add list view

mobile/services/thumbnail.ts

@@ -0,0 +1,25 @@
+import { manipulateAsync, SaveFormat } from 'expo-image-manipulator';
+
+const THUMB_SIZE = 128;
+
+function isGeneratableImage(mimeType: string): boolean {
+  return (mimeType ?? '').toLowerCase().startsWith('image/');
+}
+
+export async function generateLocalThumbnail(
+  uri: string | undefined,
+  mimeType: string,
+): Promise<string | null> {
+  if (!uri || !isGeneratableImage(mimeType)) return null;
+  try {
+    const result = await manipulateAsync(
+      uri,
+      [{ resize: { width: THUMB_SIZE } }],
+      { format: SaveFormat.JPEG, compress: 0.7, base64: true },
+    );
+    if (!result.base64) return null;
+    return `data:image/jpeg;base64,${result.base64}`;
+  } catch {
+    return null;
+  }
+}