[VB] Creating thumbnails using GDI+ (AKA How to resize an image with GDI+)
The CreateThumbnail function resizes a picture object returning the resized image in a new object. The new size can be smaller or greater than the original image size.
' ----==== GDI+ Declarations ====----
Private Type GdiplusStartupInput
GdiplusVersion As Long
DebugEventCallback As Long
SuppressBackgroundThread As Long
SuppressExternalCodecs As Long
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 GdipGetImageThumbnail Lib "GDIPlus" ( _
ByVal Image As Long, _
ByVal thumbWidth As Long, _
ByVal thumbHeight As Long, _
thumbImage As Long, _
ByVal callback As Long, _
ByVal callbackData As Long) As Long
Private Declare Function GdipDisposeImage Lib "GDIPlus" ( _
ByVal Image As Long) As Long
Private Declare Function GdipCreateHBITMAPFromBitmap Lib "GDIPlus" ( _
ByVal Bitmap As Long, _
hbmReturn As Long, _
ByVal background As Long) As Long
' ----==== OLE API Declarations ====----
Private Type PICTDESC
cbSizeOfStruct As Long
picType As Long
hgdiObj As Long
hPalOrXYExt As Long
End Type
Private Type IID
Data1 As Long
Data2 As Integer
Data3 As Integer
Data4(0 To 7) As Byte
End Type
Private Declare Sub OleCreatePictureIndirect Lib "oleaut32.dll" ( _
lpPictDesc As PICTDESC, _
riid As IID, _
ByVal fOwn As Boolean, _
lplpvObj As Object)
'----------------------------------------------------------
' Procedure : CreateThumbnail
' Purpose : Creates a thumbnail of a picture
'----------------------------------------------------------
'
Function CreateThumbnail( _
ByVal Image As StdPicture, _
ByVal Width As Long, _
ByVal Height As Long) As StdPicture
Dim tSI As GdiplusStartupInput
Dim lGDIP As Long
Dim lRes As Long
Dim lBitmap As Long
' Initialize GDI+
tSI.GdiplusVersion = 1
lRes = GdiplusStartup(lGDIP, tSI)
If lRes = 0 Then
' Create a GDI+ Bitmap from the image handle
lRes = GdipCreateBitmapFromHBITMAP(Image.Handle, 0, lBitmap)
If lRes = 0 Then
Dim lThumb As Long
Dim hBitmap As Long
' Create the thumbnail
lRes = GdipGetImageThumbnail(lBitmap, Width, Height, _
lThumb, 0, 0)
If lRes = 0 Then
' Create a GDI bitmap from the thumbnail
lRes = GdipCreateHBITMAPFromBitmap(lThumb, hBitmap, 0)
' Create the StdPicture object
Set CreatheThumbnail = HandleToPicture(hBitmap, _
vbPicTypeBitmap)
' Dispose the thumbnail image
GdipDisposeImage lThumb
End If
' Dispose the image
GdipDisposeImage lBitmap
End If
' Shutdown GDI+
GdiplusShutdown lGDIP
End If
If lRes Then Err.Raise 5, , "Cannot load file"
End Function
'----------------------------------------------------------
' Procedure : HandleToPicture
' Purpose : Creates a StdPicture object to wrap a GDI
' image handle
'----------------------------------------------------------
'
Public Function HandleToPicture( _
ByVal hGDIHandle As Long, _
ByVal ObjectType As PictureTypeConstants, _
Optional ByVal hpal As Long = 0) As StdPicture
Dim tPictDesc As PICTDESC
Dim IID_IPicture As IID
Dim oPicture As IPicture
' Initialize the PICTDESC structure
With tPictDesc
.cbSizeOfStruct = Len(tPictDesc)
.picType = ObjectType
.hgdiObj = hGDIHandle
.hPalOrXYExt = hpal
End With
' Initialize the IPicture interface ID
With IID_IPicture
.Data1 = &H7BF80981
.Data2 = &HBF32
.Data3 = &H101A
.Data4(0) = &H8B
.Data4(1) = &HBB
.Data4(3) = &HAA
.Data4(5) = &H30
.Data4(6) = &HC
.Data4(7) = &HAB
End With
' Create the object
OleCreatePictureIndirect tPictDesc, IID_IPicture, _
True, oPicture
' Return the picture object
Set HandleToPicture = oPicture
End Function
출처 : http://www.mvps.org/emorcillo/en/code/vb6/thumbnail.shtml
