var
s: TStream;
pic: Tjpegimage;
begin
if OpenPictureDialog1.Execute then
begin
Image1.Picture.LoadFromFile(OpenPictureDialog1.FileName);
s := TMemoryStream.Create;
pic := Tjpegimage.Create;
try
Image1.Picture.Graphic.SaveToStream(s);
// 以上相当于把图片存在数据库里然后取出来放在流(s)里面。 (s as TMemoryStream).SaveToFile('c:\ir.jpg');
pic.LoadFromFile('c:\ir.jpg');
// 用这两句就可以 pic.LoadFromStream(s);
// 换成这一句就不行,执行完显示的时候出错 Image2.Picture.Assign(pic);
finally
s.Free;
pic.Free;
end;
end;
end;
这样,谁能告诉我为什么?
还有怎么区分是jpg格式的数据还是bmp的数据?
s: TStream;
pic: Tjpegimage;
begin
if OpenPictureDialog1.Execute then
begin
Image1.Picture.LoadFromFile(OpenPictureDialog1.FileName);
s := TMemoryStream.Create;
pic := Tjpegimage.Create;
try
Image1.Picture.Graphic.SaveToStream(s);
// 以上相当于把图片存在数据库里然后取出来放在流(s)里面。 (s as TMemoryStream).SaveToFile('c:\ir.jpg');
pic.LoadFromFile('c:\ir.jpg');
// 用这两句就可以 pic.LoadFromStream(s);
// 换成这一句就不行,执行完显示的时候出错 Image2.Picture.Assign(pic);
finally
s.Free;
pic.Free;
end;
end;
end;
这样,谁能告诉我为什么?
还有怎么区分是jpg格式的数据还是bmp的数据?
解决方案 »
- cxgrid 如何给cell的item赋值?
- 有关dbgird的问题
- [********散分********]半年没没有动过DELPHI了今天刚装上,以后又要和大家一起学习了!散分!!!!!
- 我在用FASTREPORT打印图片时遇到这样的问题.
- 最弱智的问题,有人知道么?
- dbgrid 多选问题100分
- SQL2000的问题,在连接过程中出现 SQLQuery1:opertion not allowed on a unidirectional Dataset1
- 我用一个字符型变量保存了一个对象的名称,现在我想用这个字符型变量来访问这个对象的属性,如何实现?
- 如何存取数据库图片呢?
- 怎样实现象Winzip等软件一样,安装后在资源管理器里点右键可以选择运行?
- 怎么显示gif图片?
- 请问三层分布式数据库要用到哪些控件?
if OpenPictureDialog1.Execute then
begin
TBLOBField(DataSet.FieldByName('Img')).LoadFromFile(OpenPictureDialog1.FileName);
DataSet.FieldByName('FileExt')).AsString := ExtractFileExt(OpenPictureDialog1.FileName)
end;
//以上是保存到数据库
var
FileName:String;
begin
FileName:='temp.'+DataSet.FieldByName('FileExt')).AsString;
TBLOBField(DataSet.FieldByName('Img')).SaveToFile(FileName);
Image1.Picture.loadFromFile(FileName);
end;
//以上是从数据库中读取到TImage控件image1上。
而且我不想用文件(如果用文件我就不用来这里提问了),要用流。
DELPHI存取JPEG文件到SQL Server数据库
高红岩(ghyghost)
近日笔者书写一个小型的学生管理系统时,需要用到ADO控件存取SQL Server数据库图片,查看资料发现基本都是针对BMP文件进行操作(巨增数据库大小),但发现了★eagletian★高手翻译的ADO英文技术文档,里面涉及到了数据库存取JPEG文件的关键技术,在win98+sql server桌面版中测试通过,运行良好,现于源码公开如下:
unit Unit1;interfaceuses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
ExtCtrls, DBCtrls, Grids, DBGrids, Db, ADODB,jpeg, StdCtrls,dbtables;
{一定要USES JPEG单元,使能存储JPG文件格式}
type
TForm1 = class(TForm)
DataSource1: TDataSource;
ADOQuery1: TADOQuery;
DBGrid1: TDBGrid;
DBNavigator1: TDBNavigator;
Image1: TImage;
savebutton: TButton;
showbutton: TButton;
OpenDialog1: TOpenDialog;
ADOQuery1id: TIntegerField;
ADOQuery1pic: TBlobField;
procedure savebuttonClick(Sender: TObject);
procedure showbuttonClick(Sender: TObject);
procedure DBNavigator1Click(Sender: TObject; Button: TNavigateBtn);
private
{ Private declarations }
public
{ Public declarations }
end;var
Form1: TForm1;implementation{$R *.DFM}function JpegStartsInBlob(PicField:TBlobField):integer;
var
ghy: TADOBlobstream;
buffer:Word;
hx: string;
begin
Result := -1;
ghy := TADOBlobstream.Create(PicField, bmRead);
try
while (Result = -1) and (ghy.Position + 1 < ghy.Size) do
begin
ghy.ReadBuffer(buffer, 1);
hx:=IntToHex(buffer, 2);
if hx = ’FF’ then begin
ghy.ReadBuffer(buffer, 1);
hx:=IntToHex(buffer, 2);
if hx = ’D8’ then Result := ghy.Position - 2
else if hx = ’FF’ then
ghy.Position := ghy.Position-1;
end; //if
end; //while
finally
ghy.Free
end; //try
end;
procedure TForm1.savebuttonClick(Sender: TObject);
var
picstream:tadoblobstream;
begin
adoquery1.edit;
picstream:=tadoblobstream.Create(tblobfield(adoquery1.fields[1]),bmWrite);
if form1.opendialog1.execute then
begin
picstream.LoadFromFile(opendialog1.filename);
picstream.Position:=0;
adoquery1.edit;
tblobfield(adoquery1.Fields[1]).loadfromstream(picstream);
adoquery1.post;
end;
end;procedure TForm1.showbuttonClick(Sender: TObject);
var
ghy:TADOBlobstream;
pic:tjpegimage;
begin
ghy := TADOBlobstream.Create(Adoquery1pic, bmRead);
try
ghy.Seek(JpegStartsInBlob(Adoquery1pic),soFromBeginning);
Pic:=TJpegImage.Create;
try
Pic.LoadFromStream(ghy);
Image1.Picture.Graphic:=Pic;
finally
Pic.Free;
end;
finally
ghy.Free
end;
end;procedure TForm1.DBNavigator1Click(Sender: TObject; Button: TNavigateBtn);
begin
if button in [nbFirst, nbPrior, nbNext, nbLast] then showbutton.Click;
end;end.如果数据库中要存储的是BMP文件,则在procedure TForm1.showbuttonClick(Sender: TObject);过程中代码更改如下即可存储显示BMP文件格式的操作。
procedure TForm1.showbuttonClick(Sender: TObject);
var
ghy:TADOBlobstream;
pic:tbitmap;
begin
ghy := TADOBlobstream.Create(Adoquery1pic, bmRead);
try
{ ghy.Seek(JpegStartsInBlob(Adoquery1pic),soFromBeginning);}
Pic:=Tbitmap.Create;
try
Pic.LoadFromStream(ghy);
Image1.Picture.Graphic:=Pic;
finally
Pic.Free;
end;
finally
ghy.Free
end;
end;
到此用DELPHI存取JPEG文件到SQL Server数据库中的具体操作已经叙述完毕。
文章作者:高红岩(ghygh
文章来源:原创
作者邮箱:[email protected]
作者网站:http://delphijl.99898.com
我只想通过Stream解决。
//保存jpeg文件
procedure Tfrmado.ImageDblClick(Sender: TObject);
begin
with topendialog.Create(Self) do
begin
if execute then
begin
if not (adoquery1.State in [dsedit]) then adoquery1.Edit ;
tblobfield(adoquery1.FieldByName('jpg')).LoadFromFile(FileName) ;
end;
end;
end;//显示出来
procedure Tfrmado.DataSource1DataChange(Sender: TObject; Field: TField);
var
jpeg:tjpegimage;
stream :TMemoryStream;
begin
if adoquery1jpg.BlobSize>0 then
begin
jpeg:=tjpegimage.Create;
stream :=TMemoryStream.Create;
tblobfield(adoquery1.FieldByName('jpg')).savetostream(stream);
Stream.Seek(0,soFromBeginning);
jpeg.loadfromstream(stream);
image.Picture.Bitmap.Assign(jpeg);
jpeg.Free;
stream.Free;
end
else
image.Picture:=nil;
end;
var
sTmp:string;
MS: TMemoryStream;
begin
MS := TMemoryStream.Create;
try
TBlobField(Query.FindField('TPT_BAKIMG')).SaveToStream(MS);
if (PChar(MS.Memory)[0]=char($ff)) and (PChar(MS.Memory)[1]=char($d8)) then
Result:=True
else
Result:=False;
finally
MS.Free;
end;
end;
判断是否为jpg,当然流的数据是从BlobField中读取的
你的报错的问题有可能是TJpegImage类没有显式的注册
uses Jpeg单元
在FormCreate中:
RegisterClass(TJpegImage);
应该可以的