我正在尝试构建一个非实时人脸检测应用程序。
在这篇文章之后：http: //maniacdev.com/2011/11/tutorial-easy-face-detection-with-core-image-in-ios-5/我可以加载 jpg 并检测人脸。
我想每 20 秒自动拍照，然后在 UIImageView* 中显示图像，然后在其上运行现有的检测面部功能。
我的问题是两方面的。
有没有一种简单的方法可以从相机中获取样本图片并将其加载到 UIImageView* 中而不保存它？
如何在没有用户交互的情况下自动每 30 秒发生一次？
谢谢！
查看 AVFoundation 编程指南
本指南向您展示如何使用 AVFoundation 来捕获媒体。
您需要考虑设备旋转，因为相机将仅显示其原始输出，直到您通过 CATransformMatrix 旋转输出，但这比您想要的要深入一些。
只要知道，您就可以逃脱惩罚。您从原始点旋转 45° 到最终旋转位置。
这是我的小相机测试实用程序的代码。
构建一个 UIView 并连接 IBOutlets 和 IBActions
视图控制器.h
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController
@property (weak, nonatomic) IBOutlet UIView *previewViewContainer;
@property (weak, nonatomic) IBOutlet UIView *playerViewContainer;
- (IBAction)button1Pressed:(id)sender;
- (IBAction)button2Pressed:(id)sender;
- (IBAction)button3Pressed:(id)sender;
- (IBAction)button4Pressed:(id)sender;
- (IBAction)startPressed:(id)sender;
- (IBAction)stopPressed:(id)sender;
- (IBAction)swapInputsPressed:(id)sender;
- (IBAction)recordPressed:(id)sender;
@end
视图控制器.m
#import "ViewController.h"
#import <AVFoundation/AVFoundation.h>
@interface ViewController ()
@property (nonatomic, strong) AVCaptureSession *captureSession;
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *capturePreviewLayer;
@property (nonatomic, strong) AVCaptureDeviceInput *frontCam;
@property (nonatomic, readonly) BOOL frontCamIsSet;
@property (nonatomic, readonly) BOOL hasFrontCam;
@property (nonatomic, readonly) BOOL isUsingFrontCam;
@property (nonatomic, strong) AVCaptureDeviceInput *backCam;
@property (nonatomic, readonly) BOOL backCamIsSet;
@property (nonatomic, readonly) BOOL hasBackCam;
@property (nonatomic, readonly) BOOL isUsingBackCam;
@property (nonatomic, strong) AVCaptureDeviceInput *mic;
@property (nonatomic, readonly) BOOL micIsSet;
@property (nonatomic, readonly) BOOL hasMic;
@end
CGFloat DegreesToRadians(CGFloat degrees)
{
return degrees * M_PI / 180;
};
CGFloat RadiansToDegrees(CGFloat radians)
{
return radians * 180 / M_PI;
};
@implementation ViewController
#pragma mark - Helper Methods
- (NSArray *) inputDevices{
return [AVCaptureDevice devices];
}
- (NSArray *) videoInputDevices{
return [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
}
- (NSArray *) audioInputDevices{
return [AVCaptureDevice devicesWithMediaType:AVMediaTypeAudio];
}
#pragma mark - Properties
@synthesize captureSession = _captureSession;
- (AVCaptureSession *)captureSession{
if (_captureSession == nil){
_captureSession = [[AVCaptureSession alloc] init];
}
return _captureSession;
}
@synthesize capturePreviewLayer = _capturePreviewLayer;
- (AVCaptureVideoPreviewLayer *)capturePreviewLayer{
if (_capturePreviewLayer == nil){
_capturePreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
}
return _capturePreviewLayer;
}
@synthesize frontCam = _frontCam;
- (AVCaptureDeviceInput *)frontCam{
if (_frontCam == nil && !self.frontCamIsSet){
_frontCamIsSet = YES;
NSArray *videoDevices = [self videoInputDevices];
for (AVCaptureDevice *inputDevice in videoDevices) {
if ([inputDevice position] == AVCaptureDevicePositionFront){
NSError *error = nil;
_frontCam = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:&error];
if (!_frontCam){
NSLog(@"Error Attaching Front Cam %@",error);
}
}
}
}
return _frontCam;
}
- (BOOL)hasFrontCam{
return self.frontCam != nil;
}
@synthesize isUsingFrontCam = _isUsingFrontCam;
@synthesize backCam = _backCam;
- (AVCaptureDeviceInput *)backCam{
if (_backCam == nil && !self.backCamIsSet){
_backCamIsSet = YES;
NSArray *videoDevices = [self videoInputDevices];
for (AVCaptureDevice *inputDevice in videoDevices) {
if ([inputDevice position] == AVCaptureDevicePositionBack){
NSError *error = nil;
_backCam = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:&error];
if (!_backCam){
NSLog(@"Error Attaching Back Cam %@",error);
}
}
}
}
return _backCam;
}
- (BOOL)hasBackCam{
return self.backCam != nil;
}
@synthesize mic = _mic;
- (AVCaptureDeviceInput *)mic{
if (_mic == nil && !self.micIsSet){
_micIsSet = YES;
NSArray *audioDevices = [self audioInputDevices];
for (AVCaptureDevice *inputDevice in audioDevices) {
NSError *error = nil;
_mic = [AVCaptureDeviceInput deviceInputWithDevice:inputDevice error:&error];
if (!_mic){
NSLog(@"Error Attaching Mic %@",error);
}
}
}
return _mic;
}
- (BOOL)hasMic{
return self.mic != nil;
}
- (BOOL)isUsingBackCam{
return !self.isUsingFrontCam;
}
- (IBAction)button1Pressed:(id)sender {
if (NO && self.hasFrontCam && [self.captureSession canAddInput:self.frontCam]){
_isUsingFrontCam = YES;
[self.captureSession addInput:self.frontCam];
}
else if(self.hasBackCam && [self.captureSession canAddInput:self.backCam]){
_isUsingFrontCam = NO;
[self.captureSession addInput:self.backCam];
}
if (self.hasMic && [self.captureSession canAddInput:self.mic]) {
[self.captureSession addInput:self.mic];
}
}
- (IBAction)button2Pressed:(id)sender {
self.capturePreviewLayer.frame = self.previewViewContainer.layer.bounds;
[self.previewViewContainer.layer addSublayer:self.capturePreviewLayer];
}
- (void) orientationChanged:(NSNotification*) notification{
NSLog(@"Notification Of Orientation Change\n\n%@",notification.userInfo);
if (_capturePreviewLayer != nil){
CGFloat rotate90 = DegreesToRadians(90);
CGFloat rotateFinish = 0;
UIDeviceOrientation orientation = [UIDevice currentDevice].orientation;
switch (orientation) {
case UIDeviceOrientationLandscapeLeft:
rotateFinish += rotate90;
case UIDeviceOrientationPortraitUpsideDown:
rotateFinish += rotate90;
case UIDeviceOrientationLandscapeRight:
rotateFinish += rotate90;
case UIDeviceOrientationPortrait:
default:
break;
}
_capturePreviewLayer.transform = CATransform3DMakeRotation(rotateFinish, 0.0, 0.0, 1.0);
}
}
- (IBAction)button3Pressed:(id)sender {
}
- (IBAction)button4Pressed:(id)sender {
}
- (IBAction)startPressed:(id)sender {
[self.captureSession startRunning];
}
- (IBAction)stopPressed:(id)sender {
[self.captureSession stopRunning];
}
- (IBAction)swapInputsPressed:(id)sender {
if (!self.isUsingFrontCam){
_isUsingFrontCam = YES;
[self.captureSession removeInput:self.backCam];
[self.captureSession addInput:self.frontCam];
}
else {
_isUsingFrontCam = NO;
[self.captureSession removeInput:self.frontCam];
[self.captureSession addInput:self.backCam];
}
}
- (IBAction)recordPressed:(id)sender {
}
- (NSString *) applicationDocumentsDirectory{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *basePath = ([paths count] > 0) ? [paths objectAtIndex:0] : nil;
return basePath;
}
- (void)viewDidLoad{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(orientationChanged:)
name:UIDeviceOrientationDidChangeNotification
object:nil];
}
- (void) dealloc{
[[UIDevice currentDevice] endGeneratingDeviceOrientationNotifications];
[[NSNotificationCenter defaultCenter] removeObserver:self
name:UIDeviceOrientationDidChangeNotification
object:nil];
}
- (void)didReceiveMemoryWarning{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
对你来说幸运的是，我刚刚构建了这个用于抓取照片的测试应用程序。
哦，在我忘记之前。将 CALayer 渲染成图形就像
+ (UIImage *) captureImageOfView:(UIView *)srcView{
UIGraphicsBeginImageContext(srcView.bounds.size);
[srcView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *anImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return anImage;
}
但是，我建议您查看 AVFoundation 编程指南，了解他们如何实际捕获它。正如我所说，这只是我自己的演示应用程序。它不完整。