Need some help in compressing bmp file to jpeg file

[balu]

Hi,

We are developing a visual basic application that
compresses a bitmap file into jpeg file . We are not getting any solution
for compressing a bitmap file into jpeg file in visual basic. Eventhough we
had some solution , We are getting a problem with that solution . The
problem is that time taking to compress a bitmap file into jpeg file is
nearly 4 to 5 secs. but in vb.net , it is taking milliseconds and vb.net had
some built-in functions to do this where vb does not had. Our application
must be developed in vb.

Any kind of code or suggestions are appreciable.

Thank You .

Regards,
Balu.

 

[Jonathan Wood]

Balu,

We are developing a visual basic application that
compresses a bitmap file into jpeg file . We are not getting any solution
for compressing a bitmap file into jpeg file in visual basic. Eventhough we
had some solution , We are getting a problem with that solution . The
problem is that time taking to compress a bitmap file into jpeg file is
nearly 4 to 5 secs. but in vb.net , it is taking milliseconds and vb.net had
some built-in functions to do this where vb does not had. Our application
must be developed in vb.

The .NET library has routines written in lower levels such as C and assembly
language. They tend to be very optimized, using some optimizations that may
not be available from VB.

That said, maybe your code isn't very optimized. Since the only information
I have is that it is too slow, I can only guess at what other optimizations
might be available.

 

[Dirk Goldgar]

Hi,

We are developing a visual basic application that
compresses a bitmap file into jpeg file . We are not getting any
solution for compressing a bitmap file into jpeg file in visual
basic. Eventhough we had some solution , We are getting a problem
with that solution . The problem is that time taking to compress a
bitmap file into jpeg file is nearly 4 to 5 secs. but in vb.net , it
is taking milliseconds and vb.net had some built-in functions to do
this where vb does not had. Our application must be developed in vb.

Any kind of code or suggestions are appreciable.

Thank You .

Regards,
Balu.

Although it seems you're looking for a straight VB solution, since you
cross-posted this to an Access programming newsgroup, I'll point you to
a site containing an Access project that does what you're looking for.
If you separate the common VB aspects of the problem from the Access
object model, you may get find something useful. See Stephen Lebans'
"LoadSaveJpeg" project at:

http://www.lebans.com/loadsavejpeg.htm

 

[Martin]

You can use GDI+ API to save picture from stdPicture object in jpeg file
format.
You can find GDI+ on microsoft web site
http://www.microsoft.com/downloads/...9c-df12-4d41-933c-be590feaa05a&DisplayLang=en

Place the code below in standard module.
For example you can create a form with PictureBox.
Load bitmap into PictureBox and use SaveJPG function to save picture as jpg.

Option Explicit

' ----==== 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-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