Gradients

webcontroller/style_colors.go

@@ -0,0 +1,137 @@
+package webcontroller
+
+import (
+	"fmt"
+)
+
+type Color interface {
+	CSS() string
+}
+
+// Raw CSS
+type CSS string
+
+func (c CSS) CSS() string { return string(c) }
+
+const NoColor = CSS("none")
+
+// HSL color
+type hsl struct {
+	Hue        int
+	Saturation float64
+	Lightness  float64
+}
+
+func (orig hsl) RGB() string {
+	var r, g, b, q, p float64
+	var h, s, l = float64(orig.Hue) / 360, orig.Saturation, orig.Lightness
+
+	if s == 0 {
+		r, g, b = l, l, l
+	} else {
+		var hue2rgb = func(p, q, t float64) float64 {
+			if t < 0 {
+				t++
+			}
+			if t > 1 {
+				t--
+			}
+
+			if t < 1.0/6.0 {
+				return p + (q-p)*6*t
+			} else if t < 1.0/2.0 {
+				return q
+			} else if t < 2.0/3.0 {
+				return p + (q-p)*(2.0/3.0-t)*6
+			}
+			return p
+		}
+
+		if l < 0.5 {
+			q = l * (1 + s)
+		} else {
+			q = l + s - l*s
+		}
+
+		p = 2*l - q
+		r = hue2rgb(p, q, h+1.0/3.0)
+		g = hue2rgb(p, q, h)
+		b = hue2rgb(p, q, h-1.0/3.0)
+	}
+
+	return fmt.Sprintf("%02x%02x%02x", int(r*255), int(g*255), int(b*255))
+}
+func (orig hsl) CSS() string {
+	return "#" + orig.RGB()
+}
+
+// Add returns a NEW HSL struct, it doesn't modify the current one
+func (h hsl) Add(hue int, saturation float64, lightness float64) hsl {
+	var new = hsl{
+		h.Hue + hue,
+		h.Saturation + saturation,
+		h.Lightness + lightness,
+	}
+	// Hue bounds correction
+	if new.Hue < 0 {
+		new.Hue += 360
+	} else if new.Hue > 360 {
+		new.Hue -= 360
+	}
+	// Saturation bounds check
+	if new.Saturation < 0 {
+		new.Saturation = 0
+	} else if new.Saturation > 1 {
+		new.Saturation = 1
+	}
+	// Lightness bounds check
+	if new.Lightness < 0 {
+		new.Lightness = 0
+	} else if new.Lightness > 1 {
+		new.Lightness = 1
+	}
+
+	return new
+}
+
+type RGB struct {
+	R uint8
+	G uint8
+	B uint8
+}
+
+func (rgb RGB) CSS() string {
+	return fmt.Sprintf("#%02x%02x%02x", rgb.R, rgb.G, rgb.B)
+}
+
+type RGBA struct {
+	R uint8
+	G uint8
+	B uint8
+	A float64
+}
+
+func (rgba RGBA) CSS() string {
+	return fmt.Sprintf("rgba(%d, %d, %d, %f)", rgba.R, rgba.G, rgba.B, rgba.A)
+}
+
+type Gradient struct {
+	Angle  int
+	Colors []Color
+}
+
+func NewGradient(angle int, colors ...Color) Gradient {
+	return Gradient{angle, colors}
+}
+
+func (g Gradient) CSS() string {
+	var colors string
+	for i, color := range g.Colors {
+		if i != 0 {
+			colors += ", "
+		}
+		colors += color.CSS()
+	}
+
+	return fmt.Sprintf("linear-gradient(%ddeg, %s)", g.Angle, colors)
+}