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Sending SCI_GETTEXT (and others) causes the application to crash

I am trying to use the Scintilla editor in my RealStudio application. I can load the DLL, create a Scintilla child window, and send messages to the window as long as the message options do not apply to the line. If I try to get or install a string, then Windows will immediately terminate the application with error code 5 (access is denied).

Here is my code from the event of the Opencontaining window:

  #If TargetWin32 Then
    Declare Function CreateWindowExA Lib "User32" (ExStyle As Integer, ClassName As CString, WindowName As CString, Style As Integer, X As Integer, Y As Integer, Width As Integer, Height As Integer, Parent As Integer, Menu As Integer, Instance As Integer, Param As Ptr) As Integer
    Declare Function SendMessageA Lib "User32" (HWND As Integer, Message As UInt32, WParam As Ptr, LParam As Ptr) As Integer
    Const SCI_GETLENGTH = 2006
    Const SCI_GETTEXT = 2182
    Const WS_CHILD = &h40000000
    Const WS_CLIPCHILDREN = &h02000000
    Const WS_TABSTOP = &h00010000
    Const WS_VISIBLE = &h10000000


    ' IsFunctionAvailable calls LoadLibrary and GetProcAddress
    If System.IsFunctionAvailable("Scintilla_DirectFunction", "SciLexer") Then
      ' Create the Scintilla child window
      Dim SciHandle As Integer = CreateWindowExA(0, "Scintilla", "", WS_CHILD Or WS_CLIPCHILDREN Or WS_TABSTOP Or WS_VISIBLE, 5, 5, Me.Width - 10, Me.Height - 10, Me.Handle, 0, 0, Nil)

      Dim count, buffer As MemoryBlock
      ' Get the current character count
      Dim c As  Integer = SendMessageA(SciHandle, SCI_GETLENGTH, Nil, Nil) ' This works

      count = New MemoryBlock(4) ' Store the count in a MemoryBlock
      count.Int32Value(0) = c + 1
      buffer = New MemoryBlock(c + 1) ' allocate the buffer
      Call SendMessageA(SciHandle, SCI_GETTEXT, count, buffer) ' This crashes
    End If
  #endif

In life, I cannot understand why it does not work.

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1 answer

SCI_GETTEXT is declared as follows:

SCI_GETTEXT(int length, char *text)

This means: you pass the length parameter as an integer and a pointer to a text buffer.

. :

Declare Function SendMessageAip Lib "User32" (HWND As Integer, Message As UInt32, WParam As Integer, LParam As Ptr) As Integer
buffer = New MemoryBlock(c + 1) ' allocate the buffer
Call SendMessageAip(SciHandle, SCI_GETTEXT, c+1, buffer)
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