jquery animate background position

问题

I can't seem to get this working.

$('#product_family_options_dd').animate({
  height: '300px',
  width: '900px',
  backgroundPosition: '-20px 0px',          
},

The height and width animate but not the background.

回答1:

You don't need to use the background animate plugin if you just use separate values like this:

$('.pop').animate({
  'background-position-x': '10%',
  'background-position-y': '20%'
}, 10000, 'linear');

回答2:

I guess it might be because it is expecting a single value?

taken from the animate page on jQuery:

Animation Properties and Values

All animated properties should be animated to a single numeric value, except as noted below; most properties that are non-numeric cannot be animated using basic jQuery functionality. (For example, width, height, or left can be animated but background-color cannot be.) Property values are treated as a number of pixels unless otherwise specified. The units em and % can be specified where applicable.

回答3:

Since jQuery doesn't support this out of the box, the best solution I have come across so far is to define your own CSS hooks in jQuery. Essentially, this means to define custom methods to get and set CSS values which also works with jQuery.animate().

There is already a very handy implementation for this on github: https://github.com/brandonaaron/jquery-cssHooks/blob/master/bgpos.js

With this plugin in place, you can do something like this:

$('#demo1').hover(
  function() {
    $(this).stop().animate({
      backgroundPositionX: '100%',
      backgroundPositionY: '100%'
    });
  },
  function () {
    $(this).stop().animate({
      backgroundPositionX: '105%',
      backgroundPositionY: '105%'
    });
  }
);

For me, this worked on all browsers tested so far including IE6+.

I did put a quick demo online a while ago and you can rip it apart if you need further guidance.

回答4:

jQuery's animate function is not exclusively usable for directly animating properties of DOM-objects. You can also tween variables and use the step function to get the variables for every step of the tween.

For example, to animate a background-position from background-position(0px 0px) to background-position(100px 500px) you can do this:

$({temporary_x: 0, temporary_y: 0}).animate({temporary_x: 100, temporary_y: 500}, {
    duration: 1000,
    step: function() {
        var position = Math.round(this.temporary_x) + "px " + Math.round(this.temporary_y) + "px";
        $("#your_div").css("background-position",  position);
    }
});

Just make sure to not forget the this. inside the step function.

回答5:

In your jQuery code there is a comma after the backgroundPosition portion:

backgroundPosition: '-20px 0px',

However, when listing the various properties you want to change in the .animate() method (and similar methods), the last argument listed between curly braces should not have a comma after it. I can't say if that's why the background position isn't getting changed, but it is an error and one I'd suggest fixing.

UPDATE: In the limited testing I've done just now, entering purely numerical values (without "px") works for backgroundPosition in the .animate() method. In other words, this works:

backgroundPosition: '-20 0'

However, this does not:

backgroundPosition: '-20px 0'

Hope this helps.

回答6:

You can also use math combination "-=" to move background

$(this).animate( {backgroundPositionX: "-=20px"} ,500);

回答7:

You cannot use simple jquery's Animate to do that as it involves 2 values.

To solve it just include Background Position Plugin and you can animate Backgrounds at will.

回答8:

try backgroundPosition:"(-20px 0)"

Just to double check are you referencing this the background position plugin?

Example of it on jsfiddle with the background position plugin.

回答9:

You can change the image background position using setInterval method, see demo here: http://jquerydemo.com/demo/animate-background-image.aspx

回答10:

I have a div My_div 250px x 250px, a background image also 250 x 250

css:

#My_div {
    background: url("..//img/your_image.jpg") no-repeat;
    background-position: 0px 250px;
}

javascript:

$("#My_div").mouseenter(function() {
    var x = 250;
    (function animBack() {
        timer = setTimeout(function() {
            if (x-- >= 0) {
                $('#My_div').css({'background-position': '0px '+x+'px'});;
                animBack();
            }
        }, 10);
    })();

});
$("#My_div").mouseleave(function(){
    $('#My_div').css({'background-position': '0px 250px'}); 
    clearTimeout(timer);
});

I hope it help

回答11:

Using Firefox:
specifying two values: Doesn't work with any combination of syntax -- as several pointed out above. Using Firebug, I get "Error in parsing value for 'background-position'. Declaration dropped." until the animation ends.

'backgroundPosition': '17.5em' -- specifiying 1 value: works in FF and CHrome OPera, SF(Safari) and IE, with a caveat that the 2nd value or y position (vertical) gets set to "center". From Firebug, the element's style gets set to:
style="background-position: 17.5em center;"

回答12:

function getBackgroundPositionX(sel) {
    pos = $(sel).css('backgroundPosition').split(' ');
    return parseFloat(pos[0].substring(0, pos[0].length-2));
}

This returns [x] value. Length of number has no matter. Could be e.g. 9999 or 0.

来源：https://stackoverflow.com/questions/5171080/jquery-animate-background-position

标签

jquery

jquery-animate

background-position