TAdvStringGrid

Example 77 : Filter dropdown

To make filtering in the grid available from the UI, each column header can display a filter dropdown button from where a filter can be choosen. Upon selection of a filter from the dropdown, it is applied to the grid. The settings that control the display of the filter are grouped under grid.FilterDropDown. Following settings are available:

grid.FilterDropDown.AutoSize: boolean	When true, the size of the dropdown adapts to the text in the list
grid.FilterDropDown.Color: TColor	Sets the background color of the dropdown list
grid.FilterDropDown.ColumnWidth: boolean	When true, the filter dropdown width is equal to the column width
grid.FilterDropDown.Font: TFont	Sets the font of the filter dropdown list
grid.FilterDropDown.Glyph: TBitmap	Sets the glyph displayed in the column header indicating a filter is available
grid.FilterDropDown.Height: integer	Sets the height of the dropdown list
grid.FilterDropDown.Width: integer	Sets the width of the dropdown list

The content of the filter dropdown list is set via the event grid.OnGetColumnFilter. This event passes a TStringList that can be filled with filter specifiers. Note that the filter specifiers can be friendly names. It is only from the OnFilterSelect event that the real filtercondition must be applied. The code snippet below shows how the filter is set for different columns in the grid:


procedure TForm2.AdvStringGrid1GetColumnFilter(Sender: TObject; Column: Integer;
  Filter: TStrings);
begin
  case Column of
  1:
    begin
      Filter.Add('Clear');
      Filter.Add('Within range');
      Filter.Add('Exceptions');
    end;
  2:
    begin
      Filter.Add('Clear');
      Filter.Add('>50');
      Filter.Add('<50');
    end;
  3:
    begin
      Filter.Add('Clear');
      Filter.Add('>20');
      Filter.Add('<20');
    end;
  4:
    begin
      Filter.Add('Clear');
      Filter.Add('>20');
      Filter.Add('<20');
    end;

  end;
end;

When a selection is made from the filter dropdown list, the event OnFilterSelect is triggered. This returns the column, the index of the filter and the friendlyname of the filter. Via the parameter FilterCondition, the real filter condition can be set. In the code shown here, the OnFilterSelect converts the filter friendlyname "Clear" to an empty filter condition and it also sets a filter condition for column 1 for friendly names "Within range" and "Exceptions". It also updates the column header to show the filter that is applied.


procedure TForm2.AdvStringGrid1FilterSelect(Sender: TObject; Column,
  ItemIndex: Integer; FriendlyName: string; var FilterCondition: string);
begin
  if FilterCondition = 'Clear' then
    FilterCondition := '';

  if (Column = 1) then
  begin
    case ItemIndex of
    1: FilterCondition := '>20 & <80';
    2: FilterCondition := '<20 | >80';
    end;
  end;

  AdvStringgrid1.Cells[Column, 0] := FriendlyName;
end;

Delphi project & source files for downloading included in the main demos distribution for Delphi

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TAdvStringGrid

Example 77 : Filter dropdown