Use Image::setInstance method

Author: natanfelles

src/Image.php

@@ -88,7 +88,7 @@ public function __construct(string $filename)
                 "Image of type '{$this->getType()}' does not returned a GdImage instance"
             );
         }
-        $this->instance = $instance;
+        $this->setInstance($instance);
     }
 
     public function __toString() : string
@@ -391,7 +391,7 @@ public function crop(int $width, int $height, int $marginLeft = 0, int $marginTo
         if ($crop === false) {
             throw new RuntimeException('Image could not to crop');
         }
-        $this->instance = $crop;
+        $this->setInstance($crop);
         return $this;
     }
 
@@ -487,7 +487,7 @@ public function flatten(int $red = 255, int $green = 255, int $blue = 255) : sta
         if ($copied === false) {
             throw new RuntimeException('Image could not to flatten');
         }
-        $this->instance = $image;
+        $this->setInstance($image);
         return $this;
     }
 
@@ -547,7 +547,7 @@ public function rotate(float $angle) : static
         if ($rotate === false) {
             throw new RuntimeException('Image could not to rotate');
         }
-        $this->instance = $rotate;
+        $this->setInstance($rotate);
         return $this;
     }
 
@@ -591,7 +591,7 @@ public function scale(int $width, int $height = -1) : static
         if ($scale === false) {
             throw new RuntimeException('Image could not to scale');
         }
-        $this->instance = $scale;
+        $this->setInstance($scale);
         return $this;
     }