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esp-cpp / espp

C++ components for ESP
https://esp-cpp.github.io/espp/
MIT License
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Migrating LVGL from v8 to v9 #265

Open abrondijk opened 3 days ago

abrondijk commented 3 days ago

Answers checklist.

General issue report

I'm working on migrating LVGL from v8 to v9 and I've run into some issues in regards to your espp::Display class.

LVGL v9 no longer uses macro magic to populate the lv_color_t struct depending on the chosen color depth. Instead, it has different types for the different color depths, and lv_color_t represents RGB888. This means that lv_color_t can no longer be the type of the framebuffers if the display in question uses the RGB565 format for example.

Now this is all fine and can be implemented in the different display driver classes, but currently, the espp::Display class uses lv_color_t as well.

The vram pointers can be void pointers (also what LVGL uses internally), but the vram_size_bytes() function uses sizeof(lv_color_t). Should the AllocatingConfig and the NonAllocatingConfig structs also have a member that holds the buffer size in bytes, like the pixel_buffer_size? Or, perhaps a member that holds the amount of bytes per pixel?

Additionally, I think that the uint16_t *vram0() and uint16_t *vram1() functions should instead also be void pointers to support all color depths.

Alternatively, the espp::Display class could be templated to indicate the pixel type, but that would be a rather large refactor.

What are your thoughts?

finger563 commented 3 days ago

@abrondijk Thanks for looking into this - I've wanted to look into moving to v9, but haven't had the time to do so yet 😅

Regarding your idea - I think I prefer the template approach because I think that will keep the API cleaner and more strongly typed, while still allowing for support of both v8 and v9 should someone want to stay on v8.

abrondijk commented 3 days ago

@finger563 Ok, I'll start working on that!

As for being able to use both versions, the way to tie the framebuffers and the flush callbacks are a bit different. If you'd like to support both, I can probably work around it with macros.

finger563 commented 3 days ago

@abrondijk Personally, I'd prefer to simply migrate to v9 (since that's what would be bundled with espp anyway) if that's the case.