[camera_platform_interface] Add platform interface methods for setting auto focus.

packages/camera/camera_platform_interface/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.4.0
+
+- Added interface methods to support auto focus.
+
 ## 1.3.0
 
 - Introduces an option to set the image format when initializing.

packages/camera/camera_platform_interface/lib/src/events/camera_event.dart

@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:camera_platform_interface/src/types/focus_mode.dart';
+
 import '../../camera_platform_interface.dart';
 
 /// Generic Event coming from the native side of Camera.
@@ -50,9 +52,15 @@ class CameraInitializedEvent extends CameraEvent {
   /// The default exposure mode
   final ExposureMode exposureMode;
 
+  /// The default focus mode
+  final FocusMode focusMode;
+
   /// Whether setting exposure points is supported.
   final bool exposurePointSupported;
 
+  /// Whether setting focus points is supported.
+  final bool focusPointSupported;
+
   /// Build a CameraInitialized event triggered from the camera represented by
   /// `cameraId`.
   ///
@@ -61,18 +69,22 @@ class CameraInitializedEvent extends CameraEvent {
   CameraInitializedEvent(
     int cameraId,
     this.previewWidth,
-    this.previewHeight,
+    this.previewHeight, [
     this.exposureMode,
-    this.exposurePointSupported,
-  ) : super(cameraId);
+    this.exposurePointSupported = false,
+    this.focusMode,
+    this.focusPointSupported = false,
+  ]) : super(cameraId);
 
   /// Converts the supplied [Map] to an instance of the [CameraInitializedEvent]
   /// class.
   CameraInitializedEvent.fromJson(Map<String, dynamic> json)
       : previewWidth = json['previewWidth'],
         previewHeight = json['previewHeight'],
         exposureMode = deserializeExposureMode(json['exposureMode']),
-        exposurePointSupported = json['exposurePointSupported'],
+        exposurePointSupported = json['exposurePointSupported'] ?? false,
+        focusMode = deserializeFocusMode(json['focusMode']),
+        focusPointSupported = json['focusPointSupported'] ?? false,
         super(json['cameraId']);
 
   /// Converts the [CameraInitializedEvent] instance into a [Map] instance that
@@ -83,6 +95,8 @@ class CameraInitializedEvent extends CameraEvent {
         'previewHeight': previewHeight,
         'exposureMode': serializeExposureMode(exposureMode),
         'exposurePointSupported': exposurePointSupported,
+        'focusMode': serializeFocusMode(focusMode),
+        'focusPointSupported': focusPointSupported,
       };
 
   @override
@@ -94,15 +108,19 @@ class CameraInitializedEvent extends CameraEvent {
           previewWidth == other.previewWidth &&
           previewHeight == other.previewHeight &&
           exposureMode == other.exposureMode &&
-          exposurePointSupported == other.exposurePointSupported;
+          exposurePointSupported == other.exposurePointSupported &&
+          focusMode == other.focusMode &&
+          focusPointSupported == other.focusPointSupported;
 
   @override
   int get hashCode =>
       super.hashCode ^
       previewWidth.hashCode ^
       previewHeight.hashCode ^
       exposureMode.hashCode ^
-      exposurePointSupported.hashCode;
+      exposurePointSupported.hashCode ^
+      focusMode.hashCode ^
+      focusPointSupported.hashCode;
 }
 
 /// An event fired when the resolution preset of the camera has changed.

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

@@ -6,6 +6,7 @@ import 'dart:async';
 import 'dart:math';
 
 import 'package:camera_platform_interface/camera_platform_interface.dart';
+import 'package:camera_platform_interface/src/types/focus_mode.dart';
 import 'package:camera_platform_interface/src/types/image_format_group.dart';
 import 'package:camera_platform_interface/src/utils/utils.dart';
 import 'package:cross_file/cross_file.dart';
@@ -249,6 +250,31 @@ class MethodChannelCamera extends CameraPlatform {
         },
       );
 
+  @override
+  Future<void> setFocusMode(int cameraId, FocusMode mode) =>
+      _channel.invokeMethod<void>(
+        'setFocusMode',
+        <String, dynamic>{
+          'cameraId': cameraId,
+          'mode': serializeFocusMode(mode),
+        },
+      );
+
+  @override
+  Future<void> setFocusPoint(int cameraId, Point<double> point) {
+    assert(point == null || point.x >= 0 && point.x <= 1);
+    assert(point == null || point.y >= 0 && point.y <= 1);
+    return _channel.invokeMethod<void>(
+      'setFocusPoint',
+      <String, dynamic>{
+        'cameraId': cameraId,
+        'reset': point == null,
+        'x': point?.x,
+        'y': point?.y,
+      },
+    );
+  }
+
   @override
   Future<double> getMaxZoomLevel(int cameraId) => _channel.invokeMethod<double>(
         'getMaxZoomLevel',
@@ -331,6 +357,8 @@ class MethodChannelCamera extends CameraPlatform {
           call.arguments['previewHeight'],
           deserializeExposureMode(call.arguments['exposureMode']),
           call.arguments['exposurePointSupported'],
+          deserializeFocusMode(call.arguments['focusMode']),
+          call.arguments['focusPointSupported'],
         ));
         break;
       case 'resolution_changed':

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

@@ -8,6 +8,7 @@ import 'dart:math';
 import 'package:camera_platform_interface/camera_platform_interface.dart';
 import 'package:camera_platform_interface/src/method_channel/method_channel_camera.dart';
 import 'package:camera_platform_interface/src/types/exposure_mode.dart';
+import 'package:camera_platform_interface/src/types/focus_mode.dart';
 import 'package:camera_platform_interface/src/types/image_format_group.dart';
 import 'package:cross_file/cross_file.dart';
 import 'package:flutter/widgets.dart';
@@ -129,7 +130,7 @@ abstract class CameraPlatform extends PlatformInterface {
     throw UnimplementedError('setExposureMode() is not implemented.');
   }
 
-  /// Sets the exposure point for automatically determining the exposure value.
+  /// Sets the exposure point for automatically determining the exposure values.
   Future<void> setExposurePoint(int cameraId, Point<double> point) {
     throw UnimplementedError('setExposurePoint() is not implemented.');
   }
@@ -166,6 +167,16 @@ abstract class CameraPlatform extends PlatformInterface {
     throw UnimplementedError('setExposureOffset() is not implemented.');
   }
 
+  /// Sets the focus mode for taking pictures.
+  Future<void> setFocusMode(int cameraId, FocusMode mode) {
+    throw UnimplementedError('setFocusMode() is not implemented.');
+  }
+
+  /// Sets the focus point for automatically determining the focus values.
+  Future<void> setFocusPoint(int cameraId, Point<double> point) {
+    throw UnimplementedError('setFocusPoint() is not implemented.');
+  }
+
   /// Gets the maximum supported zoom level for the selected camera.
   Future<double> getMaxZoomLevel(int cameraId) {
     throw UnimplementedError('getMaxZoomLevel() is not implemented.');

packages/camera/camera_platform_interface/lib/src/types/exposure_mode.dart

@@ -13,6 +13,7 @@ enum ExposureMode {
 
 /// Returns the exposure mode as a String.
 String serializeExposureMode(ExposureMode exposureMode) {
+  if (exposureMode == null) return null;
   switch (exposureMode) {
     case ExposureMode.locked:
       return 'locked';
@@ -25,6 +26,7 @@ String serializeExposureMode(ExposureMode exposureMode) {
 
 /// Returns the exposure mode for a given String.
 ExposureMode deserializeExposureMode(String str) {
+  if (str == null) return null;
   switch (str) {
     case "locked":
       return ExposureMode.locked;

packages/camera/camera_platform_interface/lib/src/types/focus_mode.dart

@@ -0,0 +1,38 @@
+// Copyright 2019 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.
+
+/// The possible focus modes that can be set for a camera.
+enum FocusMode {
+  /// Automatically determine focus settings.
+  auto,
+
+  /// Lock the currently determined focus settings.
+  locked,
+}
+
+/// Returns the focus mode as a String.
+String serializeFocusMode(FocusMode focusMode) {
+  if (focusMode == null) return null;
+  switch (focusMode) {
+    case FocusMode.locked:
+      return 'locked';
+    case FocusMode.auto:
+      return 'auto';
+    default:
+      throw ArgumentError('Unknown FocusMode value');
+  }
+}
+
+/// Returns the focus mode for a given String.
+FocusMode deserializeFocusMode(String str) {
+  if (str == null) return null;
+  switch (str) {
+    case "locked":
+      return FocusMode.locked;
+    case "auto":
+      return FocusMode.auto;
+    default:
+      throw ArgumentError('"$str" is not a valid FocusMode value');
+  }
+}

packages/camera/camera_platform_interface/lib/src/types/types.dart

@@ -8,3 +8,4 @@ export 'camera_exception.dart';
 export 'flash_mode.dart';
 export 'image_format_group.dart';
 export 'exposure_mode.dart';
+export 'focus_mode.dart';

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: 1.3.0
+version: 1.4.0
 
 dependencies:
   flutter:

packages/camera/camera_platform_interface/test/camera_platform_interface_test.dart

@@ -264,6 +264,32 @@ void main() {
       );
     });
 
+    test(
+        'Default implementation of setFocusMode() should throw unimplemented error',
+        () {
+      // Arrange
+      final cameraPlatform = ExtendsCameraPlatform();
+
+      // Act & Assert
+      expect(
+        () => cameraPlatform.setFocusMode(1, null),
+        throwsUnimplementedError,
+      );
+    });
+
+    test(
+        'Default implementation of setFocusPoint() should throw unimplemented error',
+        () {
+      // Arrange
+      final cameraPlatform = ExtendsCameraPlatform();
+
+      // Act & Assert
+      expect(
+        () => cameraPlatform.setFocusPoint(1, null),
+        throwsUnimplementedError,
+      );
+    });
+
     test(
         'Default implementation of startVideoRecording() should throw unimplemented error',
         () {