How to get rid of those pesky scrollbars of a TDBGrid when you don't need them ?

This example component shows how to get rid off the horizontal and/or vertical scrollbar of a TDBGrid. The code can ofcourse be used for other types of grid. I just used a TDBGrid for this example.

You can control the horizontal and vertical scrollbar seperatly. There is
a boolean propery made available for each of the scrollbars. You can ofcourse
control these settings in a more effecient way like using the scrollbars set
property or a set of your own. The removing of the scrollbars is done by
trapping the WM_NCCALCSIZE message. In here you check the style and adjust
it to your need.

This method will work for the most controls which use the common horizontal
scrollbars, but there might be some slight problems with some controls which
work in a slightly different way.

As an added bonus, the code for this example component also shows how to
give each column of the TDBGrid a tag property like most controls have.
This is achieved by derriving a class from TColumn and adding a Tag property
to it. Then all that remains is to override the CreateColumns function of the
TDBGrid and specify that each column that is created is of an object of the
newly created column class.


Tested with Delphi 6 Professional on Windows 2000 Professional.

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unit ExtentedDBGrid;

interface

uses
  Windows, Messages, SysUtils, Classes, DBGrids, Math, Controls;

type
  TExtendedColumn = class(TColumn)
  private
    { Private declarations }
    FTag: Integer;
  protected
    { Protected declarations }
  published
    { Published declarations }
    property Tag: Integer read FTag write FTag;
  end;

  TExtendedDBGrid = class(TDBGrid)
  private
    { Private declarations }
    FVerticalBar  : Boolean;
    FHorizontalBar: Boolean;

    procedure SetVerticalBar(AValue: Boolean);
    procedure SetHorizontalBar(AValue: Boolean);
    procedure WMNCCalcSize(var msg: TMessage); message WM_NCCALCSIZE;
  protected
    { Protected declarations }
    function CreateColumns: TDBGridColumns; override;
  public
    { Public declarations }
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  published
    { Published declarations }
    property VerticalBar: Boolean read FVerticalBar write SetVerticalBar default True;
    property HorizontalBar: Boolean read FHorizontalBar write SetHorizontalBar default False;
  end;

procedure Register;

implementation

uses Grids;

procedure Register;
begin
  RegisterComponents('Own Components', [TExtendedDBGrid]);
end;

{ TExtentedDBGrid }

constructor TExtendedDBGrid.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  FVerticalBar   := True;
  FHorizontalBar := False;
end;

function TExtendedDBGrid.CreateColumns: TDBGridColumns;
begin
  Result := TDBGridColumns.Create(Self,TExtendedColumn);
end;

destructor TExtendedDBGrid.Destroy;
begin
  inherited Destroy;
end;

procedure TExtendedDBGrid.SetHorizontalBar(AValue: Boolean);
begin
  FHorizontalBar := AValue;
  RecreateWnd;
end;

procedure TExtendedDBGrid.SetVerticalBar(AValue: Boolean);
begin
  FVerticalBar := AValue;
  RecreateWnd;
end;

procedure TExtendedDBGrid.WMNCCalcSize(var msg: TMessage);
var
  style: Integer;
begin
  style := getWindowLong( handle, GWL_STYLE );
  if (style and WS_HSCROLL) <> 0 then
    if not FHorizontalBar then
      SetWindowLong( handle, GWL_STYLE, style and not WS_HSCROLL );
  if (style and WS_VSCROLL) <> 0 then
    if not FVerticalBar then
      SetWindowLong( handle, GWL_STYLE, style and not WS_VSCROLL );
  inherited;
end;

end.

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