Question

我使用IOS7中的一些新AVCapture API编写了条形码扫描程序。一切都很好，但是我希望在从捕获输出中获取满足数据后抓取图像。下面的方法是我在SKU等上查找的委托，并且也想抓取图像。这种方法有可能这样吗？

 - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
    {
    ...
    }

Answer 1

要专门回答您的问题，不，没有办法从AVCaptureMetadataOutput实例保存图片。

但是，正如编码Voldemort的优秀示例所示，您可以创建AVCaptureStillImageOutput实例并将其添加到AVCaptureSession输出中。一旦您的应用检测到某些元数据，您就可以立即在CaptureStillImageOutput实例上触发捕获。

这里有一个更明确的解决方案，使用codingVoldemort的初始代码作为基础：

首先，无论您在哪里建立AVCaptureSession，都要向其添加AVCaptureStillImageOutput：

_session = [[AVCaptureSession alloc] init];

_output = [[AVCaptureMetadataOutput alloc] init];
[_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
[_session addOutput:_output];

_stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
[_session addOutput:_stillImageOutput];

现在，在- captureOutput: didOutputMetadataObjects中，您可以在触发方法时捕获静止图像：

AVCaptureConnection *stillImageConnection = [_stillImageOutput connectionWithMediaType:AVMediaTypeVideo];
[stillImageConnection setVideoOrientation:AVCaptureVideoOrientationPortrait];
[stillImageConnection setVideoScaleAndCropFactor:1.0f];
[_stillImageOutput setOutputSettings:[NSDictionary dictionaryWithObject:AVVideoCodecJPEG
                                                                        forKey:AVVideoCodecKey]];
_stillImageOutput.outputSettings = @{AVVideoCodecKey: AVVideoCodecJPEG, AVVideoQualityKey:@1};

[stillImageOutput captureStillImageAsynchronouslyFromConnection:stillImageConnection
                                              completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
                                                  if (error) {
                                                      NSLog(@"error: %@", error);
                                                  }
                                                  else {
                                                      NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
                                                      UIImage *image =[UIImage imageWithData:jpegData];
                                                      //Grabbing the image here
                                                      dispatch_async(dispatch_get_main_queue(), ^(void) {

                                                        //Update UI if necessary.


                                                      });


                                                  }
                                              }

 ];

Answer 2

试试这个方法：

-(void)captureZoomedImage:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
    // Find out the current orientation and tell the still image output.
    AVCaptureConnection *stillImageConnection = [stillImageOutput connectionWithMediaType:AVMediaTypeVideo];
    UIDeviceOrientation curDeviceOrientation = [[UIDevice currentDevice] orientation];
    AVCaptureVideoOrientation avcaptureOrientation = [self avOrientationForDeviceOrientation:curDeviceOrientation];
    [stillImageConnection setVideoOrientation:avcaptureOrientation];
    [stillImageConnection setVideoScaleAndCropFactor:1.0f];
    [stillImageOutput setOutputSettings:[NSDictionary dictionaryWithObject:AVVideoCodecJPEG
                                                                    forKey:AVVideoCodecKey]];
     stillImageOutput.outputSettings = @{AVVideoCodecKey: AVVideoCodecJPEG, AVVideoQualityKey:@1};

    [stillImageOutput captureStillImageAsynchronouslyFromConnection:stillImageConnection
                                                  completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
                                                      if (error) {
                                                          [self displayErrorOnMainQueue:error withMessage:@"Take picture failed"];
                                                      }
                                                      else {
                                                          NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
                                                          UIImage *image =[UIImage imageWithData:jpegData];
                                                          //Grabbing the image here
                                                          dispatch_async(dispatch_get_main_queue(), ^(void) {

                                                            //Update UI if necessary.


                                                          });


                                                      }
                                                  }

     ];

}

Answer 3

我想翻译Tim对Swift的回答=）这是第1部分：

let session = AVCaptureSession()
var metadataOutput = AVCaptureMetadataOutput()
var stillCameraOutput = AVCaptureStillImageOutput()
let sessionQueue = dispatch_async(dispatch_get_main_queue(), nil)

metadataOutput.setMetadataObjectsDelegate(self, queue: sessionQueue)
        if session.canAddOutput(metadataOutput) {
            session.addOutput(metadataOutput)
        }
session.addOutput(stillCameraOutput)

这是第二个：

var image = UIImage()
let stillImageConnection = stillCameraOutput.connectionWithMediaType(AVMediaTypeVideo)
stillImageConnection.videoOrientation = .Portrait
stillImageConnection.videoScaleAndCropFactor = 1.0
stillCameraOutput.captureStillImageAsynchronouslyFromConnection(stillImageConnection, completionHandler: { (imageDataSampleBuffer, error) in
                    if (error != nil) {
                        print("There are some error in capturing image")
                    } else {
                        let jpegData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(imageDataSampleBuffer)
                        image = UIImage(data: jpegData)!
                    }
                })

从条形码扫描仪iOS 7保存图像

3 个答案: