Pagination（分页）

/** * This jQuery plugin displays pagination links inside the selected elements. * * This plugin needs at least jQuery 1.4.2 * * @author Gabriel Birke (birke *at* d-scribe *dot* de) * @version 2.1 * @param {int} maxentries Number of entries to paginate * @param {Object} opts Several options (see README for documentation) * @return {Object} jQuery Object */ (function($){ /** * @class Class for calculating pagination values */ $.PaginationCalculator = function(maxentries, opts) { this.maxentries = maxentries; this.opts = opts; } $.extend($.PaginationCalculator.prototype, { /** * Calculate the maximum number of pages * @method * @returns {Number} */ numPages:function() { return Math.ceil(this.maxentries/this.opts.items_per_page); }, /** * Calculate start and end point of pagination links depending on * current_page and num_display_entries. * @returns {Array} */ getInterval:function(current_page) { var ne_half = Math.floor(this.opts.num_display_entries/2); var np = this.numPages(); var upper_limit = np - this.opts.num_display_entries; var start = current_page > ne_half ? Math.max( Math.min(current_page - ne_half, upper_limit), 0 ) : 0; var end = current_page > ne_half?Math.min(current_page+ne_half + (this.opts.num_display_entries % 2), np):Math.min(this.opts.num_display_entries, np); return {start:start, end:end}; } }); // Initialize jQuery object container for pagination renderers $.PaginationRenderers = {} /** * @class Default renderer for rendering pagination links */ $.PaginationRenderers.defaultRenderer = function(maxentries, opts) { this.maxentries = maxentries; this.opts = opts; this.pc = new $.PaginationCalculator(maxentries, opts); } $.extend($.PaginationRenderers.defaultRenderer.prototype, { /** * Helper function for generating a single link (or a span tag if it's the current page) * @param {Number} page_id The page id for the new item * @param {Number} current_page * @param {Object} appendopts Options for the new item: text and classes * @returns {jQuery} jQuery object containing the link */ createLink:function(page_id, current_page, appendopts){ var lnk, np = this.pc.numPages(); page_id = page_id<0?0:(page_id<np?page_id:np-1); // Normalize page id to sane value appendopts = $.extend({text:page_id+1, classes:""}, appendopts||{}); if(page_id == current_page){ lnk = $("<span class='current'>" + appendopts.text + "</span>"); } else { lnk = $("<a>" + appendopts.text + "</a>") .attr('href', this.opts.link_to.replace(/__id__/,page_id)); } if(appendopts.classes){ lnk.addClass(appendopts.classes); } lnk.data('page_id', page_id); return lnk; }, // Generate a range of numeric links appendRange:function(container, current_page, start, end, opts) { var i; for(i=start; i<end; i++) { this.createLink(i, current_page, opts).appendTo(container); } }, getLinks:function(current_page, eventHandler) { var begin, end, interval = this.pc.getInterval(current_page), np = this.pc.numPages(), fragment = $("<div class='pagination'></div>"); // Generate "Previous"-Link if(this.opts.prev_text && (current_page > 0 || this.opts.prev_show_always)){ fragment.append(this.createLink(current_page-1, current_page, {text:this.opts.prev_text, classes:"prev"})); } // Generate starting points if (interval.start > 0 && this.opts.num_edge_entries > 0) { end = Math.min(this.opts.num_edge_entries, interval.start); this.appendRange(fragment, current_page, 0, end, {classes:'sp'}); if(this.opts.num_edge_entries < interval.start && this.opts.ellipse_text) { jQuery("<span>"+this.opts.ellipse_text+"</span>").appendTo(fragment); } } // Generate interval links this.appendRange(fragment, current_page, interval.start, interval.end); // Generate ending points if (interval.end < np && this.opts.num_edge_entries > 0) { if(np-this.opts.num_edge_entries > interval.end && this.opts.ellipse_text) { jQuery("<span>"+this.opts.ellipse_text+"</span>").appendTo(fragment); } begin = Math.max(np-this.opts.num_edge_entries, interval.end); this.appendRange(fragment, current_page, begin, np, {classes:'ep'}); } // Generate "Next"-Link if(this.opts.next_text && (current_page < np-1 || this.opts.next_show_always)){ fragment.append(this.createLink(current_page+1, current_page, {text:this.opts.next_text, classes:"next"})); } $('a', fragment).click(eventHandler); return fragment; } }); // Extend jQuery $.fn.pagination = function(maxentries, opts){ // Initialize options with default values opts = jQuery.extend({ items_per_page:10, num_display_entries:11, current_page:0, num_edge_entries:0, link_to:"#", prev_text:"Prev", next_text:"Next", ellipse_text:"...", prev_show_always:true, next_show_always:true, renderer:"defaultRenderer", callback:function(){return false;} },opts||{}); var containers = this, renderer, links, current_page; /** * This is the event handling function for the pagination links. * @param {int} page_id The new page number */ function paginationClickHandler(evt){ var links, new_current_page = $(evt.target).data('page_id'), continuePropagation = selectPage(new_current_page); if (!continuePropagation) { evt.stopPropagation(); } return continuePropagation; } /** * This is a utility function for the internal event handlers. * It sets the new current page on the pagination container objects, * generates a new HTMl fragment for the pagination links and calls * the callback function. */ function selectPage(new_current_page) { // update the link display of a all containers containers.data('current_page', new_current_page); links = renderer.getLinks(new_current_page, paginationClickHandler); containers.empty(); links.appendTo(containers); // call the callback and propagate the event if it does not return false var continuePropagation = opts.callback(new_current_page, containers); return continuePropagation; } // ----------------------------------- // Initialize containers // ----------------------------------- current_page = opts.current_page; containers.data('current_page', current_page); // Create a sane value for maxentries and items_per_page maxentries = (!maxentries || maxentries < 0)?1:maxentries; opts.items_per_page = (!opts.items_per_page || opts.items_per_page < 0)?1:opts.items_per_page; if(!$.PaginationRenderers[opts.renderer]) { throw new ReferenceError("Pagination renderer '" + opts.renderer + "' was not found in jQuery.PaginationRenderers object."); } renderer = new $.PaginationRenderers[opts.renderer](maxentries, opts); // Attach control events to the DOM elements var pc = new $.PaginationCalculator(maxentries, opts); var np = pc.numPages(); containers.bind('setPage', {numPages:np}, function(evt, page_id) { if(page_id >= 0 && page_id < evt.data.numPages) { selectPage(page_id); return false; } }); containers.bind('prevPage', function(evt){ var current_page = $(this).data('current_page'); if (current_page > 0) { selectPage(current_page - 1); } return false; }); containers.bind('nextPage', {numPages:np}, function(evt){ var current_page = $(this).data('current_page'); if(current_page < evt.data.numPages - 1) { selectPage(current_page + 1); } return false; }); // When all initialisation is done, draw the links links = renderer.getLinks(current_page, paginationClickHandler); containers.empty()