* fix wrong handling of values outside scale domain due to internal M…

…ath.pow usage. See [Issue 331](gka#331) Signed-off-by: regorxxx <[email protected]>
regorxxx · Mar 10, 2024 · 3b85a96 · 3b85a96
1 parent 295dbab
commit 3b85a96
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diff --git a/src/generator/scale.js b/src/generator/scale.js
@@ -109,7 +109,9 @@ module.exports = function(colors) {
             t = tMapLightness(t);  // lightness correction
         }
 
-        if (_gamma !== 1) { t = pow(t, _gamma); }
+        if (t > 1) { t = 1; } // pow fails with negative bases, but values are always clamped to the extremes
+        else if (t < 0) { t = 0 }
+        else if (_gamma !== 1) { t = pow(t, _gamma); }
 
         t = _padding[0] + (t * (1 - _padding[0] - _padding[1]));
 

diff --git a/test/scales.test.js b/test/scales.test.js
@@ -275,5 +275,15 @@ vows
                 ) 
             }
         },
+
+        'scale domain': {
+            topic: {
+                f: scale(['white','black']).domain([1, 3]).gamma(1.1)
+            },
+            'should return left color within domain'(topic) { assert.equal(topic.f(1).hex(), '#ffffff'); },
+            'should return right color within domain'(topic) { assert.equal(topic.f(3).hex(), '#000000'); },
+            'should return left color outside domain'(topic) { assert.equal(topic.f(0).hex(), '#ffffff'); },
+            'should return right color outside domain'(topic) { assert.equal(topic.f(4).hex(), '#000000'); }
+        },
 
     }).export(module);