Este es un pequeño módulo para convertir archivos de imágenes de un formato a otro. Es muy sencillo de usar, sólo basta con llamar a la función ConvertFileImage, donde pasamos como primer parámetro el Path de la imágen de origen y como segundo parámetro el Path de destino más el nombre y extensión. El tercer parámetro es opcional y es un valor de 0 a 100 en los caso que la extensión de destino sea .JPG, para elegir la calidad de conversión.
También cuenta con una función llamada IsGdiPlusInstaled que es para averiguar si el PC que ejecute el programa tiene instalado GDI Plus.
No tiene muchas opciones ya que el módulo intenta ser algo pequeño para pocas pretensiones.
Las extensiones de de lectura soportadas son: «BMP, DIB, JPG, JPEG, JPE, JFIF, GIF, PNG, TIF, TIFF, EMF, WMF, ICO, CUR».
y las extensiones de conversión soportadas son: «BMP, DIB, JPG, JPEG, JPE, JFIF, GIF, PNG, TIF, TIFF».
* Edit 06/02/2010, corrección en el código, me confundí en poner PGN, por PGN.
Option Explicit
'--------------------------------------------
'Autor: Leandro Ascierto
'Web: www.leandroascierto.com.ar
'Date: 01/11/2009
'--------------------------------------------
Private Declare Function LoadLibrary Lib "kernel32" Alias "LoadLibraryA" (ByVal lpLibFileName As String) As Long
Private Declare Function FreeLibrary Lib "kernel32" (ByVal hLibModule As Long) As Long
Private Declare Function GetProcAddress Lib "kernel32" (ByVal hModule As Long, ByVal lpProcName As String) As Long
Private Declare Function GdiplusStartup Lib "gdiplus" (Token As Long, inputbuf As GdiplusStartupInput, Optional ByVal outputbuf As Long = 0) As Long
Private Declare Function GdipLoadImageFromFile Lib "GdiPlus.dll" (ByVal mFilename As Long, ByRef mImage As Long) As Long
Private Declare Function GdipDisposeImage Lib "gdiplus" (ByVal image As Long) As Long
Private Declare Sub GdiplusShutdown Lib "gdiplus" (ByVal Token As Long)
Private Declare Function GdipSaveImageToFile Lib "gdiplus" (ByVal image As Long, ByVal FileName As Long, ByRef clsidEncoder As GUID, ByRef encoderParams As Any) As Long
Private Declare Function CLSIDFromString Lib "ole32" (ByVal str As Long, id As GUID) As Long
Private Type GUID
Data1 As Long
Data2 As Integer
Data3 As Integer
Data4(0 To 7) As Byte
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(15) As EncoderParameter
End Type
Private Type GdiplusStartupInput
GdiplusVersion As Long
DebugEventCallback As Long
SuppressBackgroundThread As Long
SuppressExternalCodecs As Long
End Type
Const ImageCodecBMP = "{557CF400-1A04-11D3-9A73-0000F81EF32E}"
Const ImageCodecJPG = "{557CF401-1A04-11D3-9A73-0000F81EF32E}"
Const ImageCodecGIF = "{557CF402-1A04-11D3-9A73-0000F81EF32E}"
Const ImageCodecTIF = "{557CF405-1A04-11D3-9A73-0000F81EF32E}"
Const ImageCodecPNG = "{557CF406-1A04-11D3-9A73-0000F81EF32E}"
Const EncoderQuality = "{1D5BE4B5-FA4A-452D-9CDD-5DB35105E7EB}"
Const EncoderCompression = "{E09D739D-CCD4-44EE-8EBA-3FBF8BE4FC58}"
Const TiffCompressionNone = 6
Const EncoderParameterValueTypeLong = 4
Public Function ConvertFileImage(ByVal SrcPath As String, ByVal DestPath As String, Optional ByVal JPG_Quality As Long = 85) As Boolean
On Error Resume Next
Dim GDIsi As GdiplusStartupInput, gToken As Long, hBitmap As Long
Dim tEncoder As GUID
Dim tParams As EncoderParameters
Dim sExt As String
Dim lPos As Long
DestPath = Trim(DestPath)
lPos = InStrRev(DestPath, ".")
If lPos Then
sExt = UCase(Right(DestPath, Len(DestPath) - lPos))
End If
Select Case sExt
Case "PNG"
CLSIDFromString StrPtr(ImageCodecPNG), tEncoder
Case "TIF", "TIFF"
CLSIDFromString StrPtr(ImageCodecTIF), tEncoder
With tParams
.Count = 1
.Parameter(0).NumberOfValues = 1
.Parameter(0).type = EncoderParameterValueTypeLong
.Parameter(0).Value = VarPtr(TiffCompressionNone)
CLSIDFromString StrPtr(EncoderCompression), .Parameter(0).GUID
End With
Case "BMP", "DIB"
CLSIDFromString StrPtr(ImageCodecBMP), tEncoder
Case "GIF"
CLSIDFromString StrPtr(ImageCodecGIF), tEncoder
Case "JPG", "JPEG", "JPE", "JFIF"
If JPG_Quality > 100 Then JPG_Quality = 100
If JPG_Quality < 0 Then JPG_Quality = 0
CLSIDFromString StrPtr(ImageCodecJPG), tEncoder
With tParams
.Count = 1
.Parameter(0).NumberOfValues = 1
.Parameter(0).type = EncoderParameterValueTypeLong
.Parameter(0).Value = VarPtr(JPG_Quality)
CLSIDFromString StrPtr(EncoderQuality), .Parameter(0).GUID
End With
Case Else
Exit Function
End Select
GDIsi.GdiplusVersion = 1&
GdiplusStartup gToken, GDIsi
If gToken Then
If GdipLoadImageFromFile(StrPtr(SrcPath), hBitmap) = 0 Then
If GdipSaveImageToFile(hBitmap, StrPtr(DestPath), tEncoder,ByVal tParams) = 0 Then
ConvertFileImage = True
End If
GdipDisposeImage hBitmap
End If
GdiplusShutdown gToken
End If
End Function
Public Function IsGdiPlusInstaled() As Boolean
Dim hLib As Long
hLib = LoadLibrary("gdiplus.dll")
If hLib Then
If GetProcAddress(hLib, "GdiplusStartup") Then
IsGdiPlusInstaled = True
End If
FreeLibrary hLib
End If
End Function
