Reset page geometry after Imagick rotation

src/Drivers/Imagick/Modifiers/RotateModifier.php

@@ -32,6 +32,12 @@ public function apply(ImageInterface $image): ImageInterface
                         'Failed to apply ' . self::class . ', unable to rotate image',
                     );
                 }
+
+                // Reset the virtual canvas page that rotateImage() leaves behind. A
+                // non-right angle produces a negative page offset which otherwise
+                // corrupts the animated-AVIF (libheif sequences) writer, leaving the
+                // bottom/right region transparent. Mirrors TrimModifier/CoverModifier.
+                $frame->native()->setImagePage(0, 0, 0, 0);
             } catch (ImagickException $e) {
                 throw new ModifierException(
                     'Failed to apply ' . self::class . ', unable to rotate image',

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

@@ -23,4 +23,19 @@ public function testRotate(): void
         $this->assertEquals(240, $image->width());
         $this->assertEquals(320, $image->height());
     }
+
+    public function testRotateResetsFramePageOffset(): void
+    {
+        // A non-right-angle rotation grows the virtual canvas; ImageMagick leaves
+        // each frame with a negative page offset. That offset mis-composes the
+        // animated-AVIF (libheif sequences) writer, leaving the bottom/right
+        // transparent, so rotate must reset every frame's page to +0+0.
+        $image = $this->readTestImage('animation.gif');
+        $image->modify(new RotateModifier(45, 'fff'));
+
+        foreach ($image as $frame) {
+            $this->assertSame(0, $frame->offsetLeft());
+            $this->assertSame(0, $frame->offsetTop());
+        }
+    }
 }