feat(background image): add the ability to css variables for backgrou…

…nd images

src/ResponsiveImageCraft.php

@@ -2,6 +2,34 @@
 
 namespace Infernalmedia\ResponsiveImageCraft;
 
+use Infernalmedia\ResponsiveImageCraft\ImageInfoFromString;
+
 class ResponsiveImageCraft
 {
+    public function getCssVariables(string $file, int $maxWidth, array $extensions = ['jpg', 'avif', 'webp'])
+    {
+        $image = new ImageInfoFromString($file);
+        $path = $image->getRelativePathnameWithoutExtension();
+
+        $fileNameSpacer = config('responsive-images.filename_spacer');
+
+        $cssVariables = $this->generateCssVariables($path, $extensions, 'full');
+
+        foreach ($image->getFilteredSizes($maxWidth) as $width) {
+            $file = $path . $fileNameSpacer . $width;
+            $cssVariables .= $this->generateCssVariables($file, $extensions, $width);
+        }
+
+        return $cssVariables;
+    }
+
+    private function generateCssVariables(string $path, array $extensions, string|int $width): string
+    {
+        $cssVariables = '';
+        foreach ($extensions as $extension) {
+            $cssVariables .= "--{$extension}-{$width}:url($path.$extension);";
+        }
+
+        return $cssVariables;
+    }
 }