module gx pub const ( black = Color{ r: 0 g: 0 b: 0 } gray = Color{ r: 128 g: 128 b: 128 } white = Color{ r: 255 g: 255 b: 255 } red = Color{ r: 255 g: 0 b: 0 } green = Color{ r: 0 g: 255 b: 0 } blue = Color{ r: 0 g: 0 b: 255 } yellow = Color{ r: 255 g: 255 b: 0 } magenta = Color{ r: 255 g: 0 b: 255 } cyan = Color{ r: 0 g: 255 b: 255 } orange = Color{ r: 255 g: 165 b: 0 } purple = Color{ r: 128 g: 0 b: 128 } indigo = Color{ r: 75 g: 0 b: 130 } pink = Color{ r: 255 g: 192 b: 203 } violet = Color{ r: 238 g: 130 b: 238 } dark_blue = Color{ r: 0 g: 0 b: 139 } dark_gray = Color{ r: 169 g: 169 b: 169 } dark_green = Color{ r: 0 g: 100 b: 0 } dark_red = Color{ r: 139 g: 0 b: 0 } light_blue = Color{ r: 173 g: 216 b: 230 } light_gray = Color{ r: 211 g: 211 b: 211 } light_green = Color{ r: 144 g: 238 b: 144 } light_red = Color{ r: 255 g: 204 b: 203 } ) // Color represents a 32 bit color value in sRGB format pub struct Color { pub mut: r byte g byte b byte a byte = 255 } // hex takes in a 32 bit integer and splits it into 4 byte values pub fn hex(color int) Color { return Color{ r: byte((color >> 24) & 0xFF) g: byte((color >> 16) & 0xFF) b: byte((color >> 8) & 0xFF) a: byte(color & 0xFF) } } pub fn rgb(r byte, g byte, b byte) Color { return Color{ r: r g: g b: b } } pub fn rgba(r byte, g byte, b byte, a byte) Color { return Color{ r: r g: g b: b a: a } } // + adds `b` to `a`, with a maximum value of 255 for each channel pub fn (a Color) + (b Color) Color { mut na := int(a.a) + b.a mut nr := int(a.r) + b.r mut ng := int(a.g) + b.g mut nb := int(a.b) + b.b if na > 255 { na = 255 } if nr > 255 { nr = 255 } if ng > 255 { ng = 255 } if nb > 255 { nb = 255 } return Color{ r: byte(nr) g: byte(ng) b: byte(nb) a: byte(na) } } // - subtracts `b` from `a`, with a minimum value of 0 for each channel pub fn (a Color) - (b Color) Color { mut na := if a.a > b.a { a.a } else { b.a } mut nr := int(a.r) - b.r mut ng := int(a.g) - b.g mut nb := int(a.b) - b.b if na < 0 { na = 0 } if nr < 0 { nr = 0 } if ng < 0 { ng = 0 } if nb < 0 { nb = 0 } return Color{ r: byte(nr) g: byte(ng) b: byte(nb) a: byte(na) } } pub fn (c Color) * (c2 Color) Color { return Color{ r: c.r * c2.r g: c.g * c2.g b: c.b * c2.b a: c.a * c2.a } } pub fn (c Color) / (c2 Color) Color { return Color{ r: c.r / c2.r g: c.g / c2.g b: c.b / c2.b a: c.a / c2.a } } // over - implements an `a` over `b` operation. // see https://keithp.com/~keithp/porterduff/p253-porter.pdf pub fn (a Color) over(b Color) Color { aa := f32(a.a) / 255 ab := f32(b.a) / 255 ar := aa + ab * (1 - aa) // rr := (f32(a.r) * aa + f32(b.r) * ab * (1 - aa)) / ar gr := (f32(a.g) * aa + f32(b.g) * ab * (1 - aa)) / ar br := (f32(a.b) * aa + f32(b.b) * ab * (1 - aa)) / ar return Color{ r: byte(rr) g: byte(gr) b: byte(br) a: byte(ar * 255) } } pub fn (c Color) eq(c2 Color) bool { return c.r == c2.r && c.g == c2.g && c.b == c2.b && c.a == c2.a } pub fn (c Color) str() string { return 'Color{$c.r, $c.g, $c.b, $c.a}' } // rgba8 - convert a color value to an int in the RGBA8 order. // see https://developer.apple.com/documentation/coreimage/ciformat [inline] pub fn (c Color) rgba8() int { return int(u32(c.r) << 24 | u32(c.g) << 16 | u32(c.b) << 8 | u32(c.a)) } // bgra8 - convert a color value to an int in the BGRA8 order. // see https://developer.apple.com/documentation/coreimage/ciformat [inline] pub fn (c Color) bgra8() int { return int(u32(c.b) << 24 | u32(c.g) << 16 | u32(c.r) << 8 | u32(c.a)) } // abgr8 - convert a color value to an int in the ABGR8 order. // see https://developer.apple.com/documentation/coreimage/ciformat [inline] pub fn (c Color) abgr8() int { return int(u32(c.a) << 24 | u32(c.b) << 16 | u32(c.g) << 8 | u32(c.r)) } const ( string_colors = { 'blue': blue 'red': red 'green': green 'yellow': yellow 'orange': orange 'purple': purple 'black': black 'gray': gray 'indigo': indigo 'pink': pink 'violet': violet 'white': white 'dark_blue': dark_blue 'dark_gray': dark_gray 'dark_green': dark_green 'dark_red': dark_red 'light_blue': light_blue 'light_gray': light_gray 'light_green': light_green 'light_red': light_red } ) pub fn color_from_string(s string) Color { return gx.string_colors[s] } pub fn (c Color) to_css_string() string { return 'rgba($c.r,$c.g,$c.b,$c.a)' }