image – 如何在vb6中将bmp转换为jpg

'Convert BMP to JPG with this code. (Note: Requires vic32.dll available from
'http://www.catenary.com/)

'PLACE ALL THIS IN A NEW MODULE

Declare Function bmpinfo Lib "VIC32.DLL" (ByVal Fname As String,bdat As BITMAPINFOHEADER) As Long
Declare Function allocimage Lib "VIC32.DLL" (image As imgdes,ByVal wid As Long,ByVal leng As Long,ByVal BPPixel As Long) As Long
Declare Function loadbmp Lib "VIC32.DLL" (ByVal Fname As String,desimg As imgdes) As Long
Declare Sub freeimage Lib "VIC32.DLL" (image As imgdes)
Declare Function convert1bitto8bit Lib "VIC32.DLL" (srcimg As imgdes,desimg As imgdes) As Long
Declare Sub copyimgdes Lib "VIC32.DLL" (srcimg As imgdes,desimg As imgdes)
Declare Function savejpg Lib "VIC32.DLL" (ByVal Fname As String,srcimg As imgdes,ByVal quality As Long) As Long



' Image descriptor
Type imgdes
  ibuff As Long
  stx As Long
  sty As Long
  endx As Long
  endy As Long
  buffwidth As Long
  palette As Long
  colors As Long
  imgtype As Long
  bmh As Long
  hBitmap As Long
End Type

Type BITMAPINFOHEADER
   biSize As Long
   biWidth As Long
   biHeight As Long
   biPlanes As Integer
   biBitCount As Integer
   biCompression As Long
   biSizeImage As Long
   biXPelsPerMeter As Long
   biYPelsPerMeter As Long
   biClrUsed As Long
   biClrImportant As Long
End Type

'PLACE THIS IN YOUR FORM DECLERATIONS

Private Sub ConvertToJPEG(bmp_fname As String,jpg_fname As String,Optional quality As Long)
  Dim tmpimage As imgdes    ' Image descriptors
  Dim tmp2image As imgdes
  Dim rcode As Long
  'Dim quality As Long
  Dim vbitcount As Long
  Dim bdat As BITMAPINFOHEADER ' Reserve space for BMP struct
  'Dim bmp_fname As String
  'Dim jpg_fname As String

  'bmp_fname = "test.bmp"
  'jpg_fname = "test.jpg"

  If quality = 0 Then quality = 75

   ' Get info on the file we're to load
  rcode = bmpinfo(bmp_fname,bdat)
  If (rcode <> NO_ERROR) Then
     msgbox "error: Unable to get file info"
     Exit Sub
  End If

  vbitcount = bdat.biBitCount
  If (vbitcount >= 16) Then  ' 16-,24-,or 32-bit image is loaded into 24-bit buffer
     vbitcount = 24
  End If

   ' Allocate space for an image
  rcode = allocimage(tmpimage,bdat.biWidth,bdat.biHeight,vbitcount)
  If (rcode <> NO_ERROR) Then
    msgbox "error: Not enough memory"
    Exit Sub
  End If

   ' Load image
  rcode = loadbmp(bmp_fname,tmpimage)
  If (rcode <> NO_ERROR) Then
     freeimage tmpimage ' Free image on error
     msgbox "error: Cannot load file"
     Exit Sub
  End If

  If (vbitcount = 1) Then ' If we loaded a 1-bit image,convert to 8-bit grayscale
      ' because jpeg only supports 8-bit grayscale or 24-bit color images
    rcode = allocimage(tmp2image,8)
    If (rcode = NO_ERROR) Then
        rcode = convert1bitto8bit(tmpimage,tmp2image)
        freeimage tmpimage  ' Replace 1-bit image with grayscale image
        copyimgdes tmp2image,tmpimage
    End If
  End If

  ' Save image
  rcode = savejpg(jpg_fname,tmpimage,quality)
  freeimage tmpimage
  Kill bmp_fname
  msgbox "picture saved: " & jpg_fname

End Sub