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Support alpha channel in as-hex #203

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merged 6 commits into from
Apr 12, 2023
Merged

Support alpha channel in as-hex #203

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531a192
Support alpha channel in `as-hex`
Apr 11, 2023
e46932f
Add `rgba->hex` test
Apr 11, 2023
d287cfc
Add `hsla->rgba` test
Apr 11, 2023
81d1712
add `as-hex` test
Apr 11, 2023
72e0808
Cover case when `alpha` is one in `rgba->hex`
Apr 11, 2023
5f143ae
Add opaque hsla test
Apr 11, 2023
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50 changes: 46 additions & 4 deletions src/garden/color.cljc
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Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,12 @@
(and (map? color)
(every? color #{:red :green :blue})))

(defn rgba?
"Return true if color is an RGBA color."
[color]
(and (map? color)
(every? color #{:red :green :blue :alpha})))

(defn hsl?
"Return true if color is an HSL color."
[color]
Expand Down Expand Up @@ -140,6 +146,17 @@
(string/replace " " "0")))]
(apply str "#" (map hex-part [r g b]))))

(defn rgba->hex
"Convert an RGB color map to a hexadecimal color."
[{r :red g :green b :blue a :alpha}]
(letfn [(hex-part [v]
(-> (util/format "%2s" (util/int->string v 16))
(string/replace " " "0")))]
(str (apply str "#" (map hex-part [r g b]) )
(if (= 1 a)
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This is an interesting approach; I'm always skeptical of using = to compare floating point numbers, but in this case I think it's okay due to how rgba works (specifically, how it ensures 0 <= a <= 1).

👍

In particular, (rgba->hex {:red 0 :green 0 :blue 0 :alpha 1.5}) produces a confusing answer, but perhaps that's okay.

Changing this line to (if (>= a 1) ... is one possible consideration.

Good work, by the way, love to see this library living/impoved.

"ff"
(hex-part (int (* 256 a)))))))

(defn trim-one [x]
(if (< 1 x) 1 x))

Expand Down Expand Up @@ -186,6 +203,24 @@
(hue->rgb m1 m2 (- h (/ 1.0 3)))])]
(rgb [r g b]))))

(defn hsla->rgba
"Convert an HSLA color map to an RGBA color map."
[{:keys [hue saturation lightness alpha] :as color}]
(if (rgb? color)
color
(let [h (/ hue 360.0)
s (/ saturation 100.0)
l (/ lightness 100.0)
m2 (if (<= l 0.5)
(* l (inc s))
(- (+ l s) (* l s)))
m1 (- (* 2 l) m2)
[r g b] (map #(int (+ 0.5 (* % 0xff)))
[(hue->rgb m1 m2 (+ h (/ 1.0 3)))
(hue->rgb m1 m2 h)
(hue->rgb m1 m2 (- h (/ 1.0 3)))])]
(rgba [r g b alpha]))))

(defn- hue->rgb
[m1 m2 h]
(let [h (cond
Expand All @@ -203,6 +238,11 @@
[color]
(-> color hsl->rgb rgb->hex))

(defn hsla->hex
"Convert an HSLA color map to a hexadecimal string."
[color]
(-> color hsla->rgba rgb->hex))

(defn hex->hsl
"Convert a hexadecimal color to an HSL color."
[color]
Expand All @@ -223,10 +263,12 @@
"Convert a color to a hexadecimal string."
[x]
(cond
(hex? x) x
(rgb? x) (rgb->hex x)
(hsl? x) (hsl->hex x)
:else (throw (ex-info (str "Can't convert " x " to a color.") {}))))
(rgba? x) (rgba->hex x)
(hsla? x) (hsla->hex x)
(hex? x) x
(rgb? x) (rgb->hex x)
(hsl? x) (hsl->hex x)
:else (throw (ex-info (str "Can't convert " x " to a color.") {}))))

(defn as-rgb
"Convert a color to a RGB."
Expand Down
51 changes: 50 additions & 1 deletion test/garden/color_test.cljc
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Original file line number Diff line number Diff line change
Expand Up @@ -13,20 +13,44 @@
(def hex-blue "#0000ff")
(def hex-white "#ffffff")

(def hexa-opaque-black "#000000ff")
(def hexa-black "#00000080")
(def hexa-red "#ff000080")
(def hexa-green "#00ff0080")
(def hexa-blue "#0000ff80")
(def hexa-white "#ffffff80")


(def rgb-black (color/rgb 0 0 0))
(def rgb-red (color/rgb 255 0 0))
(def rgb-green (color/rgb 0 255 0))
(def rgb-blue (color/rgb 0 0 255))
(def rgb-white (color/rgb 255 255 255))
(def rgb-orange (color/rgb 255 133 27))

(def rgba-opaque-black (color/rgba 0 0 0 1))
(def rgba-black (color/rgba 0 0 0 0.5))
(def rgba-red (color/rgba 255 0 0 0.5))
(def rgba-green (color/rgba 0 255 0 0.5))
(def rgba-blue (color/rgba 0 0 255 0.5))
(def rgba-white (color/rgba 255 255 255 0.5))
(def rgba-orange (color/rgba 255 133 27 0.5))

(def hsl-black (color/hsl 0 0 0))
(def hsl-red (color/hsl 0 100 50))
(def hsl-green (color/hsl 120 100 50))
(def hsl-blue (color/hsl 240 100 50))
(def hsl-white (color/hsl 0 0 100))
(def hsl-orange (color/hsl 530/19 100 940/17))

(def hsla-opaque-black (color/hsla 0 0 0 1))
(def hsla-black (color/hsla 0 0 0 0.5))
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(def hsla-red (color/hsla 0 100 50 0.5))
(def hsla-green (color/hsla 120 100 50 0.5))
(def hsla-blue (color/hsla 240 100 50 0.5))
(def hsla-white (color/hsla 0 0 100 0.5))
(def hsla-orange (color/hsla 530/19 100 940/17 0.5))

(deftest color-conversion-test
(testing "hex->rgb"
(are [x y] (= x y)
Expand All @@ -43,6 +67,14 @@
(color/rgb->hex rgb-green) hex-green
(color/rgb->hex rgb-blue) hex-blue))

(testing "rgba->hex"
(are [x y] (= x y)
(color/rgba->hex rgba-opaque-black) hexa-opaque-black
(color/rgba->hex rgba-black) hexa-black
(color/rgba->hex rgba-red) hexa-red
(color/rgba->hex rgba-green) hexa-green
(color/rgba->hex rgba-blue) hexa-blue))

(testing "hsl->rgb"
(are [x y] (= x y)
(color/hsl->rgb hsl-black) rgb-black
Expand All @@ -51,14 +83,31 @@
(color/hsl->rgb hsl-blue) rgb-blue
(color/hsl->rgb hsl-white) rgb-white))

(testing "hsla->rgba"
(are [x y] (= x y)
(color/hsla->rgba hsla-opaque-black) rgba-opaque-black
(color/hsla->rgba hsla-black) rgba-black
(color/hsla->rgba hsla-red) rgba-red
(color/hsla->rgba hsla-green) rgba-green
(color/hsla->rgba hsla-blue) rgba-blue
(color/hsla->rgba hsla-white) rgba-white))

(testing "rgb->hsl"
(are [x y] (= x y)
(color/rgb->hsl rgb-black) hsl-black
(color/rgb->hsl rgb-red) hsl-red
(color/rgb->hsl rgb-green) hsl-green
(color/rgb->hsl rgb-blue) hsl-blue
(color/rgb->hsl rgb-white) hsl-white
(color/rgb->hsl rgb-orange) hsl-orange)))
(color/rgb->hsl rgb-orange) hsl-orange))

(testing "as-hex"
(are [x y] (= x y)
(color/as-hex rgba-black) hexa-black
(color/as-hex rgba-red) hexa-red
(color/as-hex rgba-green) hexa-green
(color/as-hex rgba-blue) hexa-blue
(color/as-hex rgba-white) hexa-white)))

(deftest color-math-test
(testing "color+"
Expand Down