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src/services/imageCrop.js

@@ -4,6 +4,7 @@ const FETCH_TIMEOUT_MS = 15000;
 const MAX_BYTES = 50 * 1024 * 1024; // 50MB
 const MAX_EDGE = 1000;
 const TRIM_THRESHOLD = 10;
+const RESTORE_MARGIN = 5; // px restored per edge after trimming (up to what was trimmed)
 const AVIF_QUALITY = 80;
 const AVIF_EFFORT = 4;
 
@@ -79,7 +80,10 @@ export async function crawlImage(url, { signal } = {}) {
 }
 
 /**
- * Trims transparent and white borders from an image buffer, resizes to max 1000px, and converts to AVIF.
+ * Trims transparent and white borders from an image buffer, restores up to
+ * RESTORE_MARGIN px of the original image on each edge (never more than was
+ * actually trimmed, never enlarging beyond the original), resizes to max 1000px,
+ * and converts to AVIF.
  *
  * @param {Buffer} inputBuffer - Raw image buffer
  * @returns {Promise<{ buffer: Buffer, width: number, height: number, size: number }>}
@@ -88,56 +92,62 @@ export async function cropAndConvertToAvif(inputBuffer) {
     // 1. Initial metadata and orientation correction
     const baseSharp = sharp(inputBuffer, { failOn: 'none' }).rotate();
     const initialMeta = await baseSharp.metadata();
+    const hasAlpha = Boolean(initialMeta.hasAlpha);
 
     // Use PNG intermediate for trimming passes to preserve alpha
-    let currentBuffer = await baseSharp.png().toBuffer();
-    let currentMeta = initialMeta;
+    const originalBuffer = await baseSharp.png().toBuffer();
+    const origMeta = await sharp(originalBuffer).metadata();
+
+    // Cumulative crop box in original (oriented) pixel coordinates
+    let box = { left: 0, top: 0, width: origMeta.width, height: origMeta.height };
+    let currentBuffer = originalBuffer;
+
+    const trimPass = async (background) => {
+        try {
+            const trimmed = await sharp(currentBuffer)
+                .trim({ background, threshold: TRIM_THRESHOLD })
+                .png()
+                .toBuffer({ resolveWithObject: true });
+            if (trimmed.info.width > 0 && trimmed.info.height > 0) {
+                currentBuffer = trimmed.data;
+                box = {
+                    left: box.left - (trimmed.info.trimOffsetLeft ?? 0),
+                    top: box.top - (trimmed.info.trimOffsetTop ?? 0),
+                    width: trimmed.info.width,
+                    height: trimmed.info.height,
+                };
+            }
+        } catch {
+            // Keep currentBuffer
+        }
+    };
 
     // 2. Step A: Trim transparent borders if alpha is present
-    if (currentMeta.hasAlpha) {
-        try {
-            const trimmed = await sharp(currentBuffer)
-                .trim({ background: { r: 0, g: 0, b: 0, alpha: 0 }, threshold: TRIM_THRESHOLD })
-                .png()
-                .toBuffer({ resolveWithObject: true });
-            if (trimmed.info.width > 0 && trimmed.info.height > 0) {
-                currentBuffer = trimmed.data;
-                currentMeta = trimmed.info;
-            }
-        } catch {
-            // Keep currentBuffer
-        }
-    }
+    if (hasAlpha) await trimPass({ r: 0, g: 0, b: 0, alpha: 0 });
 
     // 3. Step B: Trim white borders
-    try {
-        const trimmed = await sharp(currentBuffer)
-            .trim({ background: '#ffffff', threshold: TRIM_THRESHOLD })
-            .png()
-            .toBuffer({ resolveWithObject: true });
-        if (trimmed.info.width > 0 && trimmed.info.height > 0) {
-            currentBuffer = trimmed.data;
-            currentMeta = trimmed.info;
-        }
-    } catch {
-        // Keep currentBuffer
-    }
+    await trimPass('#ffffff');
 
     // 4. Step C: Trim transparent borders again (handles white border containing transparent padding)
-    if (currentMeta.hasAlpha) {
+    if (hasAlpha) await trimPass({ r: 0, g: 0, b: 0, alpha: 0 });
+
+    // 4b. Restore up to RESTORE_MARGIN px per edge from the original, clamped to original bounds
+    const left = Math.max(0, box.left - RESTORE_MARGIN);
+    const top = Math.max(0, box.top - RESTORE_MARGIN);
+    const right = Math.min(origMeta.width, box.left + box.width + RESTORE_MARGIN);
+    const bottom = Math.min(origMeta.height, box.top + box.height + RESTORE_MARGIN);
+    if (left !== box.left || top !== box.top || right - left !== box.width || bottom - top !== box.height) {
         try {
-            const trimmed = await sharp(currentBuffer)
-                .trim({ background: { r: 0, g: 0, b: 0, alpha: 0 }, threshold: TRIM_THRESHOLD })
+            const restored = await sharp(originalBuffer)
+                .extract({ left, top, width: right - left, height: bottom - top })
                 .png()
                 .toBuffer({ resolveWithObject: true });
-            if (trimmed.info.width > 0 && trimmed.info.height > 0) {
-                currentBuffer = trimmed.data;
-                currentMeta = trimmed.info;
-            }
+            currentBuffer = restored.data;
         } catch {
             // Keep currentBuffer
         }
     }
+    const currentMeta = await sharp(currentBuffer).metadata();
 
     // 5. Resize to max 1000px without enlargement
     let finalPipeline = sharp(currentBuffer);