这让我发疯,因为我无法让它发挥作用。我有以下情况:
我正在使用AVCaptureSession
和AVCaptureVideoPreviewLayer
来创建自己的相机界面。界面显示一个矩形。以下是填充整个屏幕的AVCaptureVideoPreviewLayer
。
我希望以某种方式裁剪捕获的图像,结果图像显示在显示屏上的rect中看到的内容。
我的设置如下:
_session = [[AVCaptureSession alloc] init];
AVCaptureSession *session = _session;
session.sessionPreset = AVCaptureSessionPresetPhoto;
AVCaptureDevice *camera = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if (camera == nil) {
[self showImagePicker];
_isSetup = YES;
return;
}
AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
captureVideoPreviewLayer.frame = self.liveCapturePlaceholderView.bounds;
[self.liveCapturePlaceholderView.layer addSublayer:captureVideoPreviewLayer];
NSError *error;
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:camera error:&error];
if (error) {
HGAlertViewWrapper *av = [[HGAlertViewWrapper alloc] initWithTitle:kFailedConnectingToCameraAlertViewTitle message:kFailedConnectingToCameraAlertViewMessage cancelButtonTitle:kFailedConnectingToCameraAlertViewCancelButtonTitle otherButtonTitles:@[kFailedConnectingToCameraAlertViewRetryButtonTitle]];
[av showWithBlock:^(NSString *buttonTitle){
if ([buttonTitle isEqualToString:kFailedConnectingToCameraAlertViewCancelButtonTitle]) {
[self.delegate gloameCameraViewControllerDidCancel:self];
}
else {
[self setupAVSession];
}
}];
}
[session addInput:input];
NSDictionary *options = @{ AVVideoCodecKey : AVVideoCodecJPEG };
_stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
[_stillImageOutput setOutputSettings:options];
[session addOutput:_stillImageOutput];
[session startRunning];
_isSetup = YES;
我正在捕捉这样的图像:
[_stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
{
if (error) {
MWLogDebug(@"Error capturing image from camera. %@, %@", error, [error userInfo]);
_capturePreviewLayer.connection.enabled = YES;
}
else
{
NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
UIImage *image = [[UIImage alloc] initWithData:imageData];
CGRect cropRect = [self createCropRectForImage:image];
UIImage *croppedImage;// = [self cropImage:image toRect:cropRect];
UIGraphicsBeginImageContext(cropRect.size);
[image drawAtPoint:CGPointMake(-cropRect.origin.x, -cropRect.origin.y)];
croppedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self.capturedImage = croppedImage;
[_session stopRunning];
}
}];
在createCropRectForImage:
方法中,我尝试了各种方法来计算切割图像的矩形,但到目前为止还没有成功。
- (CGRect)createCropRectForImage:(UIImage *)image
{
CGPoint maskTopLeftCorner = CGPointMake(self.maskRectView.frame.origin.x, self.maskRectView.frame.origin.y);
CGPoint maskBottomRightCorner = CGPointMake(self.maskRectView.frame.origin.x + self.maskRectView.frame.size.width, self.maskRectView.frame.origin.y + self.maskRectView.frame.size.height);
CGPoint maskTopLeftCornerInLayerCoords = [_capturePreviewLayer convertPoint:maskTopLeftCorner fromLayer:self.maskRectView.layer.superlayer];
CGPoint maskBottomRightCornerInLayerCoords = [_capturePreviewLayer convertPoint:maskBottomRightCorner fromLayer:self.maskRectView.layer.superlayer];
CGPoint maskTopLeftCornerInDeviceCoords = [_capturePreviewLayer captureDevicePointOfInterestForPoint:maskTopLeftCornerInLayerCoords];
CGPoint maskBottomRightCornerInDeviceCoords = [_capturePreviewLayer captureDevicePointOfInterestForPoint:maskBottomRightCornerInLayerCoords];
float x = maskTopLeftCornerInDeviceCoords.x * image.size.width;
float y = (1 - maskTopLeftCornerInDeviceCoords.y) * image.size.height;
float width = fabsf(maskTopLeftCornerInDeviceCoords.x - maskBottomRightCornerInDeviceCoords.x) * image.size.width;
float height = fabsf(maskTopLeftCornerInDeviceCoords.y - maskBottomRightCornerInDeviceCoords.y) * image.size.height;
return CGRectMake(x, y, width, height);
}
这是我当前的版本,但甚至没有正确的比例。有人可以帮助我!
我也尝试使用此方法裁剪图像:
- (UIImage*)cropImage:(UIImage*)originalImage toRect:(CGRect)rect{
CGImageRef imageRef = CGImageCreateWithImageInRect([originalImage CGImage], rect);
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);
CGContextRef bitmap = CGBitmapContextCreate(NULL, rect.size.width, rect.size.height, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);
if (originalImage.imageOrientation == UIImageOrientationLeft) {
CGContextRotateCTM (bitmap, radians(90));
CGContextTranslateCTM (bitmap, 0, -rect.size.height);
} else if (originalImage.imageOrientation == UIImageOrientationRight) {
CGContextRotateCTM (bitmap, radians(-90));
CGContextTranslateCTM (bitmap, -rect.size.width, 0);
} else if (originalImage.imageOrientation == UIImageOrientationUp) {
// NOTHING
} else if (originalImage.imageOrientation == UIImageOrientationDown) {
CGContextTranslateCTM (bitmap, rect.size.width, rect.size.height);
CGContextRotateCTM (bitmap, radians(-180.));
}
CGContextDrawImage(bitmap, CGRectMake(0, 0, rect.size.width, rect.size.height), imageRef);
CGImageRef ref = CGBitmapContextCreateImage(bitmap);
UIImage *resultImage=[UIImage imageWithCGImage:ref];
CGImageRelease(imageRef);
CGContextRelease(bitmap);
CGImageRelease(ref);
return resultImage;
}
是否有人使用“正确组合”的方法来完成这项工作? :)
答案 0 :(得分:43)
我使用metadataOutputRectOfInterestForRect
函数解决了这个问题。
适用于任何方向。
[_stillImageOutput captureStillImageAsynchronouslyFromConnection:stillImageConnection
completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error)
{
if (error)
{
[_delegate cameraView:self error:@"Take picture failed"];
}
else
{
NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
UIImage *takenImage = [UIImage imageWithData:jpegData];
CGRect outputRect = [_previewLayer metadataOutputRectOfInterestForRect:_previewLayer.bounds];
CGImageRef takenCGImage = takenImage.CGImage;
size_t width = CGImageGetWidth(takenCGImage);
size_t height = CGImageGetHeight(takenCGImage);
CGRect cropRect = CGRectMake(outputRect.origin.x * width, outputRect.origin.y * height, outputRect.size.width * width, outputRect.size.height * height);
CGImageRef cropCGImage = CGImageCreateWithImageInRect(takenCGImage, cropRect);
takenImage = [UIImage imageWithCGImage:cropCGImage scale:1 orientation:takenImage.imageOrientation];
CGImageRelease(cropCGImage);
}
}
];
takeImage仍然是imageOrientation
依赖图像。您可以删除方向信息以进行进一步的图像处理。
UIGraphicsBeginImageContext(takenImage.size);
[takenImage drawAtPoint:CGPointZero];
takenImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
答案 1 :(得分:43)
在Swift 3中:
private func cropToPreviewLayer(originalImage: UIImage) -> UIImage {
let outputRect = previewLayer.metadataOutputRectOfInterest(for: previewLayer.bounds)
var cgImage = originalImage.cgImage!
let width = CGFloat(cgImage.width)
let height = CGFloat(cgImage.height)
let cropRect = CGRect(x: outputRect.origin.x * width, y: outputRect.origin.y * height, width: outputRect.size.width * width, height: outputRect.size.height * height)
cgImage = cgImage.cropping(to: cropRect)!
let croppedUIImage = UIImage(cgImage: cgImage, scale: 1.0, orientation: originalImage.imageOrientation)
return croppedUIImage
}
答案 2 :(得分:0)
AVMakeRectWithAspectRatioInsideRect 这个api来自AVFoundation,它将返回给定裁剪尺寸的图像的裁剪区域。
答案 3 :(得分:0)
在 Swift 4 中:
我宁愿从不强制解包以避免崩溃,所以我在我的系统中使用了可选参数和guards
。
private func cropToPreviewLayer(originalImage: UIImage) -> UIImage? {
guard let cgImage = originalImage.cgImage else { return nil }
let outputRect = previewLayer.metadataOutputRectConverted(fromLayerRect: previewLayer.bounds)
let width = CGFloat(cgImage.width)
let height = CGFloat(cgImage.height)
let cropRect = CGRect(x: outputRect.origin.x * width, y: outputRect.origin.y * height, width: outputRect.size.width * width, height: outputRect.size.height * height)
if let croppedCGImage = cgImage.cropping(to: cropRect) {
return UIImage(cgImage: croppedCGImage, scale: 1.0, orientation: originalImage.imageOrientation)
}
return nil
}