javascript DIV浮动插件介绍

时间：2012-03-15 编辑：简简单单来源：一聚教程网

如下：

代码如下
复制代码

This shows a sliding panel with no bottom boundary, and a bigger gap between the top of the viewport and the top of the panel.

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Hello, I'm a sliding panel - unless the viewport is too small to contain my full glory, in which case I will stay right here so users can see all of me.

2.?置 CSS

代?如下：


	  
		 代码如下
		复制代码

3.引用portamento.js

portamento.js代?如下：


	  
		 代码如下
		复制代码
	  
	  
		/*!
* 
* Portamento  v1.1.1 - 2011-09-02
* http://simianstudios.com/portamento
*   
* Copyright 2011 Kris Noble except where noted.
* 
* Dual-licensed under the GPLv3 and Apache 2.0 licenses: 
* http://www.gnu.org/licenses/gpl-3.0.html
* http://www.apache.org/licenses/LICENSE-2.0
* 
*/
/**
* 
* Creates a sliding panel that respects the boundaries of
* a given wrapper, and also has sensible behaviour if the
* viewport is too small to display the whole panel.
* 
* Full documentation at http://simianstudios.com/portamento
* 
* ----
* 
* Uses the viewportOffset plugin by Ben Alman aka Cowboy:
* http://benalman.com/projects/jquery-misc-plugins/#viewportoffset
* 
* Uses a portion of CFT by Juriy Zaytsev aka Kangax:
* http://kangax.github.com/cft/#IS_POSITION_FIXED_SUPPORTED
* 
* Uses code by Matthew Eernisse:
* http://www.fleegix.org/articles/2006-05-30-getting-the-scrollbar-width-in-pixels
* 
* Builds on work by Remy Sharp:
* http://jqueryfordesigners.com/fixed-floating-elements/
* 
*/
(function ($) {

    $.fn.portamento = function (options) {

        // we'll use the window and document objects a lot, so
        // saving them as variables now saves a lot of function calls
        var thisWindow = $(window);
        var thisDocument = $(document);

        /**
        * NOTE by Kris - included here so as to avoid namespace clashes.
        * 
        * jQuery viewportOffset - v0.3 - 2/3/2010
        * http://benalman.com/projects/jquery-misc-plugins/
        * 
        * Copyright (c) 2010 "Cowboy" Ben Alman
        * Dual licensed under the MIT and GPL licenses.
        * http://benalman.com/about/license/
        */
        $.fn.viewportOffset = function () {
            var win = $(window);
            var offset = $(this).offset();

            return {
                left: offset.left - win.scrollLeft(),
                top: offset.top - win.scrollTop()
            };
        };

        /**
        * 
        * A test to see if position:fixed is supported.
        * Taken from CFT by Kangax - http://kangax.github.com/cft/#IS_POSITION_FIXED_SUPPORTED
        * Included here so as to avoid namespace clashes.
        * 
        */
        function positionFixedSupported() {
            var container = document.body;
            if (document.createElement && container && container.appendChild && container.removeChild) {
                var el = document.createElement("div");
                if (!el.getBoundingClientRect) {
                    return null;
                }
                el.innerHTML = "x";
                el.style.cssText = "position:fixed;top:100px;";
                container.appendChild(el);
                var originalHeight = container.style.height, originalScrollTop = container.scrollTop;
                container.style.height = "3000px";
                container.scrollTop = 500;
                var elementTop = el.getBoundingClientRect().top;
                container.style.height = originalHeight;
                var isSupported = elementTop === 100;
                container.removeChild(el);
                container.scrollTop = originalScrollTop;
                return isSupported;
            }
            return null;
        }

        /**
        * 
        * Get the scrollbar width by Matthew Eernisse.
        * http://www.fleegix.org/articles/2006-05-30-getting-the-scrollbar-width-in-pixels
        * Included here so as to avoid namespace clashes.
        * 
        */
        function getScrollerWidth() {
            var scr = null;
            var inn = null;
            var wNoScroll = 0;
            var wScroll = 0;

            // Outer scrolling div
            scr = document.createElement('div');
            scr.style.position = 'absolute';
            scr.style.top = '-1000px';
            scr.style.left = '-1000px';
            scr.style.width = '100px';
            scr.style.height = '50px';
            // Start with no scrollbar
            scr.style.overflow = 'hidden';

            // Inner content div
            inn = document.createElement('div');
            inn.style.width = '100%';
            inn.style.height = '200px';

            // Put the inner div in the scrolling div
            scr.appendChild(inn);
            // Append the scrolling div to the doc
            document.body.appendChild(scr);

            // Width of the inner div sans scrollbar
            wNoScroll = inn.offsetWidth;
            // Add the scrollbar
            scr.style.overflow = 'auto';
            // Width of the inner div width scrollbar
            wScroll = inn.offsetWidth;

            // Remove the scrolling div from the doc
            document.body.removeChild(document.body.lastChild);

            // Pixel width of the scroller
            return (wNoScroll - wScroll);
        }

        // ---------------------------------------------------------------------------------------------------

        // get the definitive options
        var opts = $.extend({}, $.fn.portamento.defaults, options);

        // setup the vars accordingly
        var panel = this;
        var wrapper = opts.wrapper;
        var gap = opts.gap;
        var disableWorkaround = opts.disableWorkaround;
        var fullyCapableBrowser = positionFixedSupported();

        if (panel.length != 1) {
            // die gracefully if the user has tried to pass multiple elements 
            // (multiple element support is on the TODO list!) or no elements...
            return this;
        }

        if (!fullyCapableBrowser && disableWorkaround) {
            // just stop here, as the dev doesn't want to use the workaround
            return this;
        }

        // wrap the floating panel in a div, then set a sensible min-height and width
        panel.wrap('');
        var float_container = $('#portamento_container');
        float_container.css({
            'min-height': panel.outerHeight(),
            'width': panel.outerWidth()
        });

        // calculate the upper scrolling boundary
        var panelOffset = panel.offset().top;
        var panelMargin = parseFloat(panel.css('marginTop').replace(/auto/, 0));
        var realPanelOffset = panelOffset - panelMargin;
        var topScrollBoundary = realPanelOffset - gap;

        // a couple of numbers to account for margins and padding on the relevant elements
        var wrapperPaddingFix = parseFloat(wrapper.css('paddingTop').replace(/auto/, 0));
        var containerMarginFix = parseFloat(float_container.css('marginTop').replace(/auto/, 0));

        // do some work to fix IE misreporting the document width
        var ieFix = 0;

        var isMSIE = /*@cc_on!@*/0;

        if (isMSIE) {
            ieFix = getScrollerWidth() + 4;
        }

        // ---------------------------------------------------------------------------------------------------

        thisWindow.bind("scroll.portamento", function () {

            if (thisWindow.height() > panel.outerHeight() && thisWindow.width() >= (thisDocument.width() - ieFix)) { // don't scroll if the window isn't big enough

                var y = thisDocument.scrollTop(); // current scroll position of the document

                if (y >= (topScrollBoundary)) { // if we're at or past the upper scrolling boundary
                    if ((panel.innerHeight() - wrapper.viewportOffset().top) - wrapperPaddingFix + gap >= wrapper.height()) { // if we're at or past the bottom scrolling boundary
                        if (panel.hasClass('fixed') || thisWindow.height() >= panel.outerHeight()) { // check that there's work to do
                            panel.removeClass('fixed');
                            panel.css('top', (wrapper.height() - panel.innerHeight()) + 'px');
                        }
                    } else { // if we're somewhere in the middle
                        panel.addClass('fixed');

                        if (fullyCapableBrowser) { // supports position:fixed
                            panel.css('top', gap + 'px'); // to keep the gap
                        } else {
                            panel.clearQueue();
                            panel.css('position', 'absolute').animate({ top: (0 - float_container.viewportOffset().top + gap) });
                        }
                    }
                } else {
                    // if we're above the top scroll boundary
                    panel.removeClass('fixed');
                    panel.css('top', '0'); // remove any added gap
                }
            } else {
                panel.removeClass('fixed');
            }
        });

        // ---------------------------------------------------------------------------------------------------

        thisWindow.bind("resize.portamento", function () {
            // stop users getting undesirable behaviour if they resize the window too small
            if (thisWindow.height() <= panel.outerHeight() || thisWindow.width() < thisDocument.width()) {
                if (panel.hasClass('fixed')) {
                    panel.removeClass('fixed');
                    panel.css('top', '0');
                }
            } else {
                thisWindow.trigger('scroll.portamento'); // trigger the scroll event to place the panel correctly
            }
        });

        // ---------------------------------------------------------------------------------------------------

        thisWindow.bind("orientationchange.portamento", function () {
            // if device orientation changes, trigger the resize event
            thisWindow.trigger('resize.portamento');
        });

        // ---------------------------------------------------------------------------------------------------

        // trigger the scroll event immediately so that the panel is positioned correctly if the page loads anywhere other than the top.
        thisWindow.trigger('scroll.portamento');

        // return this to maintain chainability
        return this;
    };

    // set some sensible defaults
    $.fn.portamento.defaults = {
        'wrapper': $('body'), // the element that will act as the sliding panel's boundaries
        'gap': 10, // the gap (in pixels) left between the top of the viewport and the top of the panel
        'disableWorkaround': false // option to disable the workaround for not-quite capable browsers 
    };

})(jQuery);

4.在js中?用

代码如下	复制代码

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