Avoid TListView drawing/updating while mouse hovering/over - delphi

Question

I have a TListView with some modifications. It includes some icons (several, depending on the item) per row, as well as the possibility of a background for a row if certain conditions are met.
It seems to be rendering all right. But a problem occurs when I move the mouse over the window, it seems like the rows are being re-rendered, this creates an unnecessary lag and more importantly, it seems to mess with the visualisation. It should only re-draw if I do something (like select a row).
How do I force it to stop (seemingly refreshing rows upon mouse over)? Currently I am using the AdvancedCustomDrawItem to draw. It also takes like a second for the window to react to a selection of an item, that seems dull.
So basically, each row has DrawText() and drawing images onto the Sender.Canvas. This is admittedly a slow progress, but it works for now, if it just didn't seemingly redraw the rows when I hover over them! In fact, if I use the Aero theme, the rows become black when you hover over them.
Here is my event code on AdvancedCustomDrawItem:
procedure TfrmJobQueue.ListView1AdvancedCustomDrawItem(Sender: TCustomListView;
Item: TListItem; State: TCustomDrawState; Stage: TCustomDrawStage;
var DefaultDraw: Boolean);
const
DT_ALIGN: array[TAlignment] of integer = (DT_LEFT, DT_RIGHT, DT_CENTER);
var
r: TRect;
SL: TStringList;
TypeName: string;
I: Integer;
TypeState: integer;
x1,x2: Integer;
S: string;
begin
if Stage = cdPostPaint then begin
// Ways I tried to avoid it; but failed.
if cdsHot in State then
exit;
if cdsNearHot in State then
exit;
if cdsOtherSideHot in State then
exit;
if cdsMarked in State then
exit;
if cdsIndeterminate in State then
exit;
Sender.Canvas.Brush.Style := bsSolid;
if FRepLines.Items[Item.Index].IsAutoReport then begin
Sender.Canvas.Font.Color := clBlack;
Sender.Canvas.Brush.Color := clSkyBlue;
end else begin
Sender.Canvas.Font.Color := clBlack;
Sender.Canvas.Brush.Color := clWhite;
end;
if cdsSelected in State then begin
Sender.Canvas.Font.Color := clWhite;
Sender.Canvas.Brush.Color := clNavy;
end;
R := Item.DisplayRect(drBounds);
Sender.Canvas.FillRect(R);
Sender.Canvas.Brush.Style := bsClear;
if cdsFocused in State then
DrawFocusRect(Sender.Canvas.Handle, R);
x1 := 0;
x2 := 0;
for i := 0 to TListView(Sender).Columns.Count - 1 do
begin
inc(x2, Sender.Column[i].Width);
r.Left := x1;
r.Right := x2;
if i = 0 then
S := Item.Caption
else
S := Item.SubItems[i-1];
if DT_ALIGN[Sender.Column[i].Alignment] = DT_LEFT then
S := ' ' + S;
DrawText(Sender.Canvas.Handle,
S, length(S), r,
DT_SINGLELINE or DT_ALIGN[Sender.Column[i].Alignment] or
DT_VCENTER or DT_END_ELLIPSIS);
x1 := x2;
end;
r := Item.DisplayRect(drIcon);
SL := TStringList.Create;
SL.CommaText := FRepLines.Value(Item.Index, 'TypeState');
r.Left := Sender.Column[0].Width + Sender.Column[1].Width + Sender.Column[2].Width + Sender.Column[3].Width
+ Sender.Column[4].Width;
for I := 0 to SL.Count - 1 do begin
if GetTypeImagesIndex(SL.Names[I]) = -1 then
continue;
// FRepLines is a collection of items containing more information about each row.
if FRepLines.Value(Item.Index, 'State') <> '1' then begin // no error
TypeName := SL.Names[I];
TypeState := StrToIntDef(SL.Values[TypeName], 0);
// State*Images are TImageList.
if TypeState = 0 then
StateWaitingImages.Draw(Sender.Canvas, r.Left + 17*I, r.Top,
GetTypeImagesIndex(TypeName))
else
StateDoneImages.Draw(Sender.Canvas, r.Left + 17*I, r.Top,
GetTypeImagesIndex(TypeName));
CreateIconToolTip(StrToIntDef(FRepLines.Value(Item.Index, 'RepJob'), -1),
TypeName, r.Left + 17*I, ListView1.ViewOrigin.Y + r.Top,
Format(TranslateString('RepQTypeState'),
[TranslateString(Format('RepQTypeStateN%s', [TypeName])),
TranslateString(Format('RepQTypeState-%d', [TypeState]))]));
end;
end;
end;
end;
Some explanation of the code:
The list is a list of reports (a report queue). I am introducing a concept of 'AutoReports' (or scheduled reports in the UI), which I want to highlight with a light blue background (clSkyBlue).
In addition to that background, it also draws some icons on the Status-column, which indicates what stages the report are in and moreover, what formats a report has been ordered in (formats like PDF, Excel and HTML), and whether it has been printed and/or emailed. An icon only appears if such an event has been ordered, so the number of icons are variable.
The waiting state images are greyed out versions of the done state images. I have also tried to create some code, so when I hover over the specific icons, it has a tooltip message.
Because the code is rather dull in speed, I suspect I am doing something incredibly wrong.

Answer 1

HotTracking is likely enabled. That causes items to redraw as they are moused over, so the item under the mouse can be rendered differently. You are probably ignoring the hottrack state when drawing. That could account for the blackness.
You should profile your code to find the real bottleneck. Drawing code needs to be fast. I do a lot of custom drawing in a ListView and it does not behave slowly like you describe.
Update: Consider re-writing your code to draw individual columns in the OnAdvancedCustomDrawSubItem event instead of doing everything in the OnAdvancedCustomDrawItem event. Also, you don't need to calculate each column's bounds manually, you can use ListView_GetSubItemRect() instead. And lastly, you are leaking your TStringList.