Hcl and Oklch color space hue interpolation takes a method argument.

kohler · Nov 5, 2023 · f41caef · f41caef
1 parent 1e4e645
commit f41caef
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Showing 4 changed files with 64 additions and 19 deletions.
diff --git a/lib/hclcolor.php b/lib/hclcolor.php
@@ -49,18 +49,63 @@ function darker($k = null) {
         return new HclColor($this->h, $this->c, $this->l - LabColor::K * ($k ?? 1));
     }
 
+    /** @param float $h1
+     * @param float $h2
+     * @param null|'shorter'|'longer'|'increasing'|'decreasing' $method
+     * @return float */
+    static function hue_interpolate($h1, $h2, $method = null) {
+        if (is_float($method)) {
+            return $method;
+        }
+        if (is_nan($h1)) {
+            $h1 = is_nan($h2) ? 0.0 : $h2;
+        }
+        if (is_nan($h2)) {
+            $h2 = $h1;
+        }
+        if ($h1 >= 0 && $h1 < 360) {
+            $nh1 = $h1;
+        } else if (($nh1 = fmod($h1, 360.0)) < 0) {
+            $nh1 += 360.0;
+        }
+        if ($h2 >= 0 && $h2 < 360) {
+            $nh2 = $h2;
+        } else if (($nh2 = fmod($h2, 360.0)) < 0) {
+            $nh2 += 360.0;
+        }
+        $dinc = $nh2 > $nh1 ? $nh2 - $nh1 : $nh2 + 360.0 - $nh1;
+        $ddec = $nh1 > $nh2 ? $nh2 - $nh1 : $nh2 - 360.0 - $nh1;
+        if ($method === null || $method === "shorter") {
+            if ($dinc < -$ddec || ($dinc === -$ddec && $h1 < $h2)) {
+                return $dinc;
+            } else {
+                return $ddec;
+            }
+        } else if ($method === "longer") {
+            if ($nh1 === $nh2) {
+                return $h1 <= $h2 ? 360.0 : -360.0;
+            } else if ($dinc > -$ddec || ($dinc === -$ddec && $h1 < $h2)) {
+                return $dinc;
+            } else {
+                return $ddec;
+            }
+        } else if ($method === "increasing") {
+            return $dinc;
+        } else {
+            return $ddec;
+        }
+    }
+
     /** @param float $f
      * @param HclColor $end
+     * @param null|float|'shorter'|'longer'|'increasing'|'decreasing' $hue_method
      * @return HclColor */
-    function interpolate($f, $end) {
-        $d = $end->h - $this->h;
-        if ($d && $d === $d) {
-            if ($d > 180 || $d < -180) {
-                $d -= 360 * round($d / 360);
-            }
-            $h = $this->h + $f * $d;
+    function interpolate($f, $end, $hue_method = null) {
+        if (is_nan($this->h)) {
+            $h = $end->h;
         } else {
-            $h = is_nan($this->h) ? $end->h : $this->h;
+            $dh = is_float($hue_method) ? $hue_method : self::hue_interpolate($this->h, $end->h, $hue_method);
+            $h = $this->h + $dh * $f;
         }
 
         $d = $end->c - $this->c;

diff --git a/lib/labcolor.php b/lib/labcolor.php
@@ -81,7 +81,8 @@ function rgb() {
 
     /** @return string */
     function hashcolor() {
-        return sprintf("#%02X%02X%02X", ...$this->rgb());
+        $rgb = $this->rgb();
+        return sprintf("#%02X%02X%02X", round($rgb[0]), round($rgb[1]), round($rgb[2]));
     }
 
     /** @return HclColor */
@@ -99,7 +100,7 @@ static function rgb2lrgb($x) {
     /** @param float $lx
      * @return float */
     static function lrgb2rgb($lx) {
-        return 255 * ($lx <= 0.0031308 ? $lx * 12.92 : 1.055 * pow($lx, 1 / 2.4) - 0.055);
+        return 255 * ($lx <= 0.0031308 ? max($lx, 0) * 12.92 : 1.055 * pow($lx, 1 / 2.4) - 0.055);
     }
 
     /** @param float $t

diff --git a/lib/oklabcolor.php b/lib/oklabcolor.php
@@ -77,7 +77,8 @@ function rgb() {
 
     /** @return string */
     function hashcolor() {
-        return sprintf("#%02X%02X%02X", ...$this->rgb());
+        $rgb = $this->rgb();
+        return sprintf("#%02X%02X%02X", round($rgb[0]), round($rgb[1]), round($rgb[2]));
     }
 
     /** @return OklchColor */

diff --git a/lib/oklchcolor.php b/lib/oklchcolor.php
@@ -51,16 +51,14 @@ function darker($k = null) {
 
     /** @param float $f
      * @param OklchColor $end
+     * @param null|float|'shorter'|'longer'|'increasing'|'decreasing' $hue_method
      * @return OklchColor */
-    function interpolate($f, $end) {
-        $d = $end->okh - $this->okh;
-        if ($d && $d === $d) {
-            if ($d > 180 || $d < -180) {
-                $d -= 360 * round($d / 360);
-            }
-            $h = $this->okh + $f * $d;
+    function interpolate($f, $end, $hue_method = null) {
+        if (is_nan($this->okh)) {
+            $h = $end->okh;
         } else {
-            $h = is_nan($this->okh) ? $end->okh : $this->okh;
+            $dh = is_float($hue_method) ? $hue_method : HclColor::hue_interpolate($this->okh, $end->okh, $hue_method);
+            $h = $this->okh + $dh * $f;
         }
 
         $d = $end->okc - $this->okc;