Implement LimitColors

Author: Jakub Caban

README.md

@@ -46,6 +46,7 @@ $manager = new ImageManager(['driver' => 'vips']);
 - [x] InsertCommand
 - [x] InterlaceCommand
 - [x] InvertCommand
+- [x] LimitColorsCommand
 - [x] MaskCommand
 - [x] OpacityCommand
 - [x] PickColorCommand
@@ -58,7 +59,6 @@ $manager = new ImageManager(['driver' => 'vips']);
 - [x] SharpenCommand
 - [x] TrimCommand
 - [x] WidenCommand
-- [ ] LimitColorsCommand
 
 ### Shapes
 

src/Commands/LimitColorsCommand.php

@@ -4,19 +4,85 @@
 
 namespace Intervention\Image\Vips\Commands;
 
-use Intervention\Image\Exception\NotSupportedException;
+use Intervention\Image\Vips\Color;
+use Jcupitt\Vips\BlendMode;
+use Jcupitt\Vips\Image;
 
 class LimitColorsCommand extends AbstractCommand
 {
     /**
      * Execute the command.
      *
      * @param  \Intervention\Image\Image  $image
-     * @return void
-     * @throws \Intervention\Image\Exception\NotSupportedException
+     * @return bool
      */
     public function execute($image)
     {
-        throw new NotSupportedException('LimitColors command is not supported by VIPS driver.');
+        $count = $this->argument(0)->type('int')->value();
+        $matte = $this->argument(1)->value();
+
+        $bits = 8;
+        if ($count < 3) {
+            $bits = 1;
+        } elseif ($count < 5) {
+            $bits = 2;
+        } elseif ($count < 17) {
+            $bits = 4;
+        }
+
+        return $this->handleCommand(
+            function () use ($image, $bits, $matte) {
+                /** @var Image $core */
+                $core = $image->getCore();
+
+                $alpha = null;
+                if($core->hasAlpha()) {
+                    $alpha = $this->extractAlphaChannel($core);
+                    $core = $this->flattenImage($core);
+                }
+
+                if($matte) {
+                    $matteColor = new Color($matte);
+
+                    $canvas = $image->getDriver()->newImage(
+                        $core->width,
+                        $core->height,
+                        $matteColor->getRgba()
+                    );
+
+                    $buffer = $core->pngsave_buffer(
+                        [
+                            'palette' => true,
+                            'bitdepth' => $bits,
+                            'dither' => 0.5,
+                            'Q' => 90,
+                        ]
+                    );
+                    $core = Image::pngload_buffer($buffer);
+                    if($alpha) {
+                        $core = $core->bandjoin($alpha);
+                    }
+
+                    $canvas = $canvas->getCore()->composite2($core, BlendMode::OVER);
+
+                    $image->setCore($canvas);
+                } else {
+                    $buffer = $core->pngsave_buffer(
+                        [
+                            'palette' => true,
+                            'bitdepth' => $bits,
+                            'dither' => 0.5,
+                            'Q' => 90,
+                        ]
+                    );
+                    $core = Image::pngload_buffer($buffer);
+                    if ($alpha) {
+                        $core = $core->bandjoin($alpha);
+                    }
+
+                    $image->setCore($core);
+                }
+            }
+        );
     }
 }