Scroller: determine if a row is visible in the viewport

beginner_

I've enabled browser back-button support so hitting on back button will return a user to the previously selected row. However as long as that row is visible I do not want to use oScroller.fnScrollToRow, only when the row is not visible.

I have the row index of the row. How can i determine if that row is currently visible in the viewport or not?

allan

Interesting one! Currently there isn't an API method to do that, but I have taken a note of this as a future enhancement for Scroller. Thanks for the suggestion.

Allan

beginner_

Hi Allan,

yeah that would be nice. I've now implemented following custom workaround which more or less works. I guess adding parameter to the function could make it more generally usable instead of my hardcoded stuff.

[code]
function isRowVisible(rowIndex){

var oSettings = myTable.fnSettings();
var scrollBody = $('#myTable_wrapper .dataTables_scrollBody');
var scrollTop = $(scrollBody[0]).scrollTop();
var rowToPixels = oSettings.oScroller.fnRowToPixels(rowIndex);
var scrollY = parseInt(oSettings.oScroll.sY);
// for edge cases, as far as I can tell header height is 20 px
// if only 1 line high and is included in scrollY
scrollY = scrollY - 21;

if((scrollTop + scrollY) < rowToPixels
||scrollTop > rowToPixels) {
return false;
} else {
return true;
}
}
[/code]

allan

Looks good - thanks for sharing your solution with us!

Allan

beginner_

There is a big issue with this: i use fnFindCellRowIndexes to determine rowIndex. However this does not take into account by which column the table is sorted and hence if it is not sorted the same way the internal array is, the rowindex will be wrong.

EDIT:

the solution is this:

[code]
var rowIndexes = myTable.fnFindCellRowIndexes(id, "id" );
var rowIndex = rowIndexes[0];
rowIndex = oSettings.aiDisplay.indexOf(rowIndex); //aiDisplay takes sorting and filtering into account
[/code]