delphi – 检索保存在数据库中的图像

发布时间：2020-12-15 10:06:18 所属栏目：大数据来源：网络整理

导读：参见英文答案 How to insert image into database using TADOQuery Component Only2个 Store images in MS-Access Database using Delphi61个我正在使用此代码将图像加载到我的Timage中： beginif OpenPictureDialog1.Execute(Self.Handle) thenImage1.Pict

参见英文答案 > How to insert image into database using TADOQuery Component Only2个
> Store images in MS-Access Database using Delphi61个
我正在使用此代码将图像加载到我的Timage中：

begin
if OpenPictureDialog1.Execute(Self.Handle) then
Image1.Picture.LoadFromFile(OpenPictureDialog1.FileName);
end;

然后我使用此代码存储到我的ms访问数据库中：

var
AStream : TMemoryStream;
begin
Adotable1.Append;

AStream := TMemoryStream.Create;
try
Image1.Picture.Graphic.SaveToStream(AStream);
AStream.Position := 0;
if Adotable1.Active then
begin
  TBlobField(Adotable1.FieldByName('Termograma')).LoadFromStream(AStream);
  end;
finally
AStream.Free;
end;
adotable1.Post;

但现在我想在Timage上显示这些保存的图像,任何人都可以帮助我吗？
图像是.jpeg格式

解决方法

至于TPicture无法决定它必须为加载创建哪种TGraphic,因为流不具有像文件名这样的扩展名,你必须决定它,并分配Graphic.
在这种情况下,图片的TJPEGImage.

var
 JPG:TJPEGImage;
 ms:TMemoryStream;
begin
    JPG:=TJPEGImage.Create;
    ms:=TMemoryStream.Create;
    try
    TBlobField(AdoTable1.FieldByName('Termograma')).SaveToStream(ms);
    ms.Position := 0;
    JPG.LoadFromStream(ms);
    Image2.Picture.Assign(JPG);
    finally
       JPG.Free;
       ms.Free;
    end;
end;

以下单元能够在blobfields中存储不同的图形格式.
存储与图像数据的简单存储不兼容,因为存储有关thenformaformat的信息也是如此,以便能够创建所需的加载类.

unit LoadSaveImageBlobs;

// 20120224 by Thomas Wassermann
// Adapt. RegisterClasses and uses for your requirements
// based on an Idea of  Emiliano Sos

interface
uses Classes,DB,Graphics,Jpeg,PngImage;

Procedure SavePicture2Blob(Blob: TBlobField; Picture: TPicture);
Procedure LoadPictureFromBlob(Picture: TPicture; Blob: TBlobField);
implementation

Procedure SavePicture2Blob(Blob: TBlobField; Picture: TPicture);
var
  ms,ms2: TMemoryStream;
  theClassName: AnsiString;
  len: Byte;
begin
  ms := TMemoryStream.Create;
  try
    Blob.Clear;
    theClassName := Picture.Graphic.ClassName;
    len := Length(theClassName);
    ms.WriteBuffer(len,1);
    if len > 0 then
      ms.WriteBuffer(theClassName[1],len);
    ms2 := TMemoryStream.Create;
    try
      Picture.Graphic.SaveToStream(ms2);
      ms2.Position := 0;
      if ms2.Size > 0 then
        ms.CopyFrom(ms2,ms2.Size);
    finally
      ms2.Free;
    end;
    Blob.LoadFromStream(ms);
  finally
    ms.Free;
  end;
end;

Procedure LoadPictureFromBlob(Picture: TPicture; Blob: TBlobField);
var
  ms,ms2: TMemoryStream;
  len: Byte;
  theClassName: AnsiString;
  Graphic: TGraphic;
  GraphicClass: TGraphicClass;
begin
  ms := TMemoryStream.Create;
  Blob.SaveToStream(ms);
  ms.Position := 0;
  try
    ms.ReadBuffer(len,1);
    SetLength(theClassName,len);
    if len > 0 then
      ms.ReadBuffer(theClassName[1],len);
    GraphicClass := TGraphicClass(FindClass(theClassName));
    if (GraphicClass <> nil) and (len > 0) then
    begin
      Graphic := GraphicClass.Create;
      ms2 := TMemoryStream.Create;
      try
        ms2.CopyFrom(ms,ms.Size - len - 1);
        ms2.Position := 0;
        Graphic.LoadFromStream(ms2);
      finally
        ms2.Free;
      end;
      Picture.Assign(Graphic);
    end;
  finally
    ms.Free;
  end;
end;


initialization
// you might register others if wished
RegisterClasses([TIcon,TMetafile,TBitmap,TJPEGImage,TPngImage]);

end.

（编辑：李大同）

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