Ext.ns('Ext.ux.grid');
+
+/**
+ * @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, {
+ /**
+ * @cfg {Number} rowHeight
+ * The height of a row in the grid.
+ */
+ rowHeight: 19,
+
+ /**
+ * @cfg {Number} borderHeight
+ * The combined height of border-top and border-bottom of a row.
+ */
+ borderHeight: 2,
+
+ /**
+ * @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,
+
+ /**
+ * @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,
+
+ /**
+ * @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(
+ ''
+ );
+ ts.rowHolder.disableFormats = true;
+ ts.rowHolder.compile();
+
+ ts.rowBody = new Ext.Template(
+ '
',
+ '
{cells}
',
+ (this.enableRowBody ? '
{body}
' : ''),
+ '
'
+ );
+ 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 = " ";
+ }
+ 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();
+ }
+});
+
+
+
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