File handlers could receive window number

[vieiro]

When you're programming in C (or Rust, etc.) it's easy to create a C function with the following signature...

const void*(*handler)(const char* filename, int* length);

... and set it as the file handler of a given window with webui_set_file_handler(window, handler). In C it's easy to create different functions for different windows.

But when you use another (dynamic) language and you use a compiled version of webui then it may be difficult to create a new C function for each window. In these programming languages you probably want to create a single file handler and compile it as a library, and then let the file handler act differently depending on which window it's handling. Sadly the file-handlers have no idea which window they're serving.

An enhancement could be to modify the file handler signature to:

const void*(*handler)(size_t window, const char* filename, int* length);

this is, send the window num to the file handler as a first argument.

The change will require modifying the API (or augmenting it with a different file handler function, say webui_set_file_handler_window), but should be easy to implement otherwise.

I can submit a PR if this you consider this useful.

[AlbertShown]

Yes, this is very useful, you can create a PR 👍
But it should be webui_set_file_handler_window() as you suggested because modifying the existing webui_set_file_handler() will break examples and all wrappers.

Call point:

webui/src/webui.c

Line 4198 in ead9970

const void* callback_resp = win->files_handler(url, (int*)&length);

[vieiro]

I'll add a PR during this week.

Just one question, if I call webui_set_file_handler and later on webui_set_file_handler_window I assume the last one takes precedence, right?

What I mean is that:

• calling webui_set_file_handler_window(window, handler) implies a call to webui_set_file_handler(window, NULL) , resetting any previous file handler.
• and calling webui_set_file_handler(window, handler) implies a call webui_set_file_handler_window(window, NULL), resetting any previous "window" file handler.

Is this the required behaviour?

[AlbertShown]

Yes, that's right, because the HTTP server should only return one result, so one handler should be used only as you suggested.

[vieiro]

Here's a proposed implementation: #488