Implement color limit for Bitmap encoders

src/Drivers/Abstract/AbstractImage.php

@@ -84,16 +84,16 @@ public function toPng(int $color_limit = 0): EncodedImage
         );
     }
 
-    public function toBitmap(): EncodedImage
+    public function toBitmap(int $color_limit = 0): EncodedImage
     {
         return $this->encode(
-            $this->resolveDriverClass('Encoders\BmpEncoder')
+            $this->resolveDriverClass('Encoders\BmpEncoder', $color_limit)
         );
     }
 
-    public function toBmp(): EncodedImage
+    public function toBmp(int $color_limit = 0): EncodedImage
     {
-        return $this->toBitmap();
+        return $this->toBitmap($color_limit);
     }
 
     public function toAvif(): EncodedImage

src/Drivers/Gd/Encoders/BmpEncoder.php

@@ -3,16 +3,25 @@
 namespace Intervention\Image\Drivers\Gd\Encoders;
 
 use Intervention\Image\Drivers\Abstract\Encoders\AbstractEncoder;
+use Intervention\Image\Drivers\Gd\Traits\CanReduceColors;
 use Intervention\Image\EncodedImage;
 use Intervention\Image\Interfaces\EncoderInterface;
 use Intervention\Image\Interfaces\ImageInterface;
 
 class BmpEncoder extends AbstractEncoder implements EncoderInterface
 {
+    use CanReduceColors;
+
+    public function __construct(protected int $color_limit = 0)
+    {
+        //
+    }
+
     public function encode(ImageInterface $image): EncodedImage
     {
-        $data = $this->getBuffered(function () use ($image) {
-            imagebmp($image->frame()->core(), null, false);
+        $gd = $this->maybeReduceColors($image->frame()->core(), $this->color_limit);
+        $data = $this->getBuffered(function () use ($gd) {
+            imagebmp($gd, null, false);
         });
 
         return new EncodedImage($data, 'image/bmp');

src/Drivers/Imagick/Encoders/BmpEncoder.php

@@ -4,12 +4,20 @@
 
 use Imagick;
 use Intervention\Image\Drivers\Abstract\Encoders\AbstractEncoder;
+use Intervention\Image\Drivers\Imagick\Traits\CanReduceColors;
 use Intervention\Image\EncodedImage;
 use Intervention\Image\Interfaces\EncoderInterface;
 use Intervention\Image\Interfaces\ImageInterface;
 
 class BmpEncoder extends AbstractEncoder implements EncoderInterface
 {
+    use CanReduceColors;
+
+    public function __construct(protected int $color_limit = 0)
+    {
+        //
+    }
+
     public function encode(ImageInterface $image): EncodedImage
     {
         $format = 'bmp';
@@ -20,6 +28,7 @@ public function encode(ImageInterface $image): EncodedImage
         $imagick->setImageFormat($format);
         $imagick->setCompression($compression);
         $imagick->setImageCompression($compression);
+        $this->maybeReduceColors($imagick, $this->color_limit);
 
         return new EncodedImage($imagick->getImagesBlob(), 'image/bmp');
     }

src/Interfaces/ImageInterface.php

@@ -137,6 +137,13 @@ public function toAvif(): EncodedImage;
      */
     public function toPng(int $color_limit = 0): EncodedImage;
 
+    /**
+     * Encode image to Windows Bitmap
+     *
+     * @return EncodedImage
+     */
+    public function toBitmap(int $color_limit = 0): EncodedImage;
+
     /**
      * Return color of pixel at given position on given frame position
      *

tests/Drivers/Gd/Encoders/BmpEncoderTest.php

@@ -12,7 +12,7 @@
 
 /**
  * @requires extension gd
- * @covers \Intervention\Image\Drivers\Gd\Encoders\PngEncoder
+ * @covers \Intervention\Image\Drivers\Gd\Encoders\BmpEncoder
  */
 class BmpEncoderTest extends TestCase
 {
@@ -28,6 +28,6 @@ public function testEncode(): void
         $image = $this->getTestImage();
         $encoder = new BmpEncoder();
         $result = $encoder->encode($image);
-        $this->assertTrue(MimeSniffer::createFromString($result)->matches(new ImageBmp));
+        $this->assertTrue(MimeSniffer::createFromString($result)->matches(ImageBmp::class));
     }
 }

tests/Drivers/Imagick/Encoders/BmpEncoderTest.php

@@ -7,6 +7,7 @@
 use Intervention\Image\Drivers\Imagick\Encoders\BmpEncoder;
 use Intervention\Image\Drivers\Imagick\Image;
 use Intervention\Image\Tests\TestCase;
+use Intervention\Image\Tests\Traits\CanCreateImagickTestImage;
 use Intervention\MimeSniffer\MimeSniffer;
 use Intervention\MimeSniffer\Types\ImageBmp;
 
@@ -16,6 +17,8 @@
  */
 class BmpEncoderTest extends TestCase
 {
+    use CanCreateImagickTestImage;
+
     protected function getTestImage(): Image
     {
         $imagick = new Imagick();
@@ -33,4 +36,16 @@ public function testEncode(): void
             MimeSniffer::createFromString($result)->matches(new ImageBmp())
         );
     }
+
+    public function testEncodeReduced(): void
+    {
+        $image = $this->createTestImage('gradient.bmp');
+        $imagick = $image->frame()->core();
+        $this->assertEquals(15, $imagick->getImageColors());
+        $encoder = new BmpEncoder(2);
+        $result = $encoder->encode($image);
+        $imagick = new Imagick();
+        $imagick->readImageBlob((string) $result);
+        $this->assertEquals(2, $imagick->getImageColors());
+    }
 }