怎样把图片保存为jpg格式,该如何处理

怎样把图片保存为jpg格式
使用这个SavePicture,保存出来的图片是BMP格式
我怎样才可以保存为JPG格式的呢


[解决办法]
Saving images to JPG using GDI+
This function saves a StdPicture object to a file with JPG format using the GDI+ encoder. Just call the function passing the image object, the filename and, optionally, the image quality (from 1 to 100) .

VB code

'   ----====   API   Declarations   ====----Private Type GUID    Data1   As Long    Data2   As Integer    Data3   As Integer    Data4(0 To 7)       As ByteEnd Type  Private Type GdiplusStartupInput    GdiplusVersion   As Long    DebugEventCallback   As Long    SuppressBackgroundThread   As Long    SuppressExternalCodecs   As LongEnd Type  Private Type EncoderParameter    GUID   As GUID    NumberOfValues   As Long        type   As Long    Value   As LongEnd Type  Private Type EncoderParameters    Count   As Long    Parameter   As EncoderParameterEnd TypePrivate Declare Function GdiplusStartup Lib "GDIPlus" ( _        token As Long, _        inputbuf As GdiplusStartupInput, _        Optional ByVal outputbuf As Long = 0) As LongPrivate Declare Function GdiplusShutdown Lib "GDIPlus" ( _        ByVal token As Long) As LongPrivate Declare Function GdipCreateBitmapFromHBITMAP Lib "GDIPlus" ( _        ByVal hbm As Long, _        ByVal hpal As Long, _        Bitmap As Long) As LongPrivate Declare Function GdipDisposeImage Lib "GDIPlus" ( _        ByVal Image As Long) As LongPrivate Declare Function GdipSaveImageToFile Lib "GDIPlus" ( _        ByVal Image As Long, _        ByVal filename As Long, _        clsidEncoder As GUID, _        encoderParams As Any) As LongPrivate Declare Function CLSIDFromString Lib "ole32" ( _        ByVal str As Long, _        id As GUID) As Long'   ----====   SaveJPG   ====----  Public Sub SaveJPG( _        ByVal pict As StdPicture, _        ByVal filename As String, _        Optional ByVal quality As Byte = 80)    Dim tSI     As GdiplusStartupInput    Dim lRes     As Long    Dim lGDIP     As Long    Dim lBitmap     As Long    '   Initialize   GDI+    tSI.GdiplusVersion = 1    lRes = GdiplusStartup(lGDIP, tSI)    If lRes = 0 Then        '   Create   the   GDI+   bitmap        '   from   the   image   handle        lRes = GdipCreateBitmapFromHBITMAP(pict.Handle, 0, lBitmap)        If lRes = 0 Then            Dim tJpgEncoder     As GUID            Dim tParams     As EncoderParameters            '   Initialize   the   encoder   GUID            CLSIDFromString StrPtr("{557CF401-1A04-11D3-9A73-0000F81EF32E}"), _                    tJpgEncoder            '   Initialize   the   encoder   parameters            tParams.Count = 1            With tParams.Parameter                         '   Quality                '   Set   the   Quality   GUID                CLSIDFromString StrPtr("{1D5BE4B5-FA4A-452D-9CDD-5DB3505E7EB}"), .GUID                .NumberOfValues = 1                .type = 1                .Value = VarPtr(quality)            End With            '   Save   the   image            lRes = GdipSaveImageToFile( _                    lBitmap, _                    StrPtr(filename), _                    tJpgEncoder, _                    tParams)            '   Destroy   the   bitmap            GdipDisposeImage lBitmap        End If        '   Shutdown   GDI+        GdiplusShutdown lGDIP    End If    If lRes Then        Err.Raise 5, , "Cannot   save   the   image.   GDI+   Error:" & lRes    End IfEnd Sub