Hello,


On 5 Ц 2013, at 20:39 , Carlo E. Prelz <fluido / fluido.as> wrote:

> 	Subject: Change fond color based on dark/light bg [Sinatra,HAML,CSS]
> 	Date: sab 06 apr 13 02:54:01 +0900
> 
> Quoting Panagiotis Atmatzidis (atma / convalesco.org):
> 
>> The problem that the background changes in colors. It's bright
>> colored by day and dark colored by night, so I need to find a way to
>> change font-colors based on the background. I'm using HAML, CSS and
>> Sinatra. 
>> 
>> Can you think of any way of doing something like that?  Apparently I
>> can't do that using CSS or SASS (not 100% sure though).
>> 
>> Is there any way I can have ruby read the BG color and then decide
>> if I'll display the 'weather_light' route or the 'weather_dark'
>> sinatra route?
> 
> You can extract the average luminosity from an image - just decompres
> it, then sum all the bytes and divide by the number of bytes - you'll
> have a number between 0 and 255. Lower than  128 -> weather_dark,
> else weather_light.

Thanks, that's a great idea. I'll give it a shot.

> 
> Of course you should get a copy of the image yourself, in order to
> process it. It is not clear from your mail if you serve these
> backgrounds yourself or you redirect elsewhere. If you redirect, you
> can always have a background task that runs maybe once per hour, gets
> retrieves a copy of the image and sets a variable that is accessible
> within Sinatra (possibly a global variable) with the current
> luminosity.

I can easily download and process locally both images, it's not a problem :-)

> 
> Carlo
> 
> -- 
>  *         Se la Strada e la sua Virtu' non fossero state messe da parte,
> * K * Carlo E. Prelz - fluido / fluido.as             che bisogno ci sarebbe
>  *               di parlare tanto di amore e di rettitudine? (Chuang-Tzu)
> 


Panagiotis (atmosx) Atmatzidis

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