CSS3 Continuous Rotate Animation (Just like a load

问题:

I am trying to replicate an Apple style activity indicator (sundial loading icon) by using a PNG and CSS3 animation. I have the image rotating and doing it continuously, but there seems to be a delay after the animation has finished before it does the next rotation.

@-webkit-keyframes rotate {
  from {
    -webkit-transform: rotate(0deg);
  }
  to { 
    -webkit-transform: rotate(360deg);
  }
}
#loading img
{
    -webkit-animation-name:             rotate; 
    -webkit-animation-duration:         0.5s; 
    -webkit-animation-iteration-count:  infinite;
    -webkit-transition-timing-function: linear;
    }

I have tried changing the animation duration but it makes no difference, if you slow it right down say 5s its just more apparent that after the first rotation there is a pause before it rotates again. It's this pause I want to get rid of.

Any help is much appreciated, thanks.

回答1:

Your issue here is that you've supplied a -webkit-TRANSITION-timing-function when you want a -webkit-ANIMATION-timing-function. Your values of 0 to 360 will work properly.

回答2:

You also might notice a little lag because 0deg and 360deg are the same spot, so it is going from spot 1 in a circle back to spot 1. It is really insignificant, but to fix it, all you have to do is change 360deg to 359deg

my jsfiddle illustrates your animation:

#myImg {
    -webkit-animation: rotation 2s infinite linear;
}

@-webkit-keyframes rotation {
    from {-webkit-transform: rotate(0deg);}
    to   {-webkit-transform: rotate(359deg);}
}

Also what might be more resemblant of the apple loading icon would be an animation that transitions the opacity/color of the stripes of gray instead of rotating the icon.

回答3:

You could use animation like this:

-webkit-animation: spin 1s infinite linear;

@-webkit-keyframes spin {
    0%   {-webkit-transform: rotate(0deg)}
    100% {-webkit-transform: rotate(360deg)}
}

回答4:

If you're only looking for a webkit version this is nifty: http://s3.amazonaws.com/37assets/svn/463-single_spinner.html from http://37signals.com/svn/posts/2577-loading-spinner-animation-using-css-and-webkit

回答5:

Your code seems correct. I would presume it is something to do with the fact you are using a .png and the way the browser redraws the object upon rotation is inefficient, causing the hang (what browser are you testing under?)

If possible replace the .png with something native.

see; http://kilianvalkhof.com/2010/css-xhtml/css3-loading-spinners-without-images/

Chrome gives me no pauses using this method.

回答6:

I made a small library that lets you easily use a throbber without images.

It uses CSS3 but falls back onto JavaScript if the browser doesn't support it.

// First argument is a reference to a container element in which you
// wish to add a throbber to.
// Second argument is the duration in which you want the throbber to
// complete one full circle.
var throbber = throbbage(document.getElementById("container"), 1000);

// Start the throbber.
throbber.play();

// Pause the throbber.
throbber.pause();

Example.