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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js"></script>
<script>
/* scrolling:
focus is either on a specific message or at the end
when to recalculate focus?
* user scrolls
* we force a scroll to end
when to adjust scroll to focused message?
* page loaded
* window resized
* messages added
* messages deleted
* images loaded
*/
// TODO: figure out why firefox is being a fucker with regard to changing the heights
// of things when elements are removed from above
Array.prototype.random = function() {
return this[Math.floor((Math.random()*this.length))];
}
// image fetch stuff
var imageQueue = []
function fetch(){
$.ajax({
"url": "http://pipes.yahoo.com/pipes/pipe.run?_id=59b7cad3b8fb595fa7cb3c2fdf0ab328&_render=json&_callback=fetched",
"dataType": "jsonp"
})
log("fetching more images")
}
function fetched(data){
var imageUrls = []
try {
var images = data['value']['items'][0]['recent-images']['recent-image']
for(var i = 0; i < images.length; i++)
imageQueue.push(images[i]['img']);
log(images.length + " images fetched")
} catch(e) {
log("couldn't parse images :(")
console.log("couldn't parse object:")
console.log(data)
}
}
function imagePoster(){
if (!imageQueue.length){
//log("queue empty")
} else if (Paused) {
//log("paused")
} else {
log(imageQueue.length + " images in queue ... posting image")
var image = imageQueue.shift()
imagePost(image)
}
setTimeout(imagePoster, 500)
}
imagePosts = 0
function imagePost(image){
/*imagePosts += 1
while (imagePosts > maxImages.value) {
var imgs = $(".image-post:first")
if (imgs.length) {
imgs.remove()
} else {
break
}
imagePosts -= 1
}*/
var i = $("<img/>").attr("src", image) //.load(scrollIfPossible).error(scrollIfPossible)
var d = $("<div class='image-post msg'/>").html("username: ")
d.append(i).appendTo("#chat")
}
var Paused = false
function pausego(){
Paused = !Paused
$("#pausego-button").html(Paused ? "go" : "pause")
}
// end image fetch stuff
function log(html, klass){
klass = klass || ""
klass = 'log-message ' + klass
var html = "<p class='" + klass + "'>" + html + "</p>"
scrollLog.append(html)
scrollLog[0].scrollTop = scrollLog[0].scrollHeight
}
function go(){
messagePane = $("#chat")[0]
maxImages = $("#max-images")[0]
scrollLog = $("#scroll-log")
$("#chat").scroll(eventScroll)
$(window).resize(windowResizedHandler)
fetch()
//imagePoster()
messagesLoadFromPage()
scrollToEnd()
setLastKnownHeight()
setLastKnownScrollTop()
messageHeightsCalc()
highlightFocusedMessage()
//scrollWatcher()
}
// messages stuff
// Messages = [{element: aDomNode, complete: false, height: 24, imgs: []}, {...}, ...]
var Messages = []
function messageRandomButton(){
messageRandomButton.paused = !messageRandomButton.paused
if (messageRandomButton.paused)
clearTimeout(messageRandom.timer)
else
messageRandom()
$("#message-random-button").html((messageRandomButton.paused ? "start" : "stop") + " adding + removing messages")
}
messageRandomButton.paused = true
function messageRandom(){
var funcs = [messageRemoveFirst, messageAddNew, messageAddNew, messageAddNew, messageAddNew]
funcs.random()();
messageRandom.timer = setTimeout(messageRandom, 100)
}
function messageRandomImageButton(){
messageRandomImageButton.paused = !messageRandomImageButton.paused
if (messageRandomImageButton.paused)
clearTimeout(messageRandomImage.timer)
else
messageRandomImage()
$("#message-random-image-button").html((messageRandomImageButton.paused ? "start" : "stop") + " adding + removing image messages")
}
messageRandomImageButton.paused = true
function messageRandomImage(){
var funcs = [messageRemoveFirst, messageAddNew, messageAddNew, messageImageAddNew, messageImageAddNew]
funcs.random()();
messageRandomImage.timer = setTimeout(messageRandomImage, 100)
}
function messageRemoveFirst(){
//$(".msg:first").remove()
var msg = Messages.shift()
$(msg['element']).remove()
LastKnown.focus -= 1
scrollToFocus(true)
}
function messagesLoadFromPage(){
Messages = []
$(".msg").each(function(){
Messages.push({"element": this, "complete": true})
})
}
function messageAddNew(nodesToAppend){
var string = " " + Math.random() + " " + Math.random() + " " + Math.random() + " " + Math.random() + " " + Math.random() + " " + Math.random() + " " + Math.random() + " " + Math.random()
var msg = $("<div class='msg'>test" + string + "</div>")
if (nodesToAppend && nodesToAppend.length){
for(var i = 0; i < nodesToAppend.length; i++){
nodesToAppend[i].appendTo(msg)
}
}
msg.appendTo("#chat")
var imgs = msg.find("img")
if (imgs.length) {
complete = false
var truImgs = []
for (var i = 0; i < imgs.length; i++){
truImgs.push(imgs[i])
}
Messages.push({"element": msg[0], "height": msg.outerHeight(true), "complete": false, "imgs": truImgs})
startImageCompletenessMonitor()
// start completeness monitor
} else {
Messages.push({"element": msg[0], "height": msg.outerHeight(true), "complete": true})
}
scrollToFocus()
}
function messageImageAddNew(){
if (!imageQueue.length)
return
var image = imageQueue.shift()
var i = $("<img/>").attr("src", image)
messageAddNew([i])
}
function startImageCompletenessMonitor(){
if (!imageCompletenessMonitor.timer) {
imageCompletenessMonitor()
log("starting image completeness monitor")
}
}
function imageCompletenessMonitor(){
var allMessagesComplete = true
for (var m = 0; m < Messages.length; m++){
var msg = Messages[m];
if (!msg["complete"]){
allMessagesComplete = false;
var messageComplete = true;
for (var i = 0; i < msg["imgs"].length; i++){
if (!msg["imgs"][i].complete) {
messageComplete = false;
break;
}
}
msg["complete"] = messageComplete;
msg["height"] = $(msg["element"]).outerHeight(true)
}
}
if (allMessagesComplete) {
clearTimeout(imageCompletenessMonitor.timer)
imageCompletenessMonitor.timer = 0
log("stopping image completeness monitor")
} else {
scrollToFocus()
imageCompletenessMonitor.timer = setTimeout(imageCompletenessMonitor, 500)
}
}
imageCompletenessMonitor.timer = 0
// i just made this a function so i can log it...
// pass an argument to set it, otherwise returns value
function keepScrollAtBottom(){
if (arguments.length) {
log("keep scroll at bottom was: " + keepScrollAtBottom.val + ", is now: " + arguments[0], "yellow")
keepScrollAtBottom.val = arguments[0]
}
return keepScrollAtBottom.val
}
function logScrollProps(){
var props = "{ scrollTop: " + messagePane.scrollTop +
", scrollHeight: " + messagePane.scrollHeight +
", height: " + messagePane.offsetHeight + " }"
// var total = "height+scrollTop: " + (messagePane.offsetHeight + messagePane.scrollTop)
log(props)
// log(total)
}
// "scroll" event triggered if:
// user scrolls element
// we change element's scrollTop <-- not in opera
// scrollbar at bottom and stuff removed from top <-- not in opera
// scrollbar at bottom and window resized <-- not in opera
// i don't know what happens with regards to ie & i don't care (for now)
function eventScroll(e){
// added 'ignoreLastScroll' so we can ignore scroll events when we change scrollTop
if (eventScroll.ignoreLastScroll && $.browser != "opera") {
eventScroll.ignoreLastScroll = false
log("pane scrolled (ignoring)", "red")
return;
}
log("pane scrolled", "green")
findScrollFocus()
logScrollProps()
highlightFocusedMessage()
}
eventScroll.ignoreLastScroll = false
function findScrollFocus(){
if (messagePane.scrollHeight <= messagePane.offsetHeight) // no scrollbar exists yet... content not overflowing
keepScrollAtBottom(true)
else if (isScrolledToBottom())
keepScrollAtBottom(true)
else
keepScrollAtBottom(false)
var i = findMiddleMessage()
LastKnown.focus = i
}
function findMiddleMessage(){
var midpoint = (messagePane.offsetHeight / 2) + messagePane.scrollTop
var total = 0
for(var i = 0; i < Messages.length; i++){
total += Messages[i].height
if (total > midpoint) {
log("found middle item after " + i + " iterations")
return i
}
}
return i
}
function highlightFocusedMessage(){
$(".msg").removeClass("selected")
if (keepScrollAtBottom())
$(".msg:last").addClass("selected")
else
$(".msg:eq(" + LastKnown.focus + ")").addClass("selected")
}
function isScrolledToBottom(){
var threshold = 20;
// is messagePane.offsetHeight instead messagePane.style.pixelHeight in ie?
return (messagePane.scrollHeight - messagePane.scrollTop - messagePane.offsetHeight < threshold);
}
function scrollToEnd(){
eventScroll.ignoreLastScroll = true
messagePane.scrollTop = messagePane.scrollHeight
keepScrollAtBottom(true)
}
function scrollToFocus(forceUpdate){
if (keepScrollAtBottom()) { // scroll to bottom
scrollToEnd()
highlightFocusedMessage()
} else { // scroll to focused message
if ( forceUpdate ||
LastKnown.height != messagePane.offsetHeight /* was resized */ ) {
var heightToMessage = 0
for(var i = 0; i < LastKnown.focus; i++)
heightToMessage += Messages[i].height;
heightToMessage += /*Math.floor( */Messages[i].height / 2 //)
eventScroll.ignoreLastScroll = true
// _____________
// X = scrollTop | |
// | a |
// X____________ | <- scrollHeight
// offsetHeight -> | | b | |
// of |____________| |
// visible | c |
// frame |_____________|
//
// to set scrollTop to center item b, take distance to item b from top - (offsetHeight / 2)
//
messagePane.scrollTop = heightToMessage - /*Math.floor (*/messagePane.offsetHeight / 2/*)*/
highlightFocusedMessage()
setLastKnownHeight()
setLastKnownScrollTop()
}
}
}
function messageHeightsCalc() {
log("recalculated heights of each message")
for(var i = 0; i < Messages.length; i++){
Messages[i].height = $(Messages[i].element).outerHeight(true)
}
}
// there's a timeout so that while the window is getting resized, it doesn't recalculate constantly, which would be slow
function windowResizedHandler(){
log("window resized")
if (windowResizedHandler.timeout) clearTimeout(windowResizedHandler.timeout);
windowResizedHandler.timeout = setTimeout(windowResized, 250)
}
function windowResized(){
messageHeightsCalc()
scrollToFocus()
setLastKnownHeight()
setLastKnownScrollTop()
}
var LastKnown = {
"height": 0, "scrollTop": 0, "focusElement": 0
}
function setLastKnownHeight(){
LastKnown.height = messagePane.offsetHeight
}
function setLastKnownScrollTop(){
LastKnown.scrollTop = messagePane.scrollTop
}
</script>
<style>
html, body {
height: 100%; /* need dis to enable percentage heights working w/ standard doctype */
}
#chat {
width: 500px;
height: 85%;
overflow-y: scroll;
overflow-x: hidden;
}
img { max-height: 300px; }
#sidebar {
height: 85%; float: right;
}
#scroll-log { width: 300px; height: 80%; overflow: scroll; }
.log-message {
margin: 0; padding: 0;
font-size: 10px;
}
.selected, .yellow {
background-color: yellow;
}
.green {
background-color: green;
}
.red {
background-color: red;
}
</style>
</head>
<body>
<center><h3>scrolling tests</h3></center>
<div id="sidebar">
<div id="scroll-log"><h3>log</h3></div>
<button onclick="messageRemoveFirst()">purge oldest message</button>
<button onclick="messageAddNew()">add new message</button>
<br>
<button onclick="messageRandomButton()" id="message-random-button">start adding + removing messages</button>
<br>
<button onclick="messageImageAddNew()">add image message</button>
<br>
<button onclick="messageRandomImageButton()" id="message-random-image-button">start adding + removing image messages</button>
</div>
<div id="chat">
<div class="msg">test 1</div><div class="msg">test 2</div><div class="msg">test 3</div><div class="msg">test 4</div><div class="msg">test 5</div><div class="msg">test 6</div><div class="msg">test 7</div><div class="msg">test 8</div><div class="msg">test 9</div><div class="msg">test 10</div>
<div class="msg">test 11</div><div class="msg">test 12</div><div class="msg">test 13</div><div class="msg">test 14</div><div class="msg">test 15</div><div class="msg">test 16</div><div class="msg">test 17</div><div class="msg">test 18</div><div class="msg">test 19</div><div class="msg">test 20</div>
<div class="msg">test 21</div><div class="msg">test 22</div><div class="msg">test 23</div><div class="msg">test 24</div><div class="msg">test 25</div><div class="msg">test 26</div><div class="msg">test 27</div><div class="msg">test 28</div><div class="msg">test 29</div><div class="msg">test 30</div>
<div class="msg">test 31</div><div class="msg">test 32</div><div class="msg">test 33</div><div class="msg">test 34</div><div class="msg">test 35</div><div class="msg">test 36</div><div class="msg">test 37</div><div class="msg">test 38</div><div class="msg">test 39</div><div class="msg">test 40</div>
<div class="msg">test 41</div><div class="msg">test 42</div><div class="msg">test 43</div><div class="msg">test 44</div><div class="msg">test 45</div><div class="msg">test 46</div><div class="msg">test 47</div><div class="msg">test 48</div><div class="msg">test 49</div><div class="msg">test 50</div>
</div>
<p id="log"></p>
<br>
<!-- <button onclick="fetch()">add images</button>
<button onclick="pausego()" id="pausego-button">pause</button>
<br />
max image posts: <input name="max-images" id="max-images" value="50" /> -->
<pre>
goals:
initial state:
* keep scrollbar at bottom while new messages are added to bottom
* keep scrollbar at bottom while old messages purged from top
* keep scrollbar at bottom while window resized
if user scrolls up:
* keep central message location consistent while new messages added to bottom
* keep central message location consistent while new messages purged from top
* keep central message location consistent while window resized
* scroll back to bottom after a reasonable period of no activity (1 minute?)
</pre>
</body>
<script>
go()
</script>
</html>
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