如何在 iPhone 中捕获仅相机可见的视图

Question

我创建了一个视图控制器，50% 的视图是相机视图，其他 50% 是按钮等。
我面临的问题是，当我捕捉到更大的图像时，我只想捕捉在 50% 的视图中我能看到的东西。
所以它看起来像这样：
这是我在视图中看到的：

这就是我在捕获后得到的图像：

这背后的代码是：

-(void) viewDidAppear:(BOOL)animated
{
    AVCaptureSession *session = [[AVCaptureSession alloc] init];
    session.sessionPreset = AVCaptureSessionPresetMedium;

    CALayer *viewLayer = self.vImagePreview.view.layer;
    NSLog(@"viewLayer = %@", viewLayer);

    AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];

    [captureVideoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

    captureVideoPreviewLayer.frame = self.vImagePreview.view.bounds;
    [self.vImagePreview.view.layer addSublayer:captureVideoPreviewLayer];
    NSLog(@"Rect of self.view: %@",NSStringFromCGRect(self.vImagePreview.view.frame));
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    NSError *error = nil;
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (!input) {
        NSLog(@"ERROR: trying to open camera: %@", error);
    }
    [session addInput:input];

    stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
    NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil];
    [stillImageOutput setOutputSettings:outputSettings];

    [session addOutput:stillImageOutput];

    [session startRunning];
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Load camera
    vImagePreview = [[CameraViewController alloc]init];

    vImagePreview.view.frame = CGRectMake(10, 10, 300, 500);
    [self.view addSubview:vImagePreview.view];

    vImage = [[UIImageView alloc]init];
    vImage.frame = CGRectMake(10, 10, 300, 300);

    [self.view addSubview:vImage];

}

这是我尝试捕获图像时的事件：

AVCaptureConnection *videoConnection = nil;
    for (AVCaptureConnection *connection in stillImageOutput.connections)
    {
        for (AVCaptureInputPort *port in [connection inputPorts])
        {
            if ([[port mediaType] isEqual:AVMediaTypeVideo] )
            {
                videoConnection = connection;
                break;
            }
        }
        if (videoConnection) { break; }
    }

    NSLog(@"about to request a capture from: %@", stillImageOutput);
    [stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
     {
         CFDictionaryRef exifAttachments = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifDictionary, NULL);
         if (exifAttachments)
         {
             // Do something with the attachments.
             NSLog(@"attachements: %@", exifAttachments);
         }
         else
             NSLog(@"no attachments");

         NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
         image = [[UIImage alloc] initWithData:imageData];

         UIAlertView *successAlert = [[UIAlertView alloc] init];
         successAlert.title = @"Review Picture";
         successAlert.message = @"";
         [successAlert addButtonWithTitle:@"Save"];
         [successAlert addButtonWithTitle:@"Retake"];

         [successAlert setDelegate:self];

         UIImageView *_imageView = [[UIImageView alloc] initWithFrame:CGRectMake(220, 10, 40, 40)];
         _imageView.image = image;
         [successAlert addSubview:_imageView];
         [successAlert show];

         UIImage *_image = [self imageByScalingAndCroppingForSize:CGSizeMake(640,480) :_imageView.image];
         NSData *idata = [NSData dataWithData:UIImagePNGRepresentation(_image)];
         encodedImage = [self encodeBase64WithData:idata];
     }];

为什么我要获取整个相机视图 我如何缩小相机捕获的大小以便仅捕获在相机视图中看到的内容？

Answer 1

您可以在拍摄后裁剪图像。试试这个

CGImageRef imageRef = CGImageCreateWithImageInRect([largeImage CGImage], cropRect);
// or use the UIImage wherever you like
[UIImageView setImage:[UIImage imageWithCGImage:imageRef]]; 
CGImageRelease(imageRef);

或者试试这个

- (UIImage *)crop:(CGRect)rect {
if (self.scale > 1.0f) {
    rect = CGRectMake(rect.origin.x * self.scale,
                      rect.origin.y * self.scale,
                      rect.size.width * self.scale,
                      rect.size.height * self.scale);
}

CGImageRef imageRef = CGImageCreateWithImageInRect(self.CGImage, rect);
UIImage *result = [UIImage imageWithCGImage:imageRef scale:self.scale orientation:self.imageOrientation];
CGImageRelease(imageRef);
return result;
}

也请参考此链接：Crop UIImage