Fix RANDR’s gamma_to_ramp().
In order to generate a 256-entry ramp in [0,65535] which covers the full range, one must mupliply eight-bit values not by 256 but rather by 257. Many years back – well before the RANDR extension was written, and before xorg@fdo – a similar bug fix was made to the DIX for converting client-supplied eight-bit color values into sixteen-bit values. Noticed by: Elle Stone and Graeme Gill. Signed-off-by: James Cloos <cloos@jhcloos.com>
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@ -1679,11 +1679,11 @@ gamma_to_ramp(float gamma, CARD16 *ramp, int size)
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for (i = 0; i < size; i++) {
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if (gamma == 1.0)
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ramp[i] = i << 8;
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ramp[i] = i | i << 8;
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else
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ramp[i] =
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(CARD16) (pow((double) i / (double) (size - 1), 1. / gamma)
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* (double) (size - 1) * 256);
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* (double) (size - 1) * 257);
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}
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}
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