Question

vb中将bmp格式的图片转换为JPG格式。要代码，最好越简单越好

Answer 1

下面是源代码:
添加picturebox,commandbutton

Option Explicit
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, ByVal outputbuf As Long) 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
Private Declare Function GdipCreateBitmapFromFile Lib "GDIPlus" (ByVal filename As Long, Bitmap As Long) As Long

Private Sub Command1_Click()
Dim ret As Boolean

Picture1.Picture = LoadPicture("C:\a.bmp") '打开要压缩的图片

ret = PictureBoxSaveJPG(Picture1, "C:\b.jpg") '保存压缩后的图片
If ret = False Then
MsgBox "保存失败"
End If
End Sub

Private Function PictureBoxSaveJPG(ByVal pict As StdPicture, ByVal filename As String, Optional ByVal quality As Byte = 80) As Boolean
Dim tSI As GdiplusStartupInput
Dim lRes As Long
Dim lGDIP As Long
Dim lBitmap As Long

'初始化 GDI+
tSI.GdiplusVersion = 1
lRes = GdiplusStartup(lGDIP, tSI, 0)

If lRes = 0 Then
'从句柄创建 GDI+ 图像
lRes = GdipCreateBitmapFromHBITMAP(pict.Handle, 0, lBitmap)

If lRes = 0 Then
Dim tJpgEncoder As GUID
Dim tParams As EncoderParameters

'初始化解码器的GUID标识
CLSIDFromString StrPtr("{557CF401-1A04-11D3-9A73-0000F81EF32E}"), tJpgEncoder

'设置解码器参数
tParams.Count = 1
With tParams.Parameter ' Quality
'得到Quality参数的GUID标识
CLSIDFromString StrPtr("{1D5BE4B5-FA4A-452D-9CDD-5DB35105E7EB}"), .GUID
.NumberOfValues = 1
.type = 4
.Value = VarPtr(quality)
End With

'保存图像
lRes = GdipSaveImageToFile(lBitmap, StrPtr(filename), tJpgEncoder, tParams)

'销毁GDI+图像
GdipDisposeImage lBitmap
End If

'销毁 GDI+
GdiplusShutdown lGDIP
End If

If lRes Then
PictureBoxSaveJPG = False
Else
PictureBoxSaveJPG = True
End If
End Function

http://tieba.baidu.com/f?ct=335675392&tn=baiduPostBrowser&sc=3183913151&z=314561243&pn=0&rn=50&lm=0&word=vb#3183913151 http://tieba.baidu.com/f?kz=333370629http://download.csdn.net/source/1041194

Answer 2

vb中的代码简单的话很难讲.....你这个问题我在最近浏览的网页中遇到，里面介绍的比较详细...你去看看，希望对你有帮助。http://tech.ddvip.com/2009-06/1244098152122433.html