关于jpeg缩放的问题
我想把1632*1224的jpeg图片，缩小为 800*600的jpeg，有没有比较好的办法啊。
我在网上找的 龙卷风水印组件源代码
总是在 SaveJPG的最后一步 GdipSaveImageToFile 有问题，返回值是7，图片也没有生成，有没有谁有比较好的办法或者知道我这个错误怎么改也行啊。
[解决办法]
'用以下的GDI+生成jpg
Private Declare Function GetDC Lib "user32 " (ByVal hWnd As Long) As Long
Private Declare Function BitBlt Lib "gdi32 " (ByVal hDestDC As Long, ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal dwRop As Long) As Long
Dim sW As Long
Dim sH As Long
Dim lastState As Long
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
Private mblnSaveJPG As Boolean
' ----==== SaveJPG ====----
Private 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-5DB35105E7EB} "), .GUID
.NumberOfValues = 1
.type = 4
.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
[解决办法]
我的没有问题(XP下），会不会是没有GDI+的环境？
[解决办法]
你下载后，用里面的例子试一下
应该没有啥问题
[解决办法]
可以找找zyl910写的纯VB保存JPEG的代码
[解决办法]
GDIPlus.dll
看看你的机器上有没有
