Added colour mixing and various number funcs.

VERSION

@@ -1 +1 @@
-0.2309.112008
+0.2309.152202

src/Colour/Colour.php

@@ -1,11 +1,12 @@
 <?php
 // Colour.php
 // Created: 2023-01-02
-// Updated: 2023-01-02
+// Updated: 2023-09-15
 
 namespace Index\Colour;
 
 use Stringable;
+use Index\XNumber;
 
 abstract class Colour implements Stringable {
     public abstract function getRed(): int;
@@ -44,6 +45,24 @@ abstract class Colour implements Stringable {
         return self::$none;
     }
 
+    public static function mix(Colour $colour1, Colour $colour2, float $weight): Colour {
+        $weight = min(1, max(0, $weight));
+
+        if(XNumber::almostEquals($weight, 0.0))
+            return $colour1;
+        if(XNumber::almostEquals($weight, 1.0))
+            return $colour2;
+        if($colour1->shouldInherit() || $colour2->shouldInherit())
+            return self::none();
+
+        return new ColourRGB(
+            (int)round(XNumber::weighted($colour2->getRed(), $colour1->getRed(), $weight)),
+            (int)round(XNumber::weighted($colour2->getGreen(), $colour1->getGreen(), $weight)),
+            (int)round(XNumber::weighted($colour2->getBlue(), $colour1->getBlue(), $weight)),
+            XNumber::weighted($colour2->getAlpha(), $colour1->getAlpha(), $weight),
+        );
+    }
+
     private const MSZ_INHERIT = 0x40000000;
 
     public static function fromMisuzu(int $raw): Colour {

src/XNumber.php

@@ -0,0 +1,29 @@
+<?php
+// XNumber.php
+// Created: 2023-09-15
+// Updated: 2023-09-15
+
+namespace Index;
+
+use InvalidArgumentException;
+/**
+ * Provides various helper methods for numbers.
+ */
+final class XNumber {
+    public static function weighted(float $num1, float $num2, float $weight): float {
+        $weight = min(1, max(0, $weight));
+        return ($num1 * $weight) + ($num2 * (1 - $weight));
+    }
+
+    public static function almostEquals(float $value1, float $value2): bool {
+        return abs($value1 - $value2) <= PHP_FLOAT_EPSILON;
+    }
+
+    public static function easeInQuad(float $n): float {
+        return $n * $n;
+    }
+
+    public static function easeOutQuad(float $n): float {
+        return 1 - (1 - $n) * (1 - $n);
+    }
+}

tests/ColourTest.php

@@ -1,7 +1,7 @@
 <?php
 // ColourTest.php
 // Created: 2023-01-02
-// Updated: 2023-01-02
+// Updated: 2023-09-15
 
 declare(strict_types=1);
 
@@ -507,4 +507,46 @@ final class ColourTest extends TestCase {
         $this->assertEquals(140, $colour->getGreen());
         $this->assertEquals(166, $colour->getBlue());
     }
+
+    public function testMix(): void {
+        // none should always return none if involved...
+        $mixed = Colour::mix(Colour::none(), Colour::parse('lemonchiffon'), 0.243);
+        $this->assertTrue($mixed->shouldInherit());
+        $mixed = Colour::mix(Colour::parse('powderblue'), Colour::none(), 0.76);
+        $this->assertTrue($mixed->shouldInherit());
+
+        // ...unless absolute 0 or 1
+        $mixed = Colour::mix(Colour::none(), Colour::parse('lemonchiffon'), 1.0);
+        $this->assertFalse($mixed->shouldInherit());
+        $mixed = Colour::mix(Colour::parse('powderblue'), Colour::none(), 0.0);
+        $this->assertFalse($mixed->shouldInherit());
+
+        // probably a pretty naive test but its better than nothing
+        $mixed = Colour::mix(new ColourRGB(0, 100, 50), new ColourRGB(100, 0, 50), 0.5);
+        $this->assertEquals(50, $mixed->getRed());
+        $this->assertEquals(50, $mixed->getGreen());
+        $this->assertEquals(50, $mixed->getBlue());
+
+        // absolutes should return one of the args
+        $colour1 = Colour::parse('royalblue');
+        $colour2 = Colour::parse('tomato');
+
+        $this->assertSame($colour1, Colour::mix($colour1, $colour2, 0.0));
+        $this->assertSame($colour2, Colour::mix($colour1, $colour2, 1.0));
+
+        $mixed = Colour::mix($colour1, $colour2, 0.5);
+        $this->assertEquals(160, $mixed->getRed());
+        $this->assertEquals(102, $mixed->getGreen());
+        $this->assertEquals(148, $mixed->getBlue());
+
+        $mixed = Colour::mix($colour1, $colour2, 0.2);
+        $this->assertEquals(103, $mixed->getRed());
+        $this->assertEquals(104, $mixed->getGreen());
+        $this->assertEquals(194, $mixed->getBlue());
+
+        $mixed = Colour::mix($colour1, $colour2, 0.8);
+        $this->assertEquals(217, $mixed->getRed());
+        $this->assertEquals(100, $mixed->getGreen());
+        $this->assertEquals(102, $mixed->getBlue());
+    }
 }