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Added small note to ThemeModern::calcLuminance

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svn-id: r25472
This commit is contained in:
Max Horn 2007-02-10 18:09:13 +00:00
parent 9dbf7d271b
commit a14e90478c
1 changed files with 4 additions and 0 deletions
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4
gui/ThemeModern.cpp
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@ -1454,6 +1454,10 @@ OverlayColor ThemeModern::calcLuminance(OverlayColor col) {
uint8 r, g, b;
_system->colorToRGB(col, r, g, b);
// A better (but slower) formula to calculate the luminance would be:
//uint lum = (byte)((0.299 * r + 0.587 * g + 0.114 * b) + 0.5);
// Note that the approximation below will only produce values between
// (and including) 0 and 221.
uint lum = (r >> 2) + (g >> 1) + (b >> 3);
return _system->RGBToColor(lum, lum, lum);