iOS 相机相关
2017-06-01 本文已影响0人
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这里不说拍照这种大家都烂熟的东西，主要说说图像预览、人脸识别、二维码识别等，都是基于AVFoundation框架实现的。
引入 ：#import <AVFoundation/AVFoundation.h>
开启相机权限：
1.在项目中找到info.plist文件，右键点击以 Source Code形式打开
2.添加以下键值对
<key>NSCameraUsageDescription</key>
<string>此 App 需要相机权限</string>
主要属性：
//硬件设备
@property (nonatomic, strong) AVCaptureDevice *device;
//输入流
@property (nonatomic, strong) AVCaptureDeviceInput *input;
//协调输入输出流的数据
@property (nonatomic, strong) AVCaptureSession *session;
//预览层
@property (nonatomic, strong) AVCaptureVideoPreviewLayer *previewLayer;
//输出流
@property (nonatomic, strong) AVCaptureStillImageOutput *stillImageOutput; //用于捕捉静态图片
@property (nonatomic, strong) AVCaptureVideoDataOutput *videoDataOutput; //原始视频帧，用于获取实时图像以及视频录制
@property (nonatomic, strong) AVCaptureMetadataOutput *metadataOutput; //用于二维码识别以及人脸识别
首先我们需要在手机上把图像显示出来
1.1 获取硬件设备
-(AVCaptureDevice *)device{
if (_device == nil) {
_device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
//(注意调整device属性的时候需要上锁, 调整完再解锁)
if ([_device lockForConfiguration:nil]) {
//自动闪光灯
if ([_device isFlashModeSupported:AVCaptureFlashModeAuto]) {
[_device setFlashMode:AVCaptureFlashModeAuto];
}
//自动白平衡
if ([_device isWhiteBalanceModeSupported:AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance]) {
[_device setWhiteBalanceMode:AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance];
}
//自动对焦
if ([_device isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus]) {
[_device setFocusMode:AVCaptureFocusModeContinuousAutoFocus];
}
//自动曝光
if ([_device isExposureModeSupported:AVCaptureExposureModeContinuousAutoExposure]) {
[_device setExposureMode:AVCaptureExposureModeContinuousAutoExposure];
}
[_device unlockForConfiguration];
}
}
return _device;
}
device相关属性选项：
闪光灯选项
typedef NS_ENUM(NSInteger, AVCaptureFlashMode) {
AVCaptureFlashModeOff = 0,//关
AVCaptureFlashModeOn = 1,//开
AVCaptureFlashModeAuto = 2//自动
} NS_AVAILABLE(10_7, 4_0) __TVOS_PROHIBITED;
前后置摄像头选项
typedef NS_ENUM(NSInteger, AVCaptureDevicePosition) {
AVCaptureDevicePositionUnspecified = 0,//不指定
AVCaptureDevicePositionBack = 1,//后置摄像头
AVCaptureDevicePositionFront = 2//前
} NS_AVAILABLE(10_7, 4_0) __TVOS_PROHIBITED;
手电筒选项
typedef NS_ENUM(NSInteger, AVCaptureTorchMode) {
AVCaptureTorchModeOff = 0,//开
AVCaptureTorchModeOn = 1,//关
AVCaptureTorchModeAuto = 2,//自动
} NS_AVAILABLE(10_7, 4_0) __TVOS_PROHIBITED;
对焦选项
typedef NS_ENUM(NSInteger, AVCaptureFocusMode) {
AVCaptureFocusModeLocked = 0,
AVCaptureFocusModeAutoFocus = 1,
AVCaptureFocusModeContinuousAutoFocus = 2,
} NS_AVAILABLE(10_7, 4_0) __TVOS_PROHIBITED;
曝光选项
typedef NS_ENUM(NSInteger, AVCaptureExposureMode) {
AVCaptureExposureModeLocked = 0,
AVCaptureExposureModeAutoExpose = 1,
AVCaptureExposureModeContinuousAutoExposure = 2,
AVCaptureExposureModeCustom NS_ENUM_AVAILABLE_IOS(8_0) = 3,
} NS_AVAILABLE(10_7, 4_0) __TVOS_PROHIBITED;
白平衡选项
typedef NS_ENUM(NSInteger, AVCaptureWhiteBalanceMode) {
AVCaptureWhiteBalanceModeLocked = 0,
AVCaptureWhiteBalanceModeAutoWhiteBalance = 1,
AVCaptureWhiteBalanceModeContinuousAutoWhiteBalance = 2,
} NS_AVAILABLE(10_7, 4_0) __TVOS_PROHIBITED;
7.距离调整
typedef NS_ENUM(NSInteger, AVCaptureAutoFocusRangeRestriction) {
AVCaptureAutoFocusRangeRestrictionNone = 0,
AVCaptureAutoFocusRangeRestrictionNear = 1,
AVCaptureAutoFocusRangeRestrictionFar = 2,
} NS_AVAILABLE_IOS(7_0);
1.2 获取硬件的输入流
-(AVCaptureDeviceInput *)input{
if (_input == nil) {
_input = [[AVCaptureDeviceInput alloc] initWithDevice:self.device error:nil];
}
return _input;
}
创建输入流的时候，会弹出alert向用户获取相机权限
1.3 需要一个用来协调输入和输出数据的会话，然后把input添加到会话中
-(AVCaptureSession *)session{
if (_session == nil) {
_session = [[AVCaptureSession alloc] init];
if ([_session canAddInput:self.input]) {
[_session addInput:self.input];
}
}
return _session;
}
1.4 然后我们需要一个预览图像的层
-(AVCaptureVideoPreviewLayer *)previewLayer{
if (_previewLayer == nil) {
_previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.session];
_previewLayer.frame = self.view.layer.bounds;
}
return _previewLayer;
}
1.5 最后把previewLayer添加到self.view.layer上
[self.view.layer addSublayer:self.previewLayer];
1.6 找个合适的位置，让session运行起来，比如viewWillAppear
-(void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
[self.session startRunning];
}
搞一个按钮用来控制手电筒
#pragma mark - 手电筒
-(void)openTorch:(UIButton*)button{
button.selected = !button.selected;
Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
if (captureDeviceClass != nil) {
if ([self.device hasTorch] && [self.device hasFlash]){
[self.device lockForConfiguration:nil];
if (button.selected) {
[self.device setTorchMode:AVCaptureTorchModeOn];
} else {
[self.device setTorchMode:AVCaptureTorchModeOff];
}
[self.device unlockForConfiguration];
}
}
}
再搞一个按钮来切换前后置摄像头
pragma mark - 切换前后摄像头
-(void)switchCamera{
NSUInteger cameraCount = [[AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo] count];
if (cameraCount > 1) {
AVCaptureDevice *newCamera = nil;
AVCaptureDeviceInput *newInput = nil;
AVCaptureDevicePosition position = [[self.input device] position];
if (position == AVCaptureDevicePositionFront){
newCamera = [self cameraWithPosition:AVCaptureDevicePositionBack];
}else {
newCamera = [self cameraWithPosition:AVCaptureDevicePositionFront];
}
newInput = [AVCaptureDeviceInput deviceInputWithDevice:newCamera error:nil];
if (newInput != nil) {
[self.session beginConfiguration];
[self.session removeInput:self.input];
if ([self.session canAddInput:newInput]) {
[self.session addInput:newInput];
self.input = newInput;
}else {
[self.session addInput:self.input];
}
[self.session commitConfiguration];
}
}
}
-(AVCaptureDevice *)cameraWithPosition:(AVCaptureDevicePosition)position{
NSArray *devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
for ( AVCaptureDevice *device in devices )
if ( device.position == position ) return device;
return nil;
}
使用AVCaptureStillImageOutput捕获静态图片
4.1 创建一个AVCaptureStillImageOutput对象
-(AVCaptureStillImageOutput *)stillImageOutput{
if (_stillImageOutput == nil) {
_stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
}
return _stillImageOutput;
}
4.2 将stillImageOutput添加到session中
if ([_session canAddOutput:self.stillImageOutput]) {
[_session addOutput:self.stillImageOutput];
}
4.3 搞个拍照按钮，截取静态图片
//AVCaptureStillImageOutput截取静态图片，会有快门声
-(void)screenshot{
AVCaptureConnection * videoConnection = [self.stillImageOutput connectionWithMediaType:AVMediaTypeVideo];
if (!videoConnection) {
NSLog(@"take photo failed!");
return;
}
[self.stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {
if (imageDataSampleBuffer == NULL) {
return;
}
NSData * imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];
UIImage *image = [UIImage imageWithData:imageData];
[self saveImageToPhotoAlbum:image];
}];
}
使用AVCaptureVideoOutput实时获取预览图像
5.1 创建AVCaptureVideoOutput对象
-(AVCaptureVideoDataOutput *)videoDataOutput{
if (_videoDataOutput == nil) {
_videoDataOutput = [[AVCaptureVideoDataOutput alloc] init];
[_videoDataOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
[_videoDataOutput setVideoSettings:[NSDictionary dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA] forKey:(id)kCVPixelBufferPixelFormatTypeKey]];//设置像素格式
}
return _videoDataOutput;
}
5.2 将videoDataOutput添加session中
if ([_session canAddOutput:self.videoDataOutput]) {
[_session addOutput:self.videoDataOutput];
}
5.3 遵守AVCaptureVideoDataOutputSampleBufferDelegate协议，并实现它的代理方法
pragma mark - AVCaptureVideoDataOutputSampleBufferDelegate
#pragma mark - AVCaptureVideoDataOutputSampleBufferDelegate
//AVCaptureVideoDataOutput获取实时图像
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
[connection setVideoOrientation:AVCaptureVideoOrientationPortrait];
largeImage = [self imageFromSampleBuffer:sampleBuffer];
}
5.4 实现imageFromSampleBuffer:方法，将CMSampleBufferRef转为NSImage
//CMSampleBufferRef转NSImage
-(UIImage *)imageFromSampleBuffer:(CMSampleBufferRef)sampleBuffer{
// 为媒体数据设置一个CMSampleBuffer的Core Video图像缓存对象
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
// 锁定pixel buffer的基地址
CVPixelBufferLockBaseAddress(imageBuffer, 0);
// 得到pixel buffer的基地址
void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
// 得到pixel buffer的行字节数
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
// 得到pixel buffer的宽和高
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
// 创建一个依赖于设备的RGB颜色空间
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// 用抽样缓存的数据创建一个位图格式的图形上下文（graphics context）对象
CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
// 根据这个位图context中的像素数据创建一个Quartz image对象
CGImageRef quartzImage = CGBitmapContextCreateImage(context);
// 解锁pixel buffer
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
// 释放context和颜色空间
CGContextRelease(context); CGColorSpaceRelease(colorSpace);
// 用Quartz image创建一个UIImage对象image
UIImage *image = [UIImage imageWithCGImage:quartzImage];
// 释放Quartz image对象
CGImageRelease(quartzImage);
return (image);
}
5.5截取静态图
[_session setSessionPreset:AVCaptureSessionPreset1920x1080];
smallImage = [largeImage imageCompressTargetSize:CGSizeMake(512.0f, 512.0f)];
使用AVCaptureMetadataOutput识别二维码
6.1 创建AVCaptureMetadataOutput对象
-(AVCaptureMetadataOutput *)metadataOutput{
if (_metadataOutput == nil) {
_metadataOutput = [[AVCaptureMetadataOutput alloc]init];
[_metadataOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
//设置扫描区域
_metadataOutput.rectOfInterest = self.view.bounds;
}
return _metadataOutput;
}
6.2 将metadataOutput添加到session中，并且设置扫描类型
if ([_session canAddOutput:self.metadataOutput]) {
[_session addOutput:self.metadataOutput];
//设置扫码格式
self.metadataOutput.metadataObjectTypes = @[
AVMetadataObjectTypeQRCode,
AVMetadataObjectTypeEAN13Code,
AVMetadataObjectTypeEAN8Code,
AVMetadataObjectTypeCode128Code
];
}
6.3 遵守AVCaptureMetadataOutputObjectsDelegate协议，并实现其代理方法
#pragma mark - AVCaptureMetadataOutputObjectsDelegate
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
if (metadataObjects.count>0) {
[self.session stopRunning];
AVMetadataMachineReadableCodeObject *metadataObject = [metadataObjects objectAtIndex :0];
NSLog(@"二维码内容 ： %@",metadataObject.stringValue);
}
}
关于人脸识别
人脸识别也是基于AVCaptureMetadataOutput实现的，跟二维码识别的区别在于，扫描类型：
self.metadataOutput.metadataObjectTypes = @[AVMetadataObjectTypeFace];
#pragma mark - AVCaptureMetadataOutputObjectsDelegate
-(void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection{
if (metadataObjects.count>0) {
[self.session stopRunning];
AVMetadataMachineReadableCodeObject *metadataObject = [metadataObjects objectAtIndex :0];
if (metadataObject.type == AVMetadataObjectTypeFace) {
AVMetadataObject *objec = [self.previewLayer transformedMetadataObjectForMetadataObject:metadataObject];
NSLog(@"%@",objec);
}
}
}
内容根据网文整理，仅供个人学习使用，如有侵权，请联系作者删除。
