feat(dart): add resize-image quickstart sample (#1272)

Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>

Author: jhuleatt

.gitignore

@@ -3,6 +3,8 @@
 **/.firebase
 **/.firebaserc
 **/.runtimeconfig.json
+**/functions.yaml
+**/.env.local
 */npm-debug.log
 lerna-debug.log
 *~

Dart/quickstarts/resize-image/.gitignore

@@ -0,0 +1,5 @@
+.dart_tool/
+.packages
+build/
+*.dart_tool
+pubspec.lock

Dart/quickstarts/resize-image/bin/server.dart

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+import 'dart:typed_data';
+
+import 'package:google_cloud_storage/google_cloud_storage.dart'
+    show ObjectMetadata, NotFoundException;
+import 'package:firebase_functions/firebase_functions.dart';
+import 'package:image/image.dart';
+
+final defaultWidth = defineInt(
+  'DEFAULT_WIDTH',
+  ParamOptions<int>(defaultValue: 300),
+);
+
+void main(List<String> args) async {
+  await fireUp(args, (firebase) {
+    /// An https function that resizes images in Cloud Storage.
+    /// It creates a separate Storage folder to cache stored images
+    /// so that it does not need to resize an image twice.
+    ///
+    /// It returns an HTTP redirect to the public Storage download URL.
+    ///
+    /// The query params it accepts are:
+    /// - image: the image file path in Cloud Storage
+    /// - width (optional): the width in pixels to resize to
+    ///
+    /// Example call: https://<function-url>?image=myFile.png&width=400
+    firebase.https.onRequest(name: 'imageOptimizer', (request) async {
+      // Parse arguments from query params in the URL
+      final queryParams = request.url.queryParameters;
+      final imageFileName = queryParams['image'];
+      if (imageFileName == null) {
+        throw InvalidArgumentError(
+          'No image provided. Include the image file name as a query param.',
+        );
+      }
+      var width = int.tryParse(queryParams['width'] ?? "");
+      if (width == null) {
+        logger.info(
+          'Cloud not parse width from query params. Using default width.',
+        );
+        width = defaultWidth.value();
+      }
+
+      // Get the storage bucket from the built-in parameter
+      // https://firebase.google.com/docs/functions/config-env#built-in-parameters
+      final bucketName = storageBucket.value();
+      final bucket = firebase.adminApp.storage().bucket(bucketName);
+
+      // Return early if the image has been resized before
+      final cachedFileName = 'image-optimizer-cache/${width}w-${imageFileName}';
+      try {
+        await bucket.storage.objectMetadata(bucketName, cachedFileName);
+        final downloadUrl = await firebase.adminApp.storage().getDownloadURL(
+          bucket,
+          cachedFileName,
+        );
+        logger.log('Cache hit. Using existing resized image.');
+        return Response.movedPermanently(downloadUrl);
+      } on NotFoundException {
+        logger.log('Cache miss. Resizing image to width ${width}');
+      }
+
+      // Download original image
+      List<int> originalBytes;
+      try {
+        originalBytes = await bucket.storage.downloadObject(
+          bucket.name,
+          imageFileName,
+        );
+      } on NotFoundException {
+        throw InvalidArgumentError(
+          'Image ${imageFileName} does not exist in bucket ${bucketName}.',
+        );
+      }
+
+      // Decode image
+      final originalImage = decodeImage(Uint8List.fromList(originalBytes));
+      if (originalImage == null) {
+        throw InvalidArgumentError(
+          'Failed to decode image. Are you sure it was an image file?',
+        );
+      }
+
+      // Resize if needed
+      var encodedBytes;
+      if (originalImage.width >= width) {
+        final resizedImage = copyResize(
+          originalImage,
+          width: width,
+          maintainAspect: true,
+        );
+        encodedBytes = encodeNamedImage(imageFileName, resizedImage);
+        if (encodedBytes == null) {
+          throw InternalError('Failed to encode resized image.');
+        }
+      } else {
+        logger.info(
+          'Image is already smaller than the requested width. No need to resize.',
+        );
+        encodedBytes = originalBytes;
+      }
+
+      // Upload resized image to cache directory
+      await bucket.storage.uploadObject(
+        bucket.name,
+        cachedFileName,
+        encodedBytes,
+        // Tell clients to cache the resized image to reduce repeat requests
+        metadata: ObjectMetadata(cacheControl: 'public, max-age=86400'),
+      );
+
+      // Return download URL
+      final downloadUrl = await firebase.adminApp.storage().getDownloadURL(
+        bucket,
+        cachedFileName,
+      );
+      return Response.movedPermanently(downloadUrl);
+    });
+  });
+}

Dart/quickstarts/resize-image/firebase.json

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+{
+  "functions": {
+    "source": ".",
+    "codebase": "dart-quickstarts-resize-image"
+  },
+  "emulators": {
+    "functions": {
+      "port": 5001
+    },
+    "storage": {
+      "port": 9199
+    },
+    "ui": {
+      "enabled": true
+    },
+    "singleProjectMode": true
+  }
+}

Dart/quickstarts/resize-image/pubspec.yaml

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+name: resize_image
+description: Image resizer example for Firebase Functions for Dart
+publish_to: none
+
+environment:
+  sdk: ^3.11.0
+
+dependencies:
+  image: ^4.8.0
+  path: ^1.9.1
+  firebase_functions:
+    git:
+      url: https://github.com/firebase/firebase-functions-dart
+      ref: main
+  intl: ^0.20.2
+
+dev_dependencies:
+  build_runner: ^2.10.5
+  lints: ^6.0.0
+
+dependency_overrides:
+  firebase_admin_sdk:
+      git:
+        url: https://github.com/firebase/firebase-admin-dart
+        path: packages/firebase_admin_sdk
+        ref: main
+  google_cloud_firestore:
+      git:
+        url: https://github.com/firebase/firebase-admin-dart
+        path: packages/google_cloud_firestore
+        ref: main