[mapguide-users] Theme layer application - degraded color

[Kenneth Skovhede, GEOGRAF A/S]

A simple approach would be to calculate the number of increments (ea 
number of colors).
Then for each R,G,B component of the start and end color, calculate the 
difference, and divide by number of increments.
With this information you can construct each of the desired colors.
Example:
Start color: 200,100,50
End color: 50, 200, 100
Steps: 10
Increments: (200-50)/10=-15, (100-200)/10=10,(50-100)/10=-5

Color x: 200 + (-15 * x), 100 + (10 * x), 50 + (-5 * x)

Rounding and other annoying stuff obviously plays in, and needs to be 
handled.

A more elegant approach would be to use the ColorBrewer system:
http://www.personal.psu.edu/cab38/ColorBrewer/ColorBrewer_intro.html

This system takes into account the type of data you are trying to visualize.

Regards, Kenneth Skovhede, GEOGRAF A/S



Arnaud De Groof skrev:
>
> Hi,
>
>  
>
> I use the theme layer application (PHP) and I would like apply a 
> degraded color to the layer according the value. Currently, when I use 
> this application the color is given randomly. Could you explain me the 
> process to obtain a degraded color with this function?
>
>  
>
> Thanks,
>
>  
>
> Arnaud De Groof
>
>  
>
> *
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