Merge pull request #92 from danielebarbaro/fix-contrast-tests

Test Enhancements for Contrast Calculations (and mini refactor for contrast class)
spatie · Dec 23, 2024 · e0cdcdb · e0cdcdb
2 parents dde546a + fe44719
commit e0cdcdb
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Showing 3 changed files with 35 additions and 23 deletions.
diff --git a/src/Contrast.php b/src/Contrast.php
@@ -6,28 +6,25 @@ class Contrast
 {
     public static function ratio(Color $a, Color $b): float
     {
-        if (! $a instanceof Hex) {
-            $a = $a->toHex();
-        }
+        $a = $a instanceof Hex ? $a : $a->toHex();
+        $b = $b instanceof Hex ? $b : $b->toHex();
 
-        if (! $b instanceof Hex) {
-            $b = $b->toHex();
-        }
+        $l1 = self::calculateLuminance($a);
+        $l2 = self::calculateLuminance($b);
 
-        $l1 =
-            0.2126 * pow(hexdec($a->red()) / 255, 2.2) +
-            0.7152 * pow(hexdec($a->green()) / 255, 2.2) +
-            0.0722 * pow(hexdec($a->blue()) / 255, 2.2);
-
-        $l2 =
-            0.2126 * pow(hexdec($b->red()) / 255, 2.2) +
-            0.7152 * pow(hexdec($b->green()) / 255, 2.2) +
-            0.0722 * pow(hexdec($b->blue()) / 255, 2.2);
+        return round(
+            ($l1 > $l2)
+                ? ($l1 + 0.05) / ($l2 + 0.05)
+                : ($l2 + 0.05) / ($l1 + 0.05),
+            2
+        );
+    }
 
-        if ($l1 > $l2) {
-            return (float) (($l1 + 0.05) / ($l2 + 0.05));
-        } else {
-            return (float) (($l2 + 0.05) / ($l1 + 0.05));
-        }
+    public static function calculateLuminance(Hex $color): float
+    {
+        return
+            0.2126 * pow(hexdec($color->red()) / 255, 2.2) +
+            0.7152 * pow(hexdec($color->green()) / 255, 2.2) +
+            0.0722 * pow(hexdec($color->blue()) / 255, 2.2);
     }
 }
diff --git a/tests/ContrastTest.php b/tests/ContrastTest.php
@@ -1,5 +1,6 @@
 <?php
 
+use Spatie\Color\Hex;
 use function PHPUnit\Framework\assertSame;
 
 use Spatie\Color\Color;
@@ -12,3 +13,17 @@
 it('can calculate contrast from another format', function (Color $a, Color $b, float $contrast) {
     assertSame($contrast, Contrast::ratio($a->toRgba(), $b->toHsl()));
 })->with('contrast_colors');
+
+it('calculates the luminance correctly for a white color', function () {
+    $white = Hex::fromString('#FFFFFF');
+    $luminance = Contrast::calculateLuminance($white);
+
+    expect($luminance)->toBe(1.0);
+});
+
+it('calculates the luminance correctly for a black color', function () {
+    $black = Hex::fromString('#000000');
+    $luminance = Contrast::calculateLuminance($black);
+
+    expect($luminance)->toBe(0.0);
+});
diff --git a/tests/Datasets/Colors.php b/tests/Datasets/Colors.php
@@ -69,9 +69,9 @@
     [Hex::fromString('#ffffff'), Hex::fromString('#ffffff'), 1.0],
     [Hex::fromString('#ffffff'), Hex::fromString('#000000'), 21.0],
     [Hex::fromString('#000000'), Hex::fromString('#000000'), 1.0],
-    [Hex::fromString('#faebd7'), Hex::fromString('#8a2be2'), 5.0],
-    [Hex::fromString('#ff1493'), Hex::fromString('#cd5c5c'), 1.0],
-    [Hex::fromString('#f0fff0'), Hex::fromString('#191970'), 15.0],
+    [Hex::fromString('#faebd7'), Hex::fromString('#8a2be2'), 5.16],
+    [Hex::fromString('#ff1493'), Hex::fromString('#cd5c5c'), 1.08],
+    [Hex::fromString('#f0fff0'), Hex::fromString('#191970'), 15.05],
 ]);
 
 dataset('hsla_string_and_rgb_values', function () {