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GDI+ and MFC memory leak detection

Zoltan Csizmadia
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4.76/5 (16 votes)

Sep 11, 2003

2 min read

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GDI+ and MFC memory leak detection

Introduction

When I started to use GDI+ with MFC in VC++ 6.0 I ran into some annoying problems:

  1. Couldn't compile my GDI+ code with MFC without removing the DEBUG_NEW macros
  2. Couldn't compile GDI+ code with STL without tweaking my code
  3. Couldn't detect memory leaks

Here is the solution!

How to use

Include GdiplusH.h in stdafx.h:

// GDI+ helper file

#include "GdiplusH.h"

Features

  • GDI+ will be initialized when program starts
  • You can use _CrtXXX functions to detect memory leaks, set an allocation breakpoint, save and compare memory states, etc.
  • Memory leak information will be dumped to output window (MSVC IDE)
  • No more compilation problem with DEBUG_NEW
  • No more compilation problem with STL

Memory leak detection

 

GDI+ is using GdipAlloc and GdipFree for allocating memory for GDI+ objects. Probably they have their own memory allocation lists in gdiplus.dll, but unfortunately there is no exported API to get any memory leak information. But GDI+ objects can be located on stack (for example: creating a local variable in a function), so there is no special initialization for these memory regions, so we do not have to use GdipAlloc or GdipFree. If we call the CRT debug version of memory allocation and deletion functions instead of GdipAlloc/Free, we can detect memory leaks very easily using the well known _CrtXXX functions.

 

Miscellaneous defines

 

  • GDIPLUS_NO_AUTO_INIT - GDI+ won't be initialized at program startup. You have to create a GdiPlus::GdiPlusInitialize variable to initialize GDI+ (GDI+ will be uninitialized, when destructor is called for this variable).
  •  GDIPLUS_USE_GDIPLUS_MEM - GdipAlloc and GdipFree is used for memory operations. In this case _Crt functions cannot be used to detect memory leaks
  •  GDIPLUS_NO_AUTO_NAMESPACE - Gdiplus namespace won't be defined as a used namespace. In this case you have to use Gdiplus:: prefix.

Acknowledgements