# Backend dev

The basic process of creating a new Milsko backend is

- Adding a new include header into `include/Mw/LowLevel`. It must include;
  - `struct _MwLLBackendName`: Any details about a window or a subwidget
  - `struct _MwLLBackendNameColor`: An 8-bit RGB Color. You'll probably never impl this, this is for platforms like X11/GDI where they have a secondary color representation that can be stored.
  - `struct _MwLLBackendNamePixmap`: Self-explanatory. This is also used for the soft gradients in the modern theme.
  - `MwLLBackendNameCallInitImpl(void)` called by `MwLibraryInit` to address and platform globals.
  - Note that all of those structs are actually unions. They should all start with their `MwLLCommon...` equivalants.
- Fill out `Mw/LowLevel.h` appopriately, adding an include to your new file and the structs in the appropriate unions. These need to be guarded by a `USE_BACKENDNAME` macro which you'll define later when you modify the build system.
- Creating a new impl file in `src/backend`
  - Backends actually return a table of function pointers that you have to implement with static functions. Your file should end with `#include "call.c"` and then `CALL(BackendName);`, and somewhere you should have the impl for `MwLLBackendNameCallInitImpl(void)`.
- Add `MwLLBackendNameCallInitImpl` to the `MwLibraryInit` impl in `src/core.c`.
- Add a new enum variation to `MwLLBackends` in `Mw/Include/LowLevel.h`; your impl of `MwLLCreateImpl` will set `common.type` to this so the user can check which backend they're on (important for platforms with multiple supported backends).
- Either
  - a.) Modify `CMakeLists.txt` for your platform.
  - b.) Add a new perl file in `pl/ostype` that `./configure` can reference, and modify `pl/rules.pl`; If you don't know how to use perl it's fine, just copy a file like the `Linux.pl` or `Windows.pl`, the functions you'll have to change for your platform are self explanatory. Ensure it ends with `1;`.
  - c.) Both.
  - Both are recommended, but some platforms like Classic Mac OS can't be used with the `./configure` script, and that's fine.

The functions you'll have to impl are too many to list here so you should start by just copying `x11.c` and then replacing all the function impls with your own.

\*\*Pay attention to some of these functions' comments in LowLevel.h as they might not be as you expect; for example, `MwLLSetDarkThemeImpl` is for setting the accent color to dark theme on platforms like modern Windows (dark theme itself is set with `MwSetInteger(handle, MwNdarktheme, 1)`).