Trim Modifier (#1322)

Co-authored-by: Sibin Grasic <sibin.grasic@oblak.studio>

src/Drivers/Gd/Modifiers/TrimModifier.php

@@ -0,0 +1,82 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Drivers\Gd\Modifiers;
+
+use Intervention\Image\Exceptions\AnimationException;
+use Intervention\Image\Exceptions\NotSupportedException;
+use Intervention\Image\Exceptions\RuntimeException;
+use Intervention\Image\Geometry\Point;
+use Intervention\Image\Interfaces\ImageInterface;
+use Intervention\Image\Interfaces\SpecializedInterface;
+use Intervention\Image\Modifiers\TrimModifier as GenericTrimModifier;
+
+class TrimModifier extends GenericTrimModifier implements SpecializedInterface
+{
+    public function apply(ImageInterface $image): ImageInterface
+    {
+        if ($image->isAnimated()) {
+            throw new NotSupportedException('Trim modifier cannot be applied to animated images.');
+        }
+
+        // apply tolerance with a min. value of .5 because the default tolerance of '0' should
+        // already trim away similar colors which is not the case with imagecropauto.
+        $trimmed = imagecropauto(
+            $image->core()->native(),
+            IMG_CROP_THRESHOLD,
+            max([.5, $this->tolerance / 10]),
+            $this->trimColor($image)
+        );
+
+        // if the tolerance is very high, it is possible that no image is left.
+        // imagick returns a 1x1 pixel image in this case. this does the same.
+        if ($trimmed === false) {
+            $trimmed = $this->driver()->createImage(1, 1)->core()->native();
+        }
+
+        $image->core()->setNative($trimmed);
+
+        return $image;
+    }
+
+    /**
+     * Create an average color from the colors of the four corner points of the given image
+     *
+     * @param ImageInterface $image
+     * @throws RuntimeException
+     * @throws AnimationException
+     * @return int
+     */
+    private function trimColor(ImageInterface $image): int
+    {
+        // trim color base
+        $red = 0;
+        $green = 0;
+        $blue = 0;
+
+        // corner coordinates
+        $size = $image->size();
+        $cornerPoints = [
+            new Point(0, 0),
+            new Point($size->width() - 1, 0),
+            new Point(0, $size->height() - 1),
+            new Point($size->width() - 1, $size->height() - 1),
+        ];
+
+        // create an average color to be used in trim operation
+        foreach ($cornerPoints as $pos) {
+            $cornerColor = imagecolorat($image->core()->native(), $pos->x(), $pos->y());
+            $rgb = imagecolorsforindex($image->core()->native(), $cornerColor);
+            $red += round(round(($rgb['red'] / 51)) * 51);
+            $green += round(round(($rgb['green'] / 51)) * 51);
+            $blue += round(round(($rgb['blue'] / 51)) * 51);
+        }
+
+        $red = (int) round($red / 4);
+        $green = (int) round($green / 4);
+        $blue = (int) round($blue / 4);
+
+        return imagecolorallocate($image->core()->native(), $red, $green, $blue);
+    }
+}

src/Drivers/Imagick/Modifiers/TrimModifier.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Drivers\Imagick\Modifiers;
+
+use Intervention\Image\Exceptions\NotSupportedException;
+use Intervention\Image\Interfaces\ImageInterface;
+use Intervention\Image\Interfaces\SpecializedInterface;
+use Intervention\Image\Modifiers\TrimModifier as GenericTrimModifier;
+
+class TrimModifier extends GenericTrimModifier implements SpecializedInterface
+{
+    public function apply(ImageInterface $image): ImageInterface
+    {
+        if ($image->isAnimated()) {
+            throw new NotSupportedException('Trim modifier cannot be applied to animated images.');
+        }
+
+        $imagick = $image->core()->native();
+        $imagick->trimImage(($this->tolerance / 100 * $imagick->getQuantum()) / 1.5);
+        $imagick->setImagePage(0, 0, 0, 0);
+
+        return $image;
+    }
+}

src/Image.php

@@ -88,6 +88,7 @@
 use Intervention\Image\Modifiers\SharpenModifier;
 use Intervention\Image\Modifiers\SliceAnimationModifier;
 use Intervention\Image\Modifiers\TextModifier;
+use Intervention\Image\Modifiers\TrimModifier;
 use Intervention\Image\Typography\FontFactory;
 
 final class Image implements ImageInterface
@@ -749,6 +750,16 @@ public function crop(
         return $this->modify(new CropModifier($width, $height, $offset_x, $offset_y, $background, $position));
     }
 
+    /**
+     * {@inheritdoc}
+     *
+     * @see ImageInterface::trim()
+     */
+    public function trim(int $tolerance = 0): ImageInterface
+    {
+        return $this->modify(new TrimModifier($tolerance));
+    }
+
     /**
      * {@inheritdoc}
      *

src/Interfaces/ImageInterface.php

@@ -6,6 +6,7 @@
 
 use Countable;
 use Intervention\Image\Encoders\AutoEncoder;
+use Intervention\Image\Exceptions\AnimationException;
 use Intervention\Image\Exceptions\RuntimeException;
 use Intervention\Image\Origin;
 use IteratorAggregate;
@@ -615,6 +616,16 @@ public function crop(
         string $position = 'top-left'
     ): self;
 
+    /**
+     * Trim the image by removing border areas of similar color within a the given tolerance
+     *
+     * @param int $tolerance
+     * @throws RuntimeException
+     * @throws AnimationException
+     * @return ImageInterface
+     */
+    public function trim(int $tolerance = 0): self;
+
     /**
      * Place another image into the current image instance
      *

src/Modifiers/TrimModifier.php

@@ -0,0 +1,14 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Modifiers;
+
+use Intervention\Image\Drivers\SpecializableModifier;
+
+class TrimModifier extends SpecializableModifier
+{
+    public function __construct(public int $tolerance = 0)
+    {
+    }
+}

tests/Unit/Drivers/Gd/Modifiers/TrimModifierTest.php

@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Unit\Drivers\Gd\Modifiers;
+
+use Intervention\Image\Exceptions\NotSupportedException;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\RequiresPhpExtension;
+use Intervention\Image\Modifiers\TrimModifier;
+use Intervention\Image\Tests\GdTestCase;
+
+#[RequiresPhpExtension('gd')]
+#[CoversClass(\Intervention\Image\Modifiers\TrimModifier::class)]
+#[CoversClass(\Intervention\Image\Drivers\Gd\Modifiers\TrimModifier::class)]
+final class TrimModifierTest extends GdTestCase
+{
+    public function testTrim(): void
+    {
+        $image = $this->readTestImage('trim.png');
+        $this->assertEquals(50, $image->width());
+        $this->assertEquals(50, $image->height());
+        $image->modify(new TrimModifier());
+        $this->assertEquals(28, $image->width());
+        $this->assertEquals(28, $image->height());
+    }
+
+    public function testTrimGradient(): void
+    {
+        $image = $this->readTestImage('radial.png');
+        $this->assertEquals(50, $image->width());
+        $this->assertEquals(50, $image->height());
+        $image->modify(new TrimModifier(50));
+        $this->assertEquals(35, $image->width());
+        $this->assertEquals(35, $image->height());
+    }
+
+    public function testTrimHighTolerance(): void
+    {
+        $image = $this->readTestImage('trim.png');
+        $this->assertEquals(50, $image->width());
+        $this->assertEquals(50, $image->height());
+        $image->modify(new TrimModifier(1000000));
+        $this->assertEquals(1, $image->width());
+        $this->assertEquals(1, $image->height());
+        $this->assertColor(255, 255, 255, 0, $image->pickColor(0, 0));
+    }
+
+    public function testTrimAnimated(): void
+    {
+        $image = $this->readTestImage('animation.gif');
+        $this->expectException(NotSupportedException::class);
+        $image->modify(new TrimModifier());
+    }
+}

tests/Unit/Drivers/Imagick/Modifiers/TrimModifierTest.php

@@ -0,0 +1,55 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Intervention\Image\Tests\Unit\Drivers\Imagick\Modifiers;
+
+use Intervention\Image\Exceptions\NotSupportedException;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\RequiresPhpExtension;
+use Intervention\Image\Modifiers\TrimModifier;
+use Intervention\Image\Tests\ImagickTestCase;
+
+#[RequiresPhpExtension('imagick')]
+#[CoversClass(\Intervention\Image\Modifiers\TrimModifier::class)]
+#[CoversClass(\Intervention\Image\Drivers\Imagick\Modifiers\TrimModifier::class)]
+final class TrimModifierTest extends ImagickTestCase
+{
+    public function testTrim(): void
+    {
+        $image = $this->readTestImage('trim.png');
+        $this->assertEquals(50, $image->width());
+        $this->assertEquals(50, $image->height());
+        $image->modify(new TrimModifier());
+        $this->assertEquals(28, $image->width());
+        $this->assertEquals(28, $image->height());
+    }
+
+    public function testTrimGradient(): void
+    {
+        $image = $this->readTestImage('radial.png');
+        $this->assertEquals(50, $image->width());
+        $this->assertEquals(50, $image->height());
+        $image->modify(new TrimModifier(50));
+        $this->assertEquals(29, $image->width());
+        $this->assertEquals(29, $image->height());
+    }
+
+    public function testTrimHighTolerance(): void
+    {
+        $image = $this->readTestImage('trim.png');
+        $this->assertEquals(50, $image->width());
+        $this->assertEquals(50, $image->height());
+        $image->modify(new TrimModifier(1000000));
+        $this->assertEquals(1, $image->width());
+        $this->assertEquals(1, $image->height());
+        $this->assertColor(255, 255, 255, 0, $image->pickColor(0, 0));
+    }
+
+    public function testTrimAnimated(): void
+    {
+        $image = $this->readTestImage('animation.gif');
+        $this->expectException(NotSupportedException::class);
+        $image->modify(new TrimModifier());
+    }
+}