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Saving an image in an InterBase fields using TImage and savetostream (and loading)

Posted on 2004-07-30
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Last Modified: 2008-01-09
i have a blob field in an interbase database in which i would like to store an image from a TImage component (bmp, jpeg, doesn't matter as long as i can do it). It must be done with a stream. I also need to know how to load it from the database.
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Question by:kilocoder
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6 Comments
 
LVL 12

Expert Comment

by:esoftbg
ID: 11679161
I know a way to store an image into a BLOB field of a Table into a InterBase database, but without using a stream ....
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LVL 12

Accepted Solution

by:
esoftbg earned 43 total points
ID: 11679288
About visualization of the saved image, you should use a TDBImage component via TDataSource to the TIBQuery or TIBTable or TIBDataSet ....
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LVL 6

Assisted Solution

by:gwalkeriq
gwalkeriq earned 41 total points
ID: 11681129

var
  MyBlobFld: TBlobField;
  BlobStream: TMemoryStream;


MyBlobFld := tbl.FieldByName('BlobColumn') as TBlobField;
BlobStream := TMemoryStream.Create(

// assuming you have exec'd query to load data
// qry.Active := true, etc.
MyBlobFld.SaveToStream(BlobStream);

// assuming you have data you want to save
MyBlobFld.LoadFromStream(BlobStream);
// qry.Post, etc.
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LVL 12

Assisted Solution

by:Ivanov_G
Ivanov_G earned 41 total points
ID: 11763089
use the component I wrote for this purpose. You just have to use it instead of regular TImage and set its DataSource and DataSet properties...

// -----------------------------------------------------------

unit GIDBImage;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ExtCtrls, DB, DBCtrls, JPEG;

type
  TGIDBImage = class(TImage)
  private
    { Private declarations }
    FDataLink        : TFieldDataLink;
    function GetDataField: String;
    function GetDataSource: TDataSource;
    function GetField : TField;
    procedure SetDataField(const Value: String);
    procedure SetDataSource(const Value: TDataSource);
    procedure DataChange (Sender : TObject);
  protected
    { Protected declarations }
    procedure Loaded; override;
    procedure CMGetDataLink (var Message : TMessage); message CM_GETDATALINK;
    procedure Notification (AComponent : TComponent; Operation : TOperation); override;
    procedure LoadPicture; virtual;
  public
    { Public declarations }
    constructor Create (AOwner : TComponent); override;
    destructor  Destroy; override;
    property    Field      : TField         read GetField;
  published
    { Published declarations }
    property DataField     : String         read GetDataField       write SetDataField;
    property DataSource    : TDataSource    read GetDataSource      write SetDataSource;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('GI Data-Aware', [TGIDBImage]);
end;

{ TGIDBImage }

procedure TGIDBImage.CMGetDataLink(var Message: TMessage);
begin
  Message.Result := Integer(FDataLink);
end;

constructor TGIDBImage.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  ControlStyle            := ControlStyle + [csReplicatable];
  FDataLink               := TFieldDataLink.Create;
  FDataLink.Control       := Self;
  FDataLink.OnDataChange  := DataChange;
end;

procedure TGIDBImage.DataChange(Sender: TObject);
begin
  if FDataLink.Field <> nil then
    LoadPicture
  else
    Picture.Graphic := nil;
end;

destructor TGIDBImage.Destroy;
begin
  FDataLink.Free;
  FDataLink := nil;
  inherited Destroy;
end;

function TGIDBImage.GetDataField: String;
begin
  Result := FDataLink.FieldName;
end;

function TGIDBImage.GetDataSource: TDataSource;
begin
  Result := FDataLink.DataSource;
end;

function TGIDBImage.GetField: TField;
begin
  Result := FDataLink.Field;
end;

procedure TGIDBImage.Loaded;
begin
  inherited Loaded;
  if (csDesigning in ComponentState) then DataChange(Self);
end;

procedure TGIDBImage.Notification(AComponent: TComponent;
  Operation: TOperation);
begin
  inherited Notification(AComponent, Operation);
  if (Operation = opRemove) and (FDataLink <> nil) and (AComponent = DataSource) then
    DataSource := nil;
end;

procedure TGIDBImage.SetDataField(const Value: String);
begin
  FDataLink.FieldName := Value;
end;

procedure TGIDBImage.SetDataSource(const Value: TDataSource);
begin
  FDataLink.DataSource := Value;
  if Value <> nil then Value.FreeNotification(Self);
end;

procedure TGIDBImage.LoadPicture;
var
  IsJPG         : Boolean;
  JPG           : TJpegImage;
  MemStream     : TMemoryStream;
begin
  // load the picture
  // check if the field is BLOB
  if not Field.IsBlob then
    begin
      Picture.Graphic := nil;
      Exit;
    end;
  // determine the type
  with Field as TBlobField do
    begin
      IsJPG := Pos('JFIF', Copy(Value, 1, 10)) > 0;
    end;
  // if it is Bitmap - load it and exit
  if not IsJPG then
    begin
      Picture.Assign(Field);
      Exit;
    end;
  // load the JPG with MemoryStream
  MemStream := TMemoryStream.Create;
  JPG := TJPEGImage.Create;
  try
    TBlobField(Field).SaveToStream(MemStream);
    MemStream.Seek(soFromBeginning, 0);
    // load the JPG and assign it
    JPG.LoadFromStream(MemStream);
    Picture.Assign(JPG);
  finally
    JPG.Free;
    MemStream.Free;
  end;
end;

end.
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