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Map Method

Maps the StreamMemory object to a specific memory address.

Syntax

Public Sub Map(ByVal lStartAddr As Long, Optional ByVal lSize As Long = -1)

Remarks

The Map method maps the StreamMemory object to the memory block whose address and size are specified by the lStartAddr and lSize parameters. If the object previously allocated a memory block, it is freed. This method does not perform parameter validation. It is up to the programmer to ensure the memory lStartAddr points to correspond to a valid chunk.

After this method is called, the Kind property returns hbStreamMapped.

This method is typically used to manage pointers, whether they are returned by an external C function or by a predefined HB++ function. The following example uses a memory mapped StreamMemory object to access bitmap bits:

Private Sub Button1_Click()
  Dim bm As New Bitmap
  Dim s As New StreamMemory
  Dim x As Integer, y As Integer
  
  bm.Create 80,50,8,hbDensityLow
  s.Map bm.Bits, 80*50
  For y=0 To 49
    For x=0 To 79
      s.Write CByte(x)
    Next x
  Next y
  CopyArea 0,20,80,50,bm,0,0
End Sub

For further information on shared libraries and communication between HB++ and the C language, refer to the Shared library chapter in the Programmer's Guide and the description of the Declare statement.

System requirements