jQuery ui 1.8.6 position 的一个bug
在开发widget的时候，发现了一个jquery ui position的一个bug。这个bug是有关collision的。这个功能就是当当前的定位的元素超出屏幕屏幕的时候，会自动翻转定位。比如说定位在右边，而右边不够显示定位元素的时候，就定位到左边。
下面我贴出代码来分析position的代码以及这个bug出现的位置。
/*
* jQuery UI Position 1.8.6
*
* Copyright 2010, AUTHORS.txt (http://jqueryui.com/about)
* Dual licensed under the MIT or GPL Version 2 licenses.
* http://jquery.org/license
*
* http://docs.jquery.com/UI/Position
*/
(function( $, undefined ) {
$.ui = $.ui || {};
var horizontalPositions = /left|center|right/,
verticalPositions = /top|center|bottom/,
center = "center",
_position = $.fn.position,
_offset = $.fn.offset;
$.fn.position = function( options ) {
if ( !options || !options.of ) {
return _position.apply( this, arguments );
}
// make a copy, we don't want to modify arguments
options = $.extend( {}, options );
var target = $( options.of ),
targetElem = target[0],
collision = ( options.collision || "flip" ).split( " " ),
offset = options.offset ? options.offset.split( " " ) : [ 0, 0 ],
targetWidth,
targetHeight,
basePosition;
//如果相对定位的元素是document元素的话
if ( targetElem.nodeType === 9 ) {
targetWidth = target.width();
targetHeight = target.height();
basePosition = { top: 0, left: 0 };
// TODO: use $.isWindow() in 1.9
} else if ( targetElem.setTimeout ) {
targetWidth = target.width();
targetHeight = target.height();
basePosition = { top: target.scrollTop(), left: target.scrollLeft() };
} else if ( targetElem.preventDefault ) {
// force left top to allow flipping
options.at = "left top";
targetWidth = targetHeight = 0;
basePosition = { top: options.of.pageY, left: options.of.pageX };
} else {
targetWidth = target.outerWidth();
targetHeight = target.outerHeight();
basePosition = target.offset();
}
// force my and at to have valid horizontal and veritcal positions
// if a value is missing or invalid, it will be converted to center
$.each( [ "my", "at" ], function() {
var pos = ( options[this] || "" ).split( " " );
if ( pos.length === 1) {
pos = horizontalPositions.test( pos[0] ) ?
pos.concat( [center] ) :
verticalPositions.test( pos[0] ) ?
[ center ].concat( pos ) :
[ center, center ];
}
pos[ 0 ] = horizontalPositions.test( pos[0] ) ? pos[ 0 ] : center;
pos[ 1 ] = verticalPositions.test( pos[1] ) ? pos[ 1 ] : center;
options[ this ] = pos;
});
// normalize collision option
if ( collision.length === 1 ) {
collision[ 1 ] = collision[ 0 ];
}
// normalize offset option
offset[ 0 ] = parseInt( offset[0], 10 ) || 0;
if ( offset.length === 1 ) {
offset[ 1 ] = offset[ 0 ];
}
offset[ 1 ] = parseInt( offset[1], 10 ) || 0;
if ( options.at[0] === "right" ) {
basePosition.left += targetWidth;
} else if (options.at[0] === center ) {
basePosition.left += targetWidth / 2;
}
if ( options.at[1] === "bottom" ) {
basePosition.top += targetHeight;
} else if ( options.at[1] === center ) {
basePosition.top += targetHeight / 2;
}
basePosition.left += offset[ 0 ];
basePosition.top += offset[ 1 ];
return this.each(function() {
var elem = $( this ),
elemWidth = elem.outerWidth(),
elemHeight = elem.outerHeight(),
marginLeft = parseInt( $.curCSS( this, "marginLeft", true ) ) || 0,
marginTop = parseInt( $.curCSS( this, "marginTop", true ) ) || 0,
//此处就是出现问题的地方，在ie下面如果当前元素的margin没有设置或者设置为auto的话，在取$.curCss(this,"marginRight",true)的时候会去取出为
//"auto"，此问题在其他的浏览器下，不会取出为auto，而是当前元素的css实际值。,在转换的时候会为NAN，这个时候再做前面的运算，都将为NAN，
//最终此值将被计算为0. 而这样，在下面做反转的时候，将会计算出错误的值，而不会发生发转。目前的解决方法就是在当前的元素上加上
//margin-right和margin-bottom的值。
collisionWidth = elemWidth + marginLeft +
parseInt( $.curCSS( this, "marginRight", true ) ) || 0,
collisionHeight = elemHeight + marginTop +
parseInt( $.curCSS( this, "marginBottom", true ) ) || 0,
position = $.extend( {}, basePosition ),
collisionPosition;
if ( options.my[0] === "right" ) {
position.left -= elemWidth;
} else if ( options.my[0] === center ) {
position.left -= elemWidth / 2;
}
if ( options.my[1] === "bottom" ) {
position.top -= elemHeight;
} else if ( options.my[1] === center ) {
position.top -= elemHeight / 2;
}
// prevent fractions (see #5280)
position.left = parseInt( position.left );
position.top = parseInt( position.top );
collisionPosition = {
left: position.left - marginLeft,
top: position.top - marginTop
};
$.each( [ "left", "top" ], function( i, dir ) {
if ( $.ui.position[ collision[i] ] ) {
$.ui.position[ collision[i] ][ dir ]( position, {
targetWidth: targetWidth,
targetHeight: targetHeight,
elemWidth: elemWidth,
elemHeight: elemHeight,
collisionPosition: collisionPosition,
collisionWidth: collisionWidth,
collisionHeight: collisionHeight,
offset: offset,
my: options.my,
at: options.at
});
}
});
if ( $.fn.bgiframe ) {
elem.bgiframe();
}
elem.offset( $.extend( position, { using: options.using } ) );
});
};
//此处就是做翻转的函数的。
$.ui.position = {
fit: {
left: function( position, data ) {
var win = $( window ),
over = data.collisionPosition.left + data.collisionWidth - win.width() - win.scrollLeft();
position.left = over > 0 ? position.left - over : Math.max( position.left - data.collisionPosition.left, position.left );
},
top: function( position, data ) {
var win = $( window ),
over = data.collisionPosition.top + data.collisionHeight - win.height() - win.scrollTop();
position.top = over > 0 ? position.top - over : Math.max( position.top - data.collisionPosition.top, position.top );
}
},
flip: {
left: function( position, data ) {
if ( data.at[0] === center ) {
return;
}
var win = $( window ),
over = data.collisionPosition.left + data.collisionWidth - win.width() - win.scrollLeft(),
myOffset = data.my[ 0 ] === "left" ?
-data.elemWidth :
data.my[ 0 ] === "right" ?
data.elemWidth :
0,
atOffset = data.at[ 0 ] === "left" ?
data.targetWidth :
-data.targetWidth,
offset = -2 * data.offset[ 0 ];
position.left += data.collisionPosition.left < 0 ?
myOffset + atOffset + offset :
over > 0 ?
myOffset + atOffset + offset :
0;
},
top: function( position, data ) {
if ( data.at[1] === center ) {
return;
}
var win = $( window ),
over = data.collisionPosition.top + data.collisionHeight - win.height() - win.scrollTop(),
myOffset = data.my[ 1 ] === "top" ?
-data.elemHeight :
data.my[ 1 ] === "bottom" ?
data.elemHeight :
0,
atOffset = data.at[ 1 ] === "top" ?
data.targetHeight :
-data.targetHeight,
offset = -2 * data.offset[ 1 ];
position.top += data.collisionPosition.top < 0 ?
myOffset + atOffset + offset :
over > 0 ?
myOffset + atOffset + offset :
0;
}
}
};
// offset setter from jQuery 1.4
if ( !$.offset.setOffset ) {
$.offset.setOffset = function( elem, options ) {
// set position first, in-case top/left are set even on static elem
if ( /static/.test( $.curCSS( elem, "position" ) ) ) {
elem.style.position = "relative";
}
var curElem = $( elem ),
curOffset = curElem.offset(),
curTop = parseInt( $.curCSS( elem, "top", true ), 10 ) || 0,
curLeft = parseInt( $.curCSS( elem, "left", true ), 10) || 0,
props = {
top: (options.top - curOffset.top) + curTop,
left: (options.left - curOffset.left) + curLeft
};
if ( 'using' in options ) {
options.using.call( elem, props );
} else {
curElem.css( props );
}
};
$.fn.offset = function( options ) {
var elem = this[ 0 ];
if ( !elem || !elem.ownerDocument ) { return null; }
if ( options ) {
return this.each(function() {
$.offset.setOffset( this, options );
});
}
return _offset.call( this );
};
}
}( jQuery ));
