The Problem
I help maintain a big, complicated, messy old site in which everything (literally) is nested in multiple levels of iframes-- many of which are dynamically created and/or have a dynamic src. That creates the following challenges:
- Any changes to the HTML structure risk breaking scripts and stylesheets that haven't been touched in years.
- Finding and fixing all of the iframes and src documents manually would take way too much time and effort.
Of the solutions posted so far, this is the only one I've seen that overcomes challenge 1. Unfortunately, it doesn't seem to work on some iframes, and when it does, the scrolling is very glitchy (which seems to cause other bugs on the page, such as unresponsive links and form controls).
The Solution
If the above sounds anything like your situation, you may want to give the following script a try. It forgoes native scrolling and instead makes all iframes draggable within the bounds of their viewport. You only need to add it to the document that contains the top level iframes; it will apply the fix as needed to them and their descendants.
Here's a working fiddle*, and here's the code:
(function() {
var mouse = false //Set mouse=true to enable mouse support
, iOS = /iPad|iPhone|iPod/.test(navigator.platform);
if(mouse || iOS) {
(function() {
var currentFrame
, startEvent, moveEvent, endEvent
, screenY, translateY, minY, maxY
, matrixPrefix, matrixSuffix
, matrixRegex = /(.*([\.\d-]+, ?){5,13})([\.\d-]+)(.*)/
, min = Math.min, max = Math.max
, topWin = window;
if(!iOS) {
startEvent = 'mousedown';
moveEvent = 'mousemove';
endEvent = 'mouseup';
}
else {
startEvent = 'touchstart';
moveEvent = 'touchmove';
endEvent = 'touchend';
}
setInterval(scrollFix, 500);
function scrollFix() {fixSubframes(topWin.frames);}
function fixSubframes(wins) {for(var i = wins.length; i; addListeners(wins[--i]));}
function addListeners(win) {
try {
var doc = win.document;
if(!doc.draggableframe) {
win.addEventListener('unload', resetFrame);
doc.draggableframe = true;
doc.addEventListener(startEvent, touchStart);
doc.addEventListener(moveEvent, touchMove);
doc.addEventListener(endEvent, touchEnd);
}
fixSubframes(win.frames);
}
catch(e) {}
}
function resetFrame(e) {
var doc = e.target
, win = doc.defaultView
, iframe = win.frameElement
, style = getComputedStyle(iframe).transform;
if(iframe===currentFrame) currentFrame = null;
win.removeEventListener('unload', resetFrame);
doc.removeEventListener(startEvent, touchStart);
doc.removeEventListener(moveEvent, touchMove);
doc.removeEventListener(endEvent, touchEnd);
if(style !== 'none') {
style = style.replace(matrixRegex, '$1|$3|$4').split('|');
iframe.style.transform = style[0] + 0 + style[2];
}
else iframe.style.transform = null;
iframe.style.WebkitClipPath = null;
iframe.style.clipPath = null;
delete doc.draggableiframe;
}
function touchStart(e) {
var iframe, style, offset, coords
, touch = e.touches ? e.touches[0] : e
, elem = touch.target
, tag = elem.tagName;
currentFrame = null;
if(tag==='TEXTAREA' || tag==='SELECT' || tag==='HTML') return;
for(;elem.parentElement; elem = elem.parentElement) {
if(elem.scrollHeight > elem.clientHeight) {
style = getComputedStyle(elem).overflowY;
if(style==='auto' || style==='scroll') return;
}
}
elem = elem.ownerDocument.body;
iframe = elem.ownerDocument.defaultView.frameElement;
coords = getComputedViewportY(elem.clientHeight < iframe.clientHeight ? elem : iframe);
if(coords.elemTop >= coords.top && coords.elemBottom <= coords.bottom) return;
style = getComputedStyle(iframe).transform;
if(style !== 'none') {
style = style.replace(matrixRegex, '$1|$3|$4').split('|');
matrixPrefix = style[0];
matrixSuffix = style[2];
offset = parseFloat(style[1]);
}
else {
matrixPrefix = 'matrix(1, 0, 0, 1, 0, ';
matrixSuffix = ')';
offset = 0;
}
translateY = offset;
minY = min(0, offset - (coords.elemBottom - coords.bottom));
maxY = max(0, offset + (coords.top - coords.elemTop));
screenY = touch.screenY;
currentFrame = iframe;
}
function touchMove(e) {
var touch, style;
if(currentFrame) {
touch = e.touches ? e.touches[0] : e;
style = min(maxY, max(minY, translateY + (touch.screenY - screenY)));
if(style===translateY) return;
e.preventDefault();
currentFrame.contentWindow.getSelection().removeAllRanges();
translateY = style;
currentFrame.style.transform = matrixPrefix + style + matrixSuffix;
style = 'inset(' + (-style) + 'px 0px ' + style + 'px 0px)';
currentFrame.style.WebkitClipPath = style;
currentFrame.style.clipPath = style;
screenY = touch.screenY;
}
}
function touchEnd() {currentFrame = null;}
function getComputedViewportY(elem) {
var style, offset
, doc = elem.ownerDocument
, bod = doc.body
, elemTop = elem.getBoundingClientRect().top + elem.clientTop
, elemBottom = elem.clientHeight
, viewportTop = elemTop
, viewportBottom = elemBottom + elemTop
, position = getComputedStyle(elem).position;
try {
while(true) {
if(elem === bod || position === 'fixed') {
if(doc.defaultView.frameElement) {
elem = doc.defaultView.frameElement;
position = getComputedStyle(elem).position;
offset = elem.getBoundingClientRect().top + elem.clientTop;
viewportTop += offset;
viewportBottom = min(viewportBottom + offset, elem.clientHeight + offset);
elemTop += offset;
doc = elem.ownerDocument;
bod = doc.body;
continue;
}
else break;
}
else {
if(position === 'absolute') {
elem = elem.offsetParent;
style = getComputedStyle(elem);
position = style.position;
if(position === 'static') continue;
}
else {
elem = elem.parentElement;
style = getComputedStyle(elem);
position = style.position;
}
if(style.overflowY !== 'visible') {
offset = elem.getBoundingClientRect().top + elem.clientTop;
viewportTop = max(viewportTop, offset);
viewportBottom = min(viewportBottom, elem.clientHeight + offset);
}
}
}
}
catch(e) {}
return {
top: max(viewportTop, 0)
,bottom: min(viewportBottom, doc.defaultView.innerHeight)
,elemTop: elemTop
,elemBottom: elemBottom + elemTop
};
}
})();
}
})();
* The jsfiddle has mouse support enabled for testing purposes. On a production site, you'd want to set mouse=false.