39 lines
976 B
Go
39 lines
976 B
Go
package ucolor
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import "image/color"
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// Transparent returns whether or not a color has transparency.
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func Transparent (c color.Color) bool {
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_, _, _, a := c.RGBA()
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return a != 0xFFFF
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}
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// ToRGBA converts any color to a color.RGBA value.
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func ToRGBA (c color.Color) color.RGBA {
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r, g, b, a := c.RGBA()
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return color.RGBA {
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uint8(r >> 8),
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uint8(g >> 8),
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uint8(b >> 8),
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uint8(a >> 8),
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}
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}
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// Premultiply applies alpha-premultiplication that colors must apply as per
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// color.Color.RGBA. This is an intrinsically lossy proccess.
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func Premultiply (ur, ug, ub, ua uint32) (r, g, b, a uint32) {
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return (ur * ua) / 0xFFFF,
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(ug * ua) / 0xFFFF,
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(ub * ua) / 0xFFFF,
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ua
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}
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// Unpremultiply reverses alpha-premultiplication that colors must apply as per
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// color.Color.RGBA. This may or may not return the precise original color.
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func Unpremultiply (r, g, b, a uint32) (ur, ug, ub, ua uint32) {
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return (r / a) * 0xFFFF,
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(g / a) * 0xFFFF,
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(b / a) * 0xFFFF,
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a
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}
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