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Hover effect working on most browsers, but not on safari or chrome on a MAC

In my html document, there are some tiles with two pictures (one jpg as a background and one png with transparency as a foreground) and with a hover effect:
On the current tile which you are hovering, the image gets zoomed where your mouse is and the front image gets moved away from the cursor.
While moving the cursor only horizontally, all vertical pictures are animated too and the other way round.
Here is an example with all html, javascript and css:
http://jsfiddle.net/Lmcn0sxw/6/
The effect is working (with a few bugs, but that's not important).
The animations are easily added with javascript and transform3d where item is the current tile with the class .item.
Variables like topRatioFron are calculated from the current mouse position relative to the current tile.
item.find('.front').css('transform', 'translate3d(0,' + topRatioFront + 'px,0)');
item.find('.back').css('transform', 'translate3d(0,' + topRatioBack + 'px,0)');
There are some variations which you can see in the jsfiddle javascript code.
The main tile gets animated with a matrix3d effect:
self.find(itemClass).css(
'transform',
'matrix3d(1,0,0.00,' + leftRatio + ',0.00,1,0.00,' + topRatio + ',0,0,1,0,0,0,0,1)'
);
In the Google Chrome Browser on Linux Mint, it works perfectly. On Google Chrome on Windows, it works too. In Mozilla Firefox, it's not as perfect as in Google Chrome, but it's okay.
The actual problem
A friend opened this site on a Mac with Safari, and all animations were really laggy (it looked like it was shaking). Another friend opened this on a Mac in the Chrome browser, and it was shaking too, but this time not in Safari.
How can I test or find out what this is causing? It can't be the performance of the computer they used, because this site with the same effect is working perfectly in ALL browsers, regardless of the operating system.
What I tried
First, I used translate instead of translate3d (I read that the latter is faster), but It didn't help.
I later added a function called requestAnimationFrame which can help rendering animations. The result was the same.
The second problem
On Safari (I tried it with v8.0.7), the matrix3d transform works, but all other transforms don't work, not on the current tile and not on the others, but CanIUse tells me that transform3d is supported by Safari 8. When I inspect the item with the matrix3d transform, I can see it in the DOM tree being updated, but all of the elements from .back or .front, I can't see the transform3d added, and I have no idea how to fix this.

I believe that this is the cause of your lag - offset = self.offset().
On each frame you query the DOM, which forces it to render the layout, and cause the stuttering.
Instead read the offset once before the animations start.
You can also add to each element will-change: transform before the animation start.

Rendering bug in Google Chrome at certain window widths

My users and I are running into a rendering glitch in Chrome only (on both Windows and Mac) where an overlaid div that I'm using for on-hover tooltip-style "popouts"(see first image below) does not get rendered properly in certain cases (see second image below). In all other browsers I've tested, it works as expected.
Here's how the hover popouts are supposed to look (and what happens in Firefox, Safari, IE):
Here's what happens in Chrome:
You can see it in action on this site if you look at May 24 using a browser window width of ~ 1200px (significnatly wider or narrower windows do not seem to work). The glitch only affects the popouts in the bottom right of the menu that are popping left, e.g. those on May 24. Hovers using the same exact mechanism higher up in the page work just fine. Glitched popouts are invisible (except for part of the carat), but if you click on the link to lock the popout in place and then hold left click while moving your mouse around as if to "select text" in the area where the popout should be, it will then render partially. Also if I open dev tools and try to select the popout, it will render just fine at that point.
I've been looking at this all day and trying different work arounds with opacity, z-index, etc. and getting nowhere. Does this glitch ring any bells for anyone? Is there a way to force Chrome to render the div, once its been positioned and unhidden? I'm fine with any work-around or hack.
I use a custom (and fairly complicated) jquery plugin for popouts. If it would be helpful to see the non-minified javascript for the plugin, I can post or provide a link to that, but general guidance that leads me to a work around will be sufficient to be accepted as an answer.
Edit: My Browser Build: 26.0.1410.65

(Per my comments)
This does indeed seem to be a bug in Chrome, though without a smaller test case to reproduce it, it could be very hard to track down. You may want to report it to the Chrome team with as much information as possible.
In support of my "it's a bug" assertion:
The hidden/clipped elements become visible when they are selected.
The elements underneath the hidden/clipped elements are not clickable.
This indicates that z-index and height is correct.
It only happens under very specific circumstances; the rest of the items with the same style work fine. The same item may work fine at a slightly bigger/smaller screen width.
Applying a 3D transform fixes it.
The problem goes away when I apply a CSS transform such as scale3d or translate3d. I imagine this is because certain CSS properties cause the browser to switch to GPU acceleration.
In this case, switching to the fast path for rendering seems to alter the drawing sequence enough to fix the problem.

Super hacky but this fixes it for me:
$('.drop-link.food').on('hover',function() {
$('.tool-tip').css('overflow', 'hidden').height();
$('.tool-tip').css('overflow', 'auto');
});
Obviously this isn't a "good" solution, and even remaining hacky you could probably optimize it to only force the redraw on the tooltip it needs to, but hopefully it helps...
Another clue:
$('.drop-link').on('hover',function() {
$(this).siblings('.tool-tip').css('display','block');
});
This won't fix it right away, but it seems like if this is there, once you've hovered on something, it will work the next time you hover on it.

Not sure if this helps with your situation, but over the last couple of days I've started to notice that certain site elements on Facebook and Weight Watchers no longer show up. Specifically it seems to be affecting items that (I believe) to be controlled by or dependent on Javascript. When I call up these sites in Firefox and Safari they work as expected.

Repaint slowdown with CSS via Javascript in webkit browsers

I've been working on a slideshow script that uses CSS3 transitions, or jQuery's animate when they are unavailable. I've created a custom function to do the slide animations, which does so appropriately. Everything seemed to be working fine, but I've hit a major snag during testing.
For one reason or another, there is an large delay applying the jQuery CSS before and after the transition on large slideshows. For example, the slideshow in the link below is around 9900 pixels wide (container width, most of which is hidden). The container is maneuvered to display the appropriate slide, using CSS3 transition and transform properties. The delay occurs applying the CSS between lines 75 - 82 in the paste below. In particular, applying the 'transition' CSS causes the problem. Add the 'transition' CSS to the stylesheet (rather than applying it with JS), and delay disappears. This isn't really a solution however, because we only want to use CSS3 transitions on specific properties, that can vary (using 'all' in the stylesheet would transition some CSS that we don't want to animate, but change regularly).
Animation function:
http://pastebin.com/9wumQvrP
Slideshow Demo:
http://www.matthewruddy.com/demo/?p=2431
The real problem is with iOS, in which the slideshow (and even the browser sometimes) becomes completely un-usable. I can't pinpoint any errors, and have really exhausted my knowledge of debugging JS. I'm sure it is related to this section of the function after playing around a bit, and disabling CSS3 support within the plugin altogether removes the problem completely.
I'm completely stuck, and really appreciate any help anyone can give.
--- Edit ---
I've tried applying the CSS with native Javascript rather than jQuery's .css function. Same results, no better performance. Also worth noting that this isn't happening at all in Firefox, and seems to only be a problem with Webkit browsers.
Anyone with a solution, would happy to make a donation towards a few beers! I really cannot figure this out!
--- Second Edit ---
Ok, so been debugging and I can see that the slowdown is caused by the browser repaint cycle that is taking a very long time. Is there a better way to handle this that the way it is already doing? Positioning the element absolutely is a known way to reduce repaints, but that isn't really working because the slideshow is responsive. Absolutely positioning the slide images or the slides themselves causes it to collapse.
--- Third Edit ---
A day later, and I've made some progress. Adding 'transition: all 0s ease' to the elements stylesheet CSS has gotten rid of the repaint caused by adding the inline CSS transition property via the custom animation function mentioned in the original post. This causes a significant performance gain, especially when removing the inline CSS transition property when the transition itself has finished.
Good stuff! However, now there is still a slowdown when the inline CSS translate is being removed (that was used to create the hardware accelerated transition effect itself) after the transition, and the left positioning is being applied. When the two happen together, there is a slowdown.
Breaking them up into two separate tasks (the translate removed, then the left position added in a setTimeout with no time specified), again gets rid of the repaints = performance gain, and looks likes problem solved. But sometimes, the CSS transition property isn't get negated fast enough, and the translate removal gets animated. No good, and don't know where to look next to work around it.

I think the problem is you're loading HUGE images :)
They are too big for the container you have them in, so you scale them down, which is even more resource intensive.
Try resizing them.

First of all congrats for your debugging!
I have been working on the exact same stuff lately and found out that ios devices don't support a large number of images positionned in the same page. It causes crashes and the only solution I found was removing elements instead of just hiding them. The downside is that removing and appending elements causes lags so you have to do it cleverly, when your transitions are done. I thought the best way to go was keep 3 or 5 images in the DOM and replacing the rest with thumbnails of the images, resized to fit the original. When transitions are done, I'd just put the large images back into place...
Hope this helps you a bit on the ios problem at least...

After spending some time analysing your code TimeLine with Chrome Dev Tools, I believe there's some optimization you could do.
As far as I can tell, every single one of your 16 images gets fully repainted every time an animation is requested. This seems quite obvious to me, as there are 16 images in your example, and the Chrome Dev Tools reports 16 long "Paint" executions every time in hit "Next".
In my humble opinion, you should figure out a solution that considers only translating two images: the one you want to hide and the one you want to show. So, consider please, not moving the rest of the images and, instead, leaving them all side-by-side to the shown image.
One more thing, using scaled down images is probably making the paint cycles quite longer. Avoid them whenever you can.

Well, think I've managed to figure it out! Just so you know, original post links don't reflect the changes as I've done them on my localhost environment.
Absolutely positioning the slides container has fixed the problem that was occurring with repaint speeds after the transition had taken place (whilst applying CSS properties). Obviously taking them out of the DOM has done the trick, allowing painting to take place much more efficiently.
I originally didn't try this too much because I knew this would add a lot of work to the resizing functionality. I had originally intended to not resize at all in JS, and rely on percentages to do the dirty work. Absolutely positioning the container would cause the slideshow viewport to collapse, rendering the native resizing useless.
However, I was already having problems with sub-pixel rendering in other browsers anyway, so I guess it was time to bite the bullet and rely on fixed pixel values. I then used JS to handle the resizing, using the window resize event. All seems good, however the slideshow was still collapsed due to the positioning. Assigning height values wasn't working correctly, so was at a bit of a loss.
Thankfully, I came across a neat little trick of setting the 'padding-top' of the slideshow viewport to a percentage value, dynamically calculated (desired slideshow height, set in the settings panel for this script, divided by desired width). As padding-top percentages are relative to the width of the element, this did a great job of providing responsive height and correcting the viewport again (no longer looking collapsed).
Here is some info on using padding-top for responsive elements that maintain aspect ratio. Great little trick: http://f6design.com/projects/responsive-aspect-ratio/
All is good now, and things are working well in iOS and webkit browsers. Everything is extremely quick and working as it should. Four days later, and it is finally figured out. Not happy about having to resort to JS for resizing, but I guess it was always going to happen due to percentage inconsistencies between browsers. Lots of decimals = no good!
Thanks to all who tried to point me in the right direction. Definitely got me thinking, and learned a lot of debugging skills that I can use again to make sure transitions are performing well. Thanks again!

not sure if this helps or not but I noticed you use 3d translation - I would think a simple 2d translation would be enough especially since your third parameter is 0 and might accelerate the issue, also go with fewer images as Armel L. suggested, don't have an iphone to test though... alternatively, this is a solution I used before css3 but should still work move the element containing the images using javascript by modifying left (?and top - the demo only moves left and right though? without the transition effects) and this way you can fine-tune the refresh rate which I think might account for the slowdown... you can go as low as 18 fps without anyone noticing, might even be good enough with just 16fps

I had this when I was first designing a magazine carousel-style page device.
If you have a series of images within a long "tray", even if they are not within the viewport, they will still take up ram, and you can effectively have five or so before leaks and nastiness begin to happen.
What I found works is "hiding" them ... But make sure they take up the physical space necessary.
What I also found worked was that one could make the 'previous' current and 'next' image are visible and move the tray, 'unhiding' them as they reach those three positions.
In my own system, I skipped the 'tray' holding e images and only had them at -100% width, 100% width and the current one a 0.
I never had much luck with the typical long-tray carousel with large scale background images... Especially with css3 acceleration.

Scaled Transparent PNGs lose anti-aliasing after jQuery animation in Webkit browsers

I have a script that lays out these circular icons on the map, you hover over them, they spring up, text appears, etc. The icons are scaled relative to their position on the map, ie, the distance from 0 on the y-axis. I've tried to set the scale through CSS's width and height attributes and through the html width & heights on the img tag and still have the same problem:
Basically, in their dormant state, such as when the page is first loaded, or the user flicks between tabs, the images (trans' PNGs) are anti-aliased. However, when the hover() function, and thus the animate() function, is invoked, the images suddenly become jagged and horrid. I've noticed that this behaviour doesn't exist in firefox but does in safari and chrome. I don't know whether this is to do with Webkit, jQuery or just javascript itself but maybe someone could shine some light as google resulted in nothing. Any thoughts? :)
Please also note that the bottom left and bottom right icons look fine in both attached screenshots- they're unscaled ones!
Thanks a lot :)
Matt

i can only guess on this, but my assumption is that gecko and webkit use different scaling algorithms for images. thus it has nothing to do with javascript, jquery or png at all.
in fact, the image still has antialiased edges even in the webkit screenshot. (you see that when you zoom in)
the border is just messed up which is usually the result of a bad scaling algorithm.
try the following to confirm this assumption:
<img src="youricon.png" width="90%" height="90%">
and compare the result in the two browsers. you should see the same problem.
possible solutions:
make a smaller version of the image and replace image with the smaller one on hover instead of scaling it.
use a scalable vector graphics format like SVG for your icons.

IE GIF/PNG Transparency issue with jQuery

Ok, this is pretty weird...
Here's the page in question: http://s289116086.onlinehome.us/lawjournaltv/index.php
The main blue callout background was originally a PNG, but when I applied some jQuery trickery to it (click the numbers in the top right to see what I mean), an ugly white border appeared where the transparency should be. See this screenshot from IE8: http://skitch.com/darkdriving/n62bu/windows-xp-professional
I figured I could sacrifice the quality/flexibility of a PNG and just resaved each of the backgrounds as GIFs and set the matte color to white (for now). Well, I was proven wrong because IE is treating the GIF transparency the same as the original PNGs.
I've read here that the issue with PNGs, Javascript, and IE has something to do with multiple filters can't be applied to one image, but shouldn't GIFs be exempt from this because they lack the Alpha Channel? Is there any way to make this page look similar in IE to Firefox or Webkit browsers?
Thanks in advance!

This is a bug in IE.
No current version of IE supports the opacity CSS proeprty, so jQuery uses the Alpha filter instead. However, filters force the element to be fully opaque, so they don't work orrectly with transparent PNGs.
To use transparent PNGs in semi-transparent elements, the PNGs need to be applied using the AlphaImageLoader filter (even in IE8). For example:
if ($.browser.msie)
$(something).css({
background: 'none',
filter: 'progid:DXImageTransform.Microsoft.AlphaImageLoader(src="/Folder/Image.png", sizingMethod="scale"),alpha(opacity=100)'
});
(This code works; I'm using it right now)

I basically solved this by loading a different set of images (using PHP) on each page refresh. It's not as dynamic, but my attempts at using the ugly, proprietary CSS filters or other javascript-based plugins were all fruitless. In my eyes, this is clearly one of the biggest bugs I've come across in my time spent hacking away at IE. In fact, I'm suprised it took this long for me to encounter it.
Word to the wise in this case: try to back transparent imagery on a solid color or suffer the consequences in IE.