Develop Reference

DataTables ColReorder scroll when header scrolled close to boundaries

I am using DataTables for a large quantity of data gathered from various ASP databases.
In addition, I am using the following DataTables plug-ins:
FixedHeaders, FixedColumns, ColReorder.
Now, with the ColReorder function, when a header (a column actually) is dragged to reorder it and is overflowing to the sides (horizontal scrolling), I would like the table to scroll to the side with it, so that the column can be dragged not only to the viewed area of the table but to the entire table.
I have tried nomerous ways and walkarounds such as trying to make it scroll when the curser is close to the boundaries (like here in "Drag Scrolls" http://javascriptmvc.com/docs.html#!jQuery.Drag), but I did not succeed, as well as this method - http://mootools.net/docs/more/Interface/Scroller.
I would highly appreciate your help.
Thank you all in advance.

Here is an approach that may get you closer to solving it. Based on my experiments, you can copy and modify dataTables.colReorder.js in function _fnMouseMove just before this.dom.drag.css(...) code.
var scrollLeftVal = $(this.s.dt.nTableWrapper).find('.dataTables_scrollBody').scrollLeft();
if((e.pageX - this.s.mouse.offsetX) > (this.s.dt.nTableWrapper.clientWidth - 50)) {
scrollLeftVal += 10;
$(this.s.dt.nTableWrapper).find('.dataTables_scrollBody').scrollLeft(scrollLeftVal);
}
This will scroll the window to the right when dragging a column header. A reverse method would be needed as well, as well as modifying the positions of the pointer and drag elements, such as below:
this.dom.pointer.css( 'left', this.s.aoTargets[i-1].x - scrollLeftVal );
If you decided on this approach, you would be better off long term to build an extension/plugin rather than modifying core code. This is just for experimental purposes.
I started down this path, but believe I'll do my own reordering interface since this approach, even if working and scrolling properly, is not as ideal for the project I'm working on.
Hope this helps someone get closer to a solution!
Ryan

Tested with bootstrap https://jsfiddle.net/bababalcksheep/gsf2r1v4/17/
I added this code by modifying dataTables.colReorder.js in function _fnMouseMove just before this.dom.drag.css(...)
Seems to work Fine however with only one problem.
Lengthy columns have hard time snapping to next short width column.
For Example: in https://jsfiddle.net/bababalcksheep/gsf2r1v4/17/ , try dragging project column to next EXT column. I suspect this is because project column has larger width.
Any further fix to this problem will be much appreciated
var scrollHead = $(this.s.dt.nTableWrapper).find('.dataTables_scrollHead');
var scrollBody = $(this.s.dt.nTableWrapper).find('.dataTables_scrollBody');
var scrollLeftVal = e.pageX - scrollHead.parent().offset().left - this.s.mouse.offsetX;
//
var difference = scrollHead[0].clientWidth - scrollLeftVal ;
//is near Right edge, scroll to far right
if (difference < 150){
scrollLeftVal = scrollHead[0].scrollWidth - scrollHead[0].clientWidth;// max scrollleft Value
}
//is near Left edge, scroll to far Left
if(scrollLeftVal < 100){
scrollLeftVal= 0;
}
//
scrollBody.scrollLeft(scrollLeftVal);

Improving Performance on Background Parallax Scrolling

Hello StackOverflow Community,
what I am trying to achieve is a header that can be moved with the mouse.
You klick into the header and drag the mouse and the elements inside the header will move with different speeds.
I achieved the parallaxing part but the performance is not really good. It is partially a bit laggy while dragging the backgrounds.
My question now is: what can be changed in the code to get a performance boost?
That's the part of the code that takes care of parallaxing. On every mousemove a each loop is executed which I think is the reason for the performance beeing so laggy:
var dragging = false;
var clickMouseX;
//Our object for the layers
//each layer has a different scrolling speed
var movingObjects = {
'#header-l1' : {'speed': 1},
'#header-l2' : {'speed': 1.4},
'#header-l3' : {'speed': 1.85},
'#header-l4' : {'speed': 2.2},
};
$('#header-wrapper').mousedown(function(e){
dragging = true;
//Get initial mouse position when clicked
clickMouseX = e.pageX;
$(this).mousemove(function(mme){
//execute only if mousedown
if(dragging){
//iterate through all layers which have to be parallaxed
$.each(movingObjects, function(el, opt){
var element = $(el);
//get difference of initial mouse position and current mouse position
var diff = clickMouseX - mme.pageX;
//scroll-position left speed 1
if(diff < 0) diff = -1;
//scroll position right speed 1
if(diff >= 0) diff = 1;
//get current position of layer
currLeft = parseInt(element.css('left'));
//get current layer width
elWidth = element.width();
//if right border is reached don't scroll further
if(currLeft < -(elWidth - 810)){
element.css('left', -(elWidth - 810));
}
//so do with left border
if(currLeft > 0){
element.css('left', 0);
}
//parallax it! Subtract the scroll position speed multiplied by the speed of the desired
//layer from the current left property
element.css('left', parseInt(element.css('left')) - diff*opt.speed);
});
}
});
/* Cursor */
$(this).css('cursor', 'pointer');
return false;
});
I also put a fiddle up:
http://jsfiddle.net/yWGDz/
Thanks in advance,
Thomas
P.S. maybe someone even finds out why layer two and three have the same scroll speed while having different speeds defined.

I worked at this a bit, and came up with this: http://jsfiddle.net/amqER/2/
This works a lot faster than the original (especially in firefox, where it performs a whole lot better, chrome it's still pretty slow). I also changed up some of the logic in your code, to make it make more sense.
A list of things that I did:
Minify your pngs
2 of your png files were over 2 megs, so I threw them into a png compressor (tinypng) and that reduced the size a lot. This helps with loading time and overall snappiness.
Re-use values as much as possible
In your original code, you wrote to and then subsequently read from the css left property a couple times in your code. Doing this is going to make it a lot slower. Instead, I kept an left property, and would only touch $.css when I absolutely needed to. Likewise for reading each element's width each update.
Also, like I said, I modified your logic to (I think) make more sense, given what you were trying to accomplish. It calculates a new diff each update, and tries to move according to that. Also, it doesn't try to keep moving once one of the images falls off (which yours does if you move all the way to the right, and it looks really weird). You can also look at this: http://jsfiddle.net/amqER/5/, which maybe is more like the control scheme you wanted.

Just some quick performance tips.
Try not to use $(this).mousemove instead save $(this) into a variable and use that.
var th = $(this);
th.mousemove...
Try to avoid using $.each. This is probably the part that's slowing your code down.
You can replace it with a for loop, but I would suggest, in this case, sending in each element one by one.
var parallax = function(img){
};
parallax(img1);
parallax(img2);
instantly-increase-your-jquery-performance

Whilst Xymostech's answer does greatly improve upon the original poster's original code; the performance is hardly improved for me in Chrome.
Whilst inspecting the page FPS, the solution posted here runs at 15FPS for me on a Retina MacBook Pro.
I made a very simple change to the code, altering it to use translate3d properties instead of left. Now, it runs at 55-60 FPS for me. I'd call that a massive performance boost.
If 'show paint rectangles' are turned on in Chrome, you'll see the previously posted solution is continually painting changes to the dom whilst the parallax is in motion. With the translate3d solution, there's simply zero painting done the whole time the parallax is in motion.
http://jsfiddle.net/LG47e/

Content flicker/jump on infinite scroll/loop

I am looking for help / a point in the right direction / or a solution for a flicker/jump, when scrolling on a looping/infinite website, which can be seen in this fiddle.
What seems to be causing the jump is:
"$(window).scrollTop(half_way - child_height);", and what could also be a Chrome windows scrollTop bug, but it is happening in all browsers at the moment.
If I remove "- child_height" there is no longer a flicker but the page no longer scrolls correctly, which can be seen in this fiddle.
Also, on the very first scroll the right hand column jumps up by three boxes - also because of 'half_way', which I can fix by giving it a "bottom: -600px;"
The full code:
http://jsfiddle.net/djsbaker/j3d8r/1/
var num_children = $('#up-left').children().length;
var child_height = $('#up-left').height() / num_children;
var half_way = num_children * child_height / 2;
$(window).scrollTop(half_way);
function crisscross() {
$('#up-left').css('bottom', '-' + window.scrollY + 'px');
$('#down-right').css('bottom', '-' + window.scrollY + 'px');
var firstLeft = $('#up-left').children().first();
var lastLeft = $('#up-left').children().last();
var lastRight = $('#down-right').children().last();
var firstRight = $('#down-right').children().first();
if (window.scrollY > half_way ) {
$(window).scrollTop(half_way - child_height);
lastRight.appendTo('#up-left');
firstLeft.prependTo('#down-right');
} else if (window.scrollY < half_way - child_height) {
$(window).scrollTop(half_way);
lastLeft.appendTo('#down-right');
firstRight.prependTo('#up-left');
}
}
$(window).scroll(crisscross);

Okay - here is a 'working' version - and by works I mean it less flickery than before. I thought it was flicker free, and it was when I was on battery power, but plugged into the mains and the CPU is fast enough to get flicker.
As I mentioned, to get rid of the flicker you need to clone the objects, manipulate them and then replace them into the DOM, rather than just manipulating the DOM directly.
I did this by getting the contents of <div id="content"> manipulating them and then replacing them into that <div>.
Also, it's a good idea to only find things in the DOM once, and from then on use a reference to that object rather than searching repeatedly. e.g.
var leftSide = $(clone).find('.up-left');
....
lastRight.appendTo(leftSide);
....
$(leftSide).css('bottom', '-' + window.scrollY + 'px');
rather than:
lastRight.appendTo('#up-left');
$('#up-left').css('bottom', '-' + window.scrollY + 'px');
Searching the DOM is relatively slow, and so storing references can improve performance/reduce flicker.
Storing the object also makes the code easier to understand (imho) as you can easily see that you're referencing the same thing, rather than possibly different things.

I still get flickering in chrome on windows with Danack solution. For this site I would control all the scrolling (you already scroll manually one of the sides), and give elements absolute positions.
Or if you insist on using the browser scrolling, may be use animations: animate the height of the last elements till 0px then use appendTo, and then animato from 0px to the normal height...

This might be a long shot, but I had the same flickering when working with infinitescroll,
and ended up using imagesLoaded.I ended up appending the additional images (now loaded) with a fade in, and that prevented them from flickering because of the fact they were loaded.
So maybe by using the imagesloaded - or a callback on the images, you can solve the flickering. It does decrease the speed though. I can image that if you want to scroll through everything as fast as possible, this might not be the solution. Good luck!

A solution would be to not use the native scrolling functionality but to simulate scrolling. This would be done by setting the overflow of your content to "hidden" in addition with capturing the "mousewheel" event on it and triggering some action when it is called. I started to try this out here (using MooTools instead of jQuery since I'm more fimilar with it). It's currently just "working" on the left side by altering the margin-top of the first element.
My next steps would be:
Check if the negative margin-top of the first element is bigger than the height of it and move it to the right side if so.
Same logic for the last box on the right side with a negative margin-bottom.
This has some downsides, though. Simulating scrolling doesn't feel as natural as the native scrolling functionality and clicking the mousewheel doesn't work. These might be solveable but it would require some more coding to get it to work smoothly. Anyway, in the end you would have a solution without any flickering and with no sticky scrollbar at the side (An idea for a replacement could be a small area on the side that triggers the scrolling on mouseover).

How to solve element flicker while scrolling with parallax effect in JavaScript?

I am trying to re-create website with parallax effect using JavaScript. That means that I have two or more layers, that are moving different speeds while scrolling.
In my case I'm moving only one layer, the other one remains static:
layer 1 = website text;
layer 2 = element background;
for this I'm using simple source code (with jQuery 1.6.4):
var docwindow = $(window);
function newpos(pos, adjust, ratio){
return ((pos - adjust) * ratio) + "px";
}
function move(){
var pos = docwindow.scrollTop();
element.css({'top' : newpos(pos, 0, 0.5)});
}
$(window).scroll(function(){
move();
});
The Problem:
- All calculations are done right and the effect "works" as expected. But there is some performance glitch under some browsers (Chrome MAC/Windows, Opera MAC, IE, paradoxically not Safari).
What do I see during scrolling?
- While scrolling the background moves in one direction together with scroll, but it seems to occasionally jump few pixels back and then forth, which creates very disturbing effect (not fluid).
Solutions that I tried:
- adding a timer to limit scroll events
- using .animate() method with short duration instead of .css() method.
I've also observed, that the animation is smooth when using .scrollTo method (scrollTo jQuery plugin). So I suspect that there is something wrong with firing scroll events (too fast).
Have you observed the same behavior?
Do you know, how to fix it?
Can you post a better solution?
Thanks for all responses
EDIT #1:
Here you can find jsfiddle demonstration (with timer): http://jsfiddle.net/4h9Ye/1/

I think you should be using scrollTop() instead and change the background position to fixed. The problem is that setting it to absolute will make it move by default when you scroll up or down.
The flicker occurs because the position is updated as part of the default browser scroll and updated again as part of your script. This will render both positions instead of just the one you want. With fixed, the background will never move unless you tell it so.
I've created a demo for you at http://jsfiddle.net/4h9Ye/2/ .

enlarge image and move it with the pointer on mouse over

Sorry if this might seem trivial for me to ask but..
I have some images and I need them to enlarge when I hover my mouse over them. But.. I want for the enlarged image to stick next to the pointer as I move it across the image. I don't know what to call it. I'm pretty sure it's only done with javascript, just css won't work here.
Something like this http://www.dynamicdrive.com/style/csslibrary/item/css-popup-image-viewer/ , but you know, it has to move with the pointer in motion.
What's the most effective way to do this?

The previous answers may be exactly what you're looking for, and you may already have this solved. But I note that you didn't mention jquery anywhere in your post and all of those answers dealt with that. So for a pure JS solution...
I'll assume from the way the question was phrased that you already know how to pop the image up? This can be done by coding an absolutely positioned hidden img tag in the html or generated on the fly with JS. The former may be easier if you are a JS novice. In my examples I'll assume you did something similar to the following:
<img src="" id="bigImg" style="position:absolute; display:none; visibility:hidden;">
Then you need an onMouseOver function for your thumbnail. This function must do three things:
1) Load the actual image file into the hidden image
//I'll leave it up to you to get the right image in there.
document.getElementById('bigImg').src = xxxxxxxx;
2) Position the hidden image
//See below for what to put in place of the xxxx's here.
document.getElementById('bigImg').style.top = xxxxxxxx;
document.getElementById('bigImg').style.left = xxxxxxxx;
3) Make the hidden image appear
document.getElementById('bigImg').style.display = 'block';
document.getElementById('bigImg').style.visibility = 'visible';
Then you'll need to capture the onMouseMove event and update the now un-hidden image's position accordingly using the same code you would have used in (2) above to position the image. This would be something like the following:
//Get the mouse position on IE and standards compliant browsers.
if (!e) var e = window.event;
if (e.pageX || e.pageY) {
var curCursorX = e.pageX;
var curCursorY = e.pageY;
} else {
var curCursorX = e.clientX + document.body.scrollLeft;
var curCursorY = e.clientY + document.body.scrollTop;
}
document.getElementById('bigImg').style.top = curCursorY + 1;
document.getElementById('bigImg').style.left = curCursorX + 1;
And that should just about do it. Just add an onMouseOut event to hide the bigImg image again. You can change the "+1" in the last two lines to whatever you like to place the image correctly in relation to the cursor.
Note that all of the code above was for demonstration purposes only; I haven't tested any of it, but it should get you on the right track. You may want to expand upon this idea further by preLoading the larger images. You could also forgoe capturing mousemove events by using setTimeout to update the position every 20 ms or so, though I think that approach is more complicated and less desirable. I only mention it because some developers (including me when I started) have an aversion to JS event handling.
I did something similar to this with a custom ColdFusion tag I wrote that would generate a floating div users could click and drag around the screen. Same principle. If you need me to I can dig that out to answer any additional questions in more depth.
Good luck!

Liece's solution is close, but won't achieve the desired effect of the large image following the cursor.
Here's a solution in jQuery:
$(document).ready(function() {
$("img.small").hover (function () {
$("img.large").show();
}, function () {
$("img.large").hide();
});
$("img.small").mousemove(function(e) {
$("img.large").css("top",e.pageY + 5);
$("img.large").css("left",e.pageX + 5);
});
});
The HTML is:
<img class="small" src="fu.jpg">
<img class="large" src="bar.jpg">
CSS:
img { position: absolute; }

Try this links [jquery with auto positioning]
1.Simple
http://jquery.bassistance.de/tooltip/demo/
2.Good with forum
http://flowplayer.org/tools/tooltip/index.html

if I understood you correctly you want to position your big image relatively to the cursor. One solution in jquery (i'm not 100% sure of the code here but the logic is there):
$('.thumb').hover(function(e){
var relativeX = e.pageX - 100;
var relativeY = e.pageY - 100;
$(.image).css("top", relativeY);
$(.image).css("left", relativeX);
$(.image).show();
}, function(){
$(.image).hide();
})

Jquery is the easiest route. position absolute is key.

^ In addition to the above, here is a working JS Fiddle. Visit: jsfiddle.net/hdwZ8/1/
It has been roughly edited so it isnt using just overall IMG css tags, easy for anyone to use with this now.
I am using this script instead of a Lightbox in my Wordpress client site, a quick zoomed in image with mouse over is much nicer IMO. It is very easy to make efficient galleries especially with AdvancedCustomFields plug-in & in the WP PHP repeater loops!