[英]How can I capture an image from iOS camera without user interaction?
我需要從前置攝像頭捕獲靜止圖像並將其存儲在Documents目錄中。 我在其他帖子中發現了點點滴滴的代碼,但是想分享一下,以防其他人有類似的需求。
定義一個UIImage屬性,並確保您的類實現了AVCaptureVideoDataOutputSampleBufferDelegate協議:
@interface ViewController : UIViewController <AVCaptureVideoDataOutputSampleBufferDelegate>
@property (nonatomic, strong) UIImage *theImage;
@end
在viewDidLoad或適當的東西中,添加以下內容:
[self captureImage];
實現以下方法:
- (void)captureImage
{
AVCaptureSession *session = [[AVCaptureSession alloc] init];
session.sessionPreset = AVCaptureSessionPresetHigh;
AVCaptureDevice *device = [self frontCamera];
NSError *error = nil;
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (!input) {
// Handle the error appropriately.
NSLog(@"no input.....");
}
[session addInput:input];
AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
[session addOutput:output];
output.videoSettings = @{ (NSString *)kCVPixelBufferPixelFormatTypeKey : @(kCVPixelFormatType_32BGRA) };
dispatch_queue_t queue = dispatch_queue_create("MyQueue", NULL);
[output setSampleBufferDelegate:self queue:queue];
[session startRunning];
[session stopRunning];
}
- (AVCaptureDevice *)frontCamera {
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for (AVCaptureDevice *device in devices) {
if ([device position] == AVCaptureDevicePositionFront) {
return device;
}
}
return nil;
}
- (void)captureOutput:(AVCaptureOutput *)captureOutput
didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer
fromConnection:(AVCaptureConnection *)connection {
CGImageRef cgImage = [self imageFromSampleBuffer:sampleBuffer];
self.theImage = [UIImage imageWithCGImage: cgImage ];
CGImageRelease( cgImage );
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0];
NSString *filePath = [documentsPath stringByAppendingPathComponent:@"image.png"];
NSData* data = UIImagePNGRepresentation(self.theImage);
[data writeToFile:filePath atomically:YES];
}
- (CGImageRef) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer
{
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(imageBuffer,0);
uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddressOfPlane(imageBuffer, 0);
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
CGImageRef newImage = CGBitmapContextCreateImage(newContext);
CGContextRelease(newContext);
CGColorSpaceRelease(colorSpace);
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
return newImage;
}
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