animateBackground-plugin

(function ($) {
if (!document.defaultView || !document.defaultView.getComputedStyle) {
var oldCurCSS = jQuery.curCSS;
jQuery.curCSS = function (elem, name, force) {
if (name === 'background-position') {
name = 'backgroundPosition';
}
if (name !== 'backgroundPosition' || !elem.currentStyle || elem.currentStyle[name]) {
return oldCurCSS.apply(this, arguments);
}
var style = elem.style;
if (!force && style && style[name]) {
return style[name];
}
return oldCurCSS(elem, 'backgroundPositionX', force) + ' ' + oldCurCSS(elem, 'backgroundPositionY', force);
};
} var oldAnim = $.fn.animate;
$.fn.animate = function (prop) {
if ('background-position' in prop) {
prop.backgroundPosition = prop['background-position'];
delete prop['background-position'];
}
if ('backgroundPosition' in prop) {
prop.backgroundPosition = '(' + prop.backgroundPosition + ')';
}
return oldAnim.apply(this, arguments);
}; function toArray(strg) {
strg = strg.replace(/left|top/g, '0px');
strg = strg.replace(/right|bottom/g, '100%');
strg = strg.replace(/([-\.]+)(\s|\)|$)/g, "$1px$2");
var res = strg.match(/(-?[-\.]+)(px|\%|em|pt)\s(-?[-\.]+)(px|\%|em|pt)/);
return [parseFloat(res[], ), res[], parseFloat(res[], ), res[]];
} $.fx.step.backgroundPosition = function (fx) {
if (!fx.bgPosReady) {
var start = $.curCSS(fx.elem, 'backgroundPosition'); if (!start) {//FF2 no inline-style fallback
start = '0px 0px';
} start = toArray(start); fx.start = [start[], start[]]; var end = toArray(fx.end);
fx.end = [end[], end[]]; fx.unit = [end[], end[]];
fx.bgPosReady = true;
} var nowPosX = [];
nowPosX[] = ((fx.end[] - fx.start[]) * fx.pos) + fx.start[] + fx.unit[];
nowPosX[] = ((fx.end[] - fx.start[]) * fx.pos) + fx.start[] + fx.unit[];
fx.elem.style.backgroundPosition = nowPosX[] + ' ' + nowPosX[];
};
})(jQuery);

//动画调用示例
$("#viewBody").animate({ backgroundPosition: '(520px 0)' });