CODEWITHSUNDEEP
c++winapivisual-c++memory-managementmemory-leaks
Mark Hähnel
Mark Hähnel

Reputation: 175

CreatePen doesn't create memory leaks?

I've created a HPEN and selected it with the following code:

HPEN hPen = CreatePen(PS_SOLID, 1, RGB(0,0,0));
oldPen = (HPEN)SelectObject(hdc, hPen);

After this i'm drawing something and selecting the old Pen:

SelectObject(hdc, oldPen);

To see memory leaks i use:

#define CRTDBG_MAP_ALLOC
#include <crtdbg.h>

/* This in the main function */
_CrtSetDbgFlag ( _CRTDBG_ALLOC_MEM_DF | _CRTDBG_LEAK_CHECK_DF );

If i close the application no mem leak will be shown. But i thought if i don't delete the object with DeleteObject() i get memory leaks.

I've tested the flag with this and it worked:

int* leak = new int;

So there can't be a problem with the flag. Can you help me with this problem or tell me more about why no mem leak is shown?

Thank you!

Upvotes: 2

Views: 636

Answers (2)

AlwaysLearningNewStuff
AlwaysLearningNewStuff

Reputation: 3031

As others have stated, you will not be able to track down GDI leaks this way.

I personally use GDIView for this purpose and am satisfied with it ( if others can recommend other tools for tracking down GDI leaks I would appreciate it ).

Also, you will need to delete the pen after you finish using it ( DeleteObject(hPen) ).

Best regards.

Upvotes: 1

razvanp
razvanp

Reputation: 178

CreatePen is a win32 api function that (potentially) allocates some memory inside the windows kernel to be used while drawing. The memory allocated with new / new[] is allocated by the C Run-Time Library so it will be catch by the CRT debug functions. They were specifically created to catch memory leaks allocated with malloc / new / new[]

Upvotes: 4

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