// fixed.js: fix fixed positioning and fixed backgrounds in IE/Win
// version 1.8, 08-Aug-2003
// written by Andrew Clover <and@doxdesk.com>, use freely
@if (@_win32 && @_jscript_version>4)
var fixed_positions= new Array();
var fixed_backgrounds= new Array();
var fixed_viewport;
// Initialisation. Called when the <body> tag arrives. Set up viewport so the
// rest of the script knows we're going, and add a measurer div, used to detect
// font size changes and measure image sizes for backgrounds later
function fixed_init() {
fixed_viewport= (document.compatMode=='CSS1Compat') ?
document.documentElement : document.body;
var el= document.createElement('div');
el.setAttribute('id', 'fixed-measure');
el.style.position= 'absolute';
el.style.top= '0'; el.style.left= '0';
el.style.overflow= 'hidden'; el.style.visibility= 'hidden';
el.style.fontSize= 'xx-large'; el.style.height= '5em';
el.style.setExpression('width', 'fixed_measureFont()');
document.body.insertBefore(el, document.body.firstChild);
}
// Binding. Called every time an element is added to the document, check it
// for fixed features, if found add to our lists and set initial props
function fixed_bind(el) {
var needLayout= false;
var tag= el.tagName.toLowerCase();
var st= el.style;
var cst= el.currentStyle;
var anc;
// find fixed-position elements
if (cst.position=='fixed') {
needLayout= true;
fixed_positions[fixed_positions.length]= el;
// store original positioning as we'll overwrite it
st.position= 'absolute';
st.fixedPLeft= cst.left;
st.fixedPTop= cst.top;
st.fixedPRight= cst.right;
st.fixedPBottom= cst.bottom;
st.fixedPWidth= fixed_parseLength(cst.width);
st.fixedPHeight= fixed_parseLength(cst.height);
// find element that will act as containing box, for convenience later
st.fixedCB= null;
for (anc= el; (anc= anc.parentElement).parentElement;) {
if (anc.currentStyle.position!='static') {
st.fixedCB= anc;
break;
} }
// detect nested fixed positioning (only ancestor need move)
st.fixedNest= false;
for (anc= el; anc= anc.parentElement;) {
if (anc.style.fixedNest!=null)
st.fixedNest= true;
break;
}
}
// find fixed-background elements (not body/html which IE already gets right)
if (cst.backgroundAttachment=='fixed' && tag!='body' && tag!='html') {
needLayout= true;
fixed_backgrounds[fixed_backgrounds.length]= el;
// get background offset, converting from keyword if necessary
st.fixedBLeft= fixed_parseLength(cst.backgroundPositionX);
st.fixedBTop= fixed_parseLength(cst.backgroundPositionY);
// if it's a non-zero %age, need to know size of image for layout
if (st.fixedBLeft[1]=='%' || st.fixedBTop[1]=='%') {
st.fixedBWidth= 0; st.fixedBHeight= 0;
fixed_measureBack(el);
}
}
if (needLayout) fixed_layout();
}
// Layout. On every window or font size change, recalculate positioning
// Request re-layout at next free moment
var fixed_delaying= false;
function fixed_delayout() {
if (fixed_delaying) return;
fixed_delaying= true;
window.setTimeout(fixed_layout, 0);
}
var fixed_ARBITRARY= 200;
function fixed_layout() {
fixed_delaying= false;
if (!fixed_viewport) return;
var i, el, st, j, pr, tmp, A= 'auto';
var cb, cbLeft, cbTop, cbRight, cbBottom, oLeft, oTop, oRight, oBottom;
var vpWidth=fixed_viewport.clientWidth, vpHeight=fixed_viewport.clientHeight;
// calculate initial position for fixed-position elements [black magic]
for (i= fixed_positions.length; i-->0;) {
el= fixed_positions[i]; st= el.style;
// find positioning of containing block
cb= st.fixedCB; if (!cb) cb= fixed_viewport;
cbLeft= fixed_pageLeft(cb); cbTop= fixed_pageTop(cb);
if (cb!=fixed_viewport) { cbLeft+= cb.clientLeft; cbTop+= cb.clientTop; }
cbRight= fixed_viewport.clientWidth-cbLeft-cb.clientWidth;
cbBottom= fixed_viewport.clientHeight-cbTop-cb.clientHeight;
// if size is in %, must recalculate relative to viewport
if (st.fixedPWidth[1]=='%')
st.width= Math.round(vpWidth*st.fixedPWidth[0]/100)+'px';
if (st.fixedPHeight[1]=='%')
st.height= Math.round(vpHeight*st.fixedPHeight[0]/100)+'px';
// find out offset values at max size, to account for margins
st.left= A; st.right= '0'; st.top= A; st.bottom= '0';
oRight= el.offsetLeft+el.offsetWidth; oBottom= el.offsetTop+el.offsetHeight;
st.left= '0'; st.right= A; st.top= '0'; st.bottom= A;
oLeft= el.offsetLeft; oTop= el.offsetTop;
// use this to convert all edges to pixels
st.left= A; st.right= st.fixedPRight;
st.top= A; st.bottom= st.fixedPBottom;
oRight-= el.offsetLeft+el.offsetWidth;
oBottom-= el.offsetTop+el.offsetHeight;
st.left= st.fixedPLeft; st.top= st.fixedPTop;
oLeft= el.offsetLeft-oLeft; oTop= el.offsetTop-oTop;
// edge positioning fix
if (st.fixedPWidth[1]==A && st.fixedPLeft!=A && st.fixedPRight!=A) {
tmp= el.offsetLeft; st.left= A; st.width= fixed_ARBITRARY+'px';
tmp= fixed_ARBITRARY+el.offsetLeft-tmp+cbLeft+cbRight;
st.left= st.fixedPLeft; st.width= ((tmp<1)?1:tmp)+'px';
}
if (st.fixedPHeight[1]==A && st.fixedPTop!=A && st.fixedPBottom!=A) {
tmp= el.offsetTop; st.top= A; st.height= fixed_ARBITRARY+'px';
tmp= fixed_ARBITRARY+el.offsetTop-tmp+cbTop+cbBottom;
st.top= st.fixedPTop; st.height= ((tmp<1)?1:tmp)+'px';
}
// move all non-auto edges relative to the viewport
st.fixedCLeft= (st.fixedPLeft=='auto') ? oLeft : oLeft-cbLeft;
st.fixedCTop= (st.fixedPTop=='auto') ? oTop : oTop-cbTop;
st.fixedCRight= (st.fixedPRight=='auto') ? oRight : oRight-cbRight;
st.fixedCBottom= (st.fixedPBottom=='auto') ? oBottom : oBottom-cbBottom;
// remove left-positioning of right-positioned elements
if (st.fixedPLeft=='auto' && st.fixedPRight!='auto') st.fixedCLeft= 'auto';
if (st.fixedPTop=='auto' && st.fixedPBottom!='auto') st.fixedCTop= 'auto';
}
// calculate initial positioning of fixed backgrounds
for (i= fixed_backgrounds.length; i-->0;) {
el= fixed_backgrounds[i]; st= el.style;
tmp= st.fixedBImage;
if (tmp) {
if (tmp.readyState!='uninitialized') {
st.fixedBWidth= tmp.offsetWidth;
st.fixedBHeight= tmp.offsetHeight;
st.fixedBImage= window.undefined;
}
}
st.fixedBX= fixed_length(el, st.fixedBLeft, vpWidth-st.fixedBWidth);
st.fixedBY= fixed_length(el, st.fixedBTop, vpHeight-st.fixedBHeight);
}
// now call scroll() to set the positions from the values just calculated
fixed_scroll();
}
// Scrolling. Offset fixed elements relative to viewport scrollness
var fixed_lastX, fixed_lastY;
var fixed_PATCHDELAY= 300;
var fixed_patching= false;
// callback function after a scroll, because incorrect scroll position is
// often reported first go!
function fixed_patch() {
fixed_patching= false;
var scrollX= fixed_viewport.scrollLeft, scrollY= fixed_viewport.scrollTop;
if (scrollX!=fixed_lastX && scrollY!=fixed_lastY) fixed_scroll();
}
function fixed_scroll() {
if (!fixed_viewport) return;
var i, el, st, viewportX, viewportY;
var scrollX= fixed_viewport.scrollLeft, scrollY= fixed_viewport.scrollTop;
fixed_lastX= scrollX; fixed_lastY= scrollY;
// move non-nested fixed-position elements
for (i= fixed_positions.length; i-->0;) {
st= fixed_positions[i].style;
viewportX= (st.fixedNest) ? 0 : scrollX;
viewportY= (st.fixedNest) ? 0 : scrollY;
if (st.fixedCLeft!='auto') st.left= (st.fixedCLeft+viewportX)+'px';
if (st.fixedCTop!='auto') st.top= (st.fixedCTop+viewportY)+'px';
viewportX= (st.fixedCB==null || st.fixedCB==fixed_viewport) ? 0 : viewportX;
viewportY= (st.fixedCB==null || st.fixedCB==fixed_viewport) ? 0 : viewportY;
st.right= (st.fixedCRight-viewportX+1)+'px'; st.right= (st.fixedCRight-viewportX)+'px';
st.bottom= (st.fixedCBottom-viewportY+1)+'px'; st.bottom= (st.fixedCBottom-viewportY)+'px';
}
// align fixed backgrounds to viewport
for (i= fixed_backgrounds.length; i-->0;) {
el= fixed_backgrounds[i]; st= el.style;
viewportX= scrollX;
viewportY= scrollY;
while (el.offsetParent) {
viewportX-= el.offsetLeft+el.clientLeft;
viewportY-= el.offsetTop +el.clientTop;
el= el.offsetParent;
}
st.backgroundPositionX= (st.fixedBX+viewportX)+'px';
st.backgroundPositionY= (st.fixedBY+viewportY)+'px';
}
// call back again in a tic
if (!fixed_patching) {
fixed_patching= true;
window.setTimeout(fixed_patch, fixed_PATCHDELAY);
}
}
// Measurement. Load bg-image into an invisible element on the page, when
// loaded write the width/height to an element's style for layout use; detect
// when font size changes
function fixed_measureBack(el) {
var measure= document.getElementById('fixed-measure');
var img= document.createElement('img');
img.setAttribute('src', fixed_parseURL(el.currentStyle.backgroundImage));
measure.appendChild(img);
el.style.fixedBImage= img;
if (img.readyState=='uninitialized')
img.attachEvent('onreadystatechange', fixed_measureBackImage_ready);
}
function fixed_measureBackImage_ready() {
var img= event.srcElement;
if (img && img.readyState!='uninitialized') {
img.detachEvent('onreadystatechange', fixed_measureBackImage_ready);
fixed_layout();
}
}
var fixed_fontsize= 0;
function fixed_measureFont() {
var fs= document.getElementById('fixed-measure').offsetHeight;
if (fixed_fontsize!=fs && fixed_fontsize!=0)
fixed_delayout();
fixed_fontsize= fs;
return '5em';
}
// Utility. General-purpose functions
// parse url() to get value inside
function fixed_parseURL(v) {
v= v.substring(4, v.length-1);
if (v.charAt(0)=='"' && v.charAt(v.length-1)=='"' ||
v.charAt(0)=="'" && v.charAt(v.length-1)=="'")
return v.substring(1, v.length-1);
else return v;
}
// parse length or auto or background-position keyword into number and unit
var fixed_numberChars= '+-0123456789.';
var fixed_ZERO= new Array(0, 'px');
var fixed_50PC= new Array(50, '%');
var fixed_100PC= new Array(100, '%');
var fixed_AUTO= new Array(0, 'auto');
function fixed_parseLength(v) {
var num, i;
if (v=='left' || v=='top') return fixed_ZERO;
if (v=='right' || v=='bottom') return fixed_100PC;
if (v=='center') return fixed_50PC;
if (v=='auto') return fixed_AUTO;
i= 0;
while (i<v.length && fixed_numberChars.indexOf(v.charAt(i))!=-1)
i++;
num= parseFloat(v.substring(0, i));
if (num==0) return fixed_ZERO;
else return new Array(num, v.substring(i));
}
// convert parsed (number, unit) into a number of pixels
function fixed_length(el, l, full) {
var tmp, x;
if (l[1]=='px') return l[0];
if (l[1]=='%') return Math.round(full*l[0]/100);
// other units - measure by setting position; this is rather inefficient
// but then these units are used for background-position so seldom...
tmp= el.currentStyle.left;
el.style.left= '0';
x= el.offsetLeft;
el.style.left= l[0]+l[1];
x= el.offsetLeft-x;
el.style.left= tmp;
return x;
}
// convert stupid IE offsetLeft/Top to page-relative values
function fixed_pageLeft(el) {
var v= 0;
while (el.offsetParent) {
v+= el.offsetLeft;
el= el.offsetParent;
}
return v;
}
function fixed_pageTop(el) {
var v= 0;
while (el.offsetParent) {
v+= el.offsetTop;
el= el.offsetParent;
}
return v;
}
// Scanning. Check document every so often until it has finished loading. Do
// nothing until <body> arrives, then call main init. Pass any new elements
// found on each scan to be bound
var fixed_SCANDELAY= 500;
function fixed_scan() {
if (!document.body) return;
if (!fixed_viewport) fixed_init();
var el;
for (var i= 0; i<document.all.length; i++) {
el= document.all[i];
if (!el.fixed_bound) {
el.fixed_bound= true;
fixed_bind(el);
} }
}
var fixed_scanner;
function fixed_stop() {
window.clearInterval(fixed_scanner);
fixed_scan();
}
fixed_scan();
fixed_scanner= window.setInterval(fixed_scan, fixed_SCANDELAY);
window.attachEvent('onload', fixed_stop);
window.attachEvent('onresize', fixed_delayout);
window.attachEvent('onscroll', fixed_scroll);
@end
