Loading and Saving Annotation Objects From/To Databases (Delphi 4.0)

Take the following steps to create and run a program that loads and saves Annotation objects from/to a DataBase.

NOTE: You need to create a DataBase file (Annotations.mdb) with the following field to run this tutorial:

LEADAnn1.DataSource = DataSource1
DataSource1.DataSet = ADOTable1

procedure TForm1.FormCreate(Sender: TObject);
var
   nRet: Integer;
   strDataBasePath: String;
   strConnectionString: String;
begin
   try
   { Note that these are sample keys, which will not work in your toolkit. }
      LEADAnn1.UnlockSupport(L_SUPPORT_DOCUMENT, 'TestKey');
      LEADAnn1.Load('C:\Program Files\LEAD Technologies, Inc\LEADTOOLS14\Images\Image2.cmp', 0, 1, 1);
      LEADAnn1.AnnUserMode:= ANNUSERMODE_DESIGN;
      nRet:= LEADAnn1.AnnToolbar.CreateTB(0, 0, ANNTOOLALIGN_LEFT + ANNTOOLALIGN_TOP);
      if(nRet = SUCCESS)then
      begin
         LEADAnn1.AnnToolBar.Visible:= True;
         //change the sDBPath to point to your database!
         strDataBasePath := 'C:\Program Files\LEAD Technologies, Inc\LEADTOOLS14\Images\Annotations.mdb';
         strConnectionString := 'Provider=Microsoft.Jet.OLEDB.4.0;Data Source=' + strDataBasePath + ';Persist Security Info=False';
         ADOTable1.ConnectionString:= strConnectionString;
         ADOTable1.TableName:= 'Annotations';
         DataSource1.DataSet:= ADOTable1;
         LEADAnn1.DataSource:= DataSource1;
      end;
      finally
      UpdateButtons();
   end;
end;

procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
   // DeActivate the connection if it is already active.
   if(ADOTable1.State = dsBrowse)then
      ADOTable1.Active:= False;
end;

procedure TForm1.btnConnectClick(Sender: TObject);
begin
   try
      // Activate the connection.
      ADOTable1.Active:= True;
      finally
      UpdateButtons();
   end;
end;

procedure TForm1.btnDisconnectClick(Sender: TObject);
begin
   try
      // DeActivate the connection.
      if(ADOTable1.State = dsBrowse)then
         ADOTable1.Active:= False;
      finally
      UpdateButtons();
   end;
end;

procedure TForm1.btnAddClick(Sender: TObject);
var
   hMem: L_HANDLE;
   phMem: L_PHANDLE;
   uAnnSize: L_INT32;
   annStream: TMemoryStream;
   nSavedBytes: Integer;
begin
   try
      // Add new record
      ADOTable1.Append();
      // Save the current annotations into memory
      hMem:= 0;
      LEADAnn1.AnnSaveMemory(@hMem, ANNFMT_NATIVE, False, @uAnnSize, SAVE_OVERWRITE, 1);
      // Globallock the data in memory.
      phMem:= GlobalLock(hMem);
      if(phMem <> Nil)then
      begin
         // write the Annotation data into a memory stream
         annStream:= TMemoryStream.Create();
         nSavedBytes:= annStream.Write(phMem^, uAnnSize);
         if(nSavedBytes = uAnnSize)then
         begin
            // Save the BLOB into DataBase
            TBlobField(ADOTable1.FieldByName('AnnBlob')).LoadFromStream(annStream);
            ADOTable1.FieldByName('AnnSize').AsInteger:= uAnnSize;
            // Apply the DataBase changes.
            ADOTable1.Post();
         end
         else
            ShowMessage('Error Writing To DataBase');
         // Unlock and Free the Global Data
         GlobalUnlock(hMem);
         GlobalFree(hMem);
      end;
      finally
      UpdateButtons();
   end;
end;

procedure TForm1.btnDeleteClick(Sender: TObject);
begin
   try
      // Delete the Current Record data.
      ADOTable1.Delete();
      // Load the Annotations for the new active record.
      LoadAnnotations();
      finally
      UpdateButtons();
   end;
end;

procedure TForm1.btnLoadNextClick(Sender: TObject);
begin
   try
      // Move to the next record
      ADOTable1.Next();
      // Load the Annotations for the new active record.
      LoadAnnotations();
      finally
      UpdateButtons();
   end;
end;

procedure TForm1.btnLoadPreviousClick(Sender: TObject);
begin
   try
      // Move to the previous record
      ADOTable1.Prior();
      // Load the Annotations for the new active record.
      LoadAnnotations();
      finally
      UpdateButtons();
   end;
end;

Procedure UpdateButtons();

Procedure LoadAnnotations();

Procedure TForm1.UpdateButtons();
begin
   // Enable/Disable the buttons according to the current state.
   btnConnect.Enabled:= Not ADOTable1.Active;
   btnDisconnect.Enabled:= ADOTable1.Active;
   btnAdd.Enabled:= ADOTable1.Active;
   btnDelete.Enabled:= ((ADOTable1.Active) And (ADOTable1.RecordCount > 0));
   btnLoadNext.Enabled:= ((ADOTable1.Active) And (ADOTable1.RecordCount > 0) And (ADOTable1.RecNo + 1 <=    ADOTable1.RecordCount));
   btnLoadPrevious.Enabled:= ((ADOTable1.Active) And (ADOTable1.RecNo - 1 > 0));
end;

Procedure TForm1.LoadAnnotations();
var
   annStream: TMemoryStream;
begin
   if(ADOTable1.RecordCount > 0)then
   begin
      // Save the current active record annotations data into MemoryStream.
      annStream:= TMemoryStream.Create();
      TBlobField(ADOTable1.FieldByName('AnnBlob')).SaveToStream(annStream);
      // If the load succeeded
      if(annStream.Size <> 0)then
      begin
         // Load the Annotations into the VCL Annotation control.
         LEADAnn1.AnnLoadMemory(L_HANDLE(GlobalHandle(annStream.Memory)), annstream.Size, 1);
      end
      else
         // Something wrong !
      ShowMessage('Error Reading From DataBase');
   end;
end;