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// expand/collapse button (expander) is added if height of a cell content
// exceeds CLIP_HEIGHT px.
var CLIP_HEIGHT = 135;
// Height in pixels of an expander image.
var EXPANDER_HEIGHT = 13;
// Path to images for an expander.
var imgPath = "./images/expandcollapse/";
// array[group][cell] of { 'height', 'expanded' }.
// group: a number; cells of the same group belong to the same table row.
// cell: a number; unique index of a cell in a group.
// height: a number, px; original height of a cell in a table.
// expanded: boolean; is a cell expanded or collapsed?
var CellsInfo = [];
// Extracts group and cell indices from an id of the form identifier_group_cell.
function getCellIdx(id) {
var idx = id.substr(id.indexOf("_") + 1).split("_");
return { 'group': idx[0], 'cell': idx[1] };
}
// Returns { 'height', 'expanded' } info for a cell with a given id.
function getCellInfo(id) {
var idx = getCellIdx(id);
return CellsInfo[idx.group][idx.cell];
}
// Initialization, add nodes, collect info.
function initExpandCollapse() {
if (!document.getElementById)
return;
var groupCount = 0;
// Examine all table rows in the document.
var rows = document.body.getElementsByTagName("tr");
for (var i=0; i<rows.length; i+=1) {
var cellCount=0, newGroupCreated = false;
// Examine all divs in a table row.
var divs = rows[i].getElementsByTagName("div");
for (var j=0; j<divs.length; j+=1) {
var expandableDiv = divs[j];
if (expandableDiv.className.indexOf("expandable") == -1)
continue;
if (expandableDiv.offsetHeight <= CLIP_HEIGHT)
continue;
// We found a div wrapping a cell content whose height exceeds
// CLIP_HEIGHT.
var originalHeight = expandableDiv.offsetHeight;
// Unique postfix for ids for generated nodes for a given cell.
var idxStr = "_" + groupCount + "_" + cellCount;
// Create an expander and an additional wrapper for a cell content.
//
// --- expandableDiv ----
// --- expandableDiv --- | ------ data ------ |
// | cell content | -> | | cell content | |
// --------------------- | ------------------ |
// | ---- expander ---- |
// ----------------------
var data = document.createElement("div");
data.className = "data";
data.id = "data" + idxStr;
data.innerHTML = expandableDiv.innerHTML;
with (data.style) { height = (CLIP_HEIGHT - EXPANDER_HEIGHT) + "px";
overflow = "hidden" }
var expander = document.createElement("img");
with (expander.style) { display = "block"; paddingTop = "5px"; }
expander.src = imgPath + "ellipses_light.gif";
expander.id = "expander" + idxStr;
// Add mouse calbacks to expander.
expander.onclick = function() {
expandCollapse(this.id);
// Hack for Opera - onmouseout callback is not invoked when page
// content changes dynamically and mouse pointer goes out of an element.
this.src = imgPath +
(getCellInfo(this.id).expanded ? "arrows_light.gif"
: "ellipses_light.gif");
}
expander.onmouseover = function() {
this.src = imgPath +
(getCellInfo(this.id).expanded ? "arrows_dark.gif"
: "ellipses_dark.gif");
}
expander.onmouseout = function() {
this.src = imgPath +
(getCellInfo(this.id).expanded ? "arrows_light.gif"
: "ellipses_light.gif");
}
expandableDiv.innerHTML = "";
expandableDiv.appendChild(data);
expandableDiv.appendChild(expander);
expandableDiv.style.height = CLIP_HEIGHT + "px";
expandableDiv.id = "cell"+ idxStr;
// Keep original cell height and its ecpanded/cpllapsed state.
if (!newGroupCreated) {
CellsInfo[groupCount] = [];
newGroupCreated = true;
}
CellsInfo[groupCount][cellCount] = { 'height' : originalHeight,
'expanded' : false };
cellCount += 1;
}
groupCount += newGroupCreated ? 1 : 0;
}
}
function isElemTopVisible(elem) {
var body = document.body,
html = document.documentElement,
// Calculate expandableDiv absolute Y coordinate from the top of body.
bodyRect = body.getBoundingClientRect(),
elemRect = elem.getBoundingClientRect(),
elemOffset = Math.floor(elemRect.top - bodyRect.top),
// Calculate the absoute Y coordinate of visible area.
scrollTop = html.scrollTop || body && body.scrollTop || 0;
scrollTop -= html.clientTop; // IE<8
if (elemOffset < scrollTop)
return false;
return true;
}
// Invoked when an expander is pressed; expand/collapse a cell.
function expandCollapse(id) {
var cellInfo = getCellInfo(id);
var idx = getCellIdx(id);
// New height of a row.
var newHeight;
// Smart page scrolling may be done after collapse.
var mayNeedScroll;
if (cellInfo.expanded) {
// Cell is expanded - collapse the row height to CLIP_HEIGHT.
newHeight = CLIP_HEIGHT;
mayNeedScroll = true;
}
else {
// Cell is collapsed - expand the row height to the cells original height.
newHeight = cellInfo.height;
mayNeedScroll = false;
}
// Update all cells (height and expanded/collapsed state) in a row according
// to the new height of the row.
for (var i = 0; i < CellsInfo[idx.group].length; i++) {
var idxStr = "_" + idx.group + "_" + i;
var expandableDiv = document.getElementById("cell" + idxStr);
expandableDiv.style.height = newHeight + "px";
var data = document.getElementById("data" + idxStr);
var expander = document.getElementById("expander" + idxStr);
var state = CellsInfo[idx.group][i];
if (state.height > newHeight) {
// Cell height exceeds row height - collapse a cell.
data.style.height = (newHeight - EXPANDER_HEIGHT) + "px";
expander.src = imgPath + "ellipses_light.gif";
CellsInfo[idx.group][i].expanded = false;
} else {
// Cell height is less then or equal to row height - expand a cell.
data.style.height = "";
expander.src = imgPath + "arrows_light.gif";
CellsInfo[idx.group][i].expanded = true;
}
}
if (mayNeedScroll) {
var idxStr = "_" + idx.group + "_" + idx.cell;
var clickedExpandableDiv = document.getElementById("cell" + idxStr);
// Scroll page up if a row is collapsed and the rows top is above the
// viewport. The amount of scroll is the difference between a new and old
// row height.
if (!isElemTopVisible(clickedExpandableDiv)) {
window.scrollBy(0, newHeight - cellInfo.height);
}
}
}
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