Compress method example for VB

This example shows the use of the Compress and Uncompress methods for VB 6 users. Extra code is necessary in this example because it also shows you when and where to output the compressed code to a file, further process it by another function, or assign it to a 3rd party component property for file transfer. This is necessary because Variants are not correctly converted by VB into other types. The technique for converting the data ourselves into a format usable by commands such as VB's Get and Put is to use Byte arrays.

To use the example, place an XceedCompression control on a form and run the following code:

Visual Basic Copy Code

Visual Basic	Copy Code
' The byte array which will contain the data to save or transfer: Dim TempByteArray() As Byte ' We'll put some text to compress here: Dim OriginalData As Variant ' Xceed Compression will place the compressed data here: Dim CompressedData As Variant ' To uncompress the data we'll put it in this variable: Dim ToUncompress As Variant ' Xceed Compression will place the uncompressed data here: Dim UncompressedData As Variant ' The result codes will be placed in this variable Dim ResultCode As xcdCompressionError OriginalData = "Text or data to compress" Call XceedCompression1.License( "your license key" ) ResultCode = XceedCompression1.Compress(OriginalData, CompressedData, True) ' Make sure it worked successfully, display message If ResultCode <> xerSuccess Then MsgBox "Compression unsuccessful. Error # " & Str(ResultCode) & " occurred. " & _ "Description: " & XceedCompression1.GetErrorDescription(ResultCode) Else MsgBox "Compression successful." End If ' Now the CompressedData variable is a Byte Array Variant, but it still cannot ' be assigned properly to other properties or used by the Get and Put method until ' we convert it to a real byte array as follows: ReDim TempByteArray(1 To UBound(CompressedData)) As Byte TempByteArray = CompressedData ' Ok, now you can do whatever you want with the compressed data located in the ' " TempByteArray" byte array variable (not a Variant!) ' [Save, process or transfer your data here!] ' Ok, now its time to decompress your saved data, so place it in the TempByteArray byte array variable. ' [Load your saved or transferred compressed data here!] ' Lets convert it to a Variant Byte Array before uncompressing it ToUncompress = TempByteArray ' Now let's uncompress the data ResultCode = XceedCompression1.Uncompress(ToUncompress, UncompressedData, True) ' UncompressedData variable should now contain same data as the OriginalData variable ' Check to see if it worked properly, display message If ResultCode <> xerSuccess Then MsgBox "Decompression unsuccessful. Error # " & Str(ResultCode) & " occurred. " & _ "Description: " & XceedCompression1.GetErrorDescription(ResultCode) Else MsgBox "Decompression successful." End If


' The byte array which will contain the data to save or transfer:
Dim TempByteArray() As Byte  
' We'll put some text to compress here:
Dim OriginalData As Variant 
' Xceed Compression will place the compressed data here:
Dim CompressedData As Variant 
' To uncompress the data we'll put it in this variable:
Dim ToUncompress As Variant 
' Xceed Compression will place the uncompressed data here:
Dim UncompressedData As Variant 
' The result codes will be placed in this variable
Dim ResultCode As xcdCompressionError 
OriginalData = "Text or data to compress" 
Call XceedCompression1.License( "your license key" )
ResultCode = XceedCompression1.Compress(OriginalData, CompressedData, True)

' Make sure it worked successfully, display message
If ResultCode <> xerSuccess Then
   MsgBox "Compression unsuccessful. Error # " & Str(ResultCode) & " occurred. " & _
          "Description: " &  XceedCompression1.GetErrorDescription(ResultCode) 
Else 
   MsgBox "Compression successful." 
End If  
' Now the CompressedData variable is a Byte Array Variant, but it still cannot 
' be assigned properly to other properties or used by the Get and Put method until 
' we convert it to a real byte array as follows: 
ReDim TempByteArray(1 To UBound(CompressedData)) As Byte
TempByteArray = CompressedData 
' Ok, now you can do whatever you want with the compressed data located in the 
' " TempByteArray" byte array variable (not a Variant!) 
' [Save, process or transfer your data here!] 
' Ok, now its time to decompress your saved data, so place it in the TempByteArray byte array variable. 
' [Load your saved or transferred compressed data here!] 
' Lets convert it to a Variant Byte Array before uncompressing it 
ToUncompress = TempByteArray 
' Now let's uncompress the data 
ResultCode = XceedCompression1.Uncompress(ToUncompress, UncompressedData, True) 
' UncompressedData variable should now contain same data as the OriginalData variable
' Check to see if it worked properly, display message 
If ResultCode <> xerSuccess Then
   MsgBox "Decompression unsuccessful. Error # " & Str(ResultCode) & " occurred. " & _
          "Description: " & XceedCompression1.GetErrorDescription(ResultCode) 
Else 
   MsgBox "Decompression successful." 
End If