BCB数据库图像保存技术
加上头文件#include<jpeg.hpp>
1
void __fastcall TForm1::SpeedButton1Click(TObject *Sender)
{
OpenDialog2->FileName=”";
if (OpenDialog2->Execute())
{
String f=OpenDialog2->FileName;
if (FileExists(f))
{
String ext=ExtractFileExt(f).LowerCase();
if (ext==”.bmp” || ext==”.jpg”|| ext==”.jpeg”)
{
String jpg=ChangeFileExt(ExtractFileName(f),”.jpg”);
TJPEGImage *j=new TJPEGImage;
if (ext==”.bmp”)
{
Graphics::TBitmap *b=new Graphics::TBitmap;
b->LoadFromFile(f);
j->Assign(b);
j->CompressionQuality=90;
j->Compress();
delete b;
}
else
{
TFileStream *fs=new TFileStream(f,fmOpenRead);
j->LoadFromStream(fs);
delete fs;
}
DataModule1->ADODataSet1->Edit();
DBEdit2->Text=jpg;
TStream *bs=DataModule1->ADODataSet1->CreateBlobStream(
DataModule1->ADODataSet1->FieldByName(“照片图像”),bmReadWrite);
bs->Position=0;
j->SaveToStream(bs);
delete j;
delete bs;
DispJpg();
}
}
}
}
2
记住一定要在post前delete TADOBlobStream对象。
//读
TBlobField * pField=(TBlobField *)pQuery->FieldByName(“Image”);
TADOBlobStream* pmem=new TADOBlobStream (pField,bmRead);
pmem->Seek(0,soFromBeginning);
Graphics::TBitmap * pBitmap=new Graphics::TBitmap();
pBitmap->LoadFromStream(pmem);
Image1->Picture->Assign(pBitmap);
delete pBitmap;
delete pmem;
//写
pQuery->Edit();
TBlobField * pField=(TBlobField *)pQuery->FieldByName(“Image”);
TADOBlobStream * pmem=new TADOBlobStream (pField,bmWrite);
pmem->Seek(0,soFromBeginning);
Graphics::TBitmap * pBitmap=new Graphics::TBitmap();
pBitmap->Assign(Image1->Picture->Graphic);
pBitmap->SaveToStream(pmem);
delete pBitmap;
delete pmem;
pQuery->Post();
如果你在ttable中用了固定字段，就更简单了，以下的ADOTable1pic字段就是
读取access中的blob数据
TMemoryStream *s = new TMemoryStream();
ADOTable1pic->SaveToStream(s);
s->Position=0; //****流首位置必须为零***
TJPEGImage *jp = new TJPEGImage();
jp->LoadFromStream(s);
Image1->Picture->Bitmap->Assign(jp);
delete jp;
delete s;
写数据到access的blob字段
if (OpenDialog1->Execute())
{ADOTable1->DisableControls();
ADOTable1->Append();
ADOTable1pic->LoadFromFile(OpenDialog1->FileName);
ADOTable1name->Value=OpenDialog1->FileName;
ADOTable1->Post();
ADOTable1->EnableControls();
}
3
void __fastcall TForm2::DBImage2Click(TObject *Sender)
{
try
{
if(OpenPictureDialog1->Execute());
{
AnsiString MyFilesExtension = UpperCase(ExtractFileExt(OpenPictureDialog1->FileName));
if(MyFilesExtension==”.JPG”)
{
TJPEGImage *jpg=new TJPEGImage();
jpg->LoadFromFile(OpenPictureDialog1->FileName);
Clipboard()->Assign(jpg);
DBImage1->DataSource->DataSet->Edit();
DBImage1->PasteFromClipboard();
DBImage1->DataSource->DataSet->Post();
delete jpg;
}
if(MyFilesExtension==”.BMP”)
{
EditDataSource1->DataSet->Edit();
DataModule1->FindADODataSetDSDesigner7->LoadFromFile(OpenPictureDialog1->FileName);
}
}
}
catch(…)
{
StatusBar1->Panels->Items[1]->Text=”保存图像发生异常”;
}
}
4
在BCB中采用下术方法存入图片,不过显示代码不用写了,DBImage自动显示.
if(OpenPictureDialog1->Execute());
{
AnsiString MyFilesExtension = UpperCase(ExtractFileExt(OpenPictureDialog1->FileName));
if(MyFilesExtension==”.JPG”)
{
TJPEGImage *jpg=new TJPEGImage();
jpg->LoadFromFile(OpenPictureDialog1->FileName);
Clipboard()->Assign(jpg);
DBImage1->DataSource->DataSet->Edit();
DBImage1->PasteFromClipboard();
DBImage1->DataSource->DataSet->Post();
delete jpg;
}
数据类型一定要是image
存jpeg到SQL数据库：
if(OpenPictureDialog1->Execute())
{
ADOQuery1->Edit();
TBlobField *Field = (TBlobField*)ADOQuery1->FieldByName(“photo”);
Field->LoadFromFile(OpenPictureDialog1->FileName);
ADOQuery1->Post();
}
//以下是从数据库读jpeg,并显示在TDBImage控件中
#include <clipbrd.hpp>
TStream *Stream1;
TJPEGImage *Pjp;
Pjp=new TJPEGImage();
ADOQuery1->Open();
try
{
Stream1=ADOQuery1->CreateBlobStream(ADOQuery1->FieldByName(“treenodes”), bmRead);//treenodes是存放jpeg内容的字段,它的类型一定要用image
Pjp->LoadFromStream(Stream1);
//Image2是TDBImage组件,它的DateSource,和FieldName属性要空着
Image2->Picture->Bitmap->Assign(Pjp);
delete Stream1;
}
__finally
{
ADOQuery1->Close();
delete Pjp;
}
下面是别人的更好的方法，可存各种图形
以下是讀出各種類型的圖片的程序，支持ADO,BDE或TClientDataSet
#define PICTURE_MAP__(TBit) {TBit *PG = new TBit(); try {PG->LoadFromStream(TmpStream); Pic->Assign(PG); } catch(…) {delete PG ; return false; } delete PG; }
//—————————————————————-
//該模板將二進制字段中的圖像(GIF或JPG等等)使用Assign方法轉為TPicture,TBitmap等等。
template <class T >
bool LoadPhotoFromField(TField *F_Photo,const AnsiString Format,T *Pic)
{if(!F_Photo->DataSet->Active) return false ;
if(F_Photo->IsNull) return false ;
else
{TStream *TmpStream = F_Photo->DataSet->CreateBlobStream(F_Photo,bmRead);
if(Format == “.JPG” || Format == “.JPEG”)PICTURE_MAP__(TJPEGImage )
else if(Format == “.BMP”) PICTURE_MAP__(Graphics::TBitmap)
// else if(Format == “.GIF”) PICTURE_MAP__(TGIFImage )
else if(Format == “.ICO”) PICTURE_MAP__(TIcon)
else if(Format == “.WMF” || Format ==”.EMF”) PICTURE_MAP__(TMetafile)
else return false ;
}
return true;
}
#undef PICTURE_MAP__(TBit)
//如果要支持GIF，那你要安裝支持GIF的VCL類。
支持多種格式
存入：
if(OpenPictureDialog1->Execute())
{DataSet->Edit();
TBlobField *Field = (TBlobField*)DataSet->FieldByName(“photo”);
Field->LoadFromFile(OpenPictureDialog1->FileName);
DataSet->FieldByName(“photoFormat”)->AsString =
ExtractFileExt(OpenPictureDialog1->FileName).UpperCase();
DataSet->Post();
}
//
//
