NEW File converter API

src/Conversion/FileConverter.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace SilverStripe\Assets\Conversion;
+
+use SilverStripe\Assets\Storage\DBFile;
+
+interface FileConverter
+{
+    /**
+     * Checks whether this converter supports a conversion from one file type to another.
+     *
+     * @param DBFile|string $from A DBFile instance or specific file extension
+     * @param array $options Any options defined for this converter which should apply to the conversion
+     */
+    public function supports(DBFile|string $from, string $toExtension, array $options = []): bool;
+
+    /**
+     * Converts the given DBFile instance to another file type.
+     *
+     * @param array $options Any options defined for this converter which should apply to the conversion
+     */
+    public function convert(DBFile $original, string $toExtension, array $options = []): DBFile;
+}

src/Conversion/InterventionImageConverter.php

@@ -0,0 +1,71 @@
+<?php
+
+namespace SilverStripe\Assets\Conversion;
+
+use SilverStripe\Assets\Image_Backend;
+use SilverStripe\Assets\InterventionBackend;
+use SilverStripe\Assets\Storage\AssetStore;
+use SilverStripe\Assets\Storage\DBFile;
+use SilverStripe\Core\Injector\Injector;
+
+/**
+ * Image converter powered by the Intervention Image library, assuming you haven't swapped out the ImageBackend implementation.
+ */
+class InterventionImageConverter implements FileConverter
+{
+    public function supports(DBFile|string $from, string $toExtension, array $options = []): bool
+    {
+        // If backend is not InterventionBackend, return false
+        // GD and Imagick support different things so be dynamic between those
+        if ($from instanceof DBFile) {
+            $backend = $from->getImageBackend();
+            $from = $from->getExtension() ?: $from->getMimeType();
+        } else {
+            $backend = Injector::inst()->get(Image_Backend::class);
+        }
+        // This converter requires intervention image
+        if (!is_a($backend, InterventionBackend::class)) {
+            return false;
+        }
+        /** @var InterventionBackend $backend */
+        $driver = $backend->getImageManager()->config['driver'] ?? null;
+        switch ($driver) {
+            case 'gd':
+                return $this->supportedByGd($from, $toExtension);
+            case 'imagick':
+                return $this->supportedByImagick($from, $toExtension);
+            // If the driver is somehow not GD or Imagick, we have no way to know what it might support
+            default:
+              return false;
+        }
+        // We shouldn't get here, but if we do, we clearly don't know what's going on and therefore can't support it
+        return false;
+    }
+
+    public function convert(DBFile $original, string $toExtension, array $options = []): DBFile
+    {
+        // TODO allow swapping quality
+        // TODO find any other options intervention supports
+        return $original->manipulateExtension(
+            $toExtension,
+            function (AssetStore $store, string $filename, string $hash, string $variant) use ($original) {
+                $backend = $original->getImageBackend();
+                $config = ['conflict' => AssetStore::CONFLICT_USE_EXISTING];
+                $tuple = $backend->writeToStore($store, $filename, $hash, $variant, $config);
+                return [$tuple, $backend];
+            }
+        );
+    }
+
+    private function supportedByGd(string $from, string $to): bool
+    {
+        // TODO: Follow the logic in AbstractEncoder::process() and the various methods in Encoder
+        return false;
+    }
+
+    private function supportedByImagick(string $from, string $to): bool
+    {
+        // TODO: Follow the logic in AbstractEncoder::process() and the various methods in Encoder
+        return false;
+    }
+}