DataDecompress Event

Fires to decompress a block of data using a custom compression algorithm.

Syntax

• C#
• VB.NET

public event OnDataDecompressHandler OnDataDecompress;

public delegate void OnDataDecompressHandler(object sender, CbdriveDataDecompressEventArgs e);

public class CbdriveDataDecompressEventArgs : EventArgs {
  public IntPtr InData { get; }
  public int InSize { get; }
  public IntPtr OutData { get; }
  public int OutSize { get; set; }
  public int ResultCode { get; set; }
}

Public Event OnDataDecompress As OnDataDecompressHandler

Public Delegate Sub OnDataDecompressHandler(sender As Object, e As CbdriveDataDecompressEventArgs)

Public Class CbdriveDataDecompressEventArgs Inherits EventArgs
  Public ReadOnly Property InData As IntPtr
  Public ReadOnly Property InSize As Integer
  Public ReadOnly Property OutData As IntPtr
  Public Property OutSize As Integer
  Public Property ResultCode As Integer
End Class

Remarks

This event fires when the component needs to decompress a block of data using an application-defined compression algorithm. Please refer to the Compression topic for more information.

This event only needs to be handled by applications that use the CBFSSTORAGE_CM_CUSTOM compression mode. To handle this event properly, applications must decompress all InSize bytes of data in the InData buffer, write the decompressed data to the OutData buffer, and set OutSize to reflect the total number of bytes written to OutData.

Note that OutSize is initially set to the capacity of the OutData buffer, which (under normal circumstances) should be large enough to accommodate all of the decompressed data. Only if the vault is corrupted should the OutData buffer ever be too small to hold the decompressed data; so if this occurs, do not write any data to OutData. Instead, set ResultCode to CBFSSTORAGE_ERR_VAULT_CORRUPTED.

Please refer to the Buffer Parameters topic for more information on how to work with memory buffer event parameters.

The ResultCode parameter will always be 0 when the event is fired. If the event cannot be handled in a "successful" manner for some reason (e.g., a resource isn't available, security checks failed, etc.), set it to a non-zero value to report an appropriate error. Please refer to the Error Reporting and Handling topic for more information.

Note: An application should not attempt to call component's methods from handlers of this event. Doing this is guaranteed to cause a deadlock.

Note: when a storage is opened concurrently in read-only mode by several applications using CBDrive or CBMemDrive component, the event will fire only in the first application. To prevent such a situation, always open a vault in read-write mode.