AVFoundation之如何从摄像头获取图像

前言：

最近项目有个需求是对试图对手机密码进行强破解的人进行拍照(通过摄像头截图)，因为之前没做过，所以一堆坑。现在就把我的经验都分享出来，希望后来人不用再踏上坑途中。

直接上代码：

　 // 创建会话

　 self.session = [[AVCaptureSession alloc] init];

// 获取摄像头的权限信息，判断是否有开启权限

AVAuthorizationStatus status    = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];

if (status == AVAuthorizationStatusAuthorized)

{

self.setupResult = AVCamSetupResultSuccess;

}

if ( self.setupResult != AVCamSetupResultSuccess )

return;

self.backgroundRecordingID = UIBackgroundTaskInvalid;

NSError *error = nil;

// 创建输入设备

AVCaptureDevice *videoDevice = [self deviceWithMediaType:AVMediaTypeVideo preferringPosition:AVCaptureDevicePositionFront];

AVCaptureDeviceInput *videoDeviceInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];

// beginConfiguration这个很重要，在addInput或者addOutput的时候一定要调用这个，add之后再调用commitConfiguration

[self.session beginConfiguration];

if ([self.session canAddInput:videoDeviceInput])

{

[self.session addInput:videoDeviceInput]；

self.videoDeviceInput = videoDeviceInput;

}

　  // 为会话加入output设备

dispatch_queue_t videoDataOutputQueue = dispatch_queue_create("VideoDataOutputQueue", DISPATCH_QUEUE_SERIAL);

AVCaptureVideoDataOutput *videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];

videoDataOutput.videoSettings =[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA]forKey:               (id)kCVPixelBufferPixelFormatTypeKey];

// 设置self的AVCaptureVideoDataOutputSampleBufferDelegate

[videoDataOutput setSampleBufferDelegate:self queue:videoDataOutputQueue];

if ([self.session canAddOutput:videoDataOutput])

{

[self.session addOutput:videoDataOutput];

}

[self.session commitConfiguration];

// 获取前置摄像头

- (AVCaptureDevice *)deviceWithMediaType:(NSString *)mediaType preferringPosition:(AVCaptureDevicePosition)position{

NSArray *devices = [AVCaptureDevice devicesWithMediaType:mediaType];

AVCaptureDevice *captureDevice = devices.firstObject;

for ( AVCaptureDevice *device in devices ) {

if ( device.position == position ) {

captureDevice = device;

break;

}

}

return captureDevice;

}

// 实现代理方法并获取图片

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{

if (takephoto.isShutScreen)

{

NSLog(@"didOutputSampleBuffer");

UIImage *image  = [self getImageBySampleBufferref:sampleBuffer];

}

}

// 将获取的数据转换成图片，网上很多转换方式转出来的图片都是错误的，最后找到这个方法

- (UIImage *)getImageBySampleBufferref:(CMSampleBufferRef)sampleBuffer

{

CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);

/*Lock the image buffer*/

CVPixelBufferLockBaseAddress(imageBuffer,0);

/*Get information about the image*/

uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);

size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);

size_t width = CVPixelBufferGetWidth(imageBuffer);

size_t height = CVPixelBufferGetHeight(imageBuffer);

/*We unlock the  image buffer*/

CVPixelBufferUnlockBaseAddress(imageBuffer,0);

/*Create a CGImageRef from the CVImageBufferRef*/

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);

CGImageRef newImage = CGBitmapContextCreateImage(newContext);

/*We release some components*/

CGContextRelease(newContext);

CGColorSpaceRelease(colorSpace);

UIImage *image= [UIImage imageWithCGImage:newImage scale:1.0 orientation:UIImageOrientationRight];

NSLog(@"%@", image);

/*We relase the CGImageRef*/

CGImageRelease(newImage);

return image;

}

只要照着我的思路走，就可以达到摄像机截屏的效果，希望能帮到需要的人，如有其他意见，请留言。