[google_maps_flutter] Take snapshot of map (#2607)

AUTHORS

@@ -50,4 +50,5 @@ Luigi Agosti <luigi@tengio.com>
 Quentin Le Guennec <quentin@tengio.com>
 Koushik Ravikumar <koushik@tengio.com>
 Nissim Dsilva <nissim@tengio.com>
-Giancarlo Rocha <giancarloiff@gmail.com>
+Giancarlo Rocha <giancarloiff@gmail.com>
+Ryo Miyake <ryo@miyake.id>

packages/google_maps_flutter/google_maps_flutter/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.5.25+1
+
+* Add takeSnapshot that takes a snapshot of the map.
+
 ## 0.5.25
 
 * Add an optional param `mipmaps` for `BitmapDescriptor.fromAssetImage`.

packages/google_maps_flutter/google_maps_flutter/android/src/main/java/io/flutter/plugins/googlemaps/GoogleMapController.java

@@ -17,6 +17,7 @@
 import android.app.Application;
 import android.content.Context;
 import android.content.pm.PackageManager;
+import android.graphics.Bitmap;
 import android.graphics.Point;
 import android.os.Bundle;
 import android.util.Log;
@@ -27,6 +28,7 @@
 import androidx.lifecycle.LifecycleOwner;
 import com.google.android.gms.maps.CameraUpdate;
 import com.google.android.gms.maps.GoogleMap;
+import com.google.android.gms.maps.GoogleMap.SnapshotReadyCallback;
 import com.google.android.gms.maps.GoogleMapOptions;
 import com.google.android.gms.maps.MapView;
 import com.google.android.gms.maps.OnMapReadyCallback;
@@ -44,6 +46,7 @@
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugin.common.PluginRegistry;
 import io.flutter.plugin.platform.PlatformView;
+import java.io.ByteArrayOutputStream;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -276,6 +279,26 @@ public void onMethodCall(MethodCall call, MethodChannel.Result result) {
           }
           break;
         }
+      case "map#takeSnapshot":
+        {
+          if (googleMap != null) {
+            final MethodChannel.Result _result = result;
+            googleMap.snapshot(
+                new SnapshotReadyCallback() {
+                  @Override
+                  public void onSnapshotReady(Bitmap bitmap) {
+                    ByteArrayOutputStream stream = new ByteArrayOutputStream();
+                    bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
+                    byte[] byteArray = stream.toByteArray();
+                    bitmap.recycle();
+                    _result.success(byteArray);
+                  }
+                });
+          } else {
+            result.error("GoogleMap uninitialized", "takeSnapshot", null);
+          }
+          break;
+        }
       case "camera#move":
         {
           final CameraUpdate cameraUpdate =

packages/google_maps_flutter/google_maps_flutter/example/lib/main.dart

@@ -18,6 +18,7 @@ import 'place_marker.dart';
 import 'place_polygon.dart';
 import 'place_polyline.dart';
 import 'scrolling_map.dart';
+import 'snapshot.dart';
 
 final List<Page> _allPages = <Page>[
   MapUiPage(),
@@ -32,6 +33,7 @@ final List<Page> _allPages = <Page>[
   PlacePolygonPage(),
   PlaceCirclePage(),
   PaddingPage(),
+  SnapshotPage(),
 ];
 
 class MapsDemo extends StatelessWidget {

packages/google_maps_flutter/google_maps_flutter/example/lib/snapshot.dart

@@ -0,0 +1,72 @@
+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// ignore_for_file: public_member_api_docs
+
+import 'dart:typed_data';
+
+import 'package:flutter/material.dart';
+import 'package:google_maps_flutter/google_maps_flutter.dart';
+
+import 'page.dart';
+
+const CameraPosition _kInitialPosition =
+    CameraPosition(target: LatLng(-33.852, 151.211), zoom: 11.0);
+
+class SnapshotPage extends Page {
+  SnapshotPage()
+      : super(const Icon(Icons.camera_alt), 'Take a snapshot of the map');
+
+  @override
+  Widget build(BuildContext context) {
+    return _SnapshotBody();
+  }
+}
+
+class _SnapshotBody extends StatefulWidget {
+  @override
+  _SnapshotBodyState createState() => _SnapshotBodyState();
+}
+
+class _SnapshotBodyState extends State<_SnapshotBody> {
+  GoogleMapController _mapController;
+  Uint8List _imageBytes;
+
+  @override
+  Widget build(BuildContext context) {
+    return Padding(
+      padding: const EdgeInsets.all(16),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.stretch,
+        children: [
+          SizedBox(
+            height: 180,
+            child: GoogleMap(
+              onMapCreated: onMapCreated,
+              initialCameraPosition: _kInitialPosition,
+            ),
+          ),
+          FlatButton(
+            child: Text('Take a snapshot'),
+            onPressed: () async {
+              final imageBytes = await _mapController?.takeSnapshot();
+              setState(() {
+                _imageBytes = imageBytes;
+              });
+            },
+          ),
+          Container(
+            decoration: BoxDecoration(color: Colors.blueGrey[50]),
+            height: 180,
+            child: _imageBytes != null ? Image.memory(_imageBytes) : null,
+          ),
+        ],
+      ),
+    );
+  }
+
+  void onMapCreated(GoogleMapController controller) {
+    _mapController = controller;
+  }
+}

packages/google_maps_flutter/google_maps_flutter/example/test_driver/google_map_inspector.dart

@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'dart:typed_data';
 import 'package:flutter/services.dart';
 import 'package:google_maps_flutter/google_maps_flutter.dart';
 
@@ -63,4 +64,8 @@ class GoogleMapInspector {
   Future<bool> isBuildingsEnabled() async {
     return await _channel.invokeMethod<bool>('map#isBuildingsEnabled');
   }
+
+  Future<Uint8List> takeSnapshot() async {
+    return await _channel.invokeMethod<Uint8List>('map#takeSnapshot');
+  }
 }

packages/google_maps_flutter/google_maps_flutter/example/test_driver/google_maps_e2e.dart

@@ -4,12 +4,13 @@
 
 import 'dart:async';
 import 'dart:io';
+import 'dart:typed_data';
 
+import 'package:e2e/e2e.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:google_maps_flutter/google_maps_flutter.dart';
-import 'package:e2e/e2e.dart';
 
 import 'google_map_inspector.dart';
 
@@ -838,4 +839,30 @@ void main() {
     // ignore: invalid_use_of_visible_for_testing_member
     expect(scaled.toJson()[2], 2);
   });
+
+  testWidgets('testTakeSnapshot', (WidgetTester tester) async {
+    Completer<GoogleMapInspector> inspectorCompleter =
+        Completer<GoogleMapInspector>();
+
+    await tester.pumpWidget(
+      Directionality(
+        textDirection: TextDirection.ltr,
+        child: GoogleMap(
+          initialCameraPosition: _kInitialCameraPosition,
+          onMapCreated: (GoogleMapController controller) {
+            final GoogleMapInspector inspector =
+                // ignore: invalid_use_of_visible_for_testing_member
+                GoogleMapInspector(controller.channel);
+            inspectorCompleter.complete(inspector);
+          },
+        ),
+      ),
+    );
+
+    await tester.pumpAndSettle(const Duration(seconds: 3));
+
+    final GoogleMapInspector inspector = await inspectorCompleter.future;
+    final Uint8List bytes = await inspector.takeSnapshot();
+    expect(bytes?.isNotEmpty, true);
+  });
 }

packages/google_maps_flutter/google_maps_flutter/ios/Classes/GoogleMapController.m

@@ -171,6 +171,22 @@ - (void)onMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
     }
   } else if ([call.method isEqualToString:@"map#waitForMap"]) {
     result(nil);
+  } else if ([call.method isEqualToString:@"map#takeSnapshot"]) {
+    if (_mapView != nil) {
+      UIGraphicsImageRendererFormat* format = [UIGraphicsImageRendererFormat defaultFormat];
+      format.scale = [[UIScreen mainScreen] scale];
+      UIGraphicsImageRenderer* renderer =
+          [[UIGraphicsImageRenderer alloc] initWithSize:_mapView.frame.size format:format];
+
+      UIImage* image = [renderer imageWithActions:^(UIGraphicsImageRendererContext* context) {
+        [_mapView.layer renderInContext:context.CGContext];
+      }];
+      result([FlutterStandardTypedData typedDataWithBytes:UIImagePNGRepresentation(image)]);
+    } else {
+      result([FlutterError errorWithCode:@"GoogleMap uninitialized"
+                                 message:@"takeSnapshot called prior to map initialization"
+                                 details:nil]);
+    }
   } else if ([call.method isEqualToString:@"markers#update"]) {
     id markersToAdd = call.arguments[@"markersToAdd"];
     if ([markersToAdd isKindOfClass:[NSArray class]]) {

packages/google_maps_flutter/google_maps_flutter/lib/src/controller.dart

@@ -285,4 +285,9 @@ class GoogleMapController {
         await channel.invokeMethod<double>('map#getZoomLevel');
     return zoomLevel;
   }
+
+  /// Returns the image bytes of the map
+  Future<Uint8List> takeSnapshot() async {
+    return await channel.invokeMethod<Uint8List>('map#takeSnapshot');
+  }
 }