glfw folder refactor

[jwinarske]

Introduce the problem

Building LVGL without GLFW + glew dependencies requires patching the source tree.

Proposal

Refactor the glfw directory into two folders

1. glfw - glfw specific calls
2. egl_gles - generic egl/gles calls

This would introduce a new build variable. Some platforms implement the window * as an opaque data pointer (void *) and call it NativeWindow. Which requires a cast relative to the underlying "window" system.

This enables non-GLFW/glew use cases.

[jwinarske]

drmpp drm-gbm-lvgl demo running on Ubuntu 20 at 1920x1080 @ 60 FPS with above proposed changes. No GLFW, no glew.
https://github.com/user-attachments/assets/8ee20a5e-f78f-4b2e-8b97-2c9168a4df24

jwinarske/drmpp#37

[liamHowatt]

Hi, thanks for mentioning it. When I picked up the OpenGL, I knew it was only a matter of time before this separation needed to occur. The logic is separated to a reasonable degree but not properly decoupled.

Do you want to open a PR or shall I?

[jwinarske]

@liamHowatt Hi Liam. Go for it.

My only request is to use an opaque data pointer for window *, opposed to a GLFW specific one, thus making the struct agnostic. Then cast as needed per platform. This way we can reuse the struct for any platform that supports EGL/GLES, opposed to having to redefine it for each platform.

[lvgl-bot]

We need some feedback on this issue.

Now we mark this as "Abandoned" because there was no activity here for 14 days.

Remove the "Stale" label or comment else this will be closed in 7 days.

[kisvegabor]

Not stale.

[lvgl-bot]

We need some feedback on this issue.

Now we mark this as "Abandoned" because there was no activity here for 14 days.

Remove the "Stale" label or comment else this will be closed in 7 days.

[lvgl-bot]

As there was no activity here for a while we close this issue. But don't worry, the conversation is still here and you can get back to it at any time.

Feel free to comment if you have remarks or ideas on this topic.

[liamHowatt]

Hey @jwinarske I'm working on it and if it weren't for your working demo, I would assume that the GL v4 functions LVGL is using are incompatible with EGL's GL ES version. It seems that functions like glGenVertexArrays should not be working on EGL without GLAD or GLEW. Do you know how you got it to work in this respect? I'm not opposed to using pure GL ES functions but if the v4 ones work with EGL somehow I'd like to know how!

Edit: Nevermind, this helped me.