I want to create a thread about it, to sort of document it as I go, and to log my progress.

This is the image viewer I'm making. Goals: to work super fast, to have controls tuned for me, and to report anything suspicious in the images (comments, extra space, everything). This is also hilariously complicated.

Idea 1: For all data, for which I don't know the size ahead of time, I use linked lists. And I'm also using fixed size memory allocation, with VirtualAlloc. Each memory chunk is 0x1000 bytes in size. I reserve the last dword of this chunk for an address to the next chunk, so that it sort of autoexpands (or I use first dword for the "prev" pointer, quite good for stacks). Pros: don't have to realloc anything ever, don't have to move data around unnecessarily, memory fragmentation isn't an issue, allocator is super simple. Cons: I have to check for overflows very often (more code), slightly more memory wasted, and I'm not sure if this is actually better than a usual malloc.

Idea 2: every image I load, is either "big" or "thumb". "Big" are the actual images, "thumb" are thumbnails for them. "Big" images get spitted into a bunch of 512x512 textures, and a bunch of "thumb" are stored on a one or more 1024x1024 texture. All to waste less memory.

Idea 3: I'm storing info for those "big" and "thumb" in an interesting manner. All using those fixed size chunks from Idea 1. For "big", I'm storing the image width, image height, and a bunch of direct3d textures for them. For "thumb", I'm storing a direct3d texture, a "length" of currently placed thumbs on them, and a bunch of "x y width height" coordinates for each. Pros: it's more compact, and somewhat simple. Cons: you can only traverse it in one direction, too many overflow checks. I can make it better by pointing to the proper position in it, and by using "ranges" where possible. Also, I want to add the ability to load images in the reverse order (so that I can open a folder in the middle, and this program will preload images upwards too), and that will require ranges in reverse order and rendering in reverse order.

big_range will look like:
pointer_to_the_first_"big"
length
is_reverse

thumb_range will look like:
pointer_to_"thumb"_texture
starts_at
length
is_reverse

Here is the code for it. It's super raw and super buggy. Say if you have anything to comment about it.

EDIT:
By the way, it gives me "out of memory" only after 50-100 opened images. Too complicated for me to debug right now.

Also, thumbnails don't get displayed properly, their right border goes 1-2 pixels otherboard. Very noticeable if you'll set background to some color.

I want to rewrite it in directdraw now, need to see if it's fast enough. If it's not, then I'll continue with direct3d.