expose auto exposure and auto focus point of interest functionality (iOS only)

Author: fore5fire

packages/camera/android/src/main/java/io/flutter/plugins/camera/CameraPlugin.java

@@ -199,6 +199,11 @@ public void onMethodCall(MethodCall call, final Result result) {
           camera.stopVideoRecording(result);
           break;
         }
+      case "setPointOfInterest":
+        {
+          result.notImplemented();
+          break;
+        }
       case "dispose":
         {
           if (camera != null) {

packages/camera/example/lib/main.dart

@@ -95,9 +95,17 @@ class _CameraExampleHomeState extends State<CameraExampleHome> {
       );
     } else {
       return new AspectRatio(
-        aspectRatio: controller.value.aspectRatio,
-        child: new CameraPreview(controller),
-      );
+          aspectRatio: controller.value.aspectRatio,
+          child: GestureDetector(
+              child: new CameraPreview(controller),
+              onTapUp: (TapUpDetails details) {
+                final RenderBox box = context.findRenderObject();
+                final Offset localPoint =
+                    box.globalToLocal(details.globalPosition);
+                final Offset scaledPoint =
+                    localPoint.scale(1 / box.size.width, 1 / box.size.height);
+                controller.setPointOfInterest(scaledPoint);
+              }));
     }
   }
 

packages/camera/ios/Classes/CameraPlugin.m

@@ -492,6 +492,28 @@ - (void)handleMethodCall:(FlutterMethodCall *)call result:(FlutterResult)result
       });
       [cam start];
     }
+  } else if ([@"setPointOfInterest" isEqualToString:call.method]) {
+    NSNumber *offsetX = call.arguments[@"offsetX"];
+    NSNumber *offsetY = call.arguments[@"offsetY"];
+
+    NSError *error = nil;
+    [_camera.captureDevice lockForConfiguration:&error];
+    if (error) {
+      result([error flutterError]);
+    } else {
+      if ([_camera.captureDevice isFocusPointOfInterestSupported]) {
+        _camera.captureDevice.focusPointOfInterest =
+            CGPointMake(offsetY.floatValue, 1 - offsetX.floatValue);
+        [_camera.captureDevice setFocusMode:AVCaptureFocusModeContinuousAutoFocus];
+      }
+      if ([_camera.captureDevice isExposurePointOfInterestSupported]) {
+        _camera.captureDevice.exposurePointOfInterest =
+            CGPointMake(offsetY.floatValue, 1 - offsetX.floatValue);
+        [_camera.captureDevice setExposureMode:AVCaptureExposureModeContinuousAutoExposure];
+      }
+      [_camera.captureDevice unlockForConfiguration];
+      result(@{});
+    }
   } else {
     NSDictionary *argsMap = call.arguments;
     NSUInteger textureId = ((NSNumber *)argsMap[@"textureId"]).unsignedIntegerValue;

packages/camera/lib/camera.dart

@@ -335,6 +335,26 @@ class CameraController extends ValueNotifier<CameraValue> {
     }
   }
 
+  /// Sets the auto focus and auto exposure point.
+  ///
+  /// Throws a [CameraException] if the call fails.
+  Future<Null> setPointOfInterest(Offset offset) async {
+    if (!value.isInitialized || _isDisposed) {
+      throw new CameraException(
+        'Uninitialized CameraController.',
+        'takePicture was called on uninitialized CameraController',
+      );
+    }
+    try {
+      await _channel.invokeMethod(
+        'setPointOfInterest',
+        <String, dynamic>{'offsetX': offset.dx, 'offsetY': offset.dy},
+      );
+    } on PlatformException catch (e) {
+      throw new CameraException(e.code, e.message);
+    }
+  }
+
   /// Releases the resources of this camera.
   @override
   Future<Null> dispose() async {