Why is SVG scrolling performance so much worse than PNG? - performance

A site I'm working on displays a large number (>50) of complex SVG images in a scrolling dialog window. When viewing the site in Chrome, the scrolling performance of the dialog window is very poor - it is noticeably laggy and slow. However, if I replace the SVG images with PNG images, the scrolling is perfectly smooth and responsive.
Here's a demonstration of the difference: https://jsfiddle.net/NathanFriend/42knwc1s/
Why is the SVG scrolling performance so much worse than the PNG scrolling performance? After the browser renders an SVG image, I would assume it doesn't need to rerender the image until the image is manipulated in some way (like resizing). Does scrolling an element that contains SVG images cause the images to be rerendered for every frame of the scroll animation?
`

I think this is just some kind of a Chromium bug, I've found this issue on SO, because I started experiencing it as well on Mac. It works OK on Opera for instance.
I don't think anyone here will be able to explain why it's slow if it really is a bug. I've created a Chromium bug, please star it if you want the issue to be fixed soon or learn more https://bugs.chromium.org/p/chromium/issues/detail?id=681611

Related

SVG animation freezes after navigation starts

I am in the process of converting some animated GIF animated spinners to animated SVG for better/sharper display on Hi-DPI screens.
One issue I've run into is that when a user starts navigating to another page, an animated GIF continues animating but an animated SVG freezes. So if I want to have an animation that shows the next page loading, I can't find a way to get away from using GIFs.
Is there a way to have SVG animations continue animating during page navigation?
(I am specifically using Chrome for this, because if it doesn't work in Chrome I can't use it.)
EDIT: The SVG uses SMIL to do the animation.
UPDATE
After receiving no responses on this, I can't find a way to keep SVG animations animating during navigation, so I have adopted a different approach, which is to use CSS animations.
CSS animations continue animating even after navigation starts. They are a little harder to deal with, as far as inserting into a page and integrating with other elements, but they do the trick.

Chrome resizes svg images

I have an img menu with svg images that changes the svg image with a identical image with a different color when you push in menu. When I test it with Chrome it works fine until you visit one link the second time, that chrome resize it to a smaller image.
I've made a lot of tests... I've tested :visited css, user agent css, and many another properties and it seems to be all ok. When you changes some css property in developer tools it changes automagically to correct size.
My last test was to change the width from 135px to 134px (don't ask why) and it works in 1680x1050 screen but not in 1920x1200 screen (???????). Is it an aspect ratio problem?
I'm getting crazy!!
I'm using angularjs to make the black image to red image change, but I think this is not the problem (it does a src replacement)
You can see it in the webpage http://silviaperezcruz.com.
I'll apreciate any kind of help.
PD: Sorry for my bad english
I couldn't see an obvious reason why it is doing it,. But if I had to guess, I would cast a suspicious eye on respond.js first. Does it still do it if you remove that?

Pan/Zoom painfully slow in IE8 RaphaelJS

I have been working on getting this seat mapping chart for a while and have created a few iterations, and the problem I keep finding is when I get to IE8 the panning for this is way to slow and delayed.
What I have at this point to cut down on load time is created a png to replace my "strokes" since I assume ie8 wanted to re-render each time I dragged the map.
I also added controls hoping to force IE8 users this option, but still there is a delay in the pan, and if I can have users with IE8 (and ie7 if possible) still drag/pan without the controls and the respond time a little faster that would be great.
Here is my current JSFiddle
I am still a little green with JS so if you have any suggestions it would be much appreciated. (PS Chrome frame is awesome but is not a option for me)
Update
I have removed the original dragging function and replaced the code using jqueryui's draggable function. Martin had suggested to just drag the div, and not the Raphael elements. Doing so lets this thing fly in ie6-8 which is great, but then came my concern about scaling. What I was seeing before on zoom my paper element WxH would stay the same ratio, cutting off my drawing when it zoomed in. After digging through the Raphael documentation I came across paper.setSize. setSize was exactly what I needed to allow this project to move and groove in ie6-8 and pretty much conquer all browsers in its path.
So in short, using jqueryui's draggable and paper.setSize has cured my cross browser zoom n' pan blues.
From what can be seen in the Fiddle, you are triggering a new rendering of the image by calling .translate() inside of a mousemove event handler:
mapContainer.translate(currentMapPosX, currentMapPosY);
rsrGroupies.translate(currentMapPosX, currentMapPosY);
This approach is toxic for performance in all browsers, let alone IE8. When dealing with VML in IE8 you should consider that each and every DOM change inside the image will result in the image being rendered again. Doing that while panning will always be painfully slow.
I see that you are already using jQuery in your Fiddle. If you want to increase performance of your panning, you should consider doing the following:
Render the image in Raphaƫl exactly once for the current zoom level. Do not attempt to change transformations in your VML/SVG image at any point in time while panning.
With the mousemove implementation of panning you already have, move or scroll the HTML container that holds your VML/SVG image instead. Imagine a <div> with overflow: hidden and simply move the image inside relatively, or scroll to the appropriate position.
This will require some adjustment of your coordinate calculations, but it will improve your performance in all browsers.

Safari changing font weights when unrelated animations are running

I'm using css animations on my page and Safari seems to change unrelated font weights elsewhere on the page when animations are running. Any idea why this happens? All other browsers work fine, include webkit ones like Chrome.
I've detailed the bug in a video here - http://www.screenr.com/gZN8
The site is also here - http://airport-r7.appspot.com/ but it might keep changing rapidly.
I'm using compass (#transition-property, #transition-duration) on the arrow icons. No transitions applied on the heading that's flashing. On a Mac - so it might be the hardware acceleration, but I'm still trying to figure it out.
When you trigger GPU compositing (eg, through CSS animation), the browser sends that element to the GPU, but also anything that would appear on top of that element if its top/left properties were changed. This includes any position:relative elements that appear after the animating one.
The solution is to give the animating element position:relative and a z-index that puts it above everything else. That way you get your animation but keep the (superior IMO) sub-pixel font rendering on unrelated elements.
Here's a demo of the problem and solution http://www.youtube.com/watch?v=9Woaz-cKPCE&hd=1
Update: Newer versions of Chrome retain sub-pixel antialiasing on GPU composited elements as long as the element has no transparency, eg has a background with no transparent or semi-transparent pixels. Note that things like border-radius introduce semi-transparent pixels.
Apparently, that's the price you pay for hardware acceleration: all text momentarily turns into images, which causes the drop in render quality.
However, applying html {-webkit-font-smoothing: antialiased} to turn off the sub-pixel anti-aliasing makes this problem go away. That's what I'm doing for now.
UPDATE: Since then, I've also come to learn that this happens only when the browser can't be sure if the section being animated is going to affect the text. This can usually be handled by having the text above (higher z-index than) the elements being animated, and/or making sure the text has a fully opaque background.
I've faced this issue numerous times and have had success adding the following css to the animated element:
z-index: 60000;
position: relative;
It seems it needs both z-index and position to be effective. In my case I was using it with Font Awesome animated spinners.

Box-shadow very slow scrolling (particularly - opera)

I'm writing first time on this website, because I have big problem with css3 exactly box-shadow, so I start from the beginning :)
I made website and it worked good until I changed all graphic.
I did box-shadow and now my website works very slow (exactly scrolling).
It is address: skuterpl.vot.pl (version with new graphic and box-shadow)
strona.pzs1.pl (Old version with old graphic and without box-shadow, this website works very good).
I'm asking you for help me with this problem.
If you have a very large shadow radius, it can affect performance - there's a post here about it affecting webkit browsers CSS3 box-shadow causes scroll-lag (slow performance) on Safari 5.0.2? , though I believe now fixed.
Lowering the amount of box-radius blur should solve the issue.
things you should take notice of certain factors that can slow down a page:
heavy graphics (like huge backgrounds)
a fixed background
element opacity / image transparency
animated images
text/box shadows
constantly running scripts/event firing (like scrolling events)
although the old page works, i can still see some things that need optimization.

Resources