jquery的animate关于background-position属性
jQuery 的 animate 虽然能直接使用 CSS 的方式来进行动画,但有些属性其实是不支持的,例如:background-position。
- 谷歌支持 background-position-x; background-position-y ;firefox不支持。
- 使用 background-position 插件
- 使用另外一个background-position 插件:_this.animate({'background-position':'477px 0px'},750);
-
/* http://keith-wood.name/backgroundPos.html
Background position animation for jQuery v1.1.1.
Written by Keith Wood (kbwood{at}iinet.com.au) November 2010.
Dual licensed under the GPL (http://dev.jquery.com/browser/trunk/jquery/GPL-LICENSE.txt) and
MIT (http://dev.jquery.com/browser/trunk/jquery/MIT-LICENSE.txt) licenses.
Please attribute the author if you use it. */
(function($) { // Hide scope, no $ conflict
var BG_POS = 'bgPos';
var usesTween = !!$.Tween;
if (usesTween) { // jQuery 1.8+
$.Tween.propHooks['backgroundPosition'] = {
get: function(tween) {
return parseBackgroundPosition($(tween.elem).css(tween.prop));
},
set: function(tween) {
setBackgroundPosition(tween);
}
};
}
else { // jQuery 1.7-
// Enable animation for the background-position attribute
$.fx.step['backgroundPosition'] = setBackgroundPosition;
};
/* Parse a background-position definition: horizontal [vertical]
@param value (string) the definition
@return ([2][string, number, string]) the extracted values - relative marker, amount, units */
function parseBackgroundPosition(value) {
var bgPos = (value || '').split(/ /);
var presets = {center: '50%', left: '0%', right: '100%', top: '0%', bottom: '100%'};
var decodePos = function(index) {
var pos = (presets[bgPos[index]] || bgPos[index] || '50%').
match(/^([+-]=)?([+-]?\d+(\.\d*)?)(.*)$/);
bgPos[index] = [pos[1], parseFloat(pos[2]), pos[4] || 'px'];
};
if (bgPos.length == 1 && $.inArray(bgPos[0], ['top', 'bottom']) > -1) {
bgPos[1] = bgPos[0];
bgPos[0] = '50%';
}
decodePos(0);
decodePos(1);
return bgPos;
}
/* Set the value for a step in the animation.
@param tween (object) the animation properties */
function setBackgroundPosition(tween) {
if (!tween.set) {
initBackgroundPosition(tween);
}
$(tween.elem).css('background-position',
((tween.pos * (tween.end[0][1] - tween.start[0][1]) + tween.start[0][1]) + tween.end[0][2]) + ' ' +
((tween.pos * (tween.end[1][1] - tween.start[1][1]) + tween.start[1][1]) + tween.end[1][2]));
}
/* Initialise the animation.
@param tween (object) the animation properties */
function initBackgroundPosition(tween) {
if (!usesTween) {
var elem = $(tween.elem);
var bgPos = elem.data(BG_POS); // Original background position
elem.css('backgroundPosition', bgPos); // Restore original position
tween.start = parseBackgroundPosition(bgPos);
}
tween.end = parseBackgroundPosition($.fn.jquery >= '1.6' ? tween.end :
tween.options.curAnim['backgroundPosition'] || tween.options.curAnim['background-position']);
for (var i = 0; i < tween.end.length; i++) {
if (tween.end[i][0]) { // Relative position
tween.end[i][1] = tween.start[i][1] + (tween.end[i][0] == '-=' ? -1 : +1) * tween.end[i][1];
}
}
tween.set = true;
}
/* Wrap jQuery animate to preserve original backgroundPosition. */
if (!usesTween) { // jQuery 1.7-
$.fn.animate = function(origAnimate) {
return function(prop, speed, easing, callback) {
if (prop['backgroundPosition'] || prop['background-position']) {
this.data(BG_POS, this.css('backgroundPosition') || 'left top');
}
return origAnimate.apply(this, [prop, speed, easing, callback]);
};
}($.fn.animate);
}
})(jQuery);