[camera] Add zoom support to platform interface (flutter#3312)

* Add zoom support to platform interface

* Added method to retrieve min supported zoom level

* Bumped version to 1.0.2

* Fixed small typo

Author: mvanbeusekom

packages/camera/camera_platform_interface/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.2
+
+- Added interface methods to support zoom features.
+
 ## 1.0.1
 
 - Added interface methods for setting flash mode.

packages/camera/camera_platform_interface/lib/src/method_channel/method_channel_camera.dart

@@ -185,6 +185,33 @@ class MethodChannelCamera extends CameraPlatform {
         },
       );
 
+  @override
+  Future<double> getMaxZoomLevel(int cameraId) => _channel.invokeMethod<double>(
+        'getMaxZoomLevel',
+        <String, dynamic>{'cameraId': cameraId},
+      );
+
+  @override
+  Future<double> getMinZoomLevel(int cameraId) => _channel.invokeMethod<double>(
+        'getMinZoomLevel',
+        <String, dynamic>{'cameraId': cameraId},
+      );
+
+  @override
+  Future<void> setZoomLevel(int cameraId, double zoom) async {
+    try {
+      await _channel.invokeMethod<double>(
+        'setZoomLevel',
+        <String, dynamic>{
+          'cameraId': cameraId,
+          'zoom': zoom,
+        },
+      );
+    } on PlatformException catch (e) {
+      throw CameraException(e.code, e.message);
+    }
+  }
+
   @override
   Widget buildPreview(int cameraId) {
     return Texture(textureId: cameraId);

packages/camera/camera_platform_interface/lib/src/platform_interface/camera_platform.dart

@@ -113,6 +113,25 @@ abstract class CameraPlatform extends PlatformInterface {
     throw UnimplementedError('setFlashMode() is not implemented.');
   }
 
+  /// Gets the maximum supported zoom level for the selected camera.
+  Future<double> getMaxZoomLevel(int cameraId) {
+    throw UnimplementedError('getMaxZoomLevel() is not implemented.');
+  }
+
+  /// Gets the minimum supported zoom level for the selected camera.
+  Future<double> getMinZoomLevel(int cameraId) {
+    throw UnimplementedError('getMinZoomLevel() is not implemented.');
+  }
+
+  /// Set the zoom level for the selected camera.
+  ///
+  /// The supplied [zoom] value should be between 1.0 and the maximum supported
+  /// zoom level returned by the `getMaxZoomLevel`. Throws an `CameraException`
+  /// when an illegal zoom level is supplied.
+  Future<void> setZoomLevel(int cameraId, double zoom) {
+    throw UnimplementedError('setZoomLevel() is not implemented.');
+  }
+
   /// Returns a widget showing a live camera preview.
   Widget buildPreview(int cameraId) {
     throw UnimplementedError('buildView() has not been implemented.');

packages/camera/camera_platform_interface/pubspec.yaml

@@ -3,7 +3,7 @@ description: A common platform interface for the camera plugin.
 homepage: https://github.com/flutter/plugins/tree/master/packages/camera/camera_platform_interface
 # NOTE: We strongly prefer non-breaking changes, even at the expense of a
 # less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
-version: 1.0.1
+version: 1.0.2
 
 dependencies:
   flutter:

packages/camera/camera_platform_interface/test/camera_platform_interface_test.dart

@@ -224,6 +224,45 @@ void main() {
         throwsUnimplementedError,
       );
     });
+
+    test(
+        'Default implementation of getMaxZoomLevel() should throw unimplemented error',
+        () {
+      // Arrange
+      final cameraPlatform = ExtendsCameraPlatform();
+
+      // Act & Assert
+      expect(
+        () => cameraPlatform.getMaxZoomLevel(1),
+        throwsUnimplementedError,
+      );
+    });
+
+    test(
+        'Default implementation of getMinZoomLevel() should throw unimplemented error',
+        () {
+      // Arrange
+      final cameraPlatform = ExtendsCameraPlatform();
+
+      // Act & Assert
+      expect(
+        () => cameraPlatform.getMinZoomLevel(1),
+        throwsUnimplementedError,
+      );
+    });
+
+    test(
+        'Default implementation of setZoomLevel() should throw unimplemented error',
+        () {
+      // Arrange
+      final cameraPlatform = ExtendsCameraPlatform();
+
+      // Act & Assert
+      expect(
+        () => cameraPlatform.setZoomLevel(1, 1.0),
+        throwsUnimplementedError,
+      );
+    });
   });
 }
 

packages/camera/camera_platform_interface/test/method_channel/method_channel_camera_test.dart

@@ -509,6 +509,84 @@ void main() {
         expect(() => camera.handleMethodCall(MethodCall('unknown_method'), 1),
             throwsA(isA<MissingPluginException>()));
       });
+
+      test('Should get the max zoom level', () async {
+        // Arrange
+        MethodChannelMock channel = MethodChannelMock(
+          channelName: 'plugins.flutter.io/camera',
+          methods: {'getMaxZoomLevel': 10.0},
+        );
+
+        // Act
+        final maxZoomLevel = await camera.getMaxZoomLevel(cameraId);
+
+        // Assert
+        expect(maxZoomLevel, 10.0);
+        expect(channel.log, <Matcher>[
+          isMethodCall('getMaxZoomLevel', arguments: {
+            'cameraId': cameraId,
+          }),
+        ]);
+      });
+
+      test('Should get the min zoom level', () async {
+        // Arrange
+        MethodChannelMock channel = MethodChannelMock(
+          channelName: 'plugins.flutter.io/camera',
+          methods: {'getMinZoomLevel': 1.0},
+        );
+
+        // Act
+        final maxZoomLevel = await camera.getMinZoomLevel(cameraId);
+
+        // Assert
+        expect(maxZoomLevel, 1.0);
+        expect(channel.log, <Matcher>[
+          isMethodCall('getMinZoomLevel', arguments: {
+            'cameraId': cameraId,
+          }),
+        ]);
+      });
+
+      test('Should set the zoom level', () async {
+        // Arrange
+        MethodChannelMock channel = MethodChannelMock(
+          channelName: 'plugins.flutter.io/camera',
+          methods: {'setZoomLevel': null},
+        );
+
+        // Act
+        await camera.setZoomLevel(cameraId, 2.0);
+
+        // Assert
+        expect(channel.log, <Matcher>[
+          isMethodCall('setZoomLevel',
+              arguments: {'cameraId': cameraId, 'zoom': 2.0}),
+        ]);
+      });
+
+      test('Should throw CameraException when illegal zoom level is supplied',
+          () async {
+        // Arrange
+        MethodChannelMock(
+          channelName: 'plugins.flutter.io/camera',
+          methods: {
+            'setZoomLevel': PlatformException(
+              code: 'ZOOM_ERROR',
+              message: 'Illegal zoom error',
+              details: null,
+            )
+          },
+        );
+
+        // Act & assert
+        expect(
+            () => camera.setZoomLevel(cameraId, -1.0),
+            throwsA(isA<CameraException>()
+                .having((e) => e.code, 'code', 'ZOOM_ERROR')
+                .having((e) => e.description, 'description',
+                    'Illegal zoom error')));
+      });
     });
   });
 }