Upgrade to ExtJS 3.0.0 - Released 07/06/2009
[extjs.git] / docs / source / BufferView.html
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+<html>\r
+<head>\r
+  <title>The source code</title>\r
+    <link href="../resources/prettify/prettify.css" type="text/css" rel="stylesheet" />\r
+    <script type="text/javascript" src="../resources/prettify/prettify.js"></script>\r
+</head>\r
+<body  onload="prettyPrint();">\r
+    <pre class="prettyprint lang-js">Ext.ns('Ext.ux.grid');
+
+<div id="cls-Ext.ux.grid.BufferView"></div>/**
+ * @class Ext.ux.grid.BufferView
+ * @extends Ext.grid.GridView
+ * A custom GridView which renders rows on an as-needed basis.
+ */
+Ext.ux.grid.BufferView = Ext.extend(Ext.grid.GridView, {
+       <div id="cfg-Ext.ux.grid.BufferView-rowHeight"></div>/**
+        * @cfg {Number} rowHeight
+        * The height of a row in the grid.
+        */
+       rowHeight: 19,
+
+       <div id="cfg-Ext.ux.grid.BufferView-borderHeight"></div>/**
+        * @cfg {Number} borderHeight
+        * The combined height of border-top and border-bottom of a row.
+        */
+       borderHeight: 2,
+
+       <div id="cfg-Ext.ux.grid.BufferView-scrollDelay"></div>/**
+        * @cfg {Boolean/Number} scrollDelay
+        * The number of milliseconds before rendering rows out of the visible
+        * viewing area. Defaults to 100. Rows will render immediately with a config
+        * of false.
+        */
+       scrollDelay: 100,
+
+       <div id="cfg-Ext.ux.grid.BufferView-cacheSize"></div>/**
+        * @cfg {Number} cacheSize
+        * The number of rows to look forward and backwards from the currently viewable
+        * area.  The cache applies only to rows that have been rendered already.
+        */
+       cacheSize: 20,
+
+       <div id="cfg-Ext.ux.grid.BufferView-cleanDelay"></div>/**
+        * @cfg {Number} cleanDelay
+        * The number of milliseconds to buffer cleaning of extra rows not in the
+        * cache.
+        */
+       cleanDelay: 500,
+
+       initTemplates : function(){
+               Ext.ux.grid.BufferView.superclass.initTemplates.call(this);
+               var ts = this.templates;
+               // empty div to act as a place holder for a row
+               ts.rowHolder = new Ext.Template(
+                       '<div class="x-grid3-row {alt}" style="{tstyle}"></div>'
+               );
+               ts.rowHolder.disableFormats = true;
+               ts.rowHolder.compile();
+
+               ts.rowBody = new Ext.Template(
+                       '<table class="x-grid3-row-table" border="0" cellspacing="0" cellpadding="0" style="{tstyle}">',
+                       '<tbody><tr>{cells}</tr>',
+                       (this.enableRowBody ? '<tr class="x-grid3-row-body-tr" style="{bodyStyle}"><td colspan="{cols}" class="x-grid3-body-cell" tabIndex="0" hidefocus="on"><div class="x-grid3-row-body">{body}</div></td></tr>' : ''),
+                       '</tbody></table>'
+               );
+               ts.rowBody.disableFormats = true;
+               ts.rowBody.compile();
+       },
+
+       getStyleRowHeight : function(){
+               return Ext.isBorderBox ? (this.rowHeight + this.borderHeight) : this.rowHeight;
+       },
+
+       getCalculatedRowHeight : function(){
+               return this.rowHeight + this.borderHeight;
+       },
+
+       getVisibleRowCount : function(){
+               var rh = this.getCalculatedRowHeight();
+               var visibleHeight = this.scroller.dom.clientHeight;
+               return (visibleHeight < 1) ? 0 : Math.ceil(visibleHeight / rh);
+       },
+
+       getVisibleRows: function(){
+               var count = this.getVisibleRowCount();
+               var sc = this.scroller.dom.scrollTop;
+               var start = (sc == 0 ? 0 : Math.floor(sc/this.getCalculatedRowHeight())-1);
+               return {
+                       first: Math.max(start, 0),
+                       last: Math.min(start + count + 2, this.ds.getCount()-1)
+               };
+       },
+
+       doRender : function(cs, rs, ds, startRow, colCount, stripe, onlyBody){
+               var ts = this.templates, ct = ts.cell, rt = ts.row, rb = ts.rowBody, last = colCount-1;
+               var rh = this.getStyleRowHeight();
+               var vr = this.getVisibleRows();
+               var tstyle = 'width:'+this.getTotalWidth()+';height:'+rh+'px;';
+               // buffers
+               var buf = [], cb, c, p = {}, rp = {tstyle: tstyle}, r;
+               for (var j = 0, len = rs.length; j < len; j++) {
+                       r = rs[j]; cb = [];
+                       var rowIndex = (j+startRow);
+                       var visible = rowIndex >= vr.first && rowIndex <= vr.last;
+                       if (visible) {
+                               for (var i = 0; i < colCount; i++) {
+                                       c = cs[i];
+                                       p.id = c.id;
+                                       p.css = i == 0 ? 'x-grid3-cell-first ' : (i == last ? 'x-grid3-cell-last ' : '');
+                                       p.attr = p.cellAttr = "";
+                                       p.value = c.renderer(r.data[c.name], p, r, rowIndex, i, ds);
+                                       p.style = c.style;
+                                       if (p.value == undefined || p.value === "") {
+                                               p.value = "&#160;";
+                                       }
+                                       if (r.dirty && typeof r.modified[c.name] !== 'undefined') {
+                                               p.css += ' x-grid3-dirty-cell';
+                                       }
+                                       cb[cb.length] = ct.apply(p);
+                               }
+                       }
+                       var alt = [];
+                       if(stripe && ((rowIndex+1) % 2 == 0)){
+                           alt[0] = "x-grid3-row-alt";
+                       }
+                       if(r.dirty){
+                           alt[1] = " x-grid3-dirty-row";
+                       }
+                       rp.cols = colCount;
+                       if(this.getRowClass){
+                           alt[2] = this.getRowClass(r, rowIndex, rp, ds);
+                       }
+                       rp.alt = alt.join(" ");
+                       rp.cells = cb.join("");
+                       buf[buf.length] =  !visible ? ts.rowHolder.apply(rp) : (onlyBody ? rb.apply(rp) : rt.apply(rp));
+               }
+               return buf.join("");
+       },
+
+       isRowRendered: function(index){
+               var row = this.getRow(index);
+               return row && row.childNodes.length > 0;
+       },
+
+       syncScroll: function(){
+               Ext.ux.grid.BufferView.superclass.syncScroll.apply(this, arguments);
+               this.update();
+       },
+
+       // a (optionally) buffered method to update contents of gridview
+       update: function(){
+               if (this.scrollDelay) {
+                       if (!this.renderTask) {
+                               this.renderTask = new Ext.util.DelayedTask(this.doUpdate, this);
+                       }
+                       this.renderTask.delay(this.scrollDelay);
+               }else{
+                       this.doUpdate();
+               }
+       },
+
+       doUpdate: function(){
+               if (this.getVisibleRowCount() > 0) {
+                       var g = this.grid, cm = g.colModel, ds = g.store;
+                       var cs = this.getColumnData();
+
+                       var vr = this.getVisibleRows();
+                       for (var i = vr.first; i <= vr.last; i++) {
+                               // if row is NOT rendered and is visible, render it
+                               if(!this.isRowRendered(i)){
+                                       var html = this.doRender(cs, [ds.getAt(i)], ds, i, cm.getColumnCount(), g.stripeRows, true);
+                                       this.getRow(i).innerHTML = html;
+                               }
+                       }
+                       this.clean();
+               }
+       },
+
+       // a buffered method to clean rows
+       clean : function(){
+               if(!this.cleanTask){
+                       this.cleanTask = new Ext.util.DelayedTask(this.doClean, this);
+               }
+               this.cleanTask.delay(this.cleanDelay);
+       },
+
+       doClean: function(){
+               if (this.getVisibleRowCount() > 0) {
+                       var vr = this.getVisibleRows();
+                       vr.first -= this.cacheSize;
+                       vr.last += this.cacheSize;
+
+                       var i = 0, rows = this.getRows();
+                       // if first is less than 0, all rows have been rendered
+                       // so lets clean the end...
+                       if(vr.first <= 0){
+                               i = vr.last + 1;
+                       }
+                       for(var len = this.ds.getCount(); i < len; i++){
+                               // if current row is outside of first and last and
+                               // has content, update the innerHTML to nothing
+                               if ((i < vr.first || i > vr.last) && rows[i].innerHTML) {
+                                       rows[i].innerHTML = '';
+                               }
+                       }
+               }
+       },
+
+       layout: function(){
+               Ext.ux.grid.BufferView.superclass.layout.call(this);
+               this.update();
+       }
+});
+</pre>    \r
+</body>\r
+</html>
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