至于 TPicture 无法决定它必须为加载创建哪种 TGraphic,因为流没有像文件名这样的扩展名,您必须决定它并分配 Graphic。
在这种情况下,将 TJPEGImage 转换为图片。
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,因为还存储了有关图形格式的信息,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.