private ViewPortState CalculateState()
{
Logger.Debug(GetType(),
"CalculateState()'s input HasRowHeightPx?={0} tbodyFactHeightPx={1} theadFactHeight={2} allItemsCount={3} rowHeightPx={4} topScrollPosPx={5}",
HasRowHeightPx,
_view.BodyVisibleSpace,
_view.HeaderVisibleSpace,
_model.Items.Length + _groups.Count * RowsPerGroupDescr,
RowHeightPx,
_view.ScrollPosition
);
var result = new ViewPortState {
RawScrollPos = _view.ScrollPosition,
PhysicalRowsCount = _model.Items.Length,
VirtualRowsCount = _groups.Count * RowsPerGroupDescr,
AllRowsCount = _model.Items.Length + _groups.Count * RowsPerGroupDescr,
TheoreticalVisibleRowsCount = (int)ComputeMaxVisibleRows(),
FirstVisibleRow = (int)ComputeFirstVisibleRow(),
IncompleteLeadRowPad = ComputeIncompleteLeadRowPad(),
IncompleteBodyPad = ComputeIncompleteBodyRowPad()
};
Logger.Debug(GetType(), "CalculateState()'s raw outcome={0}", result);
if (result.FirstVisibleRow > result.AllRowsCount || result.FactVisibleRowsCount < 0)
{
//scroll is past data (probably many rows were deleted / grouping changed)
result.IsInvalidScrollPos = true;
if (result.AllRowsCount >= result.TheoreticalVisibleRowsCount)
{
//will scroll to real bottom of new view
result.FirstVisibleRow = result.AllRowsCount - result.TheoreticalVisibleRowsCount;
result.RawScrollPos = result.FirstVisibleRow * RowHeightPx;
}
else
{
//will just move to beginning of table
result.FirstVisibleRow = 0;
result.RawScrollPos = 0;
}
Logger.Debug(GetType(), "CalculateState()'s adjusted outcome={0}", result);
}
return(result);
}
private void PopulateRows(bool itemsChanged, bool shouldRestoreScrollPosition = false)
{
var oldState = FormerState ?? ViewPortState.CreateEmpty();
Logger.Debug(GetType(), "Former state: {0} shouldRestoreScrollPosition={1}", oldState, shouldRestoreScrollPosition);
if (InitializeRowHeightIfNeededAndPossible())
{
UpdateTbodyHeight();
}
if (shouldRestoreScrollPosition && oldState.IsEmpty)
{
shouldRestoreScrollPosition = false;
}
var newState = shouldRestoreScrollPosition ? oldState : CalculateState();
if (shouldRestoreScrollPosition || newState.IsInvalidScrollPos)
{
_view.ScrollPosition = oldState.RawScrollPos;
}
Logger.Debug(GetType(), "New state: {0}", newState);
Logger.Debug(GetType(), "Scrolled progressed rows: {0} rowHeight={1}", newState.FirstVisibleRow - oldState.FirstVisibleRow, RowHeightPx);
//see if any rows can be preserved by checking whether windows overlap
var overlap = new Overlap(
itemsChanged,
oldState,
newState);
Logger.Debug(GetType(), "calculated overlap: {0}", overlap);
//delete not overlapped leading rows (present in old BUT not present in new)
if (overlap.ToPreTrim.IsNonEmpty)
{
Logger.Debug(GetType(), "overlap - removing unneccessary {0} leading rows", overlap.ToPreTrim.Length);
for (var i = overlap.ToPreTrim.Length; i > 0; i--)
{
DestroyRowAt(0);
}
}
//delete not overlapped trailing rows
if (overlap.ToPostTrim.IsNonEmpty)
{
Logger.Debug(GetType(), "overlap - removing unneccessary {0} trailing rows", overlap.ToPostTrim.Length);
for (var i = overlap.ToPostTrim.Length; i > 0; i--)
{
var pos = _view.BodyRowCount - 1;
DestroyRowAt(pos);
}
}
//prepend not overlapped rows
if (overlap.ToPrepend.IsNonEmpty)
{
Logger.Debug(GetType(), "overlap - prepending new {0} leading rows", overlap.ToPrepend.Length);
var idx = 0;
foreach (var item in EnumerateRecords(overlap.ToPrepend).AsEnumerable())
{
switch (item.Item1)
{
case DataOrGroup.Data:
Logger.Debug(GetType(), "Prepending item {0}", item.Item2);
InsertRowFor(idx++, item.Item2);
break;
case DataOrGroup.Group:
Logger.Debug(GetType(), "Prepending group trailer for grp {0}", item.Item1);
InsertGroupTrailer(idx++, item.Item3);
break;
default: throw new Exception("unsupported DataOrGroup");
}
}
}
//append not overlapped rows
if (overlap.ToAppend.IsNonEmpty)
{
Logger.Debug(GetType(), "overlap - appending new {0} trailing rows", overlap.ToAppend.Length);
foreach (var item in EnumerateRecords(overlap.ToAppend).AsEnumerable())
{
switch (item.Item1)
{
case DataOrGroup.Data:
Logger.Debug(GetType(), "Appending item {0}", item.Item2);
AppendRowFor(item.Item2);
break;
case DataOrGroup.Group:
Logger.Debug(GetType(), "Appending group trailer for grp {0}", item.Item3);
AppendGroupTrailer(item.Item3);
break;
default: throw new Exception("unsupported DataOrGroup");
}
}
}
var padBodyToBottom =
newState.FirstVisibleRow == 0 ||
newState.LastVisibleRow != (_model.Items.Length + _groups.Count * RowsPerGroupDescr - 1);
Logger.Debug(GetType(), "Former space lead={0} trail={1}", _view.LeadSpace, _view.TrailSpace);
_view.FirstRowIndex = newState.FirstVisibleRow;
_view.LeadSpace = newState.FirstVisibleRow * RowHeightPx
+ (padBodyToBottom ? 0 : newState.IncompleteBodyPad + newState.IncompleteLeadRowPad);
_view.TrailSpace =
(newState.AllRowsCount - newState.FirstVisibleRow - newState.FactVisibleRowsCount) * RowHeightPx
+ (padBodyToBottom ? newState.IncompleteBodyPad + newState.IncompleteLeadRowPad : 0);
Logger.Debug(GetType(), "New space lead={0} trail={1} FirstVisibleRow={2}", _view.LeadSpace, _view.TrailSpace, newState.FirstVisibleRow);
FormerState = newState;
//_visRows.DebugPrintContents();
//((HtmlTableBasedTableView)_view).DebugPrintContents(1);
}
