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bigtable.js
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bigtable.js
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/*
* Copyright (c) 2010 James Brantly
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
var bigtable = function(id, columns, numRows) {
this._containerEl = document.getElementById(id);
this._columns = columns;
this._numRows = numRows;
this._rowHeight = 20;
this.createHTML();
this.createEventHandlers();
this.initializeTable();
this.renderVisibleRows();
};
bigtable.prototype.createHTML = function() {
// This creates HTML with the following structure:
//<div class="bigtable-container">
// <div class="bigtable-headers">
// <table cellspacing="0" cellpadding="0" border="0">
// <thead>
// <tr>
// <th style="width: 100px;">Column Label</th>
// ...
// </tr>
// </thead>
// </table>
// </div>
// <div class="bigtable-body">
// <table cellspacing="0" cellpadding="0" border="0">
// <thead>
// <tr>
// <th style="width: 100px;"></th>
// ...
// </tr>
// </thead>
// <tbody>
// </tbody>
// </table>
// </div>
//</div>
this._containerEl.className += ' bigtable-container';
var headersEl = document.createElement('div');
headersEl.className = 'bigtable-headers';
var headersTable = document.createElement('table');
headersTable.setAttribute('cellspacing', '0');
headersTable.setAttribute('cellpadding', '0');
headersTable.setAttribute('border', '0');
var headersTHead = document.createElement('thead');
var headersTHeadTr = document.createElement('tr');
for (var i = 0, n = this._columns.length; i<n; i++) {
var th = document.createElement('th');
th.appendChild(document.createTextNode(this._columns[i]));
th.style.width = '100px';
headersTHeadTr.appendChild(th);
}
var bodyEl = document.createElement('div');
bodyEl.className = 'bigtable-body';
var bodyTable = document.createElement('table');
bodyTable.setAttribute('cellspacing', '0');
bodyTable.setAttribute('cellpadding', '0');
bodyTable.setAttribute('border', '0');
var bodyTHead = document.createElement('thead');
var bodyTHeadTr = document.createElement('tr');
for (var i = 0, n = this._columns.length; i<n; i++) {
var th = document.createElement('th');
th.style.width = '100px';
bodyTHeadTr.appendChild(th);
}
var bodyTBody = document.createElement('tbody');
headersTHead.appendChild(headersTHeadTr);
headersTable.appendChild(headersTHead);
headersEl.appendChild(headersTable);
bodyTHead.appendChild(bodyTHeadTr);
bodyTable.appendChild(bodyTHead);
bodyTable.appendChild(bodyTBody);
bodyEl.appendChild(bodyTable);
this._containerEl.appendChild(headersEl);
this._containerEl.appendChild(bodyEl);
this._headersEl = headersEl;
this._bodyEl = bodyEl;
this._bodyTable = bodyTable;
this._bodyTBody = bodyTBody;
};
bigtable.prototype.createEventHandlers = function() {
this._curScrollLeft = null;
this._curScrollTop = null;
var headersEl = this._headersEl;
var bodyEl = this._bodyEl;
var self = this;
Event.observe(bodyEl, 'scroll', function() {
// Handle left/right scroll
var scrollLeft = bodyEl.scrollLeft;
if (self._curScrollLeft != scrollLeft) {
headersEl.scrollLeft = scrollLeft;
self._curScrollLeft = scrollLeft;
}
// Handle up/down scroll
var scrollTop = bodyEl.scrollTop;
if (self._curScrollTop != scrollTop) {
if (self._verticalScrollHandle != null) {
clearTimeout(self._verticalScrollHandle);
}
self._verticalScrollHandle = setTimeout(function() {
self.renderVisibleRows();
}, 200);
self._curScrollTop = scrollTop;
}
});
};
bigtable.prototype.initializeTable = function() {
// Setup table height
var rowHeight = this._rowHeight;
var numRows = this._numRows;
// Set the tbody height to the total height
this._bodyTable.style.height = numRows > 0 ? (numRows*rowHeight)+'px' : '1px';
// Create the initial filler tr
var filler = document.createElement('tr');
filler.style.height = (numRows*rowHeight)+'px';
this._bodyTBody.appendChild(filler);
// Leftover space filler (to keep explicit height rows from stretching)
var tr = document.createElement('tr');
this._bodyTBody.appendChild(tr);
// Create some metadata for each row to keep track of whether or not the row has been rendered yet
var rows = this._rows = [];
// Create & initialize the filler metadata
var fillers = this._fillers = [];
fillers.push({
startIndex: 0,
endIndex: numRows-1,
tr: filler
});
};
bigtable.prototype.renderVisibleRows = function() {
var visibleIndexes = this.getVisibleIndexes();
if (visibleIndexes.startIndex == null || visibleIndexes.endIndex == null) { return; }
var rows = this._rows;
var columns = this._columns;
var numColumns = columns.length;
this.createRowElementsAt(visibleIndexes.startIndex, visibleIndexes.endIndex);
for (var i = visibleIndexes.startIndex; i<=visibleIndexes.endIndex; i++) {
var rowMeta = rows[i];
var tr = rowMeta.tr;
// Create cells if not already created
if (rowMeta.cellsCreated !== true) {
for (var x = 0; x<numColumns; x++) {
var td = document.createElement('td');
td.appendChild(document.createTextNode('('+x+', '+i+')'));
tr.appendChild(td);
}
rowMeta.cellsCreated = true;
}
}
// fix for ie
this._bodyTable.className = this._bodyTable.className;
};
bigtable.prototype.createRowElementsAt = function(startIndex, endIndex) {
var rows = this._rows;
// Initialize row metadata
for (var i = startIndex; i<=endIndex; i++) {
if (rows[i] == null) {
rows[i] = {};
}
}
// quick sanity check
var atLeastOne = false;
for (var i = startIndex; i<=endIndex; i++) {
if (rows[i].tr == null) {
atLeastOne = true;
break;
}
}
if (!atLeastOne) { return; }
var tbodyEl = this._bodyTBody;
var rowHeight = this._rowHeight;
var fillers = this._fillers;
// filler has following structure:
// startIndex
// endIndex
// tr
// Find relevant fillers
var relevantFillers = [];
for (var i = fillers.length; i--;) {
var filler = fillers[i];
if (startIndex <= filler.endIndex && endIndex >= filler.startIndex) {
relevantFillers.push(filler);
}
}
// Handle each filler in turn
for (var i = relevantFillers.length; i--;) {
var filler = relevantFillers[i];
// 1 of 4 possibilities
// the entire filler is being filled
// the first portion is being filled
// the last portion is being filled
// the middle portion is being filled
// 0, 1, or 2 fillers "leftover"
// figure out which indices in this filler are being filled
var fillerStart = startIndex >= filler.startIndex ? startIndex : filler.startIndex; // max
var fillerEnd = endIndex <= filler.endIndex ? endIndex : filler.endIndex; // min
// fill the appropriate indices
for (var x = fillerStart; x<=fillerEnd; x++) {
var rowMeta = rows[x];
var tr = document.createElement('tr');
tr.className = 'bigtable-row';
tr.style.height = rowHeight+'px';
tbodyEl.insertBefore(tr, filler.tr);
rowMeta.tr = tr;
}
// 0, 1, or 2 fillers "leftover"
// filler at the beginning
// filler at the end
// filler at the beginning and end
// no filler
// reorganize fillers
var usedFiller = false;
var oldFillerStartIndex = filler.startIndex;
// if filler at end, reuse existing filler w/o moving
if (fillerEnd < filler.endIndex) {
filler.startIndex = fillerEnd+1;
filler.tr.style.height = ((filler.endIndex-filler.startIndex+1)*rowHeight)+'px';
usedFiller = true;
}
if (fillerStart > oldFillerStartIndex) {
if (usedFiller) { // create new filler
var tr = document.createElement('tr');
var filler = {
startIndex: oldFillerStartIndex,
endIndex: fillerStart-1,
tr: tr
};
filler.tr.style.height = ((filler.endIndex-filler.startIndex+1)*rowHeight)+'px';
tbodyEl.insertBefore(tr, rows[fillerStart].tr);
fillers.push(filler);
}
else { // reuse existing filler w/ moving
tbodyEl.insertBefore(filler.tr, rows[fillerStart].tr);
filler.endIndex = fillerStart-1;
filler.tr.style.height = ((filler.endIndex-filler.startIndex+1)*rowHeight)+'px';
usedFiller = true;
}
}
// remove filler if completely filled
if (!usedFiller) {
for (var x = fillers.length; x--;) {
if (filler == fillers[x]) {
fillers.splice(x, 0);
break;
}
}
tbodyEl.removeChild(filler.tr)
}
}
};
bigtable.prototype.getVisibleIndexes = function() {
var numRows = this._numRows
if (numRows == 0) {
return {startIndex: null, endIndex: null};
}
// get visible pixel coordinates
var startY = this._bodyEl.scrollTop;
var endY = startY+this._bodyEl.offsetHeight;
// translate pixels into row indices
var startIndex = Math.floor(startY/this._rowHeight);
var endIndex = Math.floor(endY/this._rowHeight);
// sanity check
if (endIndex>numRows-1) {
endIndex = numRows-1;
}
return {startIndex: startIndex, endIndex: endIndex};
};