limage - lcolor/rgb.go

     1  package lcolor // import "vimagination.zapto.org/limage/lcolor"
     2  
     3  import "image/color"
     4  
     5  // RGB is a standard colour type whose Alpha channel is always full
     6  type RGB struct {
     7  	R, G, B uint8
     8  }
     9  
    10  // RGBA implements the color.Color interface
    11  func (rgb RGB) RGBA() (r, g, b, a uint32) {
    12  	r = uint32(rgb.R)
    13  	r |= r << 8
    14  	g = uint32(rgb.G)
    15  	g |= g << 8
    16  	b = uint32(rgb.B)
    17  	b |= b << 8
    18  	return r, g, b, 0xFFFF
    19  }
    20  
    21  // ToNRGBA returns itself as a non-alpha-premultiplied value
    22  // As the alpha is always full, this only returns the normal values
    23  func (rgb RGB) ToNRGBA() color.NRGBA64 {
    24  	r := uint16(rgb.R)
    25  	r |= r << 8
    26  	g := uint16(rgb.G)
    27  	g |= g << 8
    28  	b := uint16(rgb.B)
    29  	b |= b << 8
    30  	return color.NRGBA64{r, g, b, 0xffff}
    31  }
    32  
    33  func rgbColourModel(c color.Color) color.Color {
    34  	r, g, b, _ := c.RGBA()
    35  	return RGB{
    36  		R: uint8(r >> 8),
    37  		G: uint8(g >> 8),
    38  		B: uint8(b >> 8),
    39  	}
    40  }
    41