Make GD's alpha consistent with other engines #10
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GD expects alpha values to be 0-127, with 0 being opaque and 127 being transparent (7-bit little-endian). Everything else uses 0 as transparent and 255 as opaque (8-bit big-endian). This change converts 8-bit big-endian inputs to 7-bit little-endian when used by GD. This change will be backwards incompatible, and may confuse people who already know GD handles alpha this way, but it makes ngx_small_light more consistent to use (and means users can swap engines more easily).
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Hi, @SteveMarshall Tnanks for submmitting your patch. Though I checked your patch and recognized GD's alpha channel problem, And I don't know how to convert an alpha-value which range is 0 Do you have any idea? |
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I think the inconsistency between engines is actually because the other engines aren't using the alpha channel properly. When I use With |
GD expects alpha values to be 0-127, with 0 being opaque and 127 being transparent (7-bit little-endian). Everything else uses 0 as transparent and 255 as opaque (8-bit big-endian). This change converts 8-bit big-endian inputs to 7-bit little-endian when used by GD.
This change will be backwards incompatible, and may confuse people who already know GD handles alpha this way, but it makes ngx_small_light more consistent to use (and means users can swap engines more easily).
This fixes #9.