If img1 is an ALLEGRO_BITMAP, that creates a leak, so yes, you want to call al_destroy_bitmap on img1. But you have to make sure you don't call al_destroy_bitmap on the same address twice. Also note, al_destroy_bitmap does not set the variable you pass to it to 0 or NULL. If you want that, you have to set it yourself.

Every ALLEGRO_BITMAP* you create, you should destroy. It doesn't matter how or when you assign it to another pointer as long as you don't lose a reference to a created bitmap before you destroy it.

Ex:

I'm probably missing something here, but you don't want to destroy it until you're done displaying it or whatever.

When you destroy a bitmap, the memory becomes available for other uses. When it doesn't crash, it hasn't been reused and overwritten to something else yet.

Post the code.

I meant all of the code, or at least a complete program that reproduces the issue. The more I speculate on what is going on here the more wrong I become.

Is the program single-threaded?
Can we see the draw function?

Try searching for imgBuffer in all your code, and make sure you're not accidentally destroying it somewhere or setting it to NULL.

When I use bitmaps with Allegro 5, I do the following:

Basically, don't assume, check all return values, set the initial value to NULL, if you destroy a bitmap, even if you plan to reuse it, reset it to NULL, otherwise if you check to see if it failed to load, and it contains the address of the last bitmap still, your check won't be accurate and you'll have problems. This way you know it is NULL unless it loads safely because that is what you set it to.

Edit: I am curious, how do you check for memory leaks? I use CodeBlocks with MinGW, never done that before but want to.

It seems to me that if you assign a new address to a pointer without first freeing up the memory that it is currently pointing to, than you'll create a leak, I think this is what people are talking about.

Ok I think I get it now. I think I fixed it by integrating the function into the Image class so it works with the bitmap directly instead of just making a bitmap returning it into the image loader function(that returned the bitmap into the load function then assigned the bitmap from the parameter into the classes bitmap). I gets pretty confusing when you try to make everything object oriented and organized sometimes I guess

That was something I had considered as well. Having it check to see if it is NULL, and if not, free it first. I always immediately destroy any bitmaps when I am done with them and set them to NULL so it isn't an issue.

I've done this in my own code where I had a temporary bitmap I was using to load in sprite sheets then divide them up into arrays (to avoid 3D filtering problems on tiled games). I just destroy the bitmap and set it to NULL when I am done loading etc... for each set of sprites/tiles on my latest project.

I read that the Allegro functions return NULL, but, like you, I feel safer setting it myself. Just one little line of code for peace of mind.

That sounds nice. I'm not doing much in C++ yet myself, but I'll try and keep that in mind when I do.