Resolve image ratio issues when merging over top of a QrCode

Author: Corey McCormick

src/ImageMerge.php

@@ -2,6 +2,8 @@
 
 namespace SimpleSoftwareIO\QrCode;
 
+use InvalidArgumentException;
+
 class ImageMerge
 {
     /**
@@ -46,6 +48,13 @@ class ImageMerge
      */
     protected $mergeImageWidth;
 
+    /**
+     * Holds the radio of the merging image.
+     *
+     * @var float
+     */
+    protected $mergeRatio;
+
     /**
      * The height of the merge image after it is merged.
      *
@@ -131,11 +140,13 @@ protected function createImage()
      * Sets the objects properties.
      *
      * @param $percentage float The percentage that the merge image should take up.
+     *
+     * @return void
      */
     protected function setProperties($percentage)
     {
         if ($percentage > 1) {
-            throw new \InvalidArgumentException('$percentage must be less than 1');
+            throw new InvalidArgumentException('$percentage must be less than 1');
         }
 
         $this->sourceImageHeight = $this->sourceImage->getHeight();
@@ -150,21 +161,26 @@ protected function setProperties($percentage)
 
     /**
      * Calculates the center of the source Image using the Merge image.
+     *
+     * @return void
      */
-    private function calculateCenter()
+    protected function calculateCenter()
     {
-        $this->centerY = ($this->sourceImageHeight / 2) - ($this->postMergeImageHeight / 2);
-        $this->centerX = ($this->sourceImageWidth / 2) - ($this->postMergeImageHeight / 2);
+        $this->centerX = intval(($this->sourceImageWidth / 2) - ($this->postMergeImageWidth / 2));
+        $this->centerY = intval(($this->sourceImageHeight / 2) - ($this->postMergeImageHeight / 2));
     }
 
     /**
      * Calculates the width of the merge image being placed on the source image.
      *
      * @param float $percentage
+     *
+     * @return void
      */
-    private function calculateOverlap($percentage)
+    protected function calculateOverlap($percentage)
     {
-        $this->postMergeImageHeight = $this->sourceImageHeight * $percentage;
-        $this->postMergeImageWidth = $this->sourceImageWidth * $percentage;
+        $this->mergeRatio = round($this->mergeImageWidth / $this->mergeImageHeight, 2);
+        $this->postMergeImageWidth = intval($this->sourceImageWidth * $percentage);
+        $this->postMergeImageHeight = intval($this->postMergeImageWidth / $this->mergeRatio);
     }
 }

tests/ImageMergeTest.php

@@ -28,18 +28,25 @@ class ImageMergeTest extends TestCase
     protected $testImage;
 
     /**
-     * The location of the test image to use.
+     * The location of the test image that is having an image merged over top of it.
      *
      * @var string
      */
     protected $testImagePath;
 
+    /**
+     * The location of the test image that is being merged.
+     * @var mixed
+     */
+    protected $mergeImagePath;
+
     public function setUp(): void
     {
         $this->testImagePath = file_get_contents(dirname(__FILE__).'/Images/simplesoftware-icon-grey-blue.png');
+        $this->mergeImagePath = file_get_contents(dirname(__FILE__).'/Images/200x300.png');
         $this->testImage = new ImageMerge(
             new Image($this->testImagePath),
-            new Image($this->testImagePath)
+            new Image($this->mergeImagePath)
         );
 
         $this->testImageSaveLocation = dirname(__FILE__).'/testImage.png';
@@ -54,22 +61,22 @@ public function tearDown(): void
 
     public function test_it_merges_two_images_together_and_centers_it()
     {
-        //We know the test image is 512x512
+        //We know the source image is 512x512 and the merge image is 200x300
         $source = imagecreatefromstring($this->testImagePath);
-        $merge = imagecreatefromstring($this->testImagePath);
+        $merge = imagecreatefromstring($this->mergeImagePath);
 
         //Create a PNG and place the image in the middle using 20% of the area.
         imagecopyresampled(
             $source,
             $merge,
-            204,
-            204,
+            205,
+            222,
             0,
             0,
             102,
-            102,
-            512,
-            512
+            67,
+            536,
+            354
         );
         imagepng($source, $this->compareTestSaveLocation);