V8 Some assorted feedback if interested


I have been playing with V8 today, got it working OK now. Here are a few random things I noticed
(I am using the latest V8.x.x pdf document)

  1. Latest V8.1 Doc under Getting started section (Code doesnt compile)

disp_drv.draw_buf = &draw_buf; /Assign the buffer to the display/

I think this should say

disp_drv.buffer = &disp_buf; /Assign the buffer to the display

  1. In the 8.1 Docs the keyboard example wont compile as listed.

This function documentation needs a trivial fix

static void ta_event_cb(lv_event_t * e)

lv_obj_t* kb = lv_event_get_user_data(e);

needs a cast

lv_obj_t* kb = (lv_obj_t*)lv_event_get_user_data(e);

Also in the examples search for

lv_anim_t * a = lv_event_get_param(e);

that also needs a cast to (lv_anim_t *) to make it compile

  1. Amusing one In the V8.1 source code file LVGL.Simulator.cpp
    There is an commented out function called fuck() .Not that it bothered me but it doesnt give a very professional appearance seeing that in the latest code.

  2. The Simulator was bugging me a bit in that the LCD Window kept opening up on the left hand side of my screen rather than nicely centered. I have fixed that albeit not thoroughly tested, but works for my setup. If anyone is interested in fixing this in the archive let me know and I will post my hack on the Simulator forum or try and figure out how to do a pull request. (Never used Github)

  3. The 8.1 docs refer to this function in a couple of places


A far as I can see this function does not exist in V8.1 ? This section needs a rewrite ?

  1. The example for a simple tabview looks weird to me unless I am missing something ?
    Search for void lv_example_tabview_1(void) it seems to have an extra page of the same demo code repeated ? Not sure that is what was intended.

  2. A question to finish with. The examples are working as intended, but for smallish text fonts my fonts look rather spidery and indistinct compared to native Windows text. Is there anyway to adjust the antialising for text, I am assuming its due to that or maybe just because its rendering bitmaps rather than TTF fonts. I couldnt find a way to switch text fonts antialias on or off ?



Do you mean here? It look good to me. Both places say draw_buf.

lv_event_get_user_data returns void*, so in C no casting should be required. What error did you get?

“Fortunately”, I couldn’t find it here. Have you meant this repo?

Which simulator?

Thanks, fixed.

I can’t see anything weird. Could you send a screenshot about what you mean?

Yes, there is a way. :slight_smile: The built in fonts come with bpp=4 but you can create your own font with 8 bpp too. See https://lvgl.io/tools/fontconverter
You can also use subpixel rendering: Fonts — LVGL documentation
Or use FreeType to render from TTF directly: GitHub - lvgl/lv_lib_freetype: Interface to FreeType to generate font bitmaps run time

It was removed here: Implement the LVGL file system driver support. · lvgl/lv_sim_visual_studio@252e33d · GitHub

1 Like
  1. Do you mean here ? It look good to me. Both places say draw_buf.

Ah sorry my mistake on this one. I was running v7 on hardware initially and hit that problem (gets confusing running 3 versions and variable names change). now I have rechecked V8 code and V8 docs are consistent and both refer to draw_buf

2.) Ah of course I had originally got my test code running in LVGL.simulator.cpp, so without thinking too much called my file test.cpp when the code got big and I extracted it to another file.

4.) I am running the simulator on Windows 10 using visual studio. (The archive that still defaults to an ARM build ?. Scratches head in puzzlement :slight_smile:

6.) Ah cancel this one. I am being dense :slight_smile: The 2nd panel of code that looked weird was just the python example. Sorry for the confusion

Thanks for a great library, been doing some more experimenting with it today, managed to get everything working that I tried.

Please open an issue about it here: GitHub - lvgl/lv_sim_visual_studio: LVGL PC Simulator using Visual Studio

Great, happy to hear that! Thank you for the feedback! :slight_smile: