lv_font_conv：Use the tool to generate Chinese font bin file，lv_font_load Failed to load bin file

[DragonYY123]

lv_font_conv --font MiSans-Medium.ttf -r 0x20-0x7F --size 40 --format bin --bpp 2 --no-compress -o cour40_2.bin
This bin file ok.
lv_font_conv --font MiSans-Medium.ttf -r 0x20-0x7F -r 0x4E00-0x9FA5 --size 40 --format bin --bpp 2 --no-compress -o cour40_2unicode.bin
Use lv_font_load() functions.Failed to load ambiq_cour40_2unicode.bin file.
Please advise how to deal with it?

[kisvegabor]

Please attach the ttf file and the result bin file too to reproduce the issue.

Which LVGL version do you use?

[DragonYY123]

Thank you for the response.
Uploading ttf2bin2ambiq.zip…

font_realign.py:Used to generate bin files(ambiq_cour40_2unicode.bin) supported by ambiq
LVGL version:8.1.0

[kisvegabor]

The file upload wasn't successful. It seems you have pressed the "Comment" button too early.
Please upload again.

LVGL version:8.1.0

It's pretty old. Could you try updating to v8.3.11 (latest from the release/v8.3 branch)?

[916BGAI]

@kisvegabor You can use the ttf file and bin file to reproduce errors in release/v9.0 branch
target.zip

[kisvegabor]

I've tried it out and it works but it required 7.5MB of RAM. I suggest taking a look at TinyTTF to render directly from a TTF file.

[R-YaTian]

Having a similar issue, I was using --symbols to add the common CJK characters I needed, but when loading the font on the device, I encountered a memory allocation error when loading the CMAP table, the glyph_id_ofs_list pointer was null on load_cmaps_tables function. It seems that when using the --symbols parameter, the tool does not strictly check whether the glyph data of the corresponding characters in the ttf file is valid.

[kisvegabor]

In lv_binfont_loader.c really not all mallocs are checked. If you have some time for it, can you send a Pull request to add the required checks?

[DragonYY123]

I've tried it out and it works but it required 7.5MB of RAM. I suggest taking a look at TinyTTF to render directly from a TTF file.
Thank you for your reply!
I used external PSRAM to load successfully.However, some Chinese characters may display garbled characters. The bin file converted by using the following command can be used normally, but a large number of Chinese characters need to be entered, and it is difficult to cover all of them.
lv_font_conv --font SourceHanSansCN-Normal-2.otf -r 0x20-0x7F --symbols 一丁...... --size 20 --format bin --bpp 2 --no-compress -o mycour_siyuan20_2unicode.bin
I use this command to convert the bin file.

[kisvegabor]

I used external PSRAM to load successfully.However, some Chinese characters may display garbled characters.

Which characters are scrambled? Please mention a few examples so that we can try it out.

[Linjieqiang]

I've tried it out and it works but it required 7.5MB of RAM. I suggest taking a look at TinyTTF to render directly from a TTF file.

So if I use a file (misans.bin) to load, I need to prepare 7.5MB of RAM in MCU? So do you recommend using tinyttf for real-time rendering? This only requires 4KB of RAM to complete?

And my MCU RAM is <200KB, So Which way can I use to load the font?

@kisvegabor

[DragonYY123]

I used external PSRAM to load successfully.However, some Chinese characters may display garbled characters.

Which characters are scrambled? Please mention a few examples so that we can try it out.

For example:硬件测试

[kisvegabor]

I suggest trying it out, but tiny ttf can be solution for sure.