feat(recipe): compress hero image to 400px preview on save

Adds Thumbnailator-based ImageCompressor that resizes uploaded images to a 400px-wide JPEG preview stored in hero_image_preview. The recipe list uses the preview instead of the full image URL. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-04-10 09:14:35 +02:00
parent 822b34cd14
commit f11cca534f
8 changed files with 179 additions and 10 deletions
--- a/backend/src/main/java/com/recipeapp/recipe/ImageCompressor.java
+++ b/backend/src/main/java/com/recipeapp/recipe/ImageCompressor.java
@@ -0,0 +1,60 @@
+package com.recipeapp.recipe;
+
+import net.coobird.thumbnailator.Thumbnails;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.util.Base64;
+
+@Component
+public class ImageCompressor {
+
+    private static final Logger log = LoggerFactory.getLogger(ImageCompressor.class);
+
+    private static final int PREVIEW_WIDTH = 400;
+    private static final double PREVIEW_QUALITY = 0.6;
+    private static final String DATA_URI_PREFIX = "data:image/";
+    private static final String BASE64_MARKER = ";base64,";
+    private static final String OUTPUT_PREFIX = "data:image/jpeg;base64,";
+
+    public String compressToPreview(String dataUri) {
+        if (dataUri == null || dataUri.isBlank()) return null;
+        if (!dataUri.startsWith(DATA_URI_PREFIX)) return null;
+
+        int markerIdx = dataUri.indexOf(BASE64_MARKER);
+        if (markerIdx < 0) return null;
+
+        byte[] imageBytes;
+        try {
+            imageBytes = Base64.getDecoder().decode(dataUri.substring(markerIdx + BASE64_MARKER.length()));
+        } catch (IllegalArgumentException e) {
+            return null;
+        }
+
+        try {
+            BufferedImage original = ImageIO.read(new ByteArrayInputStream(imageBytes));
+            if (original == null) {
+                log.warn("ImageIO could not decode image — unsupported format (data URI prefix: {})",
+                        dataUri.substring(0, Math.min(dataUri.indexOf(',') + 1, 40)));
+                return null;
+            }
+
+            int targetWidth = Math.min(original.getWidth(), PREVIEW_WIDTH);
+            ByteArrayOutputStream bos = new ByteArrayOutputStream();
+            Thumbnails.of(original)
+                    .width(targetWidth)
+                    .outputFormat("jpeg")
+                    .outputQuality(PREVIEW_QUALITY)
+                    .toOutputStream(bos);
+            return OUTPUT_PREFIX + Base64.getEncoder().encodeToString(bos.toByteArray());
+        } catch (Exception e) {
+            log.warn("Failed to generate image preview", e);
+            return null;
+        }
+    }
+}