Question

I’m trying to create a simple game, but I can’t find a certain memory leak. Every second or so, the program seems to use 3mb more memory.

The problem is with this draw method. If I don’t call this method, everything works fine. I’m trying to paint a sprite on several parts of the screen:

void Map::draw(HDC hBackBufferDC)   
{  
    for(int i = 0; i < 24; i++)  
    {  
        for(int j = 0; j < 27; j++)  
        {  
            if(mapState[i][j] == 'm')
            {
                blueWall->draw(hBackBufferDC, new Position(j, i));  
            }  
        }
    }
} 

If I remove the method call of draw, there are no problems, so the problem is in that method:

void StaticSprite::draw(HDC hBackBufferDC, Position* pos)  
{
    int x = (int)pos->x * 22;
    int y = (int)pos->y * 22;

    HGDIOBJ oldObj = SelectObject(this->hSpriteDC, this->hMask);

    BitBlt(hBackBufferDC, x, y, 22, 22, this->hSpriteDC, 0, 0, SRCAND);

    SelectObject(this->hSpriteDC, this->hImage);
    BitBlt(hBackBufferDC, x, y, 22, 22, this->hSpriteDC, 0, 0, SRCPAINT);

    SelectObject(this->hSpriteDC, oldObj);
}

Any idea what is causing the memory leak here? I think it’s related to this part, but I can post other parts of the code if needed.

Thanks

Answer 1

Are you using managed c++ or not ?
You are allocating new Position (24*27) times.
This lead to a 648 leaks each time you call Map::draw.

Use an automatic object.

void Map::draw(HDC hBackBufferDC)
    {
    for(int i = 0; i < 24; i++)
       {
       for(int j = 0; j < 27; j++)
         {
           if(mapState[i][j] == 'm') {
              Position tmp(j,i);
              blueWall->draw(hBackBufferDC, &tmp);
           }
         }
       }
    }
    }

Or delete the Position object after using it !
Note that dynamic allocation is very slow.

void Map::draw(HDC hBackBufferDC)
    {
    for(int i = 0; i < 24; i++)
       {
       for(int j = 0; j < 27; j++)
         {
           if(mapState[i][j] == 'm') {
              Position *tmp = new Position(j,i);
              blueWall->draw(hBackBufferDC, tmp);
              delete tmp;
           }
         }
       }
    }
    }