78 lines
1.8 KiB
Go
78 lines
1.8 KiB
Go
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package pixel
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import "image/color"
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// NRGBA represents a non-alpha-premultiplied RGBA color with components within range [0, 1].
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//
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// The difference between color.NRGBA is that the value range is [0, 1] and the values are floats.
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type NRGBA struct {
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R, G, B, A float64
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}
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// Add adds color d to color c component-wise and returns the result (the components are not clamped).
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func (c NRGBA) Add(d NRGBA) NRGBA {
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return NRGBA{
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R: c.R + d.R,
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G: c.G + d.G,
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B: c.B + d.B,
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A: c.A + d.A,
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}
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}
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// Sub subtracts color d from color c component-wise and returns the result (the components are not clamped).
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func (c NRGBA) Sub(d NRGBA) NRGBA {
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return NRGBA{
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R: c.R - d.R,
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G: c.G - d.G,
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B: c.B - d.B,
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A: c.A - d.A,
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}
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}
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// Mul multiplies color c by color d component-wise (the components are not clamped).
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func (c NRGBA) Mul(d NRGBA) NRGBA {
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return NRGBA{
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R: c.R * d.R,
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G: c.G * d.G,
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B: c.B * d.B,
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A: c.A * d.A,
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}
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}
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// Scaled multiplies each component of color c by scale and returns the result (the components are not clamped).
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func (c NRGBA) Scaled(scale float64) NRGBA {
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return NRGBA{
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R: c.R * scale,
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G: c.G * scale,
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B: c.B * scale,
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A: c.A * scale,
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}
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}
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// RGBA returns alpha-premultiplied red, green, blue and alpha components of a color.
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func (c NRGBA) RGBA() (r, g, b, a uint32) {
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c.R = clamp(c.R, 0, 1)
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c.G = clamp(c.G, 0, 1)
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c.B = clamp(c.B, 0, 1)
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c.A = clamp(c.A, 0, 1)
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r = uint32(0xffff * c.R * c.A)
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g = uint32(0xffff * c.G * c.A)
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b = uint32(0xffff * c.B * c.A)
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a = uint32(0xffff * c.A)
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return
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}
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// NRGBAModel converts colors to NRGBA format.
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var NRGBAModel = color.ModelFunc(func(c color.Color) color.Color {
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r, g, b, a := c.RGBA()
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if a == 0 {
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return NRGBA{0, 0, 0, 0}
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}
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return NRGBA{
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float64(r) / float64(a),
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float64(g) / float64(a),
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float64(b) / float64(a),
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float64(a) / 0xffff,
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}
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})
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