Add start/stopPreview for Camera

README.md

@@ -346,6 +346,14 @@ Returns whether or not the camera has flash capabilities.
 
 Ends the current capture session for video captures. Only applies when the current `captureMode` is `video`.
 
+#### `stopPreview()`
+
+Stops the camera preview from running, and natively will make the current capture session pause.
+
+#### `startPreview()`
+
+Starts the camera preview again if previously stopped.
+
 ## Component static methods
 
 #### `iOS` `Camera.checkDeviceAuthorizationStatus(): Promise`

android/src/main/java/com/lwansbrough/RCTCamera/RCTCameraModule.java

@@ -658,6 +658,18 @@ public class RCTCameraModule extends ReactContextBaseJavaModule
         }
     }
 
+    @ReactMethod
+    public void stopPreview(ReadableMap options) {
+        Camera camera = RCTCamera.getInstance().acquireCameraInstance(options.getInt("type"));
+        camera.stopPreview();
+    }
+
+    @ReactMethod
+    public void startPreview(ReadableMap options) {
+        Camera camera = RCTCamera.getInstance().acquireCameraInstance(options.getInt("type"));
+        camera.startPreview();
+    }
+
     @ReactMethod
     public void hasFlash(ReadableMap options, final Promise promise) {
         Camera camera = RCTCamera.getInstance().acquireCameraInstance(options.getInt("type"));

index.js

@@ -236,6 +236,28 @@ export default class Camera extends Component {
     return CameraManager.capture(options);
   }
 
+  startPreview() {
+    if (Platform.OS === 'android') {
+      const props = convertNativeProps(this.props);
+      CameraManager.startPreview({
+        type: props.type
+      });
+    } else {
+      CameraManager.startPreview();
+    }
+  }
+
+  stopPreview() {
+    if (Platform.OS === 'android') {
+      const props = convertNativeProps(this.props);
+      CameraManager.stopPreview({
+        type: props.type
+      });
+    } else {
+      CameraManager.stopPreview();
+    }
+  }
+
   stopCapture() {
     if (this.state.isRecording) {
       this.setState({ isRecording: false });

ios/RCTCameraManager.m

@@ -374,6 +374,28 @@ RCT_EXPORT_METHOD(capture:(NSDictionary *)options
   }
 }
 
+RCT_EXPORT_METHOD(stopPreview) {
+#if TARGET_IPHONE_SIMULATOR
+    return;
+#endif
+    dispatch_async(self.sessionQueue, ^{
+        if ([self.session isRunning]) {
+            [self.session stopRunning];
+        }
+    });
+}
+
+RCT_EXPORT_METHOD(startPreview) {
+#if TARGET_IPHONE_SIMULATOR
+    return;
+#endif
+    dispatch_async(self.sessionQueue, ^{
+        if (![self.session isRunning]) {
+            [self.session startRunning];
+        }
+    });
+}
+
 RCT_EXPORT_METHOD(stopCapture) {
   if (self.movieFileOutput.recording) {
     [self.movieFileOutput stopRecording];