Add background color setting for the output image

README.md

@@ -138,6 +138,19 @@ $pdf->layerMethod(\Spatie\PdfToImage\Enums\LayerMethod::Merge);
 $pdf->layerMethod(\Spatie\PdfToImage\Enums\LayerMethod::None);
 ```
 
+Set the background color of the output image:
+
+```php
+$pdf->backgroundColor('white') // simple text for 'white' color
+    ->save($pathToWhereImageShouldBeStored);
+
+$pdf->backgroundColor('#fff') // code for 'white' color
+    ->save($pathToWhereImageShouldBeStored);
+
+$pdf->backgroundColor('rgb(255,255,255)') // rgb for 'white' color
+    ->save($pathToWhereImageShouldBeStored);
+```
+
 ## Issues regarding Ghostscript
 
 This package uses Ghostscript through Imagick. For this to work Ghostscripts `gs` command should be accessible from the PHP process. For the PHP CLI process (e.g. Laravel's asynchronous jobs, commands, etc...) this is usually already the case. 

src/Pdf.php

@@ -12,13 +12,16 @@
 use Spatie\PdfToImage\Exceptions\InvalidSize;
 use Spatie\PdfToImage\Exceptions\PageDoesNotExist;
 use Spatie\PdfToImage\Exceptions\PdfDoesNotExist;
+use ImagickPixel;
 
 class Pdf
 {
     protected string $filename;
 
     protected int $resolution = 144;
 
+    protected ?string $backgroundColor = null;
+
     protected OutputFormat $outputFormat = OutputFormat::Jpg;
 
     protected array $pages = [1];
@@ -61,6 +64,16 @@ public function resolution(int $dpiResolution): static
         return $this;
     }
 
+    /**
+     * Set the background color e.g. 'white', '#fff', 'rgb(255, 255, 255)'
+     */
+    public function backgroundColor(string $backgroundColorCode): static
+    {
+        $this->backgroundColor = $backgroundColorCode;
+
+        return $this;
+    }
+
     /**
      * Sets the output format of the generated image.
      * Default is OutputFormat::Jpg.
@@ -234,6 +247,11 @@ public function getImageData(string $pathToImage, int $pageNumber): Imagick
 
         $this->imagick->readImage(sprintf('%s[%s]', $this->filename, $pageNumber - 1));
 
+        if (! empty($this->backgroundColor)) {
+            $this->imagick->setImageBackgroundColor(new ImagickPixel($this->backgroundColor));
+            $this->imagick->setImageAlphaChannel(Imagick::ALPHACHANNEL_REMOVE);
+        }
+
         if ($this->resizeWidth !== null) {
             $this->imagick->resizeImage($this->resizeWidth, $this->resizeHeight ?? 0, Imagick::FILTER_POINT, 0);
         }

tests/Unit/PdfTest.php

@@ -48,3 +48,15 @@
 
     expect($imagick1)->toBeInstanceOf(Imagick::class);
 });
+
+it('can set the background color', function ($backgroundColor) {
+    $image = (new Pdf($this->testFile))
+        ->backgroundColor($backgroundColor)
+        ->selectPage(1)
+        ->getImageData('page-1.jpg', 1)
+        ->getImageBackgroundColor()
+        ->getColorAsString();
+
+    $expectedSRGBValueForWhiteColor = 'srgb(255,255,255)';
+    expect($image)->toEqual($expectedSRGBValueForWhiteColor);
+})->with(['srgb(255,255,255)', 'rgb(255,255,255)', 'white', '#fff']);