[PD-dev] pd file format: color settings

[Martin Peach]

That formula should read:
  color = ([red] * 65536) + ([green] * 256) + ([blue])
In binary the idea is to shift the 8 'red' bits 16 to the left, then add 
8 'green' bits shifted 8 bits, and finally 8 'blue' bits, so in all 24 
bits are occupied.
Multiplying the blue value by -1 in the original formula has the effect 
of setting the 16 bits to the left of it to 1, so you get different 
shades of pure blue.

Martin

Robert Schwarz wrote:
> Hi all,
> 
> I recently tried writing patches in a text editor (or from scripts) and
> had problems getting the color settings right, for bang elements.
> 
> There is some documentation at
> http://puredata.info/docs/developer/fileformat
> with the explanation:
> 
>> Color: Some graphical elements have color attributes. Per color only
>> one signed integer value is stored that contains the three 8-bit
>> color components (RGB). Formula to calculate color attribute values:
>>
>> color = ( [red] * -65536) + ( [green] * -256) + ( [blue] * -1)
>>
>> Where [red], [green], [blue] obviously represent the three color
>> components, their values range from 0 to 255. They apply to the
>> attributes [background color], [front color], [label color] of
>> various elements.
> 
> I tried that, but it didn't work. Instead of showing the whole spectrum
> I just got different shades of blue. Also, when I opened one of my
> handwritten patches in PureData, looked at the color settings and saved,
> the resulting numbers changed. I assume that some kind of rounding is
> happening, and colors are actually saved in lower resolution.
> 
> Do you have any ideas?
> 
> Also, my application is a 13x13 button matrix, each triggering different
> chords via MIDI. The buttons should be color coded. Obviously, it's too
> much work setting all colors individually and I might want to create
> several of these patches with different colors.
> Maybe there is another obvious solution I didn't see.
> 
> Any help is appreciated!
> 
> (I'm using standard pd 0.42_5 on Arch Linux, but this shouldn't make a
> difference.)
>