Add ResizeCanvasModifiers

src/Drivers/Gd/Modifiers/ResizeCanvasModifier.php

@@ -0,0 +1,85 @@
+<?php
+
+namespace Intervention\Image\Drivers\Gd\Modifiers;
+
+use Intervention\Image\Colors\Rgb\Channels\Blue;
+use Intervention\Image\Colors\Rgb\Channels\Green;
+use Intervention\Image\Colors\Rgb\Channels\Red;
+use Intervention\Image\Drivers\DriverSpecializedModifier;
+use Intervention\Image\Interfaces\ColorInterface;
+use Intervention\Image\Interfaces\FrameInterface;
+use Intervention\Image\Interfaces\ImageInterface;
+use Intervention\Image\Interfaces\SizeInterface;
+use Intervention\Image\Modifiers\FillModifier;
+
+/**
+ * @method SizeInterface cropSize(ImageInterface $image)
+ * @property mixed $background
+ */
+class ResizeCanvasModifier extends DriverSpecializedModifier
+{
+    public function apply(ImageInterface $image): ImageInterface
+    {
+        $resize = $this->cropSize($image);
+        $background = $this->driver()->handleInput($this->background);
+
+        foreach ($image as $frame) {
+            $this->modify($frame, $resize, $background);
+        }
+
+        return $image;
+    }
+
+    protected function modify(
+        FrameInterface $frame,
+        SizeInterface $resize,
+        ColorInterface $background,
+    ): void {
+        // create new gd image
+        $modified = $this->driver()->createImage(
+            $resize->width(),
+            $resize->height()
+        )->modify(
+            new FillModifier($background)
+        )->core()->native();
+
+        // make image area transparent to keep transparency
+        // even if background-color is set
+        $transparent = imagecolorallocatealpha(
+            $modified,
+            $background->channel(Red::class)->value(),
+            $background->channel(Green::class)->value(),
+            $background->channel(Blue::class)->value(),
+            127,
+        );
+
+        imagealphablending($modified, false); // do not blend / just overwrite
+        imagecolortransparent($modified, $transparent);
+        imagefilledrectangle(
+            $modified,
+            $resize->pivot()->x() * -1,
+            $resize->pivot()->y() * -1,
+            $resize->pivot()->x() * -1 + $frame->size()->width() - 1,
+            $resize->pivot()->y() * -1 + $frame->size()->height() - 1,
+            $transparent
+        );
+
+        // copy image from original with blending alpha
+        imagealphablending($modified, true);
+        imagecopyresampled(
+            $modified,
+            $frame->native(),
+            $resize->pivot()->x() * -1,
+            $resize->pivot()->y() * -1,
+            0,
+            0,
+            $frame->size()->width(),
+            $frame->size()->height(),
+            $frame->size()->width(),
+            $frame->size()->height()
+        );
+
+        // set new content as recource
+        $frame->setNative($modified);
+    }
+}

src/Drivers/Imagick/Modifiers/ResizeCanvasModifier.php

@@ -0,0 +1,87 @@
+<?php
+
+namespace Intervention\Image\Drivers\Imagick\Modifiers;
+
+use ImagickDraw;
+use Intervention\Image\Drivers\DriverSpecializedModifier;
+use Intervention\Image\Interfaces\ImageInterface;
+use Intervention\Image\Interfaces\SizeInterface;
+
+/**
+ * @method SizeInterface cropSize(ImageInterface $image)
+ * @property mixed $background
+ */
+class ResizeCanvasModifier extends DriverSpecializedModifier
+{
+    public function apply(ImageInterface $image): ImageInterface
+    {
+        $size = $image->size();
+        $resize = $this->cropSize($image);
+
+        $background = $this->driver()->colorProcessor($image->colorspace())->colorToNative(
+            $this->driver()->handleInput($this->background)
+        );
+
+        foreach ($image as $frame) {
+            $frame->native()->extentImage(
+                $resize->width(),
+                $resize->height(),
+                $resize->pivot()->x(),
+                $resize->pivot()->y()
+            );
+
+            if ($resize->width() > $size->width()) {
+                // fill new emerged background
+                $draw = new ImagickDraw();
+                $draw->setFillColor($background);
+
+                $delta = abs($resize->pivot()->x());
+
+                if ($delta > 0) {
+                    $draw->rectangle(
+                        0,
+                        0,
+                        $delta - 1,
+                        $resize->height()
+                    );
+                }
+
+                $draw->rectangle(
+                    $size->width() + $delta,
+                    0,
+                    $resize->width(),
+                    $resize->height()
+                );
+                $frame->native()->drawImage($draw);
+            }
+
+            if ($resize->height() > $size->height()) {
+                // fill new emerged background
+                $draw = new ImagickDraw();
+                $draw->setFillColor($background);
+
+                $delta = abs($resize->pivot()->y());
+
+                if ($delta > 0) {
+                    $draw->rectangle(
+                        0,
+                        0,
+                        $resize->width(),
+                        $delta - 1
+                    );
+                }
+
+                $draw->rectangle(
+                    0,
+                    $size->height() + $delta,
+                    $resize->width(),
+                    $resize->height()
+                );
+
+                $frame->native()->drawImage($draw);
+            }
+        }
+
+        return $image;
+    }
+}

src/Image.php

@@ -64,6 +64,7 @@ use Intervention\Image\Modifiers\PlaceModifier;
 use Intervention\Image\Modifiers\ProfileModifier;
 use Intervention\Image\Modifiers\ProfileRemovalModifier;
 use Intervention\Image\Modifiers\RemoveAnimationModifier;
+use Intervention\Image\Modifiers\ResizeCanvasModifier;
 use Intervention\Image\Modifiers\ResizeDownModifier;
 use Intervention\Image\Modifiers\ResizeModifier;
 use Intervention\Image\Modifiers\ResolutionModifier;
@@ -521,6 +522,20 @@ final class Image implements ImageInterface, Countable
         return $this->modify(new CoverDownModifier($width, $height, $position));
     }
 
+    /**
+     * {@inheritdoc}
+     *
+     * @see ImageInterface::resizeCanvas()
+     */
+    public function resizeCanvas(
+        int $width,
+        int $height,
+        mixed $background = 'ffffff',
+        string $position = 'center'
+    ): ImageInterface {
+        return $this->modify(new ResizeCanvasModifier($width, $height, $background, $position));
+    }
+
     /**
      * {@inheritdoc}
      *

src/Interfaces/ImageInterface.php

@@ -347,6 +347,25 @@ interface ImageInterface extends IteratorAggregate, Countable
      */
     public function coverDown(int $width, int $height, string $position = 'center'): ImageInterface;
 
+    /**
+     * Resize the boundaries of the current image to given width and height.
+     * An anchor position can be defined to determine from what point of the
+     * image the resizing is going to happen. A background color can be passed
+     * to define the color of the new emerging areas.
+     *
+     * @param int $width
+     * @param int $height
+     * @param string $position
+     * @param mixed $background
+     * @return ImageInterface
+     */
+    public function resizeCanvas(
+        int $width,
+        int $height,
+        mixed $background = 'ffffff',
+        string $position = 'center'
+    ): ImageInterface;
+
     /**
      * Padded resizing means that the original image is scaled until it fits the
      * defined target size with unchanged aspect ratio. The original image is

src/Modifiers/ResizeCanvasModifier.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace Intervention\Image\Modifiers;
+
+use Intervention\Image\Geometry\Rectangle;
+use Intervention\Image\Interfaces\ImageInterface;
+use Intervention\Image\Interfaces\SizeInterface;
+
+class ResizeCanvasModifier extends AbstractModifier
+{
+    public function __construct(
+        public int $width,
+        public int $height,
+        public mixed $background = 'ffffff',
+        public string $position = 'center'
+    ) {
+    }
+
+    public function cropSize(ImageInterface $image): SizeInterface
+    {
+        return (new Rectangle($this->width, $this->height))
+            ->alignPivotTo($image->size(), $this->position);
+    }
+}

tests/Drivers/Gd/Modifiers/ResizeCanvasModifierTest.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace Intervention\Image\Tests\Drivers\Gd\Modifiers;
+
+use Intervention\Image\Modifiers\ResizeCanvasModifier;
+use Intervention\Image\Tests\TestCase;
+use Intervention\Image\Tests\Traits\CanCreateGdTestImage;
+
+/**
+ * @requires extension gd
+ * @covers \Intervention\Image\Modifiers\ResizeCanvasModifier
+ */
+class ResizeCanvasModifierTest extends TestCase
+{
+    use CanCreateGdTestImage;
+
+    public function testModify(): void
+    {
+        $image = $this->createTestImage('tile.png');
+        $this->assertEquals(16, $image->width());
+        $this->assertEquals(16, $image->height());
+        $image->modify(new ResizeCanvasModifier(18, 18, 'ff0', 'center'));
+        $this->assertEquals(18, $image->width());
+        $this->assertEquals(18, $image->height());
+        $this->assertColor(255, 255, 0, 255, $image->pickColor(0, 0));
+        $this->assertColor(180, 224, 0, 255, $image->pickColor(1, 1));
+        $this->assertColor(180, 224, 0, 255, $image->pickColor(2, 2));
+        $this->assertColor(255, 255, 0, 255, $image->pickColor(17, 17));
+        $this->assertTransparency($image->pickColor(12, 1));
+    }
+}

tests/Drivers/Imagick/Modifiers/ResizeCanvasModifier.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace Intervention\Image\Tests\Drivers\Imagick\Modifiers;
+
+use Intervention\Image\Modifiers\ResizeCanvasModifier;
+use Intervention\Image\Tests\TestCase;
+use Intervention\Image\Tests\Traits\CanCreateImagickTestImage;
+
+/**
+ * @requires extension gd
+ * @covers \Intervention\Image\Modifiers\ResizeCanvasModifier
+ */
+class ResizeCanvasModifierTest extends TestCase
+{
+    use CanCreateImagickTestImage;
+
+    public function testModify(): void
+    {
+        $image = $this->createTestImage('tile.png');
+        $this->assertEquals(16, $image->width());
+        $this->assertEquals(16, $image->height());
+        $image->modify(new ResizeCanvasModifier(18, 18, 'ff0', 'center'));
+        $this->assertEquals(18, $image->width());
+        $this->assertEquals(18, $image->height());
+        $this->assertColor(255, 255, 0, 255, $image->pickColor(0, 0));
+        $this->assertColor(180, 224, 0, 255, $image->pickColor(1, 1));
+        $this->assertColor(180, 224, 0, 255, $image->pickColor(2, 2));
+        $this->assertColor(255, 255, 0, 255, $image->pickColor(17, 17));
+        $this->assertTransparency($image->pickColor(12, 1));
+    }
+}