+offset;}
else moreX=",left="+offset;
var fullspec = specs + ww + moreH + moreX
if (newwindow!=null) {
if (newwindow.closed!=true) {newwindow.close();}}
newwindow = window.open("","brief",fullspec);
newwindow.document.open();
newwindow.document.writeln('');
newwindow.document.writeln('');
if (key > 0) {newwindow.document.writeln('THIS IS CORE MATERIAL! ')}
newwindow.document.writeln(msg);
if (key < 0) {newwindow.document.writeln(' (Background information.)')}
newwindow.document.writeln('');
newwindow.document.close();
}
//The following function clears the message on mouse out,
//unless a key has been pressed.
function RubOut() {
if (keyflag) {newwindow.close()}
else {keyflag=true}
}
//The following function modifies the message space estimates
//after the user has manually re-sized a message window. It is
//called from within the child window, but runs in the parent.
function Bodger() {
var nww=newwindow.innerWidth;
var nwh=newwindow.innerHeight;
ww = nww;
lh = lh * nwh / wh;
}
function OpenWindow(url) {
newwindow = window.open(url,"nat","resizable,width=400,height=400")}
//Temporary window. This function opens a new window in a "distant" area of the screen with
//the specified dimensions and displays the additional resources specified in "filename".
function TempWindow(ex, ey, xdim, ydim, filename) {
if (tempwindow!=null) {
if (tempwindow.closed!=true) {tempwindow.close();}}
if (ex<=hsos) {offset=sw-xdim-10;} else {offset=0};
var tempspec="width="+xdim+",height="+ydim+",left="+offset;
tempwindow = window.open("","temporary",tempspec);
tempwindow.location.href=filename;
return true;
}
function ShutIt() {
tempwindow.close();}
function Dummy(A,B,C,D) {
return true;}
//Mini self-assessment tests. This function opens a new window in a "distant" area of the screen
//and displays the self-test materials specified in "filename".
function MiniTest(ex, filename) {
if (testwindow!=null) {
if (testwindow.closed!=true) {testwindow.close();}}
if (ex<=hsos) {offset=sw-460;} else {offset=0};
var testspec="resizable,width=450,height=400,left="+offset;
testwindow = window.open("","selftest",testspec);
testwindow.location.href=filename;
return true;
}
//Self-assessment test marking: "instr" is the list of correct answers
//and "full" controls the amount of detail in the remedial text
function marktest(fname) {
var fmax = document.forms.length;
for (var iname=0; iname