Question: why is the default `HarfBuzzShaper` cache size 0?

[hajimehoshi]

Yesterday, I found that HarfBuzzShaper's cache size was 0 and NewFont was called every time different texts are rendered:

• example/gallery: switching the gallery to the 'texts' take long guigui-gui/guigui#64
• text/v2: rendering various texts causes a performance issue hajimehoshi/ebiten#3228

This issue could be prevented by settings some cache size. I was wondering why 0 is the initial value. Would it be possible to have initial cache size to avoid future troubles like me?

[benoitkugler]

I guess the reason is that we do not have a constructor for HarfBuzzShaper and the zero value for the fontLRU cache has 0 as its maxSize.

I'm not sure there is an easy fix. Perhaps a better documentation could be enough ? (cc @whereswaldon )

[hajimehoshi]

I guess the reason is that we do not have a constructor for HarfBuzzShaper and the zero value for the fontLRU cache has 0 as its maxSize.

If this struct needs to have a non-zero cache by default, I'd have an integer member substracted by the default value so that the initial value (0) indicates the default value.

[benoitkugler]

I actually thought about it, but what would SetCacheSize do then ? It would not do what the user expects

[hajimehoshi]

what would SetCacheSize do then ?

This function would update the member variable with the argument minus the default size.

[benoitkugler]

what would SetCacheSize do then ?

This function would update the member variable with the argument minus the default size.

Ah of course ! 😅

[whereswaldon]

I'm fine with adjusting the implementation to set a default cache size. I agree that size zero by default is a little silly.