Access violation exception from Delphi's Supports -> QueryInterface

Posted by Sharon on Stack Overflow See other posts from Stack Overflow or by Sharon
Published on 2010-03-21T10:10:18Z Indexed on 2010/03/21 10:11 UTC
Read the original article Hit count: 268

Filed under:

access-violation

|

delphi

|

queryinterface

Hi,

I have the following piece of code:

for i := 0 to FControlList.Count - 1 do

  if Supports(IMyControl(FControlList[i]), IMyControlEx) then
  begin
    MyControlEx := IMyControl(FControlList[i]) as IMyControlEx;
    MyControlEx.DoYourMagic(Self, SomeData);
  end;

This code is called many times during my application execution, but in some specific cases it fails inside the Supports() method. And more specifically - it seems to fall inside the QueryInterface() call within the Supports() method.

I checked that FControlList is not nil and FControlList[i] is not nil and it still happens.

Any idea will be appreciated!!!

© Stack Overflow or respective owner

Related posts about access-violation

php Access violation

as seen on Stack Overflow - Search for 'Stack Overflow'
I am trying to install Php on Vista (IIS 7). The installation and configuration seems to be fine. Pretty much followed everything mentioned in http://blogs.iis.net/bills/archive/2006/09/19/How-to-install-PHP-on-IIS7-_2800_RC1_2900_.aspx I can even bring up a test.php which is basically and can also… >>> More
deleting HBITMAP causes an access violation at runtime.

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I have the following code to take a screenshot of a window, and get the colour of a specific pixel in it: void ProcessScreenshot(HWND hwnd){ HDC WinDC; HDC CopyDC; HBITMAP hBitmap; RECT rt; GetClientRect (hwnd, &rt); WinDC = GetDC (hwnd); CopyDC = CreateCompatibleDC (WinDC); //Create… >>> More
Hide an access violation on another application

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I have an application that sometimes causes an access violation on exit. This is quite unpredictable and all attempts to locate the bug have been unsuccesful so far. The bug is harmless, as no data is lost, so I was thinking if it might be possible to just hide it. Is it possible to have another… >>> More
read access violation error

as seen on Stack Overflow - Search for 'Stack Overflow'
class Node{ private: string name; Node** adjacent; int adjNum; public: Node(); Node(string, int adj_num); Node(const Node &); bool addAdjacent(const Node &); Node** getAdjacents(); … >>> More
C++ Access violation when calling dll function

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a function definition in my VC++ Win32 DLL DEMO2_API void ProcessData(char* i_buff, unsigned short i_len, char* o_buf, unsigned *o_len, unsigned short *errorCode) { __describe (i_buff,&i_len,o_buf,o_len,errorCode); } This dll function is called by a c# application. When called, it… >>> More

Related posts about delphi

TVirtualStringTree compatibility between Delphi 7 and Delphi 2010 - 'Parameter lists differ'

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I've made a form containing a TVirtualStringTree that works in Delphi 7 and Delphi 2010. I notice that as I move between the two platforms I get the message '...parameter list differ..' on the tree events and that the string type is changing bewteen TWideString (D7) and string (D2010). The only… >>> More
Convert Delphi 7 code to work with Delphi 2009

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a String that I needed access to the first character of, so I used stringname[1]. With the unicode support this no longer works. I get an error: [DCC Error] sndkey32.pas(420): E2010 Incompatible types: 'Char' and 'AnsiChar' Example code: //vkKeyScan from the windows unit var KeyString:… >>> More
Book recommendation for moving from Delphi 6 to Delphi 2010

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi, I am a long time Delphi 6 developer. Looking for a book on Delphi 2010. Not only on the new features available in Delphi 2010, but more importantly, guideline on how different it is to develop applications in Delphi 2010, the architecture, standard and convention, etc. Thanks a lot. >>> More
Compile Delphi component package (bpl) for different Delphi versions

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello. The situation is the following. Typically I use RAD Studio 2010 for Delphi development. I have some components I would like to redistribute in binary form (*.bpl without source). But I would like people to be able to use them despite of their Delphi version. But, for example, dcu files can… >>> More
Delphi Speech recognition delphi

as seen on Stack Overflow - Search for 'Stack Overflow'
I need create a programatic equivalent using delphi language... or could someone post a link on how to do grammars in peech recogniton using the delphi. sorry for my english... XML Grammar Sample(s): <GRAMMAR>  <RULE NAME="HelloWorld"… >>> More