Implement new method ColorInterface::isClear() (#1387)

src/Colors/Cmyk/Color.php

@@ -152,4 +152,14 @@ class Color extends AbstractColor
     {
         return false;
     }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::isClear()
+     */
+    public function isClear(): bool
+    {
+        return false;
+    }
 }

src/Colors/Hsl/Color.php

@@ -120,4 +120,14 @@ class Color extends AbstractColor
     {
         return false;
     }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::isClear()
+     */
+    public function isClear(): bool
+    {
+        return false;
+    }
 }

src/Colors/Hsv/Color.php

@@ -120,4 +120,14 @@ class Color extends AbstractColor
     {
         return false;
     }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::isClear()
+     */
+    public function isClear(): bool
+    {
+        return false;
+    }
 }

src/Colors/Rgb/Color.php

@@ -178,4 +178,14 @@ class Color extends AbstractColor
     {
         return $this->alpha()->value() < $this->alpha()->max();
     }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @see ColorInterface::isClear()
+     */
+    public function isClear(): bool
+    {
+        return $this->alpha()->value() == 0;
+    }
 }

src/Interfaces/ColorInterface.php

@@ -97,4 +97,11 @@ interface ColorInterface
      * @return bool
      */
     public function isTransparent(): bool;
+
+    /**
+     * Determine whether the current color is completely transparent
+     *
+     * @return bool
+     */
+    public function isClear(): bool;
 }

tests/Unit/Colors/Cmyk/ColorTest.php

@@ -111,4 +111,10 @@ final class ColorTest extends BaseTestCase
         $color = new Color(100, 50, 50, 0);
         $this->assertFalse($color->isTransparent());
     }
+
+    public function testIsClear(): void
+    {
+        $color = new Color(0, 0, 0, 0);
+        $this->assertFalse($color->isClear());
+    }
 }

tests/Unit/Colors/Hsl/ColorTest.php

@@ -108,4 +108,10 @@ final class ColorTest extends BaseTestCase
         $color = new Color(0, 1, 0);
         $this->assertFalse($color->isTransparent());
     }
+
+    public function testIsClear(): void
+    {
+        $color = new Color(0, 1, 0);
+        $this->assertFalse($color->isClear());
+    }
 }

tests/Unit/Colors/Hsv/ColorTest.php

@@ -108,4 +108,10 @@ final class ColorTest extends BaseTestCase
         $color = new Color(1, 0, 0);
         $this->assertFalse($color->isTransparent());
     }
+
+    public function testIsClear(): void
+    {
+        $color = new Color(0, 1, 0);
+        $this->assertFalse($color->isClear());
+    }
 }

tests/Unit/Colors/Rgb/ColorTest.php

@@ -163,4 +163,19 @@ final class ColorTest extends BaseTestCase
         $color = new Color(255, 255, 255, 0);
         $this->assertTrue($color->isTransparent());
     }
+
+    public function testIsClear(): void
+    {
+        $color = new Color(255, 255, 255);
+        $this->assertFalse($color->isClear());
+
+        $color = new Color(255, 255, 255, 255);
+        $this->assertFalse($color->isClear());
+
+        $color = new Color(255, 255, 255, 85);
+        $this->assertFalse($color->isClear());
+
+        $color = new Color(255, 255, 255, 0);
+        $this->assertTrue($color->isClear());
+    }
 }