unit1.pas

使用流对象（Tstream）实现数据表中Tmemo字段的显示

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, DB, Grids, DBGrids, DBTables, ExtCtrls, DBCtrls;

type
  TForm1 = class(TForm)
    Table1: TTable;
    DBGrid1: TDBGrid;
    DataSource1: TDataSource;
    Table1CustNo: TAutoIncField;
    Table1Last_Name: TStringField;
    Table1First_Name: TStringField;
    Table1City: TStringField;
    Table1StateProv: TStringField;
    Table1Country: TStringField;
    Table1Phone: TStringField;
    Table1Remarks: TMemoField;
    DBNavigator1: TDBNavigator;
    procedure DBGrid1DrawDataCell(Sender: TObject; const Rect: TRect;
      Field: TField; State: TGridDrawState);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.DBGrid1DrawDataCell(Sender: TObject; const Rect: TRect;
  Field: TField; State: TGridDrawState);
var
  P: array [0..50] of char; {为显示Memo字段定义了一个50个长度的数组}
  bs: TBlobStream;          {流对象}
  hStr: String;

begin
  if Field is TMemoField then
  begin
    with (Sender as TDBGrid).Canvas do
    begin
      bs := TBlobStream.Create(Table1Remarks, bmRead);//为Memo字段建立一个流对象
      FillChar(P,SizeOf(P),#0); //给数组赋初值
      bs.Read(P, 50); //把流对象值读入数组
      bs.Free; //释放流对象
      hStr := StrPas(P);
      while Pos(#13, hStr) > 0 do
        hStr[Pos(#13, hStr)] := ' ';
      while Pos(#10, hStr) > 0 do
        hStr[Pos(#10, hStr)] := ' ';
      FillRect(Rect);  //建立一个Rect对象
      TextOut(Rect.Left, Rect.Top, hStr);  //将Memo字段的值在Rect中显示
    end; 
  end;
end;

end.