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DarkThemeCached [message #57072]

Thu, 20 May 2021 23:11

Didier
Messages: 726
Registered: November 2008
Location: France

Contributor

Hello,

Looking at Pradip's code I saw this DarkThemeCached()
What is it supposed to do ?

Especially this line:

cache.ii = (cache.ii + 1) & (N - 1);

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Re: DarkThemeCached [message #57073 is a reply to message #57072]

Thu, 20 May 2021 23:44

Oblivion
Messages: 1206
Registered: August 2007

Senior Contributor

Hello Didier,

That line is supposed to return the remainder of (cache.ii + 1) / N operation, namely (cache.ii + 1) % N (=8) Its function is to clamp the index between 0-7.
A known microptimization trick, if the ii is a positive integer and the N is a power of 2.

(Apparently, colors are cached in thread_local slots))

Best regards,
Oblivion

Github page: https://github.com/ismail-yilmaz
upp-components: https://github.com/ismail-yilmaz/upp-components
Bobcat the terminal emulator: https://github.com/ismail-yilmaz/Bobcat

[Updated on: Fri, 21 May 2021 00:44]

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Re: DarkThemeCached [message #57074 is a reply to message #57073]

Fri, 21 May 2021 01:34

Didier
Messages: 726
Registered: November 2008
Location: France

Contributor

Ok for the line, I did'n know this trick.

But since there are only 8 slots .... it seems to me there is a risk of overlap letting this beeing used freely ?
I still don't uderstand how this function can be used ?

I am really curius

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Re: DarkThemeCached [message #57075 is a reply to message #57074]

Fri, 21 May 2021 01:52

Oblivion
Messages: 1206
Registered: August 2007

Senior Contributor

To my understanding,

It keeps a little map (icolors = input colors, ocolors = output colors, total: 8 colors);

When you call DarkThemeCached(c)

1) It looks up c in icolors.(keys)
2) If it finds it, it returns the corresponding alternate (dark) theme color, ocolor (values).
3) If it couldn't find it in the keys, then calls DarkTheme(c) to calculate the dark theme color (ocolor). (relatively expensive)
4) Then it puts the new dark theme color variant into the map value and returns it.

Now, probably the confusing part is the index: "cache" structure seems to keep track of the current position, so that it wouldn't overwrite the last cached and used color unless it is necessary. That line with modulo operation is apparently for this purpose.
It will start over from index position 0 only if it is iterated enough ( >= 8 ), i, e. previous lookups failed to find their respective color 'c' value among the keys.

Keep in mind that this is what I see in this piece of code. Not the official explanation. Smile

Best regards,
Oblivion

Github page: https://github.com/ismail-yilmaz
upp-components: https://github.com/ismail-yilmaz/upp-components
Bobcat the terminal emulator: https://github.com/ismail-yilmaz/Bobcat

[Updated on: Fri, 21 May 2021 02:06]

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Re: DarkThemeCached [message #57078 is a reply to message #57075]

Fri, 21 May 2021 09:21

Didier
Messages: 726
Registered: November 2008
Location: France

Contributor

Hello Oblivion,

Thanks for the explanations.

If you are using many colors, I don't think using this is a good idea : the cache will be overlapping all the time

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Re: DarkThemeCached [message #57121 is a reply to message #57078]

Thu, 27 May 2021 09:21

mirek
Messages: 14257
Registered: November 2005

Ultimate Member

Didier wrote on Fri, 21 May 2021 09:21

Hello Oblivion,

Thanks for the explanations.

If you are using many colors, I don't think using this is a good idea : the cache will be overlapping all the time

That is why this is separate function from DarkTheme(Color)... You are supposed to use it only where there is a chance of speedup. Actually, the only proper use in the whole uppsrc is in the RichText, where it is used to convert the text color. Usually you do not have that many text colors...

All that said, it is entirely possible that this could be improved somehow. But I just wanted tiny simple cache for RichText...

Mirek

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Re: DarkThemeCached [message #57122 is a reply to message #57121]

Thu, 27 May 2021 09:59

Oblivion
Messages: 1206
Registered: August 2007

Senior Contributor

Well it is also a perfect fit for situations where the app/widget mainly uses the standard 8 ANSI colors and their brighter counterparts, such as TerminalCtrl. Smile

For such cases this function seems like an an optimal solution.

Best regards,
Oblivion

Github page: https://github.com/ismail-yilmaz
upp-components: https://github.com/ismail-yilmaz/upp-components
Bobcat the terminal emulator: https://github.com/ismail-yilmaz/Bobcat

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