怎样把图片保存为jpg格式

[kewy]

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

[迈克揉索芙特]

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) .

'   ----====   API   Declarations   ====----
Private Type GUID
    Data1   As Long
    Data2   As Integer
    Data3   As Integer
    Data4(0 To 7)       As Byte
End Type

  Private Type GdiplusStartupInput
    GdiplusVersion   As Long
    DebugEventCallback   As Long
    SuppressBackgroundThread   As Long
    SuppressExternalCodecs   As Long
End Type

  Private Type EncoderParameter
    GUID   As GUID
    NumberOfValues   As Long
        type   As Long
    Value   As Long
End Type

  Private Type EncoderParameters
    Count   As Long
    Parameter   As EncoderParameter
End Type

Private Declare Function GdiplusStartup Lib "GDIPlus" ( _
        token As Long, _
        inputbuf As GdiplusStartupInput, _
        Optional ByVal outputbuf As Long = 0) As Long

Private Declare Function GdiplusShutdown Lib "GDIPlus" ( _
        ByVal token As Long) As Long

Private Declare Function GdipCreateBitmapFromHBITMAP Lib "GDIPlus" ( _
        ByVal hbm As Long, _
        ByVal hpal As Long, _
        Bitmap As Long) As Long

Private Declare Function GdipDisposeImage Lib "GDIPlus" ( _
        ByVal Image As Long) As Long

Private Declare Function GdipSaveImageToFile Lib "GDIPlus" ( _
        ByVal Image As Long, _
        ByVal filename As Long, _
        clsidEncoder As GUID, _
        encoderParams As Any) As Long

Private 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 If

End Sub

Author: Edanmo

[scwbying]

这是一个我找了多次才到的好东东，非常感谢！